18' Minicruiser Alternator

[HuckMiniCruiser]

My 1981 Mini Cruiser won't hold a charge. I think the alternator may not be big enough to push both the engine battery and the house battery. What kind of alternator are you guys running in your rigs to charge both batteries?

[linda s]

Have you had your alternator tested. Most auto parts stores will do it for nothing. Need to test batteries if the alternator is OK. Most of us run stock alternators and have no problem charging. You do say not holding a charge. That is always battery unless you have a drain somewhere.

Linda S

[zero]

Size is not the issue. Early trucks have 45 amp alternators with external regulators -like my 1978 Toyota Chinook first came with. Later trucks - like my 1988 Toyota Minicruiser came with 60 amp alternators with internal regulators. Either are fine for dual, or even three or four batteries when working right. Where are you checking for charge voltage? You should first check at the alternator output-post or the alternator-post on the isolator.

You say "charge" voltage won't go above 12.8 volts? That is not "charge" voltage at all. A fully charged battery will be 12.7 to 12.9 volts. An alternator must make enough current to reach above 13 volts and usually 14 volts. So a reading of 12.8 volts may indicate no charge at all. Not unless you've got some stone-dead batteries. One easy check is do this. Go to the battery isolator under the hood. It has three posts (or maybe 4). One has the main charge wire from the alternator hooked to it. Two other posts will have wires going to the batteries - one to the cranking battery and one to the house battery. Check voltage AT the alternator post. If it now reads 13.8 - 14.2 volts (approx) the problem is the isolator. If still 12.8 volts - you've likely got an alternator problem or a regulator problem.

[zero]

All depends on the brand of isolator but it sounds correct as far as hookup goes. When the engine is off - the output post on the alternator should be whatever battery voltage is. 12.7 volts is fully charged. 12.1 volts is stone dead. Should read the same at either end . Alternator post or post it hooks to on the isolator. When you start the engine - voltage should come right up over 13 volts. If an isolator goes bad - the alternator post loses connection with the other two battery posts. When it works right power only flows one direction. From the alternator post to the battery posts but cannot flow backwards. So a continuity check (with all battery cables unhooked) should show continuity in one direction, and none in the other.

[Maineah]

What won't hold a charge the truck the coach or both? Regardless the alternator is sufficient to charge both.

[5Toyota]

first thing I would check is the batteries and just because the battery is new or almost new does not mean it is good. not long ago I bought a new starting battery which failed in just a few months. it was replaced at no cost to me .

[zero]

You say your alternator looks like the first photo here labeled "1981 Sunrader." You also said it is an alternator from a 1979 Dodge pickup.

It is NOT from a Dodge. A Dodge in 1979 uses either a Chrysler alternator or a Leece-Neville (now Prestolite). None look anything like in the photo you posted.

The picture you posted is a General Motors AC Delco alternator. Either a DN or an SI model. Both use metal fans. If it's a DN it will have an electric plug in the back and uses an external regulator. If it is an SI - it will have a plug on top somewhere and uses an internal regulator.

The original alternator is a NipposDenso and looks nothing like you have.

Note that if you DO find a harness plug on top somewhere - and it is an SI series with an internal regualtor - someone might of converted it to a "one wire" hookup with an aftermarket self-exciting regulator. Usually when that is done - a rubber plug is stuck into the harness-plug hole in top.

[zero]

Going by the new photo you took of the alternator in your Sunrader - it is a Delco 10SI. Has an internal regulator. It appears is is using GM-style OEM "three wire" hookup. It must get exciter current to get charging. I labeled your photo with #1, #2, #3, and #4. #1 is the small terminal on top left that MUST get excite current when you turn the ignition key "on." If hooked to the ignition circuit from your ignition switch - and there is no "idiot" light hooked in series - you have to stick a 5 or 10 amp diode in the circuit. If you do not - the alternator will back-feed to the ignition and you may not be able to shut the engine off. There are other ways to do it. An exciter relay can be used. Or you can hook the exciter wire to the ACC terminal of the ignition switch. This way when the IGN is on - ACC sends power to the alternator. When the key is "off" - ACC and IGN are isloated from each other an no problem. But using a $2 diode is easier.

