MAYCO's 1982 310 TD

[bkahler]

Originally Posted by mayco

Thanks Brad, on the diesel there is a solenoid that ties all the batteries together is on the side of the battery box. Its activated by turning the key all the way to the start position. (No glove box switch). The battery disconnect is right in the step well and indeed disconnects the 12v chassis battery to all chassis systems plus the starter to the generator. There is another disconnect switch that disconnects the converter to the coach batteries.
The isolator is as you describe and I just replaced it and it tests out just fine.

Could that solenoid be stuck in the "on" position and tying the two systems together ALL the time thus draining the chassis battery when the coach systems are used? The converter is doing its job keeping the coach batteries charged. The chassis battery holds its charge as long as I turn off the disconnect switch so I dont think I have a bad battery. The solenoid and the isolator are the only two places that I know of where the two 12v systems are potentially tied together.

Unfortunately it won't do any good for me to check the 310 as it is definitely different than the diesel version.

I agree with your assessment about the isolator and the solenoid being the only two points where they are typically tied together. It wouldn't surprise me if the solenoid contacts were welded together inside. Wouldn't be the first time something like that has happened!

Sorry I can't help anymore than agree what what you've found to date.

Brad

[mayco]

Ahhhhhhh, good thinkin there Brad. Ill crawl under there and see whats what. That very well could be. Thanks for the consideration.

Mike

[mayco]

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[mayco]

So thats a picture of the solenoid that ties the coach batteries to the chassis battery. It is activated by the ignition key being turned all the way to the start position. So I tested resistance between the two side battery terminals on the solenoid without the key in the ignition and it shows 0 resistance. So doesnt that mean that the two battery systems are being tied together within the solenoid all the time regardless of the switch? So Brad, would this indicate the contacts in the solenoid are indeed welded together?

Mike

[bkahler]

Originally Posted by mayco

So thats a picture of the solenoid that ties the coach batteries to the chassis battery. It is activated by the ignition key being turned all the way to the start position. So I tested resistance between the two side battery terminals on the solenoid without the key in the ignition and it shows 0 resistance. So doesnt that mean that the two battery systems are being tied together within the solenoid all the time regardless of the switch? So Brad, would this indicate the contacts in the solenoid are indeed welded together?

Mike

You would need to remove the cables from one side of the solenoid to get an accurate reading. If the two systems are indeed tied together somewhere other than through the solenoid (i.e. something you haven't found yet) then you'll be reading zero resistance (short) on your meter. By removing the two cables it gives you a clear reading of what the contacts in the solenoid are doing.

[mayco]

Gotya, thanks. I get it and it makes sense. Continuing to learn here.

Mike

[bkahler]

Do be careful when disconnecting those big battery cables. Touching them to ground could be a mini 4 of July celebration!

[bkahler]

I should add when unless I want or need to take a voltage reading I typically disconnect the battery negative terminals so I can't short anything while working on any positive side connections.

I've got way to many wrenches and screw drivers with burn marks on them

[mayco]

Ive got some side cutters that have some chunks out of em too. Well, tested it the RIGHT way and the solenoid is open so drats, its working correctly hahahahaha. Not sure where to go from here. Ill keep the disconnect off in the mean time. It may be some parasitic drain but it seems more than that. Thanks for your patience Brad.

Mike

[tevake]

Mike thanks for posting you search thru the electrical gremlins of your coach.

I'm also experiencing the same symptoms you describe as well as marginal charging of the house batts while plugged into shore power. And no charging of the house batts while driving. This makes being unplugged more than One night very taxing on the house batts.

As I'm in mid trip I'm planning to limp along till back in Az.in sept.

So I be following along as you sort out our issues and find the solutions.

All the best, Richard

[mayco]

Hey Richard,
Yup thought I had i licked a while back and then experienced the same situation after boondocking for a few days. Ill keep you posted if I make any progress. Searching back through years of threads it looks like many have experienced the same problem with the chassis battery discharging. It looks like most have just resorted to remembering to flip the battery disconnect switch when parked. Ive got one more system to check and thats my install of the suspension air compressor. Its tied directly to the chassis battery with a pressure switch/relay to activate the compressor. Dont think its the culprit but Ill take a look. After that Im a bit stumped.

Aloha, Mike

[dadstoy]

Mike, this is how I have my '82 wired...

[bkahler]

I'm pretty sure this problem never occurred on the my old 310. Probably just got lucky in that regard

My guess is the diesel 310 and the 454 310 probably have similar DC wiring with the exception of the battery tie-in for starting. I can always compare notes between yours and my old 310 (currently stored at my place).

