Chassis Battery

[Dan_Frisbie]

I usually do something in the RV on at least a weekly basis. It’s on our property, plugged in and I am in it quite a bit. Once a month or so, I run the generator and fire up the engine, allow everything to warm up just to avoid surprises.
A few weeks ago I went out to do this and the chassis battery was dead. Completely dead. Battery Boost did nothing. After a trickle charge, it seems to be okay with 13.4 vac and I have started the RV multiple times.
I thought that the converter would also charge the chassis battery. Either I am wrong about that or have a fuse/wire problem. Since the Battery Boost did nothing, does this confirm that maybe the converter/house battery is not reaching the chassis battery? I also read somewhere that Battery Boost can’t help a completely dead battery.

It is possible that something was left on after my Sister-in-Law was staying in the RV for a week or so. I have no idea what buttons she played with out there…

 

[Professor David]

I also keep my rig on my property plugged in all the time. On my rig, the convertor only charges the two house batteries. I have a separate battery maintainer for the chassis battery.

https://www.amazon.com/gp/product/B07W3QSMF9/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

I also added a charge wizard on my Progress Dynamics converter to prevent over charging the house batteries, which did not have a built in maintainer. The newer models have a built in battery maintainer.

 

[DonTom]

I thought that the converter would also charge the chassis battery.

In my Y2K RV the converter does NOT charge the chassis battery. At least not when it was new.

In my 2022 Class A, everything charges the Chassis battery, solar, converter-everything and anything that charges the stock house batteries also charge the chassis battery. This is from when new.

In my class C, I use a battery maintainer from an AC outlet to the chassis battery so it will charge from the genny or shore power.

-Don- Auburn, CA

 

[Gary RV_Wizard]

I thought that the converter would also charge the chassis battery. Either I am wrong about that or have a fuse/wire problem.

Whether it does or not is a design choice by the coach builder. Some do and others do not. In general, coaches designed and built by Fleetwood & American Coach do so, but I don't know about your Forest River coach. For many years Winnebago gas models did NOT, but their diesels did. Winnie changed their standard design back around 2010 (?) and I think all more recent Winnebago/Itasca models do charge that way. I think all Newmars do as well.

Yes, a faulty Battery Boost solenoid would prevent the converter from charging the chassis battery, so it would be wise to verify that it is working properly. You might really need it some day!

I also read somewhere that Battery Boost can’t help a completely dead battery.

When the Boost switch connects a charged battery to a very discharged one, the voltage of the good one drops quickly as it pours power into the dead one. If the difference between the two was great enough, the combined set may still be insufficient to start the engine.

 

[John From Detroit]

I would think on any RV older than around 2005 the isolator SHOULD be bi-directional (And quite a few younger) but ... alas.. save a buck applies..

Two options one is a battery tender type device..Many out there even harbor freight has them..Some of these are very good computer controlled.. CHARGE the battery with a smart charger first. A good one can be left connected.. and plugged in full time..

BUT Before you do that.. Your volt meter is your friend. It may be that for some reason a bi-direcitonal isolator "hickupped"

Measure voltage on the house system.. LESS than 13.. Not good indicates converter not converting.
about 13 1/2 (13.6) Generally indicates "Float"
Anything 14 above is "Charge"

now read the voltage on the chassis battery

Same answers

Note. Test should be no or minimum load and after an hour or two of doing nothing.

IF house is 13 1/2 but chassis is closer to 12 1/2 Isolator not bi-directional add battery tender type device.
OR.. a Trick-l-Charge (This is 3-wire device hooks to the Isolator relay. and provides the reverse path to charge the chassis off the house systems.

Finally.. What converter do you have.

 

[Arch Hoagland]

Amazon.com

I promise that will fix the problem.

 

[DonTom]

I promise that will fix the problem.

Or get one with a remote.

-Don- Auburn, CA

 

[old RV guy]

I usually do something in the RV on at least a weekly basis. It’s on our property, plugged in and I am in it quite a bit. Once a month or so, I run the generator and fire up the engine, allow everything to warm up just to avoid surprises.
A few weeks ago I went out to do this and the chassis battery was dead. Completely dead. Battery Boost did nothing. After a trickle charge, it seems to be okay with 13.4 vac and I have started the RV multiple times.
I thought that the converter would also charge the chassis battery. Either I am wrong about that or have a fuse/wire problem. Since the Battery Boost did nothing, does this confirm that maybe the converter/house battery is not reaching the chassis battery? I also read somewhere that Battery Boost can’t help a completely dead battery.

It is possible that something was left on after my Sister-in-Law was staying in the RV for a week or so. I have no idea what buttons she played with out there…

Yeah, I went out to mine 3 or 4 months back and the chassis battery was dead, dead, dead. The battery boost was no help. I've cured the parasitic draw problem for me with disconnects on both the chassis and house batteries.

 

[Kirk]

Battery Boost did nothing.

If using the boost to start the chassis engine, first start the generator and allow it to run for a few minutes and then hold the boost switch down for several more minutes before starting the chassis engine. That will allow the generator to charge the chassis battery at least a little bit. When it is really bad, hold that boost switch for 10 or 15 minutes first.

