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Comment by mhb | Hacker News Reader

I didn't think that the absolute series voltage would matter much - the right number of cells will be close enough for the voltage regulation in the laptop. My big concern with that approach is matching the cells. It's not practical for me to do that myself since I would need to test a lot of cells. Or maybe I am overestimating the negative consequences of using unmatched cells. But I don't think so.

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How do you mean matching them? Just get 8 NCRs or whatever and that's that.

The absolute series voltage matters in that you don't want to over- or undervolt it by 3.7V usually.

Matched in terms of voltage and discharge characteristics. Many of the battery guides mention the possibility of the weakest cell in an unmatched pack being improperly charged. And that that would result in shorter life for the pack or worse consequences.

Eh, sure it matters somewhat. But if you think you're getting matched cells when you buy anything with a battery pack from China you're kidding yourself. So a home made pack isn't going to be any worse off that the cheapest kit you already have. If you go to the trouble to assemble your own pack with matched cells you'll be ahead of the game, if that floats your boat.

Hmm, I was assuming the charger would have a balancer, if it doesn't you can get in trouble, yes.

Maybe you are right that it is a balancing charger. That would simplify things a lot. Although some of the packs have some of the cells in parallel so would have to be carefully matched.

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