Hi,
I've been reading quite a bit on this subject, here and elsewhere for a couple days. As someone relatively new to EV (e-bike to be specific), the information and choices are daunting... SLA, LifePO4, NMC, flat foil packs, round cells, building from hobby LiPos, etc. What's tough is some information is great but it can be dated by a year or two and this seems like such a rapidly evolving space in terms of tech and prices that what applied a few months ago likely doesn't apply as much at present.
My vehicle is a e-bike, so feel free to move this post to that forum, but I figure this was more of a battery specific question that was somewhat vehicle agnostic so I would post it here.
After buying a pair of those cheap 48v 1000w direct drive hub kits off ebay I was initially planning on buying SLA batteries... they were cheap (at least upfront) and the weight savings, while important, was not important enough to me personally to pony up 3x as much for a lithium based battery. After doing more research I started reading that some chemistries can have 5x the cycles. Other articles indicated that a 12AH SLA would provide less range than a 12AH Lithium counterpart. I figured AH was AH regardless of the source, but I'm no expert in this and still learning. These two factors change things a lot, because if one can truly expect 5x (or more) cycles and/or if the same capacitance in Li based batteries does provide more range then it makes sense. Coupled with the weight and form factor advantages it becomes all but a no brainer.
The initial outlay for these batteries is quite steep though and I'd be concerned if I'm investing so much into batteries that is the right battery. I use LiPo all the time for RC, but never in sizes like this. But I have enough experience to know that it is not uncommon with the value oriented (and sometimes with the more expensive ones) to get failures, puffy packs, etc - at least in LiPo and especially in the foil flat packs. At $5 - $20 its cheap enough to retire without being too annoyed. At $200, $300 or $500 that would be painful. And since I have two bikes to power I would hate to think about replacing buying another pair any time soon.
A lot of what I've read suggests LifePO4 is still currently the best battery in terms of value and performance, at least for an application like mine, would that be correct? Or would you suggest looking for another type of chemistry or technology? There seems to be a lot of really good cells out there also, and I'm not opposed to building my own packs as I've done a lot on smaller scales, but I see a lot talk about fake or subpar cells and I can't seem to find retailers selling certain cells at prices some are claiming. As much as I would like to have the time to buy recycled laptop batteries and build a pack I just don't think I have the time or fortitude to test all the cells and have the confidence in them being stored in my motorhome while I am sleeping.
At this point in time the best priced battery has been one on ebay (albeit from China) for a 48v 12AH for $230, and is only described as a ebike Li-Ion, so I would hope it was LifePO4 as opposed to LiPo, but who knows.
I guess the ultimate question is, for someone making their first battery purchase at this point in time, which solution has the best watt/dollar ratio over the course of the lifetime, and can anyone recommend any suppliers that have good prices and quality? If there was a quality pack available that had the 1000 cycle life I see claimed at under $2 per watt hour that would be a pleasant surprise, but everything I've seen so far makes me believe it is wishful thinking. :?
Thanks!
Bobo
I've been reading quite a bit on this subject, here and elsewhere for a couple days. As someone relatively new to EV (e-bike to be specific), the information and choices are daunting... SLA, LifePO4, NMC, flat foil packs, round cells, building from hobby LiPos, etc. What's tough is some information is great but it can be dated by a year or two and this seems like such a rapidly evolving space in terms of tech and prices that what applied a few months ago likely doesn't apply as much at present.