What I'm not sure I understand yet is why your chassis battery is not being charged by the DC converter (aka Univolt) with the disconnect switch closed yet the coach batteries are (or are they?). If the chassis and coach batteries are tied together when the disconnect is closed then the chassis battery should be getting a charge from the converter. You can test this theory by taking voltage readings of each battery with the disconnect switch open. If the chassis and coach batteries read the same voltage then they are probably connected together somewhere. If they are not reading the same (i.e. within .2 volts or so) then they are not tied together. Now do the same thing with the disconnect closed. Are the readings the same or different?

I know you've verified the diode isolator wiring but for some reason I keep thinking back to that device due to the fact that it has a diode in it. Lets leave that on the back burner for now and do some more testing.

As onerous as this may sound the best way to isolate a problem like this is to literally disconnect all electrical devices from the batteries. Disconnect via pulling fuses, disconnecting wires from terminals and any other method required to isolate each individual circuit from having power.

Once you have every known circuit isolated then monitor the batteries with the disconnect switch closed. If the coach battery still drains then you haven't isolated everything. If it stops draining you have at least proven that one of the circuits is the culprit.

A side benefit of this sort of testing is you can map out your wiring and have a nice handy reference chart that will help in diagnosing problems down the road.

Hope this helps!

Brad

[bkahler]

Originally Posted by dadstoy

Mike, this is how I have my '82 wired...

Dean, aside from the inverter and solar is the wiring still factory?

The reason I ask is the DC converter appears to be feeding the DC buss through a 30 amp circuit breaker. All the wiring diagrams I've seen for these coaches shows a fuse (usually 50 amp) instead of a breaker along with a fuse on the negative feed as well.

[dadstoy]

I don't tie the coach and chassis batteries together with the main disconnect. The only time the coach and chassis batteries are tied together is when I press the "engine assist" button when needed for extra amps to the engine starter.

My chassis battery is only charged by the engine alternator via the isolator up on the firewall.

If the chassis and coach batteries are tied together and your 12v converter is charging your coach and chassis batteries at the same time, this would not be a good idea. You are charging to different types of batteries with different levels of charge. Also when boondocking, you would be discharging your couch and chassis batteries, possibly leaving you without a battery to start your engine.

Since I'm parked a lot at the ranch, there isn't much chance of my engine recharging the chassis battery so I have a small Sears charger hooked up to the chassis battery and plug it into 110v to keep it charged.

I'm not sure Brad from your last post if you have your chassis and coach batteries tied together with a single main disconnect switch?

I also have a "knife" switch on the chassis battery to completely disconnect the chassis battery as well if I am storing the MH for a long period of time without being able to leave it connected to 110v.

[bkahler]

Originally Posted by dadstoy

I don't tie the coach and chassis batteries together with the main disconnect. The only time the coach and chassis batteries are tied together is when I press the "engine assist" button when needed for extra amps to the engine starter.

My chassis battery is only charged by the engine alternator via the isolator up on the firewall.

That is the way my old 310 was configured as well.

If the chassis and coach batteries are tied together and your 12v converter is charging your coach and chassis batteries at the same time, this would not be a good idea. You are charging to different types of batteries with different levels of charge. Also when boondocking, you would be discharging your couch and chassis batteries, possibly leaving you without a battery to start your engine.

Definitely agree. The DC converter should not be charging the chassis battery. What my last post was trying to identify is whether Mike's chassis battery is being charged (inadvertently or otherwise) by the DC converter.

Since I'm parked a lot at the ranch, there isn't much chance of my engine recharging the chassis battery so I have a small Sears charger hooked up to the chassis battery and plug it into 110v to keep it charged.

That's a good idea. I tried a solar charger one time that plugged into the cigarette lighter on the chassis side of things but over time the solar charger finally gave out. This was some years ago and I'm assuming the technology has gotten better.

I'm not sure Brad from your last post if you have your chassis and coach batteries tied together with a single main disconnect switch?

No not mine. It seems that Mike's may set up that way or he might possibly have something miss wired that creates that effect.

I also have a "knife" switch on the chassis battery to completely disconnect the chassis battery as well if I am storing the MH for a long period of time without being able to leave it connected to 110v.

Good idea and will be something that I implement on my Argosy.

[dadstoy]

Originally Posted by bkahler

Dean, aside from the inverter and solar is the wiring still factory?

The reason I ask is the DC converter appears to be feeding the DC buss through a 30 amp circuit breaker. All the wiring diagrams I've seen for these coaches shows a fuse (usually 50 amp) instead of a breaker along with a fuse on the negative feed as well.

The converter, 12v fuse panel and 30amp circuit breakers are not original.

