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I need a dc output of 12V 60AH through 18650 li-ion battery cells to use with a 1000W AC inverter to power a 650 Watts computer ( each cell 3,7 Volts 3500 mAh )

One way would be make 17 packs in parallel ( each pack is 4 cells connected in series 4x3,7v=14,8 volts, 3500 mAh ) so the outcome would be 14,8 volts and 59,5 AH ( from total of 68 cells )

How about using a DC-DC step up converter? ( I know Boost converters are not 100% efficient )

Connecting 68 cells in parallel ( 68 x 3500 mAH = 238 AH and 3,7 Volts ) and using a DC-DC Step up converter to convert 3,7 to 12 volts? What is the downside?

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    \$\begingroup\$ The tesla cars did not become sensational for nothing. Once false move, and you risk major fires. Ideally, every cell should have its own controller. Cell voltages should range from 3.7 to 4.2V if you want a long life. \$\endgroup\$
    – Indraneel
    Commented Aug 16, 2018 at 14:46
  • \$\begingroup\$ Four fully charged Li-Ion cells in series produce 16.8V then the "12V" inverter output voltage will also be 1.4 times higher than you want (168V instead of 120V). \$\endgroup\$
    – Audioguru
    Commented Jan 1, 2023 at 17:44

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You can buy a ready-made battery, such as the 60 Ah unit from AA Portable Power or the 100Ah Li through Amazon for ~US$600, or heavier, less environmentally-friendly but cheaper lead-acid batteries for ~US$160.

This would be simpler than designing your own pack and balancing circuit, and avoid some of the liability should something go wrong... which is not to say that commercial products have no issues.

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  • \$\begingroup\$ Lead-acid car batteries are vastly more environmentally friendly than small lithium batteries. How can that possibly be? The rate of recycling. 99.something% of "car battery sized" lead-acids get recycled, because the recycling infrastructure is superb. Every garage, tire shop and auto parts shop has the dead battery bin and charges a $10 core when selling a new battery. Set one out on the curb and someone will take it. Scrapyards pay money for them. Contrast with lithium batteries where recycling is not ready for prime time, and random 18650s tend to end up in the trash. \$\endgroup\$
    – Harper - Reinstate Monica
    Commented May 4, 2023 at 4:49
  • \$\begingroup\$ @Harper-ReinstateMonica, lead is quite toxic, lithium and other metals in a cell are not. There are whole villages poisoned by lead battery "recycling". Some citations of the issue: thestate.com/news/local/environment/article270259797.html , e360.yale.edu/features/… , qz.com/africa/1231792/…, unicef.org/rosa/press-releases/… . \$\endgroup\$
    – DrMoishe Pippik
    Commented May 4, 2023 at 17:43
  • \$\begingroup\$ I'm not here to fight about that, but you're presenting an extremely lopsided view there. Those aren't lead problems; those are local governance problems that those citizens need to sort out. Scrap lead-acid batteries have far, far too low a weight-to-value ratio to ship very far, so they tend to be recycled locally, and it is easy to do well (just make an effort). But saying lithium has no environmental cost is dumb. You don't seem to be willing to be balanced here, so best of luck with that. \$\endgroup\$
    – Harper - Reinstate Monica
    Commented May 4, 2023 at 23:53
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I like to use the LiFePO4 batteries, which don't burn like regular lithium batteries, and you can buy them in "12 volt" units, say from Dakota Lithium or from the Amazon links that @DrMoishe Pippik recommended. The actual voltage ranges from 14 down to 11 or 12 as they discharge. I like the idea of using a converter, because you'll get a much more stable voltage. Make sure your converter won't discharge the cells too far or you might damage them. I haven't looked lately but there should be some converters available that can be set to protect your batteries. I use mine to power some ham radio equipment, and the problem with the converter idea is that it will generate a bunch of high frequency noise, inversely proportional to how much you spent on the converter. If you're handy you can build a filtered enclosure and solve that problem.

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