Deep cycle batt. won't charge

[TexasToy]

My deep cycle batt. won't charge.When I use a test light on the positive cable coming from the truck batt.going to the deep cycle, I have a light,but it is weak.Does anyone know what this could be?Thanks John

[WME]

Isolater, especially if it looks like a Ford starter solenoid.

[TexasToy]

I replaced the isolater with a ford solenoid,The auto parts said it would be the same.Any other suggestions?.

[motoyhomme]

Try a solid state isolator.

[WME]

I replaced the isolater with a ford solenoid,The auto parts said it would be the same.Any other suggestions?.

The Ford starter solenoid is NOT a correct sub. It is not rated for continous duty.

You will need a volt meter not just a test light. Start at the alternator side of the isolator and check voltage with the engine running, check v on the engine battery. Check v on the isolator that feeds the house battery. Check v on the house battery they should all be over 14v with the engine running.

If the v coming from the isolator is good and the v at the battery is bad then you have a bad battery or bad wiring.

[TexasToy]

Thanks for the info.I will try that and let you know what I found.

[ChairmanMeow7]

My coach battery won't charge from the alternator. It will charge from shore power.

Sounds like I need a battery isolator ?

Mine has 3 posts , with 2 large black wires on it and 1 small white wire. What does the white wire go to ? And , are the large black wires positive (even though they are black) ?

I do need to try and clean up the posts/nuts as they are a bit rusty. Hopefully that will solve the problem , but I'm not counting on it.

Also , there is a wire from the battery , that leads to a small relay , which I beleive has a wire that leads to something with fins on it , which leads to the isolator (does this sound right ??).

What is the small relay and what does it do ?

And what is the thingy with the fins on it (and what does it do) ?

I see some isolators for sale that have 4 posts instead of 3. Are these interchangeable (and what does the 4th post/wire go to) , or do I have to stay with the 3 post isolator if I need to replace it ?

Sorry I can't be more precise , but the camper is not here right now.

If necessary , I will post a pic.

Thanks again , and what a great site !!

[WME]

Yes several pictures would be good

Not sure but from your discription it sound like you have two isolators

[TexasToy]

My coach battery won't charge from the alternator, or from shore power.

Do I need a battery isolator ?Or is the isolator just needed when i'ts not charging from the alternator?I have not used a volt meter yet thats next.

[Gulfstream Greg]

Isolator 101 (quick). There are two types of isolators. The originals are a mechanical solenoid which is activated when the ignition is on. When activated it connects the coach battery to the starting battery in parallel with a direct connection to the alternator. The other type is the solid state diode switching isolator. It is not a mechanical switch. When the coach or starting battery needs a charge this solid state isolator directs current only to that battery. Here is the main difference - advantage. The mechanical isolator directs charge to both batteries and can result in one battery being overcharged. In the same sense because one battery may be charged more than the other, the lesser charged battery might not get a full charge. The solid state isolator only directs the charge to the battery that needs it. Also the mechanical type are prone to partial failures. Corrosion (carbon from arcing) builds up on its internal contacts which causes a high resistance and results in less charge to the battery. They can also fail completely. The solid state ones rarely fail.

Testing on both needs to be done with a good voltmeter preferably digital.

Testing the mechanical one: The mechanical one has two large poles and one small. One large pole is from the alternator, the other goes to the coach battery. The small pole goes to the ignition switch, it engages the relay when the engine is running. The key here is to test the voltage on each pole with the engine running. The two large poles should have close to the same voltage, a small voltage drop is acceptable. The small pole should have 12 or so volts with the key on and nothing with it off. If the voltages on both large poles are largely different, IE the coach side is lower, then the mechanical isolator has bad internal contacts. With the engine off the voltage on the two large poles should be close to what the voltage is on each battery, There can be a slight voltage drop due to wire length. If it is not like say the coach side is considerably lower than the battery then something is wrong with the circuit from the isolator to the coach battery. The same holds true for the alternator side.

Testing the solid state: This is a bit different. In this system both the starting and coach batteries are not directly connected to the alternator. The alternator wire has been severed and redirected to the isolator and then the batteries connect directly to the isolator. When the engine is running the alternator terminal will have a high voltage and which ever battery needs a charge will also have a high voltage. The small terminal connects the the ignition circuit at the alternator.

