Charger working but not charging lithium batteries

[steve2777]

I have a 2018 Thor Siesta ST, and recently had my 2 100 ah Battleborn lithium batteries severely discharged. When I connected to shore power, the Progressive Dynamics lithium charger converter started charge mode. It cycled through several charge cycles, with an audible "click" every few seconds that stopped the charging, but would reset in a few seconds. After a few minutes, the click stopped and no further charging occurred. My first conclusion was that there was an auto-reset breaker that failed or overheated. I tested the charger at its output terminals, and it was putting out 14.55 volts, so I concluded there was no breaker in the charger itself. However no charging was reaching the batteries.

Both the batteries and the PD charger were upgrades from the coach's original lead acid system, but no change was made to the intervening wiring. When the coach's engine is running, an installed dc to dc charger charges the batteries per normal. But no charging voltage is making it from the PD charger to the batteries.

Does anyone know if there is a breaker between the converter charger and the battery compartment, per Thor's original installation, that could have failed? Thanks.

[DavidEM]

With no shorepower connected do the lights and other DC stuff work? If no, then the battery is somehow disconnected.

David

[steve2777]

The batteries are charged from my running the engine (dc to dc charger), so yes, dc accessories are working. The problem is, that (or some solar) is the only way to charge the batteries. The converter charger's output is not making it to the batteries.

[16ACE27]

Originally Posted by steve2777

Does anyone know if there is a breaker between the converter charger and the battery compartment, per Thor's original installation, that could have failed? Thanks.

You have two points of interruption for that current path:

The reverse polarity fuses in the breaker panel, and:

The latching relay AKA battery disconnect - USE/STORE switch.

[steve2777]

Thanks Ace. I'm going to try a continuity test for the + and - wires from the charger to the batteries to see if I can figure out where the disconnect is.