Bonwit said:
It appears the BMS on my Luna Wolf-Pack battery has gone south. The unit cuts out way early, and exhibits other odd behavior.
A bad BMS usually results in no output, or not charging, or some other pretty much non-functional behavior.
Cutting out early is typically a symptom of a cell group that has lost capacity, either from fail(ing)(ed) cells, or an interconnect problem between cells so some of them are no longer participating in current flow.
It is *possible* for a BMS with a stuck-on balancer to *cause* a cell group to have lower capacity than the rest...but you have to have access to the BMS sense wire connector to disconnect it and test some things to find out if that is the case.
With a potted pack, you would need to remove the potting at least around that connector sufficiently to measure voltages on all of the sense wires in pairs, starting from the battery negative to the most negative sense wire, then moving up one wire at a time, moving both meter leads at the same time, and writing down each voltage as you go. Any that are different indicate problematic cell groups.
If they are all identical, then the entire pack could be losing capacity, or a group could have sufficiently high internal resistance (or disconnected cells) that it causes votlage sag under load but not just sitting there.
I recommend asking Luna what specific resin or other compound was used to do the potting, so that you can find out what solvent to use to remove it, without experimenting or just hacking around in there.
