HD High Output Alternator

[ChairmanMeow7]

Anyone know where to get a DECENT heavy duty high output alternator ?

I understand the stock one pushes 60 amps and Auto Zone , Advance and Napa all carry the stock one and a HD that pushes 70 amps. 10 extra amps doesn't sound like that big a differance to justify the big price increase I have seen at 1 or 2 stores.

Advance quoted me $88 for the stock 60 amp and $251 for the 70 amp !!!

I did buy a "160" amp oe on E-Bay from a seller who had lots of great feedback. But , after just shy of 2 years and about 10k the alternator is shot already. I ahve had 2 different mechanics "test" it and they came to the same conclusion. One went on to say it is now only pushing 9 amps. What would cause the huge drop in amperage (regulator ???).

Also , it seems that a local guy who rebuilds alternators out of his basement said he could not help with this. His friend who was there with him said he doubted that such a small alternator (as in our Toys) could even be "beefed up" enough to push 160 amps ?

Does this sound right and does it sound like the seller may have "overstated" it's capabilities ?

Also , not so sure I want to deal with the company I bought this from on E-Bay (ace_alternators). I called there twice trying to find out if they stocked replacement parts for a re-build. 1st time the "guy" I needed to talk to was out. 2nd time he "just left" for the PO. The "guy" was supposed to call me back , but never did. Starting to see a pattern here.....I realize that this only had a 1 year warranty , so I am out of luck. I was at least hoping to be able to buy the needed replacement parts for an alternator repair shop to rebuild with.

What do you think , do I really need a alternator over 100 amps , or do you think the 60 or 70 will suffice.

Bear in mind , I just bought a small (1.8 CF) dorm fridge at Wally World that I want to run off an inverter. They said it was a "new" technology , combining the best features of both a compressor driven fridge (ability to get cold) , with the quiteness and low power consuption of the thermo-electric fridge. It has NO compressor and it says it only draws as much power as a 60 watt light bulb (although I think it is "rated" at .95 amps , so the math is off. But maybe this is the startup amperage ?). I know 1.8 CF won't work for some people , but for me and my GF it will work just fine...

All I know is I ran it for a day with 2 cans of soda and a bottle of water in there. Much to my surprise , they were ICY cold. My 2 thermometers read about 36 degrees. I checked it on day 2 and the fridge thermometers were reading about 34 degrees ! Man those soda's were ice cold !!

Just wondering if the smaller alternator will be able to keep my marine (coach) battery charged if I am not plugged in for a day or 2 (but I AM putting some miles on and hopefully getting some charge from the alternator)? I really don't have any plans of staying parked anywhere for more than a day , without either being on shore power (and charging) or driving a bit (and hopefully charging).

I am really itching to take my 1st trip of the season , and it seems like it's been a series of "incidents" which are putting a dent in things. But I guess on the bright side , it's much better I am discovering these things at home , instead of on the road !

Just debating whether to try and find a QUALITY HD althernator somewhere or just go with what they stock so I can be on the road for a weekend get-away.

[Bodybagger]

Anyone know where to get a DECENT heavy duty high output alternator ?

I understand the stock one pushes 60 amps and Auto Zone , Advance and Napa all carry the stock one and a HD that pushes 70 amps. 10 extra amps doesn't sound like that big a differance to justify the big price increase I have seen at 1 or 2 stores.

Advance quoted me $88 for the stock 60 amp and $251 for the 70 amp !!!

I did buy a "160" amp oe on E-Bay from a seller who had lots of great feedback. But , after just shy of 2 years and about 10k the alternator is shot already. I ahve had 2 different mechanics "test" it and they came to the same conclusion. One went on to say it is now only pushing 9 amps. What would cause the huge drop in amperage (regulator ???).

A fully charged battery would cause this. If the charging system were constantly pushing a hundred amps into your battery, it would cook it and boil out the electrolyte. The rating of an alternator is the maximum amperage it can supply under essentially a dead short. It only puts out a large amount of amps if the battery is low or there is a huge demand on the electrical system, such as a large inverter drawing a big load.

The question is this: Does it maintain the ballpark of 14 volts on your electrical system while it's running? Now does it do so under load?

Now, if it doesn't, the problem may not be your alternator. It could be the charging isolator (splitter) that takes the input from your alternator and routes it to the two different batteries. It looks like this: http://www.pplmotorhomes.com/parts/rv-conv...ry-isolator.htm

Bear in mind , I just bought a small (1.8 CF) dorm fridge at Wally World that I want to run off an inverter. They said it was a "new" technology , combining the best features of both a compressor driven fridge (ability to get cold) , with the quiteness and low power consuption of the thermo-electric fridge. It has NO compressor and it says it only draws as much power as a 60 watt light bulb (although I think it is "rated" at .95 amps , so the math is off. But maybe this is the startup amperage ?).

.95A @120V is 114W which is what its using when it is running. So it is assumed to run at a 52% duty cycle to maintain temperature, thus having an average consumption of 60W.

