I will openly admit, after seeing that video on YouTube that the cells are providing different current from the different capacities cells, my theory was flawed..
I was working on the assumption that the loads are equal from each cell, which would in theory drain each cell equally, which makes...
Shame you are not in the UK, I have just had an ebike battery come in for repair with NCR18650PF cells that seems to be dropping voltage...
Still got to finish testing cells to see if only a few are off... But the plan at the moment is to recell with LG MJ1 and give a higher capacity pack...
If I were quoting and building the pack, I would be asking the following questions
1: what is the space that you have available to fill with cells for a pack?
2: what is the rating of the controller... 3000W at 72v is around 42A, is that Peak or continuous?
I have designed batteries for ebikes...
I used to do this with 6s RC Charger... It is a Pain in the Arse to do but yes it can.... I advise adding the balance leads though so that the RC Charger will Balance up the cells....
The other option i use is a MingHe BST 900w and a computer power supply, i have even done this with a 42V 5A...
From China makes me very suspicious, especially after my conversations with some of the suppliers that eventually when questioned on why so cheap, admitted that they were clones or rewrapped grade B or Grade C cells
That has made me steer clear of the Chinese market for cells unless i can get...
The ebike world seems to be transitioning to the 21700 cells although i find that most of the cases readily available and the frames(stealth Bomber) are made for the 18650 sizes with internal diameter of 142mm which allows for a folded pack to fit in perfectly with protection fitted around them.
Samsung 35E with max continuous discharge or 8-10A
Or
LG MJ1 with 8-10A max discharge
Both are between 3400 and 3500mAh
I use those for lower power ebike batteries to give max range
Note that these cells are quite good but degrade quickly at close to max discharge and any charge more than...
This took a while to find... But here is what eventually happens when a string is connected to a single nickel strip...
This was a reputable brand name battery that came in for repair...
The easiest way to redo this without a total dismantle would be to Disconnect the single series connections that are grey.... Connect series Red... and then use 3 x 14AWG pref 12AWG at the bottom... Blue... if you connect all series like the top set of red you will get good current flow.
Also...
From the Pictures of your battery pack, when you are discharging, can you feel where the series connectors are, are they getting warm?
Although building a pack that way will work, its not advised to have 1 single connection to each series string...
I know this is probably going to be a pain...
No worries Floyd...
You were right though the mAh is way too high that they advertise, they are calculating it at 3.5Ah per x the 30 that are in... Its actually 35Ah
I have one of the Allpowers Here that was brought in for repair and same guy has another one with similar issues...
The problem with this one is that it wont charge from either solar or mains power... I took it to bits and it looks like the BMS has a problem... I didnt take any photos of...
This is the only video that i can see that shows what @daromer and @ajw22 meant by higher capacity cells will give higher current which will in turn keep the voltage and capacity drain equal through the pack...
@Wolf
That sounds fantastic and probably as close as you can possibly get.
Other than the results, my interest would be to 2 points.
1: If we see depletion of the lower capacity cells first, is there a current flow from higher capacity cells to depleted cells across the parallel connection
2...
@givre
Sorry My Bad, i was just in auto pilot with 18650 - 3.0v - 4.2v cells
but yes you can still use an ANT BMS, you just have to make sure the settings are all in for the correct cell voltages.
I am sure that once a month maybe twice a month would be ok. if you go with the ANT BMS, you can set the charge and Discharge Min and Max
It lets you set the BMS to cut power at Cell level... so each 1s would be monitored to say 3.1v and cutoff and then charge would be set to 4.1v and stop...
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