So, again . .

#1 gets switched positive power and must have a diode or a resistor wired in.

#2 gets 12 volt power ALL the time and you can cheat and just hook it to the big output terminal #3 if you want

#3 is the charge output terminal and goes to the battery positive post.

#4 is a regulator bypass/test port. If the alternator won't charge - you can stick a nail in there and bypass the regulator to see if the rest of the alternator works.

I'm trying not make things too complicated. But just in case you want to know why #2 can get hooked to #3 and wonder why it is even there? It is a battery voltage sensing wire and normally runs all the way to the battery post instead of taking a short-cut and going to the output terminal. The reason being that the voltage is always slightly different at the battery. Might just be 1/10th of a volt but still different.

[linda s]

JD what photo. I see no photos except for the ones you posted and no new pics in the photo section.

Linda S

[zero]

They must of gotten lost in cyber-space. I'll try again. The one labeled "81 Sunrader" was a photo taken by the poster/owner here. It is a Delco 10SI. I stuck the #s on it. #1 for switched-field power, #2 for full-time battery power, #3 for full-time battery power/output, and #4 for regulator testing.

I included the Denso photos just to show him what was in there OEM before someone swapped in that Delco.

[zero]

Hey - I just went back and looked. My first post is there with all the photos. At least it is on my screen. Shows it was posted a day ago at 9:05 AM.

[linda s]

Yes you posted pictures. The person who started this thread didn't. He never said his alternator was from a Dodge. Whose question are you answering here.

Linda S

[zero]

His questions (the incipient poster here who has the Sunrader). The confusion lies in the fact that he's been posting here and to me directly with private messages. So some facts from him are here and others are in what he sent to me directly. Seems he had the alternator checked and was told it's OK and it is listed for a 1979 Dodge truck (which is wrong).

1979 GM product yes as well as many other years. It was used from approx. 1969 to 1983 in all sorts of GM cars and trucks. He also sent me a photo of it which I reposted here. It is easy to identify as a 10SI instead of a 12SI or a DN series because it has a metal fan and harness-plug on top.

[linda s]

There is no poster on this thread who owns a Sunrader except for me. If someone is sending you messages privately please keep it that way. Your responding to a conversation we have no knowledge of is confusing and not permitted as of now.

Linda S

[zero]

Good grief !! I got 81 Sunrader and 81 Minicrusier mixed up somewhere in my head. I guess I committed a huge crime here? The photo of the Delco alternator I posted here is indeed from the person who started this post (HuckMiniCruiser). The info I posted is 100% relevant to his problem and questions. Linda - I think you've either lost touch of the reason why some people use this forums. I.e., gleaning information. Seems you've got some sort of anger issues? I took the time to review the guy's questions and give him useful answers. Yes, he did post here and in private - a mix of both. So what? Was there anything indecent about what I posted here? I tried to give some context when I replied here to ALL his questions - asked here and in PM. But yes - I am guilty of the egregious act of mixing up "Sunrader" with "Minicruiser." Maybe now I need to go to confession and say three Hail Marys?

[linda s]

I repeat for the last time. If you guys want to have a private conversation keep it there.

Linda

[zero]

Here. Is this "public" enough for you Linda? The info I already posted could be useful to anyone here with a similar problem. Why it upsets you so escapes me. Doesn't the person who initiated this post get any say on what is allowed and not allowed (assuming nothing lewd or political is posted) ?

Whoever it is that "owns" this forum ought to be glad that people take the time to help others when possible instead of of getting their collective "shorts in a knot"

HUCKMINICRUISER: I picked up an 81 Mini Cruiser 18'. The rig came with a "new alternator" but its not charging the engine battery more than 12.8. I think mine may not be big enough to push both the "house" battery and the engine battery?