Now an inverter putting out 120 volts with 85% efficiency will require an average of 5.88 amps at 12 volts. Each 24 hour period, you will consume 141 ampere-hours of charge. A good starting point would be to use 2 parallel group 27 deep cycle batteries in your coach. This will provide you with 24 hours of reliable fridge use, with a little reserve and not overly discharging the batteries.

Now recharging them should (in theory) only take 2 1/2 hours of driving with your 60 amp alternator. Of course some of its output will be diverted to running the ignition, instruments, headlights, etc.

Just wondering if the smaller alternator will be able to keep my marine (coach) battery charged if I am not plugged in for a day or 2 (but I AM putting some miles on and hopefully getting some charge from the alternator)? I really don't have any plans of staying parked anywhere for more than a day , without either being on shore power (and charging) or driving a bit (and hopefully charging).

If that's the case, I'd recommend getting a 100W solar battery charging panel and mounting it to the roof.

Just debating whether to try and find a QUALITY HD althernator somewhere or just go with what they stock so I can be on the road for a weekend get-away.

My recommendation is to go stock, but insure that the charging isolator (splitter) is functioning properly. Edited May 22, 2009 by Bodybagger

[ChairmanMeow7]

Bodybagger , you are the best and thanks for all the help with my recent posts and "problems" !!

I certainly owe you a case of your favorite sudsy beverage , and if we ever meet up at like a Toy rally (which I'd like to attend one day) , I will see to it you get it !

Or maybe if I am passing through "your neck of the woods" we could meet up sometime ? Im in CT . and I took a trip to Atlanta last fall when my GF's niece got married. Boy , the little Toy sure came in handy ! I could have swung by then as I think we drove through WV on that trip. Does I-95 go through WV ? I would like to take another trip down South , hopefully this year. Me and my GF also have plans to head out West before gas prices get too high again !

As far as the stock alternator , I think I will take your advice here , as I think the place I bought my old one from on E-Bay either mis-stated it's capacity or it was just not a good quality re-build as it doesn't (APPEAR) to be working after a little less than 2 years and about 10k on the odometer.

Wish I knew this about the alternator only pushing 9 amps as you have mentioned (as maybe the battery was close to being fully charged ?? ) , before I went through the trouble of REMOVING the old alternator last night.

My mechanic who worked on my tranny seals (and fitting) as they were leaking , told me last week it was not charging.

After the tranny was fixed , I took it to an RV shop to have them hook up the new solid state isolator I hooked up for a little while last year. My old (3 post) mechanical isolator stopped working , so I bought a new Vanner 3 post model (model 50-140 , which is supposed to handle the 160 amps ??).

I was having some problems installing this last year. I had some people (both on here , Toyota , Vanner etc) telling me I needed the 4 post solid state model , while others (even the guy who supplied the re-built alternator) INSISTED I needed the 3 post solid state model. Well I finally said I am going to hook it up just as the old one was. With the front and back large posts (labled battery) hooked up to each battery. I took the old , small white wire (ignition wire ????) and put a bigger loop on it so I could connect it to the center post. Well shortly after hooking it up this way and driving , I smelled smoke coming from the coach (which I beleive was unrelated , and caused by a cigarette) but I immediately unhooked the isolator and this was last year. The battery did seemed to be staying charged on numerous trips. I posted on here and folks told me there was only so much could be done online , and I should probably bring it in if I am not certain what I am doing as far as hooking up the isolator.

I brought it to an RV place and the guy was playing around for a good hour and still didn't get it hooked up. He tightened the belt on the alternator , but still seemed to be having trouble finding the wire from the alternator that goes to the center post of the Vanner battery isolator. He tested the alternator and he is the one who tested it and said it was not to specs (that it was only pushing 9 amps). My other mechanic said it was not charging properly either.

Well I did remove it yesterday , so I guess the next step is to have it tested again.

I did see a note on the quote I got from Advance stating "a blown fuse in the ignition circuit may cause a no charge condition. Veri-voltage is present at the ignition terminal of the alternator plug , see tech tip 572 , Test Chart Page # ND"

Also , I found the paperwork that came with the alternator and it included a "technical bulletin". It says "CAUTION -Note to store: "This alternator has a plug which is identical to other plugs which perform differently". "When bench testing , be sure you have selected the correct test plug harness for this regulator type. If the wrong test harness is selected , the alternator will test as bad , even though it is good "

So I guess the next step would be to bring the alternator to one (or preferably 2 or more) auto parts stores ALONG with the "technical bulletin". Maybe it is not bad after all (if so , I just wished I had found the bulletin BEFORE removing the alternator) !!

Sorry for the rambling post. I will try to keep it as short and to the point as possible. But , I am also a FIRM beleiver that when having something "diagnosed" , such as an auto repair or even in a Dr's office that the more information you provide , the better the diagnosis. My current Dr. just loves when I write him a detailed note describibing my "condition" (honestly) !!

