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I don't think this has been covered in other posts.

I have a 3.7V 6000mAh li battery pack and three 3.7V 2000mAh li battery packs. If I wire the three 2000s in parallel to make a 6000mAh cell, then wired that cell in parallel with the single 6000mAh pack, would that negate the issues of wiring parallel with batteries of differing capacity?

I am trying to increase the capacity of a power bank I just put inside a Bluetooth speaker I built, (think of JBL Charge series, but with more features and a much bigger battery.) I have the 6000mAh battery, and tons of smaller ones, and the idea occurred to me that if all the smaller ones were identical in age, capacity, voltage, and charge, and I matched their total charge (6000) to the other battery (6000) then for charge/discharge purposes that might alleviate the load on any other batteries in the parallel whose total capacity is less than the largest.

What do you think? Might it work? If not, is there anything I can add into the circuit to allow me to use the diverse capacities I have of battery? My thought was just adding a switch, to switch from the 6000mAh battery to the three 2000mAh parallel battery cell.

JRE
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  • Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. – Community Oct 12 '21 at 11:02
  • You are adding a lot of *ifs* in your matching… the problem is not only charge but internal impedance of the cells. *The* most important thing is avoid cell reversal – Lorenzo Marcantonio Oct 12 '21 at 11:12
  • *Might it work?* Yes, it **can** work, I've seen commercial products doing this **BUT** then the batteries were identical (manufacturer, type, **age**) except their size and capacity. If you **know** that the cells are the same chemistry type and you balance them first (make them the same voltage) there should be no issue. But **only** if you connect **all** in **parallel**, not in series. In series capacitances **must** match. When in parallel that matters less. – Bimpelrekkie Oct 12 '21 at 12:04
  • Why would it matter if you parallel three 2 Ah batteries first and then parallel that 6 Ah pack with another 6 Ah pack? The batteries will all be a single 12 Ah made of various paralleled packs anyway. – Justme Oct 12 '21 at 12:12
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    Does this answer your question? [Connect 3 Lithium Polymer battery with different capacity in parallel](https://electronics.stackexchange.com/questions/401834/connect-3-lithium-polymer-battery-with-different-capacity-in-parallel) – Marcus Müller Oct 12 '21 at 18:14

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