JDEMARIS: Size is not the issue. Early trucks have 45 amp alternators with external regualtors -like my 1978 Toyota Chinook. Later trucks - like my 1988 Toyota Minicruiser came with 60 amp alternators with internal regulators. Either are fine for dual, or even three batteries when working right. Where are you checking for charge voltage? You should first check at the alternator output-post or the alternator-post on the isolator.

HUCKMINICRUISER: I was checking at the battery, that's where it was registering 11.84 this morning. When I checked at the alternator it was only spitting off 1.6 or so. The isolator box was all over the place though. It would spike up to 15 then go down 3 and any where in-between. Would that be a bad isolator box? Also, I have the alternator going into the middle post then front battery on the left and house battery on the right. Does that sound right? This rig came with no manual.

JDEMARIS: All depends on the brand of isolator but it sounds correct. When the engine is off - the output post on the alternator should be whatever battery voltage is. 12.7 volts is fully charged. 12.1 volts is stone dead. Should read the same at either end . Alternator post or post it hooks to on the isolator. When you start the engine - voltage should come right up over 13 volts. If an isolator goes bad - the alternator post loses connection with the other two battery posts. When it works right power only flows one direction. From the alternator post to the battery posts but cannot flow backwards. So a continuity check (with all battery cables unhooked) should show continuity in one direction, and none in the other.

HUCKMINICRUISER: I've come to the conclusion that my alternator was not working. Just picked up a new one, (Autozone took my old one back because it was under warranty), so I'm going to drop that in today and see how it works. Thanks for the help! I'll keep you posted.

So the alternator is working, according to Autozone, so I've come to the conclusion its not fielded correctly. How is your’s fielded in your mini Cruiser? If got it running to the same wire the carb and the distribution cap is running to (assuming its the ignition switch). It worked for a bit then quit on me... Any ideas?

JDEMARIS: I'm assuming you have the 45 amp alternator that uses an external regulator. It is that regulator that sends field current to the alternator.

HUCKMINICRUISER: For some reason I'm running a 79 Dodge 1/2 ton pick up alternator. That's what the guy before me had in it. What would the external regulator look like/where would it be?

JDEMARIS: A 1979 Dodge does not use an alternator anything like in that photo. The photo is of a Delco from a GM (Chevy, GMC, etc.). A 1979 Dodge would have a Chrysler alternator with an external regulator. A 1979 Chevy would have a Delco 10SI alternator with an internal regulator. The Delco alternators look the same from the front so I can't tell what model the photo is. If the electric plug goes into the top vertically - it is a DN series with an external regulator. If the plug goes in the back it is an SI series with an internal regulator. On second thought - I had things backwards. A Delco DN has the plug that goes into the back and that uses an external regulator. If the plug goes in the top it uses an internal regulator. The photo you posted looks like a DN since I see no plug on top but I can't see the back. Here is what the back of a Delco DN looks like with the external regulator plug.

HUCKMINICRUISER: The picture from my phone was to big but here's a link to it. Let me know if it doesn't work
https://www.dropbox....090718.jpg?dl=0

JDEMARIS: That is a Delco 10Si with GM-style OEM "three wire" hookup. It must get exciter current to get charging. I labeled your photo with #1, #2, #3, and #4. #1 is the small terminal on top left that MUST get excite current when you turn the ignition key "on." If hooked to the ignition circuit from your ignition switch - and there is no "idiot" light hooked in series - you have to stick a 5 or 10 amp diode in the circuit. If you do not - the alternator will backfeed to the ignition and you may not be able to shut the engine off.