[Maineah]

Alternators are voltage regulated not current regulated. The output at max is full voltage to the field. A high output alternator has larger field windings and heavier diodes if the battery is charged it lowers the field current and the amps drop so an unloaded alternator could only be putting out 9 amps even though it is rated 100 amp or more. Generally no one pays much attention to amp output only voltage of an alternator as long as it’s 13.8 there about all is well. The technology has improved dramatically in the last few years and 200 amp alternators are common place usually found on police cars and the likes. I would be skeptical of a 160 amp alternator for an older Toyota. I have no problem keeping 200+ amps of batteries charged with the bone stock alternator with normal driving. If you were running emergency lights, A/C, two way radios etc. you may need 160 amps to keep up but not to recharge your coach batteries. It sounds like the fridge you are talking about is solid state, it uses a device called a Pelletier junction when you power it one side is hot the other cold they work but they are slow to cool and slow to recoup so just be aware of that get what you need out and close it quick. Your original one toes up? Frankly a gas fridge in a motor home can’t be beat.

[WME]

With the alternator removed, take it to a Auto parts place. Most of them can check it.

A tester can dial up a load so it can work the alternator at full output or at a lower rating.

[ChairmanMeow7]

OK , here's where I am at...

1st mechanic said it wasn't charging. 2nd guy at RV store (and repair) told me it wasn't up to specs (and pushing only 9 amps).

I took it out last night. Napa said they couldn't test it , and Auto Zone said they couldn't test it (lack of test plugs). I was able to get it tested at Advance , but all he was able to tell me it was in the "green" as far as voltage output. I asked about checking the amps and he said he had no way to check that. I beleive he also said it would only be putting out full (or higher) amperage under load. Also , I stopped in and talked to the guy who checked it out at the RV store. I said to him I heard that it would only be pushing full amperage if the battery was discharged or it was under load. He disagreed saying he checked it right at the alternator and it should have been pushing what it was rated for. We then got into a discussion about the INTERNAL voltage regulator. He claimed that it was the voltage regulator that would tell the alternator to stop charging if the battery was fully charged (also bear in mind my isolator is NOT hooked up , only the positive wires to each battery , but NOT the wire to the center post from the alternator). And I said , YES , is that why it may have read 9 amps , because the battery was fully charged ? He still insisted it should be reading the full output (amperage wise). HMMmmmm... Anywho he did know my main concern was keeping the coach battery charged because of the power drain from the small electric fridge I want to "test" in there (before deciding if I should permanently mount it in there). He said there was really NO need for a high amperage alternator , as the coach battery (being a marine deep cycle) likes to discharge slowly , but ALSO be charged slowly , so a high output alternator would not really come into play. Does this sound right ?

Now I am beginning to wonder if the alternator is indeed good and the battery bad ??? (I am having the battery tested tommorrow). I mean it tested in the "green" at about 15 volts or so on the bench test at Advance. Now of it is reading 15 volts or so , it doesn't sound like it could be bad now does it ?

And again , I went back and showed EVERYONE about the bulletin that came with the alternator saying it has a similar looking plug that acts differently that some that look exactly the same. I asked my mechanic and the RV store guy if this could have gave the bad reading. They didn't beleive so.

I wonder what is up here ? Can it be test at 15 volts and still be bad (not pushing enough amps) ? If so I am running out of places to have it tested..... Napa , Advance and Auto Zone are 3 of the big ones , but I guess I could try Pep Boys or something. I probably need to have it (bench) tested at a place that can check the amperage (like maybe a custom alternator re-build shop) ???

[Bodybagger]

If your battery isolator is shot, your alternator will not put anything out!

It will "see" a disconnected lead and will shut down voltage to the field.

See http://bluesea.com/viewresource/91 for a pretty good generic description of the system.

This is called overvoltage protection, or open circuit protection, or various other names.

On some alternators, particularly older ones, if the alternator's charging post is disconnected from the electrical system, it will have no load and the voltage will surge wildly out of control and it will instantly fry the rectification diodes.

Think of ohm's law. If the alternator idles at 10 amps and the resistance of the load is changed to infinity (open circuit), then what is the voltage? V=IR or 10 times infinity.

If your isolator is preventing the alternator from seeing battery voltage, it will not operate correctly. Now whether it fries the diodes or shuts down, or simply puts out less power depends on the alternator and what voltage it is seeing.

With the engine running, and the black lead of a DVM connected to the chassis ground of the vehicle, measure the following voltages... They should all be 14V give or take.

Voltage of alternator output (measure at the lug on the alternator being careful not to short it). Make sure this corresponds to the voltage at the charging input lug of the isolator.

Voltage at the engine battery lug of the charging isolator. Make sure this corresponds to the voltage at the engine battery.

Voltage at the coach battery lug of the charging isolator. Make sure this corresponds to the voltage between the + and - terminals at the coach battery.