Yes, when on shore power, the 12v main bus A is feed via the 30amp circuit breaker. The coach 12v systems are fed off the 12v fuse panel as you know and when on shore power (inverter), the coach batteries are "back fed" to charge them. As well as the firewall bus B is being fed (12v outlets on dash board and dash board stereo system.

The original 12v fuse panel with its two large fuses like you described went up in smoke one late evening about 5 years back. That's when I installed the new components and the circuit breakers.

I'm using the circuit breakers instead of the fuses. Most of the modern wiring that I have seen doesn't have a fuse on the negative side. Fusing/Circuit breakering the firewall bus B is also new...it used to be feed off the main coach disconnect with no fusing.

The main disconnect is located on the stair well and the batteries (all) are located right behind the step well. The circuit breakers are located right in this area as well as to keep them as close to the battery + terminal as possible. All are withing 1-2 feet of each other (except for the 12v fuse panel and converter which are under the bed).

[dadstoy]

I would like to replace the chassis battery "knife" shutoff switch with the same type of main disconnect that the coach batteries use. If there was ever an electrical fire on the engine side, I would have to lift up the battery hatch and rich down between the batteries to get the the knife switch and I'm afraid that just might be where the electrical fire might start!

[mayco]

Originally Posted by bkahler

I'm pretty sure this problem never occurred on the my old 310. Probably just got lucky in that regard

My guess is the diesel 310 and the 454 310 probably have similar DC wiring with the exception of the battery tie-in for starting. I can always compare notes between yours and my old 310 (currently stored at my place).

What I'm not sure I understand yet is why your chassis battery is not being charged by the DC converter (aka Univolt) with the disconnect switch closed yet the coach batteries are (or are they?). If the chassis and coach batteries are tied together when the disconnect is closed then the chassis battery should be getting a charge from the converter. You can test this theory by taking voltage readings of each battery with the disconnect switch open. If the chassis and coach batteries read the same voltage then they are probably connected together somewhere. If they are not reading the same (i.e. within .2 volts or so) then they are not tied together. Now do the same thing with the disconnect closed. Are the readings the same or different?

I know you've verified the diode isolator wiring but for some reason I keep thinking back to that device due to the fact that it has a diode in it. Lets leave that on the back burner for now and do some more testing.

As onerous as this may sound the best way to isolate a problem like this is to literally disconnect all electrical devices from the batteries. Disconnect via pulling fuses, disconnecting wires from terminals and any other method required to isolate each individual circuit from having power.

Once you have every known circuit isolated then monitor the batteries with the disconnect switch closed. If the coach battery still drains then you haven't isolated everything. If it stops draining you have at least proven that one of the circuits is the culprit.

A side benefit of this sort of testing is you can map out your wiring and have a nice handy reference chart that will help in diagnosing problems down the road.

Hope this helps!

Brad

If indeed the two systems are mistakenly tied together I also dont understand why the converter wouldn't be charging the chassis battery also. I dont have a clear understanding of this entire ignition/charging system. When I replaced the battery isolator under the hood, I referred to the Airstream manual to insure that the new isolator was installed the same as the original (or what was there).

The chassis battery seems to hold a good charge (12.4-12.5) when I use the disconnect but I havent taken the battery out to have it tested. It was under 10.0 the last time I had forgotten to use the disconnect but after a couple hours on the road it had charged back to about 12.43 and thats where it is at aprx right now. The alternator is putting out between 14.7 and over 15 depending on rpm.

A couple of days ago I turned on both my exhaust fans in the afternoon, chassis battery at 12.43 , and let them run till early the next morning. Plugged into shore power. Tested voltage and the chassis battery was down to under 10 volts. Coach batteries stayed charged, coverter doing its job. The only thing that I could come up with is that those exhaust fans had drained my chassis battery down, nothing else on over night. So thus my thinking that somewhere the two systems are tied together somewhere and the coach batteries are reveiving a charge from the converter and the chassis battery is not, duh! You would think it would if indeed they are somehow commingling.

So, converter is working, alternator is working, looks like the battery combining solenoid is working, but the battery isolator? Even though I removed and replaced as the old one was, same type isolator but a little higher amp, dunno. At first glance at the wiring for the isolator I thought the alt post and battery #1 post should be reversed but I installed according to the manual and the one that was removed. Ill post pics of the isolator wiring/ old and new.

[mayco]

Old isolator


New isolator


Center terminal on both is alternator, left terminal coach batteries, right terminal "to engine battery through Chevrolet harness" (quote from manual) at a glance, I thought the wire on the right terminal and the wire on the center terminal should be flip flopped but as you can see from the pictures I installed as per the old isolator.


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