mickk wrote: ↑
Aug 25 2018 1:59am
IM leaning toward 1 x 48v 13ah or similar frame mounted pack, I can use the existing downtube 36v 12 as well then.
I figure that will give me 100k range in pedal assist mode.
There are no hard numbers for range, but you can do some reasonable estimates. If your previous battery was 36v 12Ah that means you had 432 watt/hours and that got you 40-50 km. A 48v 13Ah gives you 624 watt/hours so that suggests more like 60-70 km range.
Let's figure it another way. using my personal experience. My moderately fast commuting averages about 20 wh/mi. But I'm going up and down hills and trying to cruise at between 20 and 25 mph most of the time. This is probably faster than you intend to go, but not a lot faster. At this rate you have a 50 km range. If I slow down a lot, turn off my headlight, and bypass my boost converter, I figure I could probably get 15 wh/mi which gives me a 67 km range.
Now it is perfectly possible to get more than a 15 wh/mi range. After all, regular bicycles can cover many miles with zero electric assist. But the reality is that I seldom see an ebike getting better than 15 wh/mi and covering distance at a "reasonable" clip unless it is a recumbent.
If we now consider that batteries will age and that you don't want to run your battery down to empty very often, it seems pretty likely that 60-70 km is probably going to be your practical range limit. If you want to go 100 km regularly, you need a bigger battery. a 48v 20Ah battery might get you there. But going a bit bigger would make it more of a sure thing.
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats