question

I think you are on the right track with the battery being the cause of the problem as it is common to both chargers and both chargers are exhibiting similar symptoms.

The chargers are displaying classic symptoms of their output being suddenly disconnected from the battery. The BMS inside the battery would be doing this sudden disconnection as it deems the battery to be full or more likely it deems the charge current too high near the top of its charge. Hence the reason why you only see this happening in your absorb phase.

You could try to reduce your absorb Voltage setting a bit so that the charge current will be less close to the top of the charge and the current will be within the bounds that the BMS has reduced it to at that point.

@Adam Dobbs

I agree with wkirby. But there's one other issue that shows in your first screen. The pv Voltage spikes are the mppt tracking every 10 min, and that's normal. But then the tracked V settles down way too close to Vbat. You'll forever have trouble with the mppt cutting out when this happens. Doesn't appear to be charging much anyway, and the panel may be faulty too.

I appreciate both of your inputs. I emailed SOK about my battery since they have a 7 year warranty. Hopefully it's not too much hassle to get it resolved. I did try lowering the absorb voltage at varying stages and I couldn't seem to get the spikes to stop unless I lowered it dramatically enough (below battery voltage) then it seems to skip absorb and go straight to float. I may tinker with it again.

JohnC, I'm a little confused on the voltage settling too low. Do you mean it's settling too low between the spikes every 10 minutes (~16-17v)? The watts it pulls in Bulk charge seem to be consistent with what I'd expect, however, I originally had two 100w panels and one went bad on me already. They are flexible panels that I know aren't reliable long-term yet. I still have the bad one connected in parallel. I get very weak voltage out of it but I don't pull any watts from it. I thought maybe that panel could be causing issues but it seemed to make no difference when I disconnect it during the voltage spikes. I'm glad you mentioned those spikes every 10 minutes as I was wondering what those were.

@Adam Dobbs did you ever get an answer from SOK on this? I have been having issues with my inverter/batteries shutting off and finally figured out it was the same issue as you. At first I thought it was my fridge kicking in causing a big voltage drop due to the in rush current... however recently this happened and I noticed the same trend as you, I get a big spike in voltage and the inverter starts beeping and goes into "protect" mode.