I’m doing a 12S10P pack and I don’t expect to draw more than 50A, so max ~5A/cell. I’m leaning toward the 50E because it’s cheaper and higher capacity, and its 15A max current isn’t a bottleneck. 50E datasheet quotes 70% capacity after 1000 cycles (3.0V discharge cutoff), and P45B datasheet quotes 85% capacity after 500 cycles (2.5V discharge cutoff), which extrapolates to 70% after 1000 cycles, so both have good cycle life.
It seems like the P45B might handle a deeper 2.5V discharge better…? But since the 50E is rated 500mAh higher it may not matter. Both cells are rated down to 2.5V. Mooch seems to like both cells, but only reports cycle life for 50E, not for P45B…
Molis are pretty popular here, and the P45B’s resistance is MUCH lower, so I wanted to see if anyone had any opinions or experience with P45Bs that might make it a better choice than the 50E for performance, longevity, etc.
Yes, just to be clear, this is the EVE 50E, NOT the Samsung 50E. Title, price screenshot, and datasheet links also all show I’m talking about the EVE cell.
10P group with an energy cell is gonna generate a lot more heat than a 10p group of a power cell in the same usage, likely negating any supposed cycle life advantages.
mooch often states that the Cycle life claims are just guaranteed minimums, and not to be compared
Dont get hung up on capacity numbers, unless you are discharging below 3.0v at 0.2c.
My first battery used cells adequate on paper with ple ty of overhead for my intended expected load.
It ran way too hot, and had atrocious sag.
Dont use an energy cell in a power cell application, even with 10 in parallel, in my opinion.
If I may play devil’s advocate, the EVE 50E cell datasheet shows that the cell is operational at a 60C ambient temperature, with a higher cell discharge cutoff of 70C.
You’re right about the thermals, at high current it can work up some heat. I only expect 50A sustained around acceleration and hill climbing, but cruising is closer to 15-20A (25A if we’re being conservative on thermal budgeting). If we look at Mooch’s measured resistances and do some napkin math with DC resistance losses calculated by (I^2 * R) per cell, parallel group, and pack:
EVE @ 50A: (5A/cell ^ 2) * (21mOhm) = 0.525W/cell, 5.25W/parallel, 63W in 12s pack
EVE @ 25A: (2.5A/cell ^ 2) * (21mOhm) = 0.131W/cell, 1.31W/parallel, 15.75W in 12s pack
My pack will be stacked at most 2 cells high, which should be a standard surface area-to-volume ratio for esk8 packs. It’s a beefy pack so it has a high thermal mass too. I appreciate any anecdotal experience on pack thermals vs current draw, especially when the pack has multiple layers of insulation.
If this is true, then I think you’ll be totally fine with the 50E. If you want headroom for more current in the future (which, realistically, a 12s10p pack is MASSIVE for a low power build like you’re describing) then I’d go for the higher current cells. Maybe not the P45B though. There seems to be better options these days, on both power and price.
According to the battery mooch chart the EVE 50E outputs more energy than a P45B even at 10A but the EVE has approx 2.2x the resistance so it will get much hotter under high load or charging.
With a very rough calculation if you get 20wh/km and 100% of the energy from the cells the 50E would get you 8.4km further based off the 5A discharge Wh output.
If you are building a 12S10P you only plan to use for light riding that a 10S4P would be strong enough for and you just want more range, and don’t intend on charging very fast either I would get the 50E because of the big cost difference too.
When run at 5A the EVE 50E delivered about 8.5% more energy (Wh) than the Molicel P45B down to 2.8V. Longer run time should be about the same.
The cycle life specs in the datasheets are just guaranteed minimums and are practically useless for comparing cells with. Any cell we might use will last for years if not abused.