I have put a link for the solid state schematic below. Hope this helps with the trouble shooting. The solid state really is the best type to have.

http://www.toyotamotorhomes.com/technicald...eingDiagram.pdf

[ChairmanMeow7]

On mine there is a small 12V 40amp relay that leads to the isolator.

I checked the voltage to the isolator withn the engine running. I found NO voltage on the post that leads from the positive side of the battery (although there WAS 12 volts or so on the loop connector).

I assume the relay is bad as the posts are quite rusty and corroded. I tried soaking them with WD-40 to get the nuts off the posts , but I broke the relay in the process.

What exactly does this relay do ? Does it limit the voltage or amperage going to the isolator ?

I think I may need to clean up the posts on the isolator as well (after REALLY soaking them in WD-40). Hopefully they will break loose after this , or else I will probably just try to clean them up best I can with the wires connected (as I don't want to ruin the isolator !!).

I wonder if giving them a coating of dialectric grease would help (and help prevent further corrosion and PREVENT the new relay posts from corroding) ?

[Lance Andrus]

Where exactly is the isolater? Since everyone describes it as similar to a Ford selonoid I have an idea what it should look like. I have an '86 so would that have the mechanical or solid state isolater?

[motoyhomme]

On mine there is a small 12V 40amp relay that leads to the isolator.

I checked the voltage to the isolator withn the engine running. I found NO voltage on the post that leads from the positive side of the battery (although there WAS 12 volts or so on the loop connector).

I assume the relay is bad as the posts are quite rusty and corroded. I tried soaking them with WD-40 to get the nuts off the posts , but I broke the relay in the process.

What exactly does this relay do ? Does it limit the voltage or amperage going to the isolator ?

I think I may need to clean up the posts on the isolator as well (after REALLY soaking them in WD-40). Hopefully they will break loose after this , or else I will probably just try to clean them up best I can with the wires connected (as I don't want to ruin the isolator !!).

I wonder if giving them a coating of dialectric grease would help (and help prevent further corrosion and PREVENT the new relay posts from corroding) ?

I believe what you are desribing as a relay is actually a 40A automotive in-line circuit breaker, at least that is what I have on mine. Available at most auto stores. Also my isolator connections are quite rusty but since my isolator is working, I'm not touching them because they are probably tight and shiny under the nuts at the actual connections.

Allen

[motoyhomme]

Where exactly is the isolater? Since everyone describes it as similar to a Ford selonoid I have an idea what it should look like. I have an '86 so would that have the mechanical or solid state isolater?

The isolator is usually located under the hood on the driver's side fender. You may have either one. It was the motorhome manufacturer's choice and they usually opted for less expensive which would be mechanical. The solid state is an aluminum box usually about 3X4X1 that is finned with 3 or 4 posts on it.

Allen

[Maineah]

Good diagram Greg. There is merit to both types of isolators as Greg said the solid state one does a better job of charging the batteries both types work. The relay type does give you the benefit of connecting all of the batteries together this maybe a good thing if you are in the middle of no where with a weak one. When you turn your key on it closes the isolator relay and connects every thing together (that way you do not end up with a dead truck battery). This is the ford starter looking thing it’s not a starter relay it is continues duty if you replace it with a starter relay it will cook in short order. It is directly connected to the truck battery on one side and the coach batteries on the other. When the key is turned on the relay closes and power flows between all the batteries it’s about a simple as it gets and probably what all the Toyota motor homes were fitted with new.

[Lance Andrus]

I know exactly where it is located. I'll check it out when I get home, I also ordered a solar battery maintainer so that the battery can stay fully charged.

[ChairmanMeow7]

What's the differance between the 3 post and 4 post solid state isolators (and what is the "exciter") ?

I had the old mechanical style with 2 large posts and 1 small post on my 1986 Winnie.

I just purchased a solid state one with 3 posts. The 3 posts are marked battery 1 , battery 2 and alternator.

I'm not sure what wire to tap into to hook to the alternator post. I ASSUME I shouldn't connect the small white wire that was on the small post of my old mechanical isolator to the alternator post , CORRECT ? (If so , do I just cut this wire off and tape it up ??)

And , if I do need to tap into a wire from the wiring harness on the alternator , what color is it (I don't see any of them marked , as in the schematic). Also , what gauge wire should be used if I DO need to tap into a wire from the alternator.

Also , I did briefly (I know , I probably SHOULDN'T have done this without thoroughly reading this post 1st) connect the white wire from the small post of the old isolator to the alternator post on my new solid state isolator. It DID show about 14-15 volts on both battery posts of the new isolator.

