thuktunflishithy
New here
- Joined
- Jul 10, 2015
- Messages
- 7
Time to build a new battery. I built the last one from generic laptop cells. It was a 14s10p build made for use with a Golden Motor Smart Pie. I cracked the rim right around the time I won a Magic Pie Edge and I've been riding with that ever since. My bike is my commuter, I ride it to work pretty much every day, even in the winter as long as the roads are clear. It's a short ride, 6kms each way, depending on the wind I use 2.5-3.5Ah each way. The motor draws 21A.
I don't want to build such a large battery again, I'm riding with a small 10Ah battery I bought from China a few years ago and it handles so much better with less weight and the ability to mount it in the frame triangle instead of on a rack on the back. This battery doesn't deliver enough current though so I had to reprogram the motor to only draw 15A. Yeah. Sucks.
I'm looking at a couple of sources for cells, one is low capacity but high discharge rate and the other low current but higher capacity. 15A/1300mAh vs 5A/2400mAh. It'll cost about the same amount for the same number of cells. I'm thinking of 14s5p-14s7p. My last homemade battery still has lots of capacity but just won't deliver current well anymore, the voltage sag is about 10v now and recovery time is slow. I used it for 2 years, put about 6000kms on it so I got my money's worth. My goal for the next build is to try to extend that lifespan.
How are 15A low capacity cells over time? Do they retain high current capability as they age? 9.1Ah would be enough capacity for me and my typical usage. If I'm going to find myself with a 10v sag in 2 years again though I'd just as soon as use the larger capacity cells and have the option for long weekend rides occasionally.
So to summarize, which is a better cell for longevity, a high discharge rate/low capacity cell or a low discharge rate/high capacity cell?
I don't want to build such a large battery again, I'm riding with a small 10Ah battery I bought from China a few years ago and it handles so much better with less weight and the ability to mount it in the frame triangle instead of on a rack on the back. This battery doesn't deliver enough current though so I had to reprogram the motor to only draw 15A. Yeah. Sucks.
I'm looking at a couple of sources for cells, one is low capacity but high discharge rate and the other low current but higher capacity. 15A/1300mAh vs 5A/2400mAh. It'll cost about the same amount for the same number of cells. I'm thinking of 14s5p-14s7p. My last homemade battery still has lots of capacity but just won't deliver current well anymore, the voltage sag is about 10v now and recovery time is slow. I used it for 2 years, put about 6000kms on it so I got my money's worth. My goal for the next build is to try to extend that lifespan.
How are 15A low capacity cells over time? Do they retain high current capability as they age? 9.1Ah would be enough capacity for me and my typical usage. If I'm going to find myself with a 10v sag in 2 years again though I'd just as soon as use the larger capacity cells and have the option for long weekend rides occasionally.
So to summarize, which is a better cell for longevity, a high discharge rate/low capacity cell or a low discharge rate/high capacity cell?
I need to use 48v+ packs, the 2ah ego that I have now is over the limit (112wh). It was dirt cheap though - only $42 with a charger so I will just sell it offbefore we leave. I think the echo 58v 2ah is like 106wh and just over the limit too. I plan on completely disassembling our full suspension bike and stuffing it into 2 suitcases and the carryon and use my clothes for padding 