Measure those and let us know what you find out.

[Maineah]

There were different types of Toyota alternator wiring they changed year to year I can not tell you when they changed but your note is correct they are different. Do your self a favor forget about amps if the voltage is correct the amps will follow. Bad regulator, bad diode, bad field windings, bad stator windings, bad connections, dead indicator bulb, etc all equal low voltage pointing to the alternator. If you have a bad connection to your battery the voltage will be low and perhaps B+ at the alternator will be high. Run a few lights for awhile check the battery voltage then start the engine the voltage should climb and level out around 13.8 volts. When you load a battery the voltage drops the voltage regulator senses battery voltage and adjusts the field current to compensate for the voltage drop across the battery. If it takes a large hit it supplies more current to the field the amps and voltage climb they go hand in hand. Never disconnect the battery to check an alternator output unless you are prepared to replace any thing solid state in your motor home that used to be an old trick with generators years ago I have seen alternators spike in excess of 50 volts. Your motor home is the best test bench that is home to the alternator that is where it does its work.

[ChairmanMeow7]

I think maybe posting a few pics on here will DEFINATELY help !

1st off , I don't beleive my isolator is shot , just not connected ! My old mechanical (3 post) went so I added a Vanner 50-140 solid state one. I seemd to be getting varying opinions no matter who I talked to as to whether my 22-RE motor should be using the 3 post or 4 post model. I got different answers on here , from Toyota (no help was told to call Toyota or place I got alternator) , from Vanner (actually they seemed to be of very little help at all) , and from the guy I bought the HD alternator on E-Bay from. The guy I bought the alternater from seemed CERTAIN I needed the 3 post model , but again , I followed HIS instructions (I beleive) and hooked the solid state one up just as the old mechanical one was hooked up. I added a bigger "loop" to the small white wire that went to the center post of the old isolator (I think this is an ignition wire and doesn't seem to be large enough to charge the battery).

Shortly after this and driving for about 10 minutes , I smelled smoke coming from the coach. Smelled like burned wood (not a plastic smell as in wiring frying). Also , I beleive my GF tossed a butt and we think it may have flown back into the coach !! I told her NEVER , EVER throw a butt out the window !!!! Not only is it littering , but dangerous as it could "fly" back into the coach and from a legal standpoint. I am certain that the cops in some States or Cities would just love to give a ticket to an out-of-stater for littering !! We never did find the source of the smoke , although it seemed to be a bit more concentrated in the cabinet above the sink.

Anywho.... After describing this "condition" on here last fall , I was told to "bring it in" as there was only so much that could be done online. So I did.... My mechanic said he was not all that certain about wiring the isolator and I should bring it to an RV repair place. I did , and the guy spent like an hour (kind of long , wouldn't you say ?) trying to find the wire to hook up to the isolator. He was chaecking voltages at various places and finally checked the alternator and said it was bad. Now why is it he couldn't spot the isolator being unhooked (I even told him it was un-hooked anf that is WHY I was there). He said I need a new alternator as this one was only pushing 9 amps. He still insists it's bad , even after I told him that some of you said it would NOT push out full amps with a fully charged battery. Not to mention the isolator is not even hooked up !!!

So this is my dilema .... I have been TRYING (VERY unsuccessfully) since last fall to get this darn isolator hooked up.

Right now , as it stands , there are 3 wires hooked o the positve post of the battery. One is like a 12 gauge wire that was hooked to the old isolator and is now hooked to the post labled "Battery 1" on the new isolator. The other is (like) an 8 gauge or so wire that goes under the engine block (to the starter ?) and the last one is like a 12 gauge wire that come OUT of the fuse box and to the positive battery post. Now doesn't it sound like the wire coming out of the fuse box MUST be the charging wire ???

I tried unhooking the one to the isolator and (of course) it had no affect and it starts just fine. I tried unhooking the one that leads under the engine block (starter ???) and it will not turn over or even make a sound. When I unhook just the one from the fuse box , I beleive I was getting like a clicking sound when I turned the key.

I can understand why it won't start and it makes no sound when I disconnect the wire that leads under the engine block. This MUST be the starter wire , and I WILL confirm this. So , that would leave the wire coming FROM the fuse box as the ONLY POSSIBLE charging wire , that must end up being connected to the center post of my isolator , correct ????

Another FUNNY thing here. I drove this quite a bit last year with the NO wire connected to the center post of the isolator and had NO problems (other than the obvious , my coach battery NOT being charged as I drive) , so the truck battery has to be getting a charge !!!

Sorry for the long posts and ALL the questions , but this thing is driving me nuts , and it doesn't evn seem as if I can count on a mechanic or an RV repairman to get this darn thing hooked up PROPERLY !!!

Also , seeing the alternator bench tested at 15 volts or so , do you think it is safe to re-install ? I'd hate to install it and have to remove it again. But I certainly don't want to downgrade to a lower capacity alternator (and trade in this HD core) if this is still good........

