DC Circuit Wiring Help

Topic: DC Circuit Wiring Help (Read 911 times) previous topic - next topic

DC Circuit Wiring Help

October 09, 2017, 09:01:08 pm

Hey Guys and Gals,

I finally got deep cycle batteries for my house. Got a couple Lifeline 6v 200Amp hours. They are nice.

Got them installed. They work great... but I'm 100% certain my something in my battery bay is wired wrong.

I get power for both the house and the chassis from either the house or the chassis battery banks.

So, with chassis battery disconnected entirely, and house battery bank hooked up with master switch ON... I can start the coach and use all the dc accessories throughout the house.

With chassis battery disconnected entirely, and house battery bank hooked up with master switch OFF... I have no power to anything anywhere. Which makes sense... cause no batteries are connected in this configuration.

With chassis battery connected, and house battery bank disconnected... I can start the coach and use all the dc accessories throughout the house.

Which leads me to believe that something is connected improperly, likely to the charge boost solenoid.

The charge boost solenoid is functional as far as I can tell. It clicks when you hit the switch on the dash. So, I don't think it's staying closed or anything.

So, I've started a basic wiring diagram, that I've attached below.

I'll add some images of the things I've got labeled in there.

But the right side of the charge boost solenoid I believe those two wires are heading out to the Isolator in the front of the chassis.

The left side of the charge boost solenoid I believe those three wires are heading to the back energy area where the Charge controller from shore power is.

The center wire on the charge boost solenoid I believe is going to the dash switch for the solenoid.

I literally have no idea where the unknown solenoid or the unknown black thingy go to.

Any ideas what might be wired wrong or what I should be tracing to figure this out?

I have labeled all the wires in the battery bay (R1, R2, B1, B2, etc.). Just don't know what they all go to yet.

I have a wire tracer... but I'm not entirely sure what all I need to disconnect to trace the big fat wires that go to the front or back of the chassis (do I have to disconnect shore power and all batteries to trace wires safely? - cause that means I have to shut off the house and kick the family out...).

Re: DC Circuit Wiring Help

Reply #1 – October 09, 2017, 09:05:47 pm

On our 84 foretravel the boost solenoid was bad, it would click, but internally never did disconnect. so all batteries were hooked together all the time.

Re: DC Circuit Wiring Help

Reply #2 – October 09, 2017, 09:23:21 pm

Here are images of the things in the battery bay.

UPDATE: Unknown black thingy and Unknown Solenoid thingy have been identified by Old Phart Fred as Circuit Breakers.

Re: DC Circuit Wiring Help

Reply #3 – October 09, 2017, 09:24:02 pm

Quote from: red tractor – October 09, 2017, 09:05:47 pm

On our 84 foretravel the boost solenoid was bad, it would click, but internally never did disconnect. so all batteries were hooked together all the time.

Any idea how to test that? Solenoids are cheap anyways... so maybe I just buy a new one.

Re: DC Circuit Wiring Help

Reply #4 – October 09, 2017, 09:26:40 pm

You can take off the wires from one of the posts and with the switch off should not have power on that post. If there is power on that post then the contacts inside the solenoid are welded together.

Re: DC Circuit Wiring Help

Reply #5 – October 09, 2017, 10:25:37 pm

Unknown black things both rectangular and round are circuit breakers for over current protection of the wiring. Some reset themselves after an issue, some have a manual reset button. I installed a $100 Cole hersee smart isolator. It always defaults to charge the engine and generator start battery first. Then switches the alternator or shore power to the the house batteries and/or start batteries. Little rectangular cb should go to your fridge, larger round one on your right goes to the salesman switch on the floor to the right of the door. Turn it on.

Re: DC Circuit Wiring Help

Reply #6 – October 09, 2017, 11:33:34 pm

Quote from: Old phart phred – October 09, 2017, 10:25:37 pm

Unknown black things both rectangular and round are circuit breakers for over current protection of the wiring.

Good to know. They don't have reset buttons. So I suspect they reset themselves.

Quote from: Old phart phred – October 09, 2017, 10:25:37 pm

I installed a $100 Cole hersee smart isolator. It always defaults to charge the engine and generator start battery first. Then switches the alternator or shore power to the the house batteries and/or start batteries.

Interesting... that means the shore power goes from the charge controller in the back all the way to the isolator in the front, and then back to the batteries in the middle, doesn't it? Is it worth upgrading the one I have installed? I assume it's original from '86. Got a link for yours?

Quote from: Old phart phred – October 09, 2017, 10:25:37 pm

Little rectangular cb should go to your fridge, larger round one on your right goes to the salesman switch on the floor to the right of the door. Turn it on.

