I want to make a battery pack out of 18650’s like 10s5p will make it bigger up to 8p to get the range I want. how much battery is needed for 25+ real world miles?
General rule of thumb is 10wh per km, on flats. Hills and air resistance will heavily affect the range you’re able to output on your pack. 10s5p should get you 28 miles on flats. Drastically lower if you go up a bunch of hills or face a lot of air resistance/bad roads.
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I thought it was 1,000mAh is about one mile.
no, that doesn’t include working voltage which is just as important for range estimation. You compare with watt hours, which is amperage multiplied by nominal voltage.
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In my own experience you want to have at least 60 cells in a pack made of 18650’s regardless of discharge rating. Anything smaller will die an early death and be a waste of investment. A year ago people thought this was ridicules but we are starting to see smaller packs die sooner than expected. Heat is the killer and larger packs just don’t get as hot as when pushed hard.
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What’s the capacity of the cell you’ll use ?
true however the possibilty of a short or bad cell also increases
A proper pack is built with cell level fusing. 
hmm never thought bout that
Somehow this rule works only for belt drives. Hub motors seem to chew up a little bit more juice.
Probalby due to the higher current needed to push hub drives to speed. If you were to be at speed 100% of the time, you’d probably see similar results.
Time for 26650 to replace 18650’s for esk8.
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Is there a significant amount of energy efficiency with a single motor?
18650’s have a longer track record. 26650’s also die early if driven past 1C for too long. Ideally you want to cruise at 0.5C and burst no more than 2C. High discharge cells do not last long when pushed hard till DOD. They work in power tools but they are allowed to cool between driving screws etc…
Guess we’ll have to follow up with @Namasaki in a couple months to see how his pack is lasting 
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I well designed pack should last at least 3 to 4 years. At least that is my design goal.
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430 watt hours will do it in a typical 15/36 belt drive system street build with 83mm wheels and 190kv motors. I did it on a 12S build. As long as you’re mostly on flats, you can get 25 miles while doing 15-20mph easily. I’ve actually achieved close to 25 miles on a 360 watt hour lipo pack while keeping it around 15mph, that was on a similar set up but at 6S with NTM 5060 270KVs.
Depends on how/where you ride too. With hub motors you don’t have nearly the resistance from the motor, so you can cruise much farther without power. On my belt drive, there are grades where I needed power to go down, whereas my hub does it at good speed without. You can also push a hub almost like a regular board if you need to increase your range.
I don’t think I could fit 60 cells on my deck with electronics. I barely fit 20 26650’s
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Then it is time to go to larger decks.
I had to built one by myself to fit 72, it is definitely very large and very heavy. I think it is no solution for an everyday commuter, as you do not want to carry it around, but very nice for long distance driving for fun.