Will pics help ?????

[ChairmanMeow7]

OK , here's where I am at now.

I went to differant Advance store. They tested alternator on what appears to be a newer machine. Said it was testing at 15 volts , but diode was bad.

I bought a 70 amp HD alternator from them and I am going to install it now. Kinda funny but I bought this at a store about 20 miles from where I had the 1st one tested and they wanted like $114 and I only paid $89 for this one (a $25 differance).

But it seemed like they really wanted to keep the core of the old one , even though I told them I will just pay the core charge and have it re-built , or the diode replaced (as it may be ?). Guy kept insisting it would cost just as much to have the old one rebuilt , but seemed like he really wanted the trade in (I wonder why ???). Anyhow I decided to hang onto the old core to have it tested at an alternator re-build shop. Besides , I really didn't want to give up that beefed up core. It looks like a good thing , as the pulley on the new one is not the same (so I guess I made a good call in not taking the $35 for the core).

After I get this on , maybe I can finally get the isolator hooked up.....

[Maineah]

Pictures maybe be good. You have not had any problems with the truck battery? All of the isolators work pretty much the same some use a exciter post that has to attach to the alternator generally its #1 to the truck battery #2 to the coach and "A" to the alternator it may have a "E" that needs to be connected to the "ign lead of the alternator that is the one that only has power when the key is on in the "run" position. Greg knows the isolators pretty well I'm thinking you need that "e" post for it to work on a Toyota not just 3 heavy wires pm Greg and ask. The alternator B+ lead goes to the truck battery that needs to come off and connect to the #1 post the wire to your coach battery needs to go to your #2 post and a new wire needs to go to the alternator from the isolator "A" post (or what ever the left over post is marked) Be sure to use a heavy enough wire #8 or 6 would be good. I have no ideal where your wiring might go some people are really good at hooking things up in unusual manors. If it goes to the starter it should be hooked to the large battery post. Have a look at this and see if it makes any sense to you www.countryhomescampers.com/pdf/Multibattery_Isolator_Instructions.pdf Disconnecting the isolator wire should not effect the starting of the truck if it's wired properly. As far as the alternator its hard to say from here but I think it's all right.

[Bodybagger]

1st off , I don't beleive my isolator is shot , just not connected !

It's hard to tell if it works until it's connected... See below.

Right now , as it stands , there are 3 wires hooked o the positve post of the battery. One is like a 12 gauge wire that was hooked to the old isolator and is now hooked to the post labled "Battery 1" on the new isolator. The other is (like) an 8 gauge or so wire that goes under the engine block (to the starter ?) and the last one is like a 12 gauge wire that come OUT of the fuse box and to the positive battery post. Now doesn't it sound like the wire coming out of the fuse box MUST be the charging wire ??? .....So , that would leave the wire coming FROM the fuse box as the ONLY POSSIBLE charging wire , that must end up being connected to the center post of my isolator, correct ????

No!

The wire between the battery + post and the fusebox connects your vehicle battery to the positive buss of your fusepanel. This is where your ignition system and ECM etc gets its voltage from.

It's true that the battery is charged through this wire, but the positive buss receives its charging voltage from the alternator.

If you disconnect this wire and attempt to start the vehicle, it will try to pull the starting current from the coach battery, and the voltage drop will be enormous (hench the clicking and not actually starting).

The alternators charging post (in a stock truck) is connected to an 80 amp fuse or breaker in the fusepanel. It is labeled ALT, or CHARGE, or something obvious. See the attached diagrams at the bottom of post.

Another FUNNY thing here. I drove this quite a bit last year with the NO wire connected to the center post of the isolator and had NO problems (other than the obvious , my coach battery NOT being charged as I drive) , so the truck battery has to be getting a charge !!!

Right. That's expected given your current hookup.

Also , seeing the alternator bench tested at 15 volts or so , do you think it is safe to re-install ? I'd hate to install it and have to remove it again. But I certainly don't want to downgrade to a lower capacity alternator (and trade in this HD core) if this is still good........

If it actually charged at 80 or more amps, it would blow the charging fuse. Realistically, can your wiring even handle 80 amps going into the coach for a sustained period of time? You'd need 4 gauge wire for that and I bet you don't have nearly that heavy wire. Besides, they say it has a blown diode. Go stock.

[Maineah]

Bodybagger you are correct the alternator is fused as are several body wires. There is only one power wire to the body fuse from the battery if you loose that fuse nothing will be powered or if you disconnect the the battery lead to the fuse you will get the same results. You still have to add a alternator wire to the isolator and you are talking 960 watts the existing wiring is #8. Realistically you would need a big, fairly dead battery to even take an 80 amp charge and you probably would not have enough voltage to bring the alternator up to full output. The need for a 160 amp alternator is just not there but if he owns it it's worth a try to see if it works a bad diode will reduce the voltage output. He really needs to have a good look at his isolator set up I am fairly certain that he needs the 4 wire isolator to make this work.

