jonescg wrote:Those $1 per Wh Nano LiPo cells look pretty crazy, but how do they go when built into a 6-8 kWh pack for a motorbike, say? It seems like a lot of dicking around with BMSs etc. I mean, 5 of these packs in series will give you the desired voltage, and need 30 BMS units. If you don't plan on going very far... Any need for a BMS on these guys??
When you make packs with LiPo in parallel, you just connect them in parallel at the balance taps. If you wish to run say something like a 30S 112v nominal pack (127v HVC), then it makes no BMS difference if you just connect 5 x 6s packs in series, or 50 x 6s packs in series. The pack made from 50 would just be 5 groups of cells paralleled 10p, so they charge/discharge/behave the same as if they were just 50Ah cells.
For a racing application, no need for a BMS. I've never used a BMS for LiPo, and see no reason for the additional complexity and failure points if you're a competent user. Yes this means you have to use judgement and not over-discharge the pack and wreck it, and keep an eye on cell voltages once in a while to make sure things aren't getting out of wack, but that's a task that takes about 1minute total to check with a battery medic, and I only bother to check once every 10-20 charge cycles or so.
For a race bike, you just buy the amount of packs that can be configured to suit your voltage and capacity demand, plug in all the balance taps to parallel them, connect all the discharge leads as needed, and go for it. Charge it all as 1 big pack with however many meanwell chargers you need to meet your charge time requirements.
That method would be TERRIBLE for an ebike for your grandma or some clueless newb, but it's the very lightest, most compact, and least things-to-go-wrong solution for a race bike by a wide margin.
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