Will I damage the isolator if I run it like this , or does it sound like it should be OK , since both battery posts are showing about 14-15 volts (that's WITHOUT the loop connectors attached to the isolator that hook up to either battery) with the engine running ??

[turtle]

Read this....

http://www.pplmotorhomes.com/parts/rv-conv...ry-isolator.pdf

The type used on newer Toyotas is down a ways on page 3

[ChairmanMeow7]

Thanks moosepucky !

From what I can gather , it appears that since I have an 86 Toyota , I will need an isolator with a 4th terminal for excitation, correct ?

I wish I had known this (and came on here and asked) BEFORE I got the solid state isolator with 3 posts. I figured since the old mechanical one had 3 posts , then the new solid state one should have 3 posts as well.

I am reading that correctly about NEEDING one with a 4th post for excitation , correct ????

(Please forgive me if I sound repititious , but I get a bit confused at times).

[turtle]

Yup.....

I figured I would let you read it rather than hear it from me....

Now my 1981 diesel is old enough that it uses a 3 post. I am not sure what the cut off year was on these.

To be on the safe side I would call your Toyota dealer and give them the low down on which alternator you have and hear it from someone who knows.

If the dealer does not know call the manufacture of the isolator and give them your alternator info. They WILL know for sure.....

[futar]

It looks like you have a Winnebago. They have a few thermal overload breakers in the coach battery compartment. You may want to check them out. The terminals get rusted and the points on the bi-metallic strips inside get worn or get tits on them. Read the resistance between the terminals. It should only be a few ohms. You can buy them in any auto parts store.

[ChairmanMeow7]

I have a 1986 Winnbago with the 22-RE engine.

According to that article on isolators , when upgrading to a solid state isolator , I would need the 4 post solid state isolator. Both the Toyota dealer and the person (company that rebuilds alternators) I bought my re-built alternator from told me it is internally regulated.

BUT , when I asked the Toyota dealer if I should be using a 3 or 4 post model they said they were not sure and I should contact an RV center for more advice.

I did contact the person who sold me the rebuilt alternator and he told me that I needed the 3 post model solid state isolator (when upgrading from a mechanical one). I asked if he was sure and he ASSURED me he was.

I asked him if the white wire that was on the center post of the old mechanical isolator was the one to connect to the center post of the new 3 post solid state isolator. He ASSURED me this WAS the wire from the alternator , as he said that all Toyota alternators used a white wire (for this).

Now here's where it get's a little crazy. I KNOW I should have done some more homework and contacted Vanner (the manufacturer of my isolator) and CONFIRMED that I needed the 3 post model.

But , seeing how I had already purchased , and then installed (but DIDN'T hook up the wires) the 3 post isolator BEFORE I read this article about isolators , I figured well , the guy who sold me the alternator sounds quite certain of himself , so why not hook it up and give it a try.

I did , started the vehicle and was reading about 14 or so volts on BOTH posts leading to the batteries. So I figure all is well.

I start driving down the road and I get about 10 mins from home and I smell the smell of burning wood inside my MH !!

I pull over and open the back of the coach and see some smoke !!!

I can't locate the source for the life of me. I open the cupboards and I see smoke coming out from some of them ( I ESPECIALLY notice it in the cupboard above the sink).

I open a couple of the windows and vents , and try FRANTICALLY to locate the source , to no avail.

I open the hood , feel the isolator , the wires coming from it , the battery (under the hood) and none of them feels unusually warm.

So I rush back to the coach and to my relief the smoke seems to be dissapating slowly but surely (as I was getting about ready to call 911).

I spent about 15 mins trying to laocate the source of the smoke , or look for a burned spot in all the access doors , under th coach , but couldn't find a thing.

So I disconnect the isolator and slowly drive down the road , keeping my nose open for the slightest hint of the smoke smell. I thought I smelled it again , but when I stopped again , I saw no more smoke in the coach , so maybe it was just a lingering smell.

After about 10 mins I started up again and AS SOON as I started , both me and my GF swore we smelled it again. But , I left the engine idling , and a little while after I started up we no longer smelled it.

I CAUTIOUSLY went to Home Depot and bought an extra fire extinguisher and smoke/co alarm which I had been planning on installing anyways. I installed this as soon as I got out of the store.