 

[John From Detroit]

I found boost alone would not start my rig... Forget ..Oh ran a jumper battery to battery.. cables not big enough for Boost.

Then once I parked pulled the old and shoved a new in.
(Along with an improvement in the connector)

 

[chuckbear]

I'm having close to the same issue right now. Normally both battery banks are charged from either the alternator or the converter. Right now, I can only charge the house batteries from the converter and only charge the chassis battery from the alternator. So if the coach is just sitting on shore power the chassis battery will run down. It will start using the combiner switch if it doesn't run down too far. I'm trying to troubleshoot the problem right now. It will all depend on how yours was set up at the factory. An Echo charger will solve the problem if it was not made to charge the chassis. Chuck

 

[House Husband]

I'm having close to the same issue right now. Normally both battery banks are charged from either the alternator or the converter. Right now, I can only charge the house batteries from the converter and only charge the chassis battery from the alternator. So if the coach is just sitting on shore power the chassis battery will run down. It will start using the combiner switch if it doesn't run down too far. I'm trying to troubleshoot the problem right now. It will all depend on how yours was set up at the factory. An Echo charger will solve the problem if it was not made to charge the chassis. Chuck

There you go Chuck, you just answered you problem. When you push the combiner switch, you've energized the isolator relay. So the isolator relay is good and the circuit board is not doing it's job.

Richard

 

[gwinger]

If that was lead acid battery, would be concerned about it. An LA battery ran below 50% is questionable. 10.5 volts is 50%. if it was below 10.5 the battery may have been damaged, even though the charger brought it back up.
Also,idling the engine for short periods will draw moisture into the crankcase when it cools. A half hour or so drive is the best way. That also circulates the transmission fluid.

 

[John From Detroit]

There you go Chuck, you just answered you problem. When you push the combiner switch, you've energized the isolator relay. So the isolator relay is good and the circuit board is not doing it's job.

Richard

Perhaps..Perhaps not..

The isolator and the combiner might be different solenoids.

 

[chuckbear]

There you go Chuck, you just answered you problem. When you push the combiner switch, you've energized the isolator relay. So the isolator relay is good and the circuit board is not doing it's job.

Richard

Not necessarily. These solenoids are famous for working fine when the combiner switch is pushed but do not allow both battery banks to be charged simultaneously. This is the least expensive fix, so I will post back once the solenoid is replaced. If it turns out to be the circuit board, that's a whole different problem. Chuck

 

[chuckbear]

Perhaps..Perhaps not..

The isolator and the combiner might be different solenoids.

They are the same solenoid. Chuck

 

[CharlesinGA]

Winnebago for years used a solenoid that had plain copper contacts and was rated for 80 amps. It is famous for the contacts burning up and while solenoid functioned, it clicked when power was applied to the windings, it would not pass current. My 2007 View was in this situation when I bought it in 2015 with 18K miles on it.

The fix is to install a Cole Hersee 24213 which is rated at 200 amp continuous and has silver-tungsten plated contacts. It has two small terminals (one positive and one negative, doesn't matter which is which) vs the original solenoid with one small terminal (positive, with the case being the ground) so it requires a short jumper from a small terminal to ground.

If you have this type of solenoid, I can highly recommend this one. It is commonly used as a replacement in the WBO community. Caution, never let the nuts against the body of the solenoid or the terminal studs. to turn as the contacts can become misaligned.

Charles

 

[chuckbear]

Winnebago for years used a solenoid that had plain copper contacts and was rated for 80 amps. It is famous for the contacts burning up and while solenoid functioned, it clicked when power was applied to the windings, it would not pass current. My 2007 View was in this situation when I bought it in 2015 with 18K miles on it.

The fix is to install a Cole Hersee 24213 which is rated at 200 amp continuous and has silver-tungsten plated contacts. It has two small terminals (one positive and one negative, doesn't matter which is which) vs the original solenoid with one small terminal (positive, with the case being the ground) so it requires a short jumper from a small terminal to ground.

If you have this type of solenoid, I can highly recommend this one. It is commonly used as a replacement in the WBO community. Caution, never let the nuts against the body of the solenoid or the terminal studs. to turn as the contacts can become misaligned.

Charles

Thanks, Charles. This is the solenoid I am replacing the current one with. Chuck

 

[Gary RV_Wizard]

If that was lead acid battery, would be concerned about it. An LA battery ran below 50% is questionable. 10.5 volts is 50%. if it was below 10.5 the battery may have been damaged, even though the charger brought it back up.
Also,idling the engine for short periods will draw moisture into the crankcase when it cools. A half hour or so drive is the best way. That also circulates the transmission fluid.

All the Voltage vs State-of-Charge tables I've ever seen put the 50% level between 12.0v & 12.1v. Here's one stating 12.06v. 10.5v is considered 0% - totally dead!

 

[gwinger]

All the Voltage vs State-of-Charge tables I've ever seen put the 50% level between 12.0v & 12.1v. Here's one stating 12.06v. 10.5v is considered 0% - totally dead!

Those are static measurements. Putting a load on the battery will give you the actual battery condition.
If the battery voltage drops below 10.5 with a load, it's time to replace it. My wife's car would not start, only clicking. the battery showed 12 volts, until she hit the starter. It dropped to 4 volts.