My fridge 12v is disconnected at the moment. Cause we have a small residential fridge installed. Waiting on the purchase of a new fridge... but they don't make a 3-way that fits in my hole anymore.. just 110v/Propane models. So I probably don't have to worry about that cb at all.

The larger round one on the right doesn't go tho the salesman switch (assuming your referring to what I have labeled as the "house battery switch" in the wiring diagram. That's on the floor next to the door. And I do have it on.

There is a separate wire running from house battery 1 positive straight to that round cb. Then a small wire on the same post goes to the rectangular cb. Then the other post on that round CB goes off into never never land (the frame of the coach where I'd have to trace it to see where it goes).

Re: DC Circuit Wiring Help

Reply #7 – October 09, 2017, 11:37:38 pm

Most of the older model coaches seem to have a total of 3 of the silver solenoid switches, like the one in your 4th photo. There is one up front in the vicinity of the instrument panel. That is the "ignition" solenoid. There is the "boost" solenoid, which as you know is used to temporarily connect the two battery banks. The third one is the "aux start" solenoid. When you turn the key to crank the engine, power from the ignition switch energizes the "aux start" solenoid, which in turn connects the start battery to the starter solenoid (mounted on the starter motor). The starter solenoid energizes the starter motor, and (hopefully) the engine starts.

SO, you have already identified the "ignition" solenoid (in the dash area) and the "boost" solenoid (the one that clicks when you operate the boost switch). That means the mystery solenoid is most likely the "aux start" solenoid. Easy to check - just use a jumper wire to momentarily apply 12V power to the small terminal on the mystery solenoid. You should hear the engine try to crank. If so, mystery solved!

Edit: Never mind. I thought you had 2 of the silver solenoids in the battery area, and didn't know what the 2nd one was for.

Re: DC Circuit Wiring Help

Reply #8 – October 09, 2017, 11:49:55 pm

Quote from: Old phart phred – October 09, 2017, 10:25:37 pm

Unknown black things both rectangular and round are circuit breakers for over current protection of the wiring.

Updated Wiring diagram based on this wonderful bit of info. And moved the rectangles to better indicate that there are separate wires for each thing.

Also, I'll be disconnecting one side of the Charge Boost solenoid in the morning after the kids wake up and testing to see if it's fuzed into the closed position. And replacing it if I find it bad. Hoping it's that simple to fix.

Though I'll probably still trace and label all of the wires anyways... just for my sanity. (and I'm a bit anal retentive... so since I started the circuit diagram... I've got to get rid of all the ? marks. Lol).

Re: DC Circuit Wiring Help

Reply #9 – October 10, 2017, 02:56:36 pm

AKA,
I think is hard for many of us to give you advice since your coach is older than most of ours. Here's the "automotive" schematic from my 91 coach that might give you insight into how yours might be wired and hopefully let you troubleshoot where the two battery banks might be tied together. You can see in the schematic a vertical row of 8 "unknown black thingy" auto reset circuit breakers (with a single 15A by itself), along with 3 "unknown solenoid" auto resetting circuit breakers (90 amp) in the schematic. If you ever encounter a situation where something is going ON and OFF in a repeating cycle it's likely these auto resetting circuit breakers.

The forum has a library with schematics section that you might also look at: http://www.foreforums.com/index.php?action=media;sa=album;in=194
I just added the attached schematic to the library.
Hope this helps.

Re: DC Circuit Wiring Help

Reply #10 – October 10, 2017, 04:14:33 pm

My first guess is the boost solenoid. Second guess could be the isolator. Maybe it fried and shorted out both outputs together.

Re: DC Circuit Wiring Help

Reply #11 – October 10, 2017, 07:59:05 pm

@All - Occam's Razor has failed me! Lol. The Charge boost solenoid is working exactly as it should connecting and disconnecting power at both sides. Tested the way @OldPhartPhred had recommended.

@JohnFitz - Thanks for the links! I'll look for more circuit breakers. To be clear it's not going ON and OFF... The circuit is always ON all the time from both sets of battery banks. So something is connecting them both together somewhere.

@turbojack - That's my next thing to test I think.... happen to have any idea how to test the Isolator?

Re: DC Circuit Wiring Help

Reply #12 – October 10, 2017, 08:13:56 pm

AHA! Look what I found in my books.

A wiring diagram. This is how it's supposed to be wired.

I'm not seeing the Isolator in this original diagram. Also not seeing the small red wire that's coming off the right side of my Boost Solenoid.

Any ideas where I should be looking for the incorrectly hooked up or broken thing that's causing my battery circuits to be connected all the time?

Re: DC Circuit Wiring Help

Reply #13 – October 10, 2017, 08:24:02 pm

Does you alternator have 2 posts on it with the 4 gauge red wires Some of that time frame coaches had a lestec alternator which had a built in isolator in it. If someone replaced it with a standard GM alternator with only one battery terminal then that might be where the 2 battery banks might be tied together.

