Pylontech x Sofar - battery in standby mode far too early

[dangermouse]

You can probably disconnect the batteries from the inverter, power them up and leave them to balance themselves, my rationale for charging each individually first was simply to make the process quicker overall.

[Caesium]

I thought this balancing would happen pretty much whenever they're in a stack, ie even when in use. They're just batteries connected in parallel after all, and any batteries connected in parallel will self-balance. The one with greater voltage will feed current to the one with lesser.

Having them in use might make this take longer but it'll still happen.

[dangermouse]

I thought this balancing would happen pretty much whenever they're in a stack, ie even when in use. They're just batteries connected in parallel after all, and any batteries connected in parallel will self-balance. The one with greater voltage will feed current to the one with lesser.

Having them in use might make this take longer but it'll still happen.

You would think so, but from comments I've read in other places on the internet this isn't necessarily true. But "the internet" isn't always right!

[Tinbum]

You would think so, but from comments I've read in other places on the internet this isn't necessarily true. But "the internet" isn't always right!

To say the least, their is so much incorrect stuff that most can't be believed especially on Facebook.

The batteries should stay balanced if set up correctly. I do have one pylontech that does seem to be different to all the rest. It works fine but the full capacity always shows different to all the rest. If you watch its charge and discharge currents they always differ from the rest. It can be over 1amp difference.

[nowty]

The batteries should stay balanced if set up correctly. I do have one pylontech that does seem to be different to all the rest. It works fine but the full capacity always shows different to all the rest. If you watch its charge and discharge currents they always differ from the rest. It can be over 1amp difference.

A runt of the litter and a bitch because it works so you can't have a replacement.
But its always going to annoy.

[Oldgreybeard]

To say the least, their is so much incorrect stuff that most can't be believed especially on Facebook.

Absolutely spot on, and there are many internet sources that I just never bother looking at now as they are mostly full of self-perpetuating false information. It seems few bother to properly check anything now, there's a culture of "I saw it on Facebook/Instagram/YouTube or whatever so it MUST be true".

The batteries should stay balanced if set up correctly. I do have one pylontech that does seem to be different to all the rest. It works fine but the full capacity always shows different to all the rest. If you watch its charge and discharge currents they always differ from the rest. It can be over 1amp difference.

Maybe this is what I saw last night, one pack behaving differently to the others. What you say makes sense, I measured the energy used to recharge the pack to 100% (I set it to charge to 100% last night just to do this check) and the capacity seems spot on, it took 16.8kWh to charge to 100% from the 20% the Sofar was reporting, which seems right for a stack of six US3000Cs. Easy to start worrying that something is amiss when it may well not be.

[ducabi]

I'm thinking if it's another parameter (e.g. actual voltage) rather than SOC which prevents for further discharge. I've switched batteries around and am charging them to 100% for the last couple days. I've seen maybe 1 day when it allowed for 19% SOC but most of the time it stops at exactly 29%.
When I updated the software (3.36) and increased DOD to 90% (from 80%) it allowed for SOC around 15-16%, but that was only once, at the day of change. Annoyingly I can't get my diy cable to work to see what happens inside and I don't remember how it worked when temperatures where higher (now it's 2-5 in garage).

[openspaceman]

This subject is why I conjectured that it is less problematical to have a single battery of 280 prism cells with individual cell balancing and leave the inverter to manage maximum voltage, current and DOD rather than have a gang of batteries and one master but there were comments that the BMS is more complicated than that.

[Tinbum]

This subject is why I conjectured that it is less problematical to have a single battery of 280 prism cells with individual cell balancing and leave the inverter to manage maximum voltage, current and DOD rather than have a gang of batteries and one master but there were comments that the BMS is more complicated than that.

Im the opposite, I'd much rather the battery bms telling the inverter what to do.

[openspaceman]

This subject is why I conjectured that it is less problematical to have a single battery of 280 prism cells with individual cell balancing and leave the inverter to manage maximum voltage, current and DOD rather than have a gang of batteries and one master but there were comments that the BMS is more complicated than that.

Im the opposite, I'd much rather the battery bms telling the inverter what to do.

Not really a matter of being opposite, I'm looking for an explanation of why the BMS needs to tell the inverter what to do?