RV House and Chassis battery question

[Tom_Whitney]

Hello,

We recently purchased a 2022 Sunseeker 2400B. This included the solar package and I also added 200W of external panels. We did our first boondocking camping this past weekend and of course the batteries did not hold up as well as I had hoped and we had to run the generator more than what I would have wanted.

One thing that I noticed that has me confused. As the battery level on the house batteries dropped, the chassis batteries dropped by the same amount. Why would this be? I would think that these two battery systems would be totally isolated.

Any ideas on why my chassis battery charge level would drop as power was consumed in the RV?

Thanks for any ideas that you have!

Tom W

[Reverse_snowbird]

Originally Posted by Tom_Whitney

I would think that these two battery systems would be totally isolated.

That would be an incorrect assumption. Usually the house and chassis batteries are connected in a class C. For example, driving our class C charges the house battery fairly quickly.
However, I have no idea why draining one would drain the other.

Welcome to the forum!

[BehindBars]

Originally Posted by Tom_Whitney

I would think that these two battery systems would be totally isolated.

Originally Posted by Reverse_snowbird

That would be an incorrect assumption. Usually the house and chassis batteries are connected in a class C. For example, driving our class C charges the house battery fairly quickly.
However, I have no idea why draining one would drain the other.

Welcome to the forum!

The batteries can be connected, but not usually. Connections are routed by the Battery Isolation Manager, which is inside the Battery Control Center. The chassis alternator or house converter charger can charge both battery sets, but not at the same time. The BIM will cycle through selection of battery(ies). I believe the only time all batteries are interconnected is when you push the momentary emergency start switch.

Originally Posted by Tom_Whitney

Thanks for any ideas that you have!

Tom W

The short answer is that the house 12 volt load should not be discharging the chassis battery. The batteries could possibly be wired incorrectly or the BCC/BIM has a fault. Or, possibly the installation of the solar setup has somehow interconnected the battery sets.

[PhilFromMaine]

Originally Posted by Tom_Whitney

Hello,

We recently purchased a 2022 Sunseeker 2400B. This included the solar package and I also added 200W of external panels. We did our first boondocking camping this past weekend and of course the batteries did not hold up as well as I had hoped and we had to run the generator more than what I would have wanted.

One thing that I noticed that has me confused. As the battery level on the house batteries dropped, the chassis batteries dropped by the same amount. Why would this be? I would think that these two battery systems would be totally isolated.

Any ideas on why my chassis battery charge level would drop as power was consumed in the RV?

Thanks for any ideas that you have!

Tom W

I don't have any experience with class Cs. However, I would think there should be a battery isolation system "stock" in the vehicle. If not get one installed. Better yet, get a DC-DC charger that allows your alternator to charge the house batteries, but protects the engine battery from being drained.

[BehindBars]

Originally Posted by PhilFromMaine

I don't have any experience with class Cs. However, I would think there should be a battery isolation system "stock" in the vehicle. If not get one installed. Better yet, get a DC-DC charger that allows your alternator to charge the house batteries, but protects the engine battery from being drained.

The OP’s unit will have come standard with a battery isolator in the Battery Control Center. The diagram attached, specific to their model, shows it located in the entry stepwell.

[Tom_Whitney]

Here's an update on my issue with the chassis battery discharging from the house/RV 12v load.

I contacted Forest River tech support. Although they answered very quickly and attempted to assist, they didn't have an answer to my problem and suggested that I bring the RV in for service to have this looked at.

So, I contacted Precision Circuits, which makes the Battery Isolation Manager (BIM160) used in my RV. They also replied very quickly, and we did some diagnosing over e-mail. It seems that my BIM was in a confused state (out to lunch!). So, we jumped the "ground to sig" terminals on the BIM, which engaged the BIM. I took some voltage readings and then removed the jumper.

I think ran through another set of tests where I ran a heavy 12v house load for a while, which did draw down the house batteries as expected, but did NOT draw down the chassis battery.

So, it seems that by jumping the BIM it got everything back into a correct state where it could function properly. If I do see this situation happening again, where the chassis battery is being drawn down, then it will be time for a new BIM.

Thanks for all that replied to this thread

[BehindBars]

Thanks for your update on this issue. What was found about the BIM will possibly help someone else now or in the future. I think there is at least one other thread running on the forum with a similar symptom.

[JLeising]

Sounds similar to problem described in this thread:
https://www.forestriverforums.com/fo...in-258940.html

[Sunseeker16]

I dread the day I have to purchase a new unit with all these fancy electronics. My 2016 with manual switches and not much technology suites me just fine. I always wonder what people will do in 10 or 15 years when these fancy controllers and devices are no longer available and quit working.

[tomkatb]

The future will be difficult with the new fancy electronics.

Many cannot handle new stuff! In 5 years?

I am a KISS person. My 18 Hathaway is very simple.