[ChairmanMeow7]

Man , not to be a complainer but this is quickly turning into the alternator jon from #e!! .

I could not get the pulley off the one they sold me yesterday. It had a different pully , and was told to do a pulley swap. I said no problem. WRONG ! I took it home and realized the pulley on the new 70 amp alternator had the retaining nut recessed much lower than the original. After fighting with it , breaking my strap wrench I gave up for the evening. I did find and old tool in my tool box that belonged to my Dad. It was a 15/16 offset box wrench and had it ONLY been a 23MM I would have been all set as I could grip both the large retaining nut and the small hex head on top of the shaft to prevent the shaft from spinning.

Anywho , I call Advance and ask if I can borrow or even buy an 23 MM offset. No got. Told to bring in. 1st guy fought with it to remove it with an impact wrench. No luck. 2nd guy was able to get both nuts off with an impact wrench and a rag to hold the pulley. He swapped out the pulleys and I am thinking fine , now I am in bussiness ! WRONG !!! He decides to test it before I leave. I say "great idea". He tests it and says it has a bad diode. HMMMmmmmm A rebuild off the shelf. Bad. OK.... So he substitutes another of the same part #. It tests GOOD ! Do pulley swap. After pulley swap he says "you are not going to beleive this" I say oh yeah ? "Just try me"... This was the same part # they sold me the day before. He points out how the mounting holes are different than the one I brought in off the camper. He checks part #. Says there is no corresponding part # to fit my engine. This was off an '86 Celica....

Finally looks up my engine again and says he only has one 60 amp re-build in stock. I said give it to me. We both agree test may not be bad idea. It tests bad (bad diode) just as 3 of the 4 re-builds we tried did , and the only good one did not fit my vehicle

Now I inform that I had the one out of my vehicle tested at a different Advance store and they said it was GOOD. I said let's test it and if it's good , it's going back in. NOPE !!! Tests bad dioide......

At this point both store employees inform me "I am driving them to drink". I asked the "think of how I feel" ??? I been trying to get this isolator hooked up since last fall. I finally agree with folks on here to break down and bring it in. My mechanic says he is not that good with the isolators , so bring it to RV repair place. But , before I leave (the mechanic) he informs me alternator tests bad. I go to RV repair place. Guy spends an hour checking wires , does not hook up isolator , but also tests and says alternator is bad , it is only pushing 9 amps. Charges me $110 .

Now , all these supposed "bad" alternators DID show to be putting out 15 volts or so on the bench tests. But they all show a bad diode. I got a note with the old alternator stating "test plug looks the same as others but performs differently. If wrong test plug is used , it will test bad , even though it is good". NO ONE I have showed this to at multiple auto parts stores seems to be able to get what they are talking about. They say all I can do is punch in the vehicle , and it gives me a test plug #. Also , ALL the auto parts stores told me they had no way of checking the amperage.......

Now I am really beginning to wonder if my old one was really bad , because why would 3 out of 4 re-builds on the shelf test bad diode as well ??? But why does my mechanic AND the guy at the RV repair place who tested in vehicle say it's bad (maybe bad ground ??). And 1 of the off the shelfs re-build did not show a bad diode , but IT was the wrong alternator.

Anywho , he let me take the 1 alternator that was re-built and fit my engine without paying (just leaving my AAA card). I told him I was heading over to Auto Zone as they were open till 10 . But I guess they closed early tonight , either because of Sunday , Holiday or both.

I want to take both my old one , the new one and 1 or more off of Auto Zone's shelf if neccessary and have them tested BEFORE I install it.

I feel like dinking , screaming , screaming , drinking not neccessarily in that order ! I know one thing , IF (and when) this does get straightened out , I am certainly going to TREAT myself to a MUCH-DESERVED vacation !!!!!!!!

[Bodybagger]

Just curious. Why are you changing the pulley? Does one have a serpentine pulley while the other has a V-groove pulley? Or are they both V-groove with different diameters?

I would not change the pulley diameter.

And my personal 2 cents is that there is something anomylous about how they are testing those alternators. If 3 of 4 alternators were bad right off the shelf, they'd have jumper cables in the impulse buying section at the walmart checkout.

You don't have to be an ASE certified mechanic to work at a discount auto parts store.

My first question is, did the alternators test WITH or WITHOUT the pulley changed?

Also, what is the part number of the 60 amp alternator?

And lastly, do those 2 schematics help you somewhat?

[Gulfstream Greg]

My old (3 post) mechanical isolator stopped working , so I bought a new Vanner 3 post model (model 50-140 , which is supposed to handle the 160 amps ??).