[HuckMiniCruiser]

Hey Linda, Sorry our convo got mixed up from private to forum format. JD was extremely helpful and now has my problem solved. I was not fielding the alternator right and he went as far as to label a picture of my alternator for me and direct me where to wire it to. I'm new to this forum stuff and even more new to the mechanical wonders of these little joy machines we all love so much. Sorry for the confusion but JD was just trying to help and he accomplished it in a big way saving me from having to take my rig to a mechanic and spend some serious $$$. Thanks for hosting this site it has a ton of super helpful answers!

[Derek up North]

Welcome to the (sometimes dysfunctional) family.

[linda s]

Yes JD I agree the information could be useful to someone but only in context. Until I pressed for an answer as to what you were talking about it sounded like you were having mental issues suddenly talking about Dodge and GM alternators when none had been mentioned previously. Glad you could help the poster but a simple answer to my original question would have much more effective than all your raving

Linda S

[zero]

Hey Linda . . I was responding to the person who began this thread. He knew, all along, exactly what I was talking about. And I'm raving? Look who is calling the "kettle black."

[MI Chinook]

Hello ZERO,

   I am glad you mixed up the conversation and then clarified it. It has helped me years after you posted. Thank you.  I'm helping my daughter with her 76 Chinook and some one hooked up a GM one wire alt ( I THINK 1 wire) and it has gone bad. I took the alt to a starter/alternator shop (not big box auto parts) and had it tested. Now I am trying to find a replacement alt but do not know what years to look for.  The dead unit ( based on the #4 picture), the E and F are switched but the N is in the same place.  The battery post is next to the EFN plug ins and the other B post has a wire going to a tin can bolted to the back of the unit.

Is there a way to test the external reg to see if it works? The bad unit has ONE 28" piece of household romex connecting the alt to the truck harness. I would like to remove it, but I do not know what the gazillion other owners have done to the wiring harness. Some things were working until the alt died. The rig does not have the isolater hooked up and no house battery installed. I do not want to install house bat until I know the truck wiring/charge system is working properly first. Then I will move on to the house charge wiring.

Thank you to all who have contributed to this site. It has been a real help. Some day I may know enough to help contribute.

 

[linda s]

Zero is no longer active on this site. You can ask him questions here

https://groups.yahoo.com/neo/groups/toyotachinook/info

Linda S

[Maineah]

17 hours ago, MI Chinook said:

Hello ZERO,

   I am glad you mixed up the conversation and then clarified it. It has helped me years after you posted. Thank you.  I'm helping my daughter with her 76 Chinook and some one hooked up a GM one wire alt ( I THINK 1 wire) and it has gone bad. I took the alt to a starter/alternator shop (not big box auto parts) and had it tested. Now I am trying to find a replacement alt but do not know what years to look for.  The dead unit ( based on the #4 picture), the E and F are switched but the N is in the same place.  The battery post is next to the EFN plug ins and the other B post has a wire going to a tin can bolted to the back of the unit.

Is there a way to test the external reg to see if it works? The bad unit has ONE 28" piece of household romex connecting the alt to the truck harness. I would like to remove it, but I do not know what the gazillion other owners have done to the wiring harness. Some things were working until the alt died. The rig does not have the isolater hooked up and no house battery installed. I do not want to install house bat until I know the truck wiring/charge system is working properly first. Then I will move on to the house charge wiring.

Thank you to all who have contributed to this site. It has been a real help. Some day I may know enough to help contribute.

 

A GM one wire alternator needs to be reved up to work from a dead start so sitting there at a startup idle it won't charge. The Toyota "E" terminal is keyed, (exciter) the "F" is a field wire for the alt. field circuit. If you have no islator the alt B+ wire goes directly to the truck battery the solid state isolator requires the B+ wire to be landed on the isolator "B+"  (or "A") not the truck battery. Solid copper wire in an automotive application will eventually fail the alt supply wire is a #8 stranded wire. There are two types of external regulators the test procedures are different one has relays the other is solid state. If there is a one wire alt my guess they have modified something to make it fit so you maybe be stuck with the one wire they are OK but it has to be turning a good bit faster than an idle to charge from a dead start.