Re: DC Circuit Wiring Help

Reply #14 – October 10, 2017, 08:35:58 pm

open your "main disconnect switch" if that isolates your batteries then the problem is as Ron says and they are tied at the alternator.
You have a #4 red wire going to both batteries from your alternator. They must be separated there.

Re: DC Circuit Wiring Help

Reply #15 – October 10, 2017, 08:38:09 pm

If that is what you have then you would need to install an isolator. which would have one wire from the alternator to the center post of the isolator and then one post from the isolator to the house batteries and one post from the isolator to the chassis battery

Re: DC Circuit Wiring Help

Reply #16 – October 10, 2017, 09:44:36 pm

Do you have an isolator? Do you have a boost switch that is on?

I think I'd unplug the coach, physically disconnect all battery connections, and use the wire tracer to verify your wiring diagram. I suspect that you will find something that doesn't match your diagram. I'd also like to know what works with only one battery connected, salesman's switch on, then off.

Re: DC Circuit Wiring Help

Reply #17 – October 10, 2017, 11:35:14 pm

I do have an isolator. It's in the engine bay. One center post goes to alternator. Two other posts. One side I assume goes to house battery. other side goes to chassis. Have done the tracing yet to confirm that.

I don't know how to check if the isolator is good.

@RedTractor - I replaced the alternator when I got the coach. Got the same kind that was in there already. It's a standard GM/Chevy alternator.

Quote from: kb0zke – October 10, 2017, 09:44:36 pm

Do you have an isolator? Do you have a boost switch that is on?

I think I'd unplug the coach, physically disconnect all battery connections, and use the wire tracer to verify your wiring diagram. I suspect that you will find something that doesn't match your diagram. I'd also like to know what works with only one battery connected, salesman's switch on, then off.

Yes to isolator. Boost switch isn't on. I used it to check charge boost solenoid function. Both switch and solenoid function as expected.

As for what works....

With chassis battery DISconnected, & house battery CONNECTED with master switch OFF. I have no DC power to anything.

With chassis battery DISconnected, & house battery CONNECTED with master switch ON. I have DC power to chassis and house (meaning I can crank the engine and turn on house lights). This configuration is presumably powering everything from the house batteries.

With chassis battery CONNECTED, & house battery CONNECTED with master switch OFF. I have DC power to chassis and house (meaning I can crank the engine and turn on house lights). This configuration is presumably powering everything from the chassis batteries.

I haven't tested chassis battery CONNECTED, house battery DISconnected with master switch OFF. Because I assumed I'd have the same result as the above test.

Sounds like my best bet is to finish off my own wiring digram of what's actually in the coach by unplugging everything and tracing wires and comparing that to what in in the manual's diagram.

That sound about right guys?

Re: DC Circuit Wiring Help

Reply #18 – October 11, 2017, 12:43:15 am

As I found out the wire tracers don't really work well on large gauge cable or even 12 gauge unless it's disconnected at both ends. Spent the entire labor day weekend, trying to sort out the mess a mobile rv mechanic made when he wired all the hots going to the isolator together just because the alternator belt was visually slipping badly, and too old to squeal. Lots of so called service records of replacements that the PO paid for, but did not appear to be done except every other time.

Re: DC Circuit Wiring Help

Reply #19 – October 11, 2017, 04:30:31 am

your diagram shows two 4 gauge wires going to your alternator............ is this correct?

If so how are they isolated?
If not isolated then that is your problem........

Re: DC Circuit Wiring Help

Reply #20 – October 11, 2017, 09:50:06 am

Quote from: AKATheAlchemist – October 10, 2017, 08:13:56 pm

AHA! Look what I found in my books.
A wiring diagram. This is how it's supposed to be wired.

I'm not seeing the Isolator in this original diagram. Also not seeing the small red wire that's coming off the right side of my Boost Solenoid.

Any ideas where I should be looking for the incorrectly hooked up or broken thing that's causing my battery circuits to be connected all the time?

I'm guessing perhaps there wasn't any isolator in the original setup? On the factory diagram, it looks to me like the "main disconnect switch" was meant to act like a manual isolator. With the disconnect switch closed, the two batteries are tied together at the alternator, and both batteries can be charged by either the alternator or the battery charger. With the disconnect switch open, the two batteries are separated to prevent completely discharging your start battery. In that case, the alternator can only charge the engine battery, and the coach battery can only be charged by the battery charger (assuming the "BOOST" switch is "OFF").

With the main disconnect switch "OPEN", only the engine battery would be available to start the engine, unless the "BOOST" switch (solenoid) was activated. Then both batteries would be available for starting, even if the main disconnect switch was open.