I was having some problems installing this last year. I had some people (both on here , Toyota , Vanner etc) telling me I needed the 4 post solid state model , while others (even the guy who supplied the re-built alternator) INSISTED I needed the 3 post solid state model. Well I finally said I am going to hook it up just as the old one was. With the front and back large posts (labled battery) hooked up to each battery. I took the old , small white wire (ignition wire ????) and put a bigger loop on it so I could connect it to the center post. Well shortly after hooking it up this way and driving , I smelled smoke coming from the coach (which I beleive was unrelated , and caused by a cigarette) but I immediately unhooked the isolator and this was last year. The battery did seemed to be staying charged on numerous trips. I posted on here and folks told me there was only so much could be done online , and I should probably bring it in if I am not certain what I am doing as far as hooking up the isolator.

As far as I know all toyotas need the 4 post isolator. The 4th post is the exciter circuit.

If your battery isolator is shot, your alternator will not put anything out!

Bypass the isolator.

On some alternators, particularly older ones, if the alternator's charging post is disconnected from the electrical system, it will have no load and the voltage will surge wildly out of control and it will instantly fry the rectification diodes.

Think of ohm's law. If the alternator idles at 10 amps and the resistance of the load is changed to infinity (open circuit), then what is the voltage? V=IR or 10 times infinity.

If your isolator is preventing the alternator from seeing battery voltage, it will not operate correctly. Now whether it fries the diodes or shuts down, or simply puts out less power depends on the alternator and what voltage it is seeing.

With the engine running, and the black lead of a DVM connected to the chassis ground of the vehicle, measure the following voltages... They should all be 14V give or take.

Voltage of alternator output (measure at the lug on the alternator being careful not to short it). Make sure this corresponds to the voltage at the charging input lug of the isolator.

Voltage at the engine battery lug of the charging isolator. Make sure this corresponds to the voltage at the engine battery.

Voltage at the coach battery lug of the charging isolator. Make sure this corresponds to the voltage between the + and - terminals at the coach battery.

Measure those and let us know what you find out.

I don't think the rectifiers will fry.

1st off , I don't beleive my isolator is shot , just not connected ! My old mechanical (3 post) went so I added a Vanner 50-140 solid state one. I seemd to be getting varying opinions no matter who I talked to as to whether my 22-RE motor should be using the 3 post or 4 post model.

The isolator is a rectifier circuit. A rectifier is a common name applied to a type of circuit. What you really have are diodes configured into a full bridge rectifier circuit. The alternator has 4 diodes. They are configured with two in one direction and 2 in the opposite direction. In one direction they only allow positive to flow from the alternating current the alternator produces and in the other direction only the negative flows through thus you have direct current positive and negative 12vdc. A no load condition will not blow the diodes in the alternator. Other factors such as a bad diode or short, got too hot and other factors can destroy a diode.

Your isolator is also a diode assembly but its just configured differently. Think of a diode as a one way gate where you can only travel through it but not go back. The way the isolator is set up is to allow positive voltage to travel thorough it but not back, the result is two batteries can be charged but will not draw current from the other. You can test a 3 pole isolator with a ohm meter. Disconnect all the cables from it. Now see if you can get continuity through the center pole to the other two poles. You might have to reverse your leads on the poles to get the current direction correct. There will be a small amount of resistance across each pole (diode) with the leads in one direction and no current flow with the leads reversed. I think the 4 pole exciter type tests the same. The 4th pole actually tells the alternator to produce current, that is the type the toyotas have. Here is a link to the wiring diagram for the 4 pole isolator. http://toyotamotorhomes.com/technicaldocs/WireingDiagram.pdf

[ChairmanMeow7]

Alternator is in. Now Im just hope I can keep the belt tight. I am also a little concerned reading the post about amperage draw and not going with a HD high output (100+ amp) alternator. I guess time will tell.

Now if I can just get the isolator hooked up.

Greag , can you tell me why Toyotas , specifically need the 4 post solid state isolator ? I hate to buy another one if this 3 post model can be made to work. But the guy at the RV repair shop didn't seem to know about whether I needed the 4 post or 3 post model. Actually he didn't seem to be all that concerned whether I had a 3 post or 4 post. I would think , or at least hope , that since they do RV repairs he would have seen both types and realized some vehicles need 1 type and other vehicles the other.

What would happen if the 3 post model was hooked up , with a charging wire from the alternator going to the center charging post of the isolator ? Would it blow up the battery or cause some other sort of serious harm ? Or would it just not charge ???

And why do some vehicles use the 3 post and others a 4 post ? This is a bit confusing.

[Gulfstream Greg]

Alternator is in. Now Im just hope I can keep the belt tight. I am also a little concerned reading the post about amperage draw and not going with a HD high output (100+ amp) alternator. I guess time will tell.

Now if I can just get the isolator hooked up.

Greag , can you tell me why Toyotas , specifically need the 4 post solid state isolator ? I hate to buy another one if this 3 post model can be made to work. But the guy at the RV repair shop didn't seem to know about whether I needed the 4 post or 3 post model. Actually he didn't seem to be all that concerned whether I had a 3 post or 4 post. I would think , or at least hope , that since they do RV repairs he would have seen both types and realized some vehicles need 1 type and other vehicles the other.