So I asked GF if she wanted to try and continue on our 100 mile or so journey we had planned or heading back home (as we we only about 15 mins away). After much debate we decided to press forward EVER so CAUTIOUSLY.

Needless to say , we had NO more problems on our 100 mile (one way) excursion and back. But that was after I disconnected all the wires from the isolator.

There is another (at least one I know of) possible source of the smoke. I was smoking (and yes , I am quitting VERY soon , hopefully for GOOD this time) , and I went to flick the ash off my butt out the window. The butt got away from me and out of the corner of my eye I seen it go flying up in the air and I could NOT tell for sure if it had blown back into the cab and possibly into the coach.

But , try as I may I saw NO burned spots anywhere in , under or on the MH. But we both swore we smelled the distict smell of burning wood.......

This has truly got me puzzled , becuase if it were due to the isolator shouldn't I have blown a fuse or tripped a breaker ? And wouldn't I be smelling burned plastic (either in addition to or in place of) the burned wood smell ????

This has me puzzled , but I DO plan on contact Vanner (the isolator manufacturer) to find out which one THEY reccomend.

And , I realize something MUST be wired wrong , as the engine battery seems to continue to hold a charge despte it NOT being hooked up to the isolator (which tells me it has to be hooked to the alternator some how).

And I know when hooking up the isolator you are supposed to disconnect the wire from the alternator to the battery. But I can NOT seem to locate this wire.

All I see coming from the positive post is a large wire that goes into the breaker box (and I realize this must be to power everthing in the engine and cab) and a smaller wire that I had hooked up to the #1 battery terminal of the isolator. This is the same wire that went to one of the large posts on my old 3 post mechanical isolator.

I realize something is wrong here. Can someone help point me in the right direction or give me an idea of where they think that burnt wood smell (and smoke can from) ?????

[turtle]

The problem may be related to the isolator or it may be completely unrelated and only a coincidence that you just changed isolators.

First thing you need to do is find the source of the fire.

BEFORE YOU DO ANYTHING DISCONNECT BOTH BATTERIES to avoid getting zapped or starting another electric fire.

I would suggest that you start at the DC distribution panel and follow the wires until you find the one that is burned. One will obviously be burned if the source of the problem was electric. Wires run under the false bottoms of the upper cabinets so you will need to remove the interior cabinet bottoms to view the wires (cabinet interior bottoms are held in with very small brads or stables and the wood panel can be pried out easily). It is easier to remove the cabinet interior bottoms then to disconnect the lights under the cabinets and remove the exterior bottoms. It did sound to me like you said the smoke was coming from an upper cabinet.

You do need to contact the manufacturer of the isolator and get the scoop from them on what you need to use, regardless of whether the problem was with the isolator or something else.

You will not know the cause until you find the source.

[ChairmanMeow7]

I contacted Vanner , the maker of my isolator and they didn't seem to be of much help. When I spoke to someone from "tech support" they didn't seem to sure of which isolator I should be using.

They told me to contact Toyota , which I already did , and Toyota told me to contact the manufacturer of the isolator.

Big run-around here.

At Vanner they DID say that if the people who rebuilt my alternator told me I need the 3 post model , then it must be so ( Hmmmm , a lot of help there).

I realize that the center post of the isolator should be hooked up to the alternator , but the only wire I see coming from the positive post is a large (4 gauge ??) wire to the fuse/breaker box and the old (12 guage ??) wire that went to one of the large posts on my old mechanical isolator. I really don't see a wire leading back to the alternator , but there HAS to be one connected , because I can run the engine without running down the battery (even though I am NOT connected to the isolator at this point , and I just have those wires taped up).

The tech support from Vanner said it did NOT sound as if the wires to and from the isolator were heavy enough to carry the current.

I guess I am going to have to take this in to either an RV shop or a place that specializes in automotive electronics.

Or should I be taking some pics to post on here so someone might point me in the right direction ?

[turtle]

You can only go so far with internet help and there comes a time when someone needs to look at your problem physically to attach some instruments and hands on trouble shoot.

If your alt has been replaced/rebuilt you would be better off going to a place that specializes in automotive charging repair and let them see what is up.

I know that my 1981 uses a 3 post isolator but it is a diesel and the alternator is specific to that engine (the alternator drives a vacuum pump off of the alternator rear shaft for power brakes and other vacuum needs) and my 1991 V6 sunrader uses a 4 post isolator.

When you start talking about potential fires you need to get the unit to someone who can repair it properly.