Why does BMS say my CATL pack is 100 ah? It's 302 ah.

[gaveupontv]

I was going to top balance my new 4s CATL battery pack, but decided to charge it first, and then 'top up' any cells to 3.65 Volts. I'm using the victron12./30 1 output. It's showing 30 amps going in right now, around 420 watts. I'm using 8 gauge 2 foot long leads with ring terminals. These are the 302 ah cells. with the overkill solar 4s BMS.
The BMS is all put together and hooked up, and I'm charging to the brass terminals on the exterior of battery box.

This how it's done, right? Anybody see any errors? I'll come back and individually charge the cells, taking off the bms is I have to. At this point, the bms app (overkill solar) is showing the 4 cell voltages only .004 volt difference (low of 3.343 and high of 3.346-3.347) I assume I'm in the "knee" so that doesn't tell you a lot about the SOC?

Richard

 

[gaveupontv]

The charger has a option to drop the amperage to 15 amps (from 30) I assume these values are well within normal amounts of current going in? The bms is controlling everything, I think?

 

[gaveupontv]

Overkill solar bms is showing SOC is 43% (43.4 ah of 100 ah- but they are 302 amp hour? The charger has probably been on the battery pack for about an hour.

 

[gaveupontv]

There is room in the battery box for my bms. I know some people put plywood and some kind of clamps (I was thinking of a large hose clamp around the pack.
What are advantages? It's harder to 'bulge' them? Any disadvantages? I'm interested in these cells lasting a long time. If I don't have enough capacity, I'll get another pack to run in parallel. I've already purchased by 12 volt Victron shunt, and Victron 12 inverter.

 

[Brett V]

Why not parallel the cells and do a proper top balance? Without seeing individual cell voltages and the BMS settings, its hard to tell what's happening in there.

 

[gaveupontv]

The bms tells me the individual cell voltages. I'm sure it has the settings of cells somewhere too. I'm pretty fuzzy there. Are the charge controller and bms setting the same? If not, which ones?

 

[Brett V]

If you're using the Overkill app, you need to go in to settings and set up your battery capacity.

 

[gaveupontv]

Cool, thank you, I will do that!

 

[gaveupontv]

Cool, thank you, I will do that!

when I updated the Overkill bms app for capacity, it instantly showed I had the cells/battery 95% full, it was less than 50% before that.