What would happen if the 3 post model was hooked up , with a charging wire from the alternator going to the center charging post of the isolator ? Would it blow up the battery or cause some other sort of serious harm ? Or would it just not charge ???

And why do some vehicles use the 3 post and others a 4 post ? This is a bit confusing.

Most of us run the stock alternator with out any worries.

Toyota alternators use an exciter circuit. It tells the alternator to output. Without the wire only the truck battery will have an effect on charging. The exciter circuit monitors pole #2 (coach battery) of the isolator and tells the alternator to output when it senses low voltage on the coach circuit. Its supposed to be connected as close to the alternator as possible to operate correctly. From what I can tell it energizes the internal regulator.

Here is a link for some great testing info.

http://www.autoshop101.com/forms/h8.pdf

[Maineah]

Nice site Greg. I’m not sure but I’m wondering if the coach side is not an SCR and the “IGN” turns on the SCR to allow current flow from the coach battery you have played with the isolators far more then I so I’m just guessing. I know there are several type 2 alternators that require a IGN input to the isolator. What I am thinking is that the alternator “S” (sense) terminal would only see voltage from the truck battery and think all is well so the only battery it would charge would be the truck battery. This thread has really got me thinking my batteries are still isolated with a plain old relay and I have done some research into battery combiners or ACR’s (automatic charging relay) they would be a direct replacement for the stock relay with out any wiring chances. They are voltage sensing and have no break over voltage loss sounds like a real winner. Here is one manufacture http://bluesea.com/category/2/productline/overview/386 they are not cheap but not far off the isolator price.

[Gulfstream Greg]

Nice site Greg. I'm not sure but I'm wondering if the coach side is not an SCR and the "IGN" turns on the SCR to allow current flow from the coach battery you have played with the isolators far more then I so I'm just guessing. I know there are several type 2 alternators that require a IGN input to the isolator. What I am thinking is that the alternator "S" (sense) terminal would only see voltage from the truck battery and think all is well so the only battery it would charge would be the truck battery. This thread has really got me thinking my batteries are still isolated with a plain old relay and I have done some research into battery combiners or ACR's (automatic charging relay) they would be a direct replacement for the stock relay with out any wiring chances. They are voltage sensing and have no break over voltage loss sounds like a real winner. Here is one manufacture http://bluesea.com/category/2/productline/overview/386 they are not cheap but not far off the isolator price.

You might be right about it opening the scr. For those who are asking "What the oooo is a SCR" its a diode. SCR is short for "Silicon Controlled Rectifier". Its a diode with 3 connections. The SCR is controllable in that like a switch it can be turned on or off (open or closed).

Any how it makes sense. In the Sunrader I had a voltmeter in the cab and a switch so that I could monitor the starting or coach battery and I could see that the coach battery would be getting a different charge rate than the starting battery. I do remember reading somewhere that both sides of the isolator (diodes) are SCR's so I don't think the 4th pole is specific to the coach battery pole. I have searched all over the net and can't find the answer as to how these actually work. It would be nice to know and would clear up a ton of questions.

[Gulfstream Greg]

OK, I emailed Surepower the makers of my isolator and got this reply.

The E terminal is not used to turn on the isolator but to send a signal to the output bolt of the alternator to get the alternator to start up and charge. The internal regulator of the alternator needs to have battery voltage come back into itself to get it up to start charging. The E terminal is just a 25 amp diode in the reverse direction. anode is the E terminal, and cathode is attached to the A terminal of the isolator.

So there we have it. I guess the battery gets its charge because the low voltage state of the battery creates a load on the circuit and the alternator supplies current until the battery evens itself (voltage state) with the regulator. The E terminal is connected to the A terminal or coach side of the isolator. For the isolator to operate correctly the coach circuit needs to be connected to the A terminal and the truck starting battery to the B terminal. Seems though that when the coach battery is connected, the e terminal is always hot even with the ignition off. So the ignition wire supplies voltage to the regulator for the starting battery and the A E terminal of the isolator supplies voltage to the regulator from the coach battery.

[Maineah]

OK now I get it. The "A" terminal has no battery input because both batteries are isolated from the "A" terminal so when you turn the key on the "E" terminal and the regulator "ign" are both powered, the "E" terminal supplies the B+ to the "A" terminal through the diode. Yes the type 2 alternators have to have B+ voltage at their output in order to work so once it starts to charge the "E" terminal is blocked by the diode and the output goes to 1 and 2. So actually it would not matter weather the coach was connected to the 1 or 2 terminal as long as voltage is supplied to the "A" terminal by the key switch via the "E" terminal. OK so with a simple add on diode a 3 post isolator would work you would just need to put it between the "ign" alternator wire and the "A" terminal anode to "ign and cathode to "A" could actually be added right at the alternator.