Yes, its declared in their specs 
Alright, thanks ill look around some more and check my battery’s max
Pretty sure my charger uses the same software, when actually charging try hitting the arrow key to see the individual cell charges. You never want to charge a LiPo at more than 1C or 1 times its capacity in Ah, so if you have a 3Ah battery 3A should be the maximum charge current set on the charger (for the safety of the battery and anything around it). The charger should end with showing ‘full’ and the mAh put into the battery at the end of the charge cycle.
As to the original issue as others have said there is likely some sort of connection issue if you aren’t seeing power pulled from cells then they aren’t connected to the circuit show us pics of the wiring between the batteries and the ESC (actual pics not product pics)
alright, taking pictures
Sorry it took a while, phone ran out of battery, here is the actual wiring of the board:
Okay nothing obvious in the pics wrong (possibly issues in the connections themselves/soldering the wire to the xt-90s but seems pretty unlikely). Are you able to see the individual cell voltages when you hook the batteries up choose charge then hit the arrow key? would be nice to see pics of those per cell voltages on each battery just to see where things stand right now. When manufacturers make the battery packs they match the internal resistance across groups of cells so each cell in a given pack will have roughly the same internal resistance, in theory all the 30C or whatever C rating cells have the same internal resistance but the IR will increase over time as the cells are used so older cell may end up with higher IR than newer ones. IR is just the same as any other resistance except it’s the resistance in the battery itself, if you have higher resistance it will resist the flow of current and produce heat as a result (higher resistance or higher current equals more loss).
The only way it can be really pulling only charge from one battery in your case is if the resistance is so high between one of the batteries and the rest of the circuit that no charge is pulled through/from the battery but since they are connected in series that can’t possibly be true (kirchoffs law basically states same current going in one side comes out the other).
Anyhow long story short I’m still confused as to what’s going on, but would help if we can all see the individual voltage on the cells to maybe.
Alright, so right now i just charged both batteries in series on balance mode for about an hour, and this is the cell situation:
At this state it takes ages for it to go up 0.05v so this is basically the max I can charge for this setup and current batteries. If you want, I can connect the packs to the board and just run the motor on idle to discharge the batteries and see what cells/battery gets drained you can still see that the battery that was drained first has a little less voltage in it, mabye it can tell you something about the problem? Thanks
It all looks a bit botched together. Uncertain if you hooked up your balance leads correctly to the charger. Does a single 3s charge correctly using an original balance cable?
Would go with what @telnoi said as well just hook up directly with the original balance cable each battery individually and try to charge that way. If the cells are too out of whack voltage wise and you try to do the ‘balance charge’ I’m pretty sure it will attempt to drain charge out of whatever cells are too high, perhaps it is stuck attempting to drain charge from the higher cells/battery and attempting to push power into the entire battery is resulting in the ones with lower IR to get pumped up more and therefore out of balance again. I’d charge both batteries individually up to 4.2V if possible then try hooking them up and do a discharge test on the board (run it for a few minutes) then check the voltage on all the cells again to see how far they’ve drifted from each other and how much they’ve dropped from 4.2V (typically most of the mAh [juice] is in the 3.6-3.8 range so will generally drop in voltage pretty quickly from 4.2 to near 3.8 and most of the ‘life’ of the battery will be in that range of 3.6-3.8V)
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Alright, ill try that, and telnoi, im sure i connected it correctly because i made a post about it asking how to do it and they said its good, ill try to charge them alone now, what mode should i use? normal charge? fast charge? or balance?
Do balance charge but yeah just 1 of the 3S at a time.
ok, charging now at 5 amps (shows 4.2A actual charge)
Yeah the 5A you set is a maximum it will typically show less amps drawn as it gets closer to actually fully charged so nothing to worry about there.
its been 10 mins and it went from 3.84 3.84 3.83 to 3.95 3.97 3.95
pretty slow but going up
Yeah for 8Ah capacity charging at 5A it will take 8/5 = 1.6hrs (96 minutes) to charge from empty (around 3.5-3.6V) when putting them in series you are charging up at a higher voltage but the amperage and time should stay the same so long as you aren’t changing the capacity (Ah) or the charge rate (A). I’d guess you have about 20-30 minutes left to get it fully charged (tends be slower at the end since the current is going lower as the voltages get closer to each other… that is what the charger is putting out and what the battery is currently at, the voltage difference between the two is ultimately what determines the amperage).
ok that makes sense, thanks for explaning, makes me feel a little better knowing the long wait time is normal and that thats not another problem i have to deal with
@ShakeNBake7000 Just skimmed through this thread and looks like you’re getting lots of help here, no need for me to add anything technical, however can i check that at this point you’re charging in LiPo safe bags with possibly a fire extinguisher nearby.
I don’t expect you’ll need them, but i have that stuff even with batteries that i consider to be in top-notch condition, and these look like they’ve been through a bit. Not many people have the fire extinguisher, but a LiPo safe bag at this point is a must. Use it when charging please.
Well, i dont have a safe bag, you mind linking me one? ill buy it right now if its not expensive, and either way i never charge without me being there to watch it if something happens
battery seems to be stuck at 4.18 4.20 4.17 0.2A ill just start charging the other one
that’s the charger balancing the voltages, let it finish. It’s at 0.2A as it’s fine-tuning the voltages, most of the work is done at the end of a charge cycle when balancing.
£3 for a bag that’ll prevent a LiPo fire, jumbo version, this shouldn’t be a secondary concern.
*get 2