Of course, since your coach has been "modified" with the addition of a isolator and replacement alternator, the above ideas are not really helpful. When the previous owners have made "improvements" to the electrical system, all bets are off.

Re: DC Circuit Wiring Help

Reply #21 – October 11, 2017, 12:12:05 pm

Quote from: Chuck & Jeannie – October 11, 2017, 09:50:06 am

When the previous owners have made "improvements" to the electrical system, all bets are off.

Brett did make"improvements" to ours, for a good reason. Bothers me not, as I've got paperwork from all the work!

Re: DC Circuit Wiring Help

Reply #22 – November 20, 2017, 02:34:35 am

UPDATE: Solved (mostly).

Visited my business partner in Vegas this week. His brother has electrical engineering schooling. He helped me today to diagnose and solve my wiring issue. Ended up taking us 7 hours to figure out fully. Lol.

There were a number of issues.

1: The charge boost solenoid was cross wired.
2: The solid state isolator was bad internally at some point
3: To compensate for a bad isolator switch a previous owner had shorted one of the poles to the ignition switch wire with a one way diode for power. And in so doing also created the need for a second wire off of the starter solenoid to be run down to the isolator to get ignition to work. This wire was causing the short in between the house and the chassis system so they acted as one.

We replaced the solid state isolator with a mechanical relay isolator (cause that's what we had available locally). Removed the extra Ignition wire going to the isolator. And fixed the crossed wires at the charge boost.

Now the master switch in the floor actually disconnects the house batteries from the system. The alternator should charge both sets of batteries. The engine still starts (so we didn't break that, lol).

I feel like the way this isolator is setup that it may make the charge boost solenoid redundant.... So I may still need to actually order a solid state isolator in the future. Because I think the starting which closes the relay may pull power from both banks. But... the driving of the coach seems to require the house batteries to be connected because the dash accessories (face fans and radio) are on the same circuit as the house. Dash instrument clusters are on the chassis circuit. So I'm still not sure if it's totally right.

Also fixing it so the systems are capable of acting independently revealed another issue. The Shore power doesn't provide enough 12v power to run the 12v systems in the coach. It'll run one of my LED lights with the house switch off. But turn on a florescent light and it doesn't have enough juice to turn it on fully. Though I'm not sure it's supposed to in that configuration. It may be that the system is designed to simply charge the batteries and the batteries run the 12v system. So that may not be an actual problem and could be my naiveté about how the 12v system is supposed to operate. Or it could be the shore power converter doesn't have enough amperage draw to actually run lights.

Anyways. It's working. Mostly. And much better than before. Nothing is janky anymore.

Re: DC Circuit Wiring Help

Reply #23 – November 20, 2017, 10:33:11 am

Sounds like you are making progress! Reading your post, I had a few thoughts which may or may not be of any value.

The diode based battery isolator, or any other "smart" relay that replaces it, is simply a safety device. It protects the coach owner from their own stupidity. When dry camping, it should not allow the owner to deplete both sets of batteries to the point that the coach won't start. This same function can be performed by a simple mechanical 2-way switch, as long as the owner remembers to flip the switch. So whether or not you may actually need a isolator depends on how much you trust your own judgement.

With your setup as it is now, the fact that both of your battery banks are connected during starting doesn't seem like a problem (to me) as long as the starting batteries are always fully charged.

If you have a stand-alone battery charger/power converter (separate from the inverter), then I believe it should have sufficient output to power the 12 volt devices in the coach, even if the batteries are totally disconnected. When we first got our coach, it came with a separate inverter and charger/converter (also called a "power supply"). See photo below. It was rated at 75 amps max output - sufficient to power most of the 12 volt stuff in the coach all by itself. Problem was, the battery charger function would boil the batteries. Outdated technology. If you do replace your charger/converter, look at both the maximum power output and the charging process. 3 or 4 stage smart charger/converters are the norm now, and you should accept nothing less.

Re: DC Circuit Wiring Help

Reply #24 – November 20, 2017, 11:44:12 am

Quote from: Chuck & Jeannie – November 20, 2017, 10:33:11 am

If you have a stand-alone battery charger/power converter (separate from the inverter), then I believe it should have sufficient output to power the 12 volt devices in the coach, even if the batteries are totally disconnected.

Yeah. I think ours may be not putting out enough amperage. Or possibly also not connected properly, but I doubt that... cause the batteries stay topped up. I'm gonna check that out soon, but I didn't even know it was a problem before because I couldn't disconnect any of my batteries from the house or chassis. lol. Now that I can completely isolate both battery bays... I discover other problems with the power system. Lol.

I'll keep you updated.

Today is new refrigerator day though... So that should be fun.

Affiliate Notice