Nice project! How about an 18650 cell in a holder? This way, the battery is replaceable, with spares available anywhere, and with tons of well tested and reputable cells on the market.
Guess I did a bad job when researching 18650 the first time. I need around 10A of max current draw, and the batteries I looked at was limited between 5A and 8A. I shouldn't have stopped there, when I look now, 18650 comes with all kind of different current ratings. And, yeah, they are the perfect size, and more trustworthy than the lipo I use now. I also think I will get almost twice the capacity with a 18650 (around 3000 mAh compared to 1500mAh). I will definitely test out a few 18650.
And bear in mind that 18650s are
capable of delivering enormous currents, far above what they’re rated at. (The rated current is what you can draw without damaging the battery.)
I had an oopsiedaisy with a 1s3p battery (in all-metal holders, which shorted when one battery’s plastic sleeve was damaged with a tiny pinhole right near the positive terminal). Within seconds — and I mean literally 2 or 3 seconds — the battery holders were glowing bright red hot. I pried the batteries out within 5-10 seconds, but even so the damaged one then spewed its contents on the floor. Luckily nothing caught fire.
Anyhow, some quick research found that 18650s are capable of short-circuit currents of 50-100A EACH, so my three in parallel shoved 150-300A through a battery contact!
Those were Samsung cells rated for 8A, IIRC.
Two lessons: 1. Don’t rely on the battery’s insulating sleeve alone. 2. Make sure your protective circuits are in order.
So using 18650s, sufficient current is the least of your problems.
Don’t invent your own lithium charging, protection, or battery level monitoring circuits. There are dedicated ICs for all of those. (The latter are called “fuel gauges”, by the way.)