Should Shore Power Charge the Chassis Battery on a 2021 DX3?

[Gregarious]

When plugged into 50-amp shore power overnight, is the charging system supposed to charge the chassis batteries at any time, even if only after the house batteries are fully charged?

Two mornings ago, I checked the batteries on the hallway control panel and it showed both house and chassis batteries were fully charged.

I then drove to an RV park and plugged into 50A service at about 8 PM. Around 7:30 AM, I checked the batteries from the hallway panel. The house batteries were fully charged but the chassis batteries were only partially charged (see the attached screen shot).

The key was not in the ignition, the headlights were in the off position and no accessories were plugged into the chassis' 12V receptacles.

If the system is supposed to charge the chassis batteries, how should I troubleshoot the issue? Thanks!

[rskeans]

My DX3 is a 2018, different from yours. I have a B.I.R.D. i had a situation where the chassis battery was not getting charged when connected to 50A. I accidentally discovered that if I ran the engine so that the chassis battery was at 14V then the solenoid connecting the chassis and house batteries closed solving the problem.

Try running the engine and monitor the chassis battery voltage using the instrument cluster. Just might solve the problem.

[KRedburn]

looks like you may have lithium coach batteries and AGM chassis batteries.

from your panel
13.9 coach batteries lithium full charge
12.8 chassis batteries AGM full charge.


However, with shore power chassis batteries will be charged AFTER coach batteries. It does not show when or if your BIM switched to charging the chassis.

[Gregarious]

Originally Posted by KRedburn

looks like you may have lithium coach batteries and AGM chassis batteries.

from your panel
13.9 coach batteries lithium full charge
12.8 chassis batteries AGM full charge.


However, with shore power chassis batteries will be charged AFTER coach batteries. It does not show when or if your BIM switched to charging the chassis.

Thanks. That's correct--lithium coach and AGM chassis. You may have misread the panel voltage for the chassis batteries--it read 12.6v, not 12.8.

When I checked the panel yesterday morning, I didn't note the voltage of the chassis batteries, I just observed the visual meter was green and completely filled. However, this morning it was yellow, not completely filled, and showed 12.6V.

From Googling it, I see that AGM batteries generally have 12.8-12.9V when fully charged. That, and the fact the panel showed a reduction in their charge, suggests they didn't charge despite being plugged into 50A all night.

The charger/inverter remote panel showed the house batteries were fully charged before I went to sleep last night so it seems something is off since the chassis batteries degraded overnight instead of getting topped off.

[bclemens]

The link below, takes you to the interactive owners manual on the Dynamax website.

In the component manual section, there is a manual that explains the operation of the Li-Bim.
https://forestriverinc.help/#/dynama...ltiple-1068137

MOST charts will show a 12V AGM battery being at 12.73 volts at 100% charge and that would be with a battery in perfect health, with nothing connected. Your chassis batteries will always have "some" load on them. Radio memory, truck sensors, the electric step.

If it is only dropping to12.6 over night I would not give that a single thought.

[bubbles]

Maybe this

The Li-BIM monitors the battery voltage of both the lead acid engine and lithium-ion house batteries over long periods of time. If it senses a charging voltage, it connects the two batteries together. It will both charge the house battery from the alternator, as well as the engine battery from shore power, depending in where it sees a charging Voltage. It will disconnect the house battery if the alternator exceeds 14.4 Volt, to prevent overcharging of lithium-ion batteries. The Li-BIM will charge the house battery for 15 minutes when it sees a charging Voltage on the engine side, then disconnect for 15 minutes to allow the alternator to cool down, and repeat that cycle until the house battery is full.

For the engine battery the Li-BIM will monitor the battery Voltages on both sides, and charge from the house battery if it sees a charging Voltage there, and less than 12.6 Volt on the engine side. It will charge for a maximum of 1 hour this way, then disconnect again to take another Voltage reading.

[KRedburn]

Originally Posted by Gregarious

Thanks. That's correct--lithium coach and AGM chassis. You may have misread the panel voltage for the chassis batteries--it read 12.6v, not 12.8.

When I checked the panel yesterday morning, I didn't note the voltage of the chassis batteries, I just observed the visual meter was green and completely filled. However, this morning it was yellow, not completely filled, and showed 12.6V.

From Googling it, I see that AGM batteries generally have 12.8-12.9V when fully charged. That, and the fact the panel showed a reduction in their charge, suggests they didn't charge despite being plugged into 50A all night.

The charger/inverter remote panel showed the house batteries were fully charged before I went to sleep last night so it seems something is off since the chassis batteries degraded overnight instead of getting topped off.

I would say you are working just fine. There is always a "load" on the chassis batteries. Only way to drop all loads on the chassis batteries is to physically disconnect the battery terminals.

[Gregarious]

Thanks, everyone, for your feedback. That was helpful and I'll consider this issue resolved as my charging system working properly.

Greg