Any way to tell if parallel Chins batteries are disconnecting?

So I bought two 280ah Chins dumb batteries. That was a weird decision for me to make, both buying an off the shelf solution and skipping out on the ability to view any BMS data - but they were on sale

A series of mistakes followed, or at least things I would have done differently... but here's how it played out:

1) Both arrived at 13.18 volts, so I immediately paralleled them since the voltages matched and that's how they'll be used (let rest for a day paralleled)
2) I charged them with a new Victron BlueSmart 30 amp, my first time using one of their battery chargers
3) I set absorption voltage to 14.4 volts (Chins specs 14.2-14.6) and charged through 8 gauge welding wire cables
4) Since I hadn't set up (or even received) the rest of my stuff, there was no Victron smart network to connect to, so I banked on general accuracy of voltage due to using the thickest & shortest wire that would fit the charger

Result:

I fell asleep and woke up to the charger saying the process had ended due to disconnect, shy of 14.4v (IIRC 14.2), with 290ah pumped in. The batteries were resting at 13.6v after this, probably many hours after charging had ended. I'm expecting 560ah of capacity but if I only supplied 290ah and everyone says they arrive at well below 50% SOC (like 5%) then I'm not feeling so great about it.

The next mistake was just throwing them in my camper, paralleled. So I have no idea how well balanced the cells are inside of each battery. I don't know if one battery will disconnect at 13.9v and the other at 14.2v, or anything in between. They've been sitting in my camper with fridge running on a storage lot, being charged daily by solar to 14.2v with a 2hr absorption period for the last several days and all seems good, but I don't have any idea if one battery is disconnecting during this.

What would be your next step that doesn't include going back in time and running actual capacity tests on each battery individually? I have no idea if balancing actually starts at 14.2, so I don't know if I'm gradually smoothing things out with the 14.2 absorption voltage, and no clue if one is disconnecting during this

TL;DR regret buying dumb batteries

Seeing as they're both in parallel, what could you possibly do to bring them up equally that just running them wouldn't do? What's your peak charging amps?

Imbalanced batteries in series are a problem but I don't think parallel is except during initial connect so you don't trip or needlessly stress the BMS.

Yeah, I get that would be detrimental to a series system since components would cease to work, but having 300ah out of a 560ah bank would also be a major drag and not knowing what I can even set my mppt charging voltage to without knowing if its tripping one battery is double drag

Max I've seen from solar is 275w but I'm not discharging enough with fridge running (camper in storage lot) to not be back to 100% before the sun is even directly overhead. Anyway, 400w of solar (another 400 on the way), and can do a deep discharge this weekend on first trip in new camper and then recharge with converter/charger, victron 12v charger, and solar.. so I could probably find a way to hit it with 75+ amps

hour said:

Yeah, I get that would be detrimental to a series system since components would cease to work, but having 300ah out of a 560ah bank would also be a major drag and not knowing what I can even set my mppt charging voltage to without knowing if its tripping one battery is double drag

Max I've seen from solar is 275w but I'm not discharging enough with fridge running (camper in storage lot) to not be back to 100% before the sun is even directly overhead. Anyway, 400w of solar (another 400 on the way), and can do a deep discharge this weekend on first trip in new camper and then recharge with converter/charger, victron 12v charger, and solar.. so I could probably find a way to hit it with 75+ amps

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Set your boost and equalize voltage to 13.8V with a 2 hour equalize time. That's likely lower than your BMS turnoff voltage for your out of balance cells and give it time to equalize over a period of days. You really don't gain much more capacity going to a higher charge voltage. I test a lot of small LFP batteries for reviews and for say a 20AH LFP battery, the difference between stopping at 13.8V with a long equalization and 14.4V has been less than 0.5 AH.

AlpineJoe said:

Set your boost and equalize voltage to 13.8V with a 2 hour equalize time. That's likely lower than your BMS turnoff voltage for your out of balance cells and give it time to equalize over a period of days. You really don't gain much more capacity going to a higher charge voltage. I test a lot of small LFP batteries for reviews and for say a 20AH LFP battery, the difference between stopping at 13.8V with a long equalization and 14.4V has been less than 0.5 AH.

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Right, I always ran my main diy build to 13.8, but I had a bluetooth BMS on that so I wasn't operating blind, and I could customize the voltage that balancing began. I don't have that with the Chins batteries. With the Chins having charge specs of 14.2 - 14.6, it's likely that balancing occurs somewhere in there. I'd be happy with running 13.8 usually, and only running to higher voltages periodically to balance, but I already know there's some imbalance (assuming both batts) with the charger having cut off with "Disconnected" as the cause @ 14.2

If the batteries are in parallel its impossible for one to be at 13.9 and one at 14.2 by the very nature of them being in parallel so your early disconnect of one battery is not a concern.

shavermcspud said:

If the batteries are in parallel its impossible for one to be at 13.9 and one at 14.2 by the very nature of them being in parallel so your early disconnect of one battery is not a concern.

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oh yeah