Batteries not charging while chassis engine running

[Redram99]

Hi all
I have a 2010 triple e senator class c. Ford v10.
Recently I noticed my house batteries weren’t charged after a long road trip. Even when the v10 was idling the house battery voltage didn’t match the chassis battery voltage. As soon as I plug into shore power or fire the genny the house batteries start to charge.
In my battery compartment I have a 12v dc coil and a bi directional isolator relay delay.

I have 14v to one side of the coil while the engine is running but it doesn’t continue thru the coil to the house batteries. It appears that the bi directional isolator “runs” the coil??

As a quick fix, I jumped a wire direct from the chassis side of the coil direct to the house batteries so they would charge while driving. Quick fix but now the house is also running off the chassis batteries which could cause issues(dead battery and no engine start)!!!

Would it be the coil or the isolator that is broken? How do I figure it out?

Ps. I am probably the worlds worst electrician...

Thanks in advance.

Jamie

[CharlesinGA]

If it has a round silver solenoid/relay with two large terminals and one small terminal, it is probably the same cheap 80 amp unit Winnebago uses. They fail often.

Everyone with one of those in a Winnebago replaces them with a Cole Hersee 24213 which is 200 amp continuous rated and has silver-tungsten plated contacts instead of plain copper ones that burn up easily. It has four terminals, the coil ground is made externally in it rather than internally like the cheap three terminal one. You simply run a ground from one of the small terminals to the mounting bolt or good ground and hook the existing small wire to the other small terminal, you will never again need to replace the solenoid/relay.

Less than $50 on Amazon. Amazon Cole Hersee 24213 relay

Charles

[A_Good_Cigar]

Sam Spade wrote:

A Good Cigar wrote:
Simple fix, I bought the generic 3 pole solenoid off of Amazon, $15 & 15 minutes to replace!

Should have bought several.
Likely that it will fail again in about a year.....or less.

I figured for $15 apiece that I should buy two, so I did lol! Good call:B

[Redram99]

Fixed.
The isolating solenoid was pooched. Electric supply company said the one that was on there was a cheap pos and not designed for constant duty.

Put a new one in and all good to go!!

Thanks for the input.

[Sam_Spade]

A Good Cigar wrote:
Simple fix, I bought the generic 3 pole solenoid off of Amazon, $15 & 15 minutes to replace!

Should have bought several.
Likely that it will fail again in about a year.....or less.

[Sam_Spade]

theoldwizard1 wrote:

Get rid of the relay and replace it with a CTEK D250SA

And then what happens when you want to utilize the "emergency start" feature that bridges the house batteries to the engine ????
Hint: You lose that feature.

[A_Good_Cigar]

Do you have an auxiliary start switch on the dashboard? Flip/press that switch, do you hear a click from the solenoid in the battery box? If so, you probably have the same problem I had, the contacts on the solenoid have so much carbon buildup that it won't allow current to pass through. Simple fix, I bought the generic 3 pole solenoid off of Amazon, $15 & 15 minutes to replace!

[DrewE]

theoldwizard1 wrote:
Read this regarding charging a house battery from a vehicle alternator.

DC-DC battery charging


Get rid of the relay and replace it with a CTEK D250SA

There is (at least often) a significant practical difference in the battery isolator circuitry on a motorhome and the house battery charging via the 7 pin connector for a trailer. On a motorhome, the batteries are physically closer together and connected by much heavier connections, so the charging of the house battery via the engine alternator is significantly better.

I have actually observed over 50A of house battery charge current on my class C. If memory serves, the wires are fused at 175A. The voltage drop is fairly minimal, and the house battery can get fully charged (or at least close enough to that for practical purposes) just as well as the chassis battery can. The CTEK unit, with its 20A limit, would be an expensive downgrade on the whole.

[D_E_Bishop]

theoldwizard1 wrote:
Read this regarding charging a house battery from a vehicle alternator.

DC-DC battery charging


Get rid of the relay and replace it with a CTEK D250SA

It seems to me that $300 dollars is a pretty expensive alternative to what is probably a $25, 250 amp constant duty solenoid. Even replacing the BIRD and the solenoid is less than $100 and no rewiring. Check out the link.

Link to BIRD

[maillemaker]

I don't know about your RV, but my old 1990 has a switch that I have to flip to get the engine to charge the house batteries.

Steve

[theoldwizard1]

Read this regarding charging a house battery from a vehicle alternator.

DC-DC battery charging


Get rid of the relay and replace it with a CTEK D250SA

[Sam_Spade]

tobydad wrote:

I had the same problem and changed the battery isolator solenoid and that solved the problem.

Me too. On TWO used Rvs; one a C and one an A.
Seems to be a common failure point.

An RV service center should only charge you a half hour labor to put a new one on. IIRC, price of the part is about $50.

[tobydad]

Start with the simplest first. Remove and clean all house battery terminals and make sure they are tight.
I had the same problem and changed the battery isolator solenoid and that solved the problem. The most difficult part was reaching the solenoid which was inside a storage cabinet where all the wiring came together. Easy to replace as long as you disconnect and connect one wire at a time.

[D_E_Bishop]

Normally a B.I.R.D., senses when the chassis batteries have reach a full charge and energizes a relay or solenoid, whatever you wish to call it. When the solenoid energizes, the house batteries receive power from the chassis alternator.

There should be two heavy wires attached to the contacts and one small wire to the coil of the solenoid..

Jumper from the hot side of the solenoid to the smaller wire,if the solenoid makes a loud click, it would appear to be working and using atest light or DMM connected to the load side of the slenoid should light up.

If you start the engine and allow it to run for a few minutes, the BIRD should send 12 volts through the small wire on the coil of the solinod. A test light connected to that small wire and ground should light up when the chassis battery is charged enough and the BIRD sends power through that wire.

If after starting the engine and letting in run for 10 or 15 minutes and the test light doesn't come on, it would seem you have a bad BIRD.

You should be able to search on line and find more concise testing instructions.

[pianotuna]

Jamie,

The relay may have burned contacts. Replace it.