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I dont think any of you will ever build a battery pack but if you do, here is a "rule of thumbs" when reading the cell datasheet:
1. Take the maximum continuous discharge rate (CDR) stated by the datasheet and cut it in half. This is your peak discharge rate. Take your newly calculated peak discharge rate and cut it in half again. This is your maximum continuous discharge rate.
While Battery manufacturers are not lying about their CDR ratings, when they don't tell you is your cells will get very hot (think 100C) if you discharge them at CDR all the time. On top of this, your battery will not last nearly as long, maybe only a few hundred cycles. If you want a battery pack to both last a long time (think 5+ years) you need to be discharging the cell at 1/4 what it is rated by the manufacturer UNLESS you have a way to actively cool the battery pack. Automakers have active heating and cooling systems for their battery pack but you likely do not, so keep discharge rates at a quarter of the rated datasheet.
For example, my previous ebike had a peak discharge rate of 72v at 50A. When the bike was cruising, I was only drawing 25A. This means I have to build a battery pack that could theoretically do 100A continuously.
2. RC lipo batteries are grossly overrated. Take the maximum CDR stated on the battery and cut it in half. This is the true manufacturer rated maximum CDR.
I know this because I have done tests discharging RC lipo batteries at it's rated CDR and it only lasted a few cycles before the cells puffed. RC lipo batteries are notoriously overrated, so take the stated maximum CDR and cut it in half. This is now the " true" manufacturer rated discharge.
I have built at 12 battery packs before out of all sorts of chemistries from SLA to RC lipo to 18650. 18650 is my favorite because its easily accessable and cheap, but I some people like RC lipo because they hold their voltage really well until the very end of their cycle. I had to learn the hard way about all thus stuff so maybe you won't have to.
The thing that is really keeping me from getting back into my ebike hobby is I have no practical reason to have an ebike these days. I would prefer to have $1500 in the bank than an unnecessary electric bike for just getting around college campus when my 2011 diamondback outlook did the job just fine.
I need to figure out a way to monetize these skills. I monetized my computer obsession by starting circletech, maybe I could build custom ebikes for stupid people that feel the need to go 60mph on a bike (cough cough @BuckGup). Hmm..
Also if you are reading this buckgup, there is a reason I stopped at 60v for my bike. Last year I got in a bike crash at 72v that broke my jaw, and I still have the scars from that accident. If you for some reason feel to need to go 40mph on a bicycle, just get yourself a motorcycle. Is it cool to show off to people that your creation can go dangerously fast? Of course! But it's not worth it as a daily driver vehicle. There is a good reason most ebike manufacturers bikes top out at 30mph, and that is because bicycle frames just aren't designed to handle speeds greater than that. Please be very careful on your bike because I have first hand experience of what can happen when things go wrong.
lol you could sell premade packs on eBay. Most are Chinese mystery cells for insane mark ups. Also I have a full face motorcycle helmet for this reason. I plan to mount a 3 position switch as my ESC supports 50%, 80% and 120% speed limits. Not sure what the 120% is yet lol. But for riding on campus I can’t be going 50mph as I’ll end up with tickets and a law suit.