Yes, that would work. Any arrangement is fine, as long as there are the same number of new and old cells in each p-group.
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ok thanks. i initially thought of that but didnt know if it would actually work.
about putting packs in parallel, if i had my 10s8p and a older 10s2p, wouldnt the 2p pack die first and since the 8p pack still has juice, would it keep pulling from the 2p pack? or does it pull from both packs in a way that makes it both stay at same voltage meaning both will die at the same time. besides keeping voltage the same, does the type of cell matter? for example 30q parallel with vtc6 or 30q with 40t?
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As long as they’re connected in parallel, the packs will discharge at the same rate. So if you start with both at 42, and ride them down till they’re both 36, at no point will one be at a different voltage than the other.
That’s the reason for making sure each p-group has the same number of new and old cells as well, so that the old cells keep the new cells in line, basically.
The 2p pack will die first, that’s correct. As it continues to drain both packs, that pack will become more dangerous and eventually will need to be replaced.
No, this is incorrect.
Current will not be shared evenly, and this may be an issue, but the voltage (and thus overall state of charge) will never be different between them.
So you can put a new 10s higher p and an older less p packs? I would assume otherwise according to the other forums.
Why do you use these style connectors?
Running whole packs in parallel is a much worse way to do it than on a p-group basis due to the current sharing issue. But one isn’t going to “die” beofre the other. They will both reach LVC at the same time.
Plus you need a second BMS for the second pack.
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The bms is understandable. So basically the current flow of one pack will end and it will just consume the second? I was told it would still consume the depleted.
No. They will both supply current at the same time. The pack with higher capacity/lower resistance will supply proportionally more current (uneven current sharing), but it’s not going to use one all the way down and then switch. It doesn’t work like that.
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Edited: oh okay. Thanks. I was unaware.
No, One will not still have juice while the other is done. They will both be running out of juice at the same rate.
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a little confused. so how would it work for the current, would i have more amps to use by combining a bigger and smaller battery pack? or since the smaller battery is giving a portion of current it would be somewhere in between the amount of rated amps of 1 pack and the total rated amount of both packs? is uneven current bad?
This is why mixing packs is less desirable:
The answer is “It’s complicated.”
It depends on the exact size and type of pack, the age of the cells, the type of cell, the difference in size (or cell, or type) between the two packs, as well as the phase of the moon and whether Mars is retrograde or not at the moment of calculation.
As a general guide, the closer in type/size/age/etc the two packs are, the closer it is to a direct 1+1=2 relationship.
The farther from that you get, the more you should derate the current split.
If you have a big difference and push things hard, the smaller pack can unintentionally end up providing a bigger fraction of the overall current than it should, which is Bad.
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simply, Yes and yes
This is why we always advise against mixing. It will just degrade faster overtime anyway and you have to replace
Either use all old, or all new
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I agree. I gotta look more into batteries now.
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so it would be safer to set the battery + setting to at or below just 1 of the packs rated amps?
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Yes, that would be the safest.
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no, because when u r draining the 2p pack, the 8p pack is also charging it to (trying to) keep it in same voltage of the 8p pack. that’s where the uneven current drain comes from. this wear out the 8p pack faster by having higher load on them, but at the same time u r killing the 2p pack even faster since its being charge and discharge constantly, also since this charging is bypassing the bms, it probably will get unbalance very quick
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ahh i see. guess im not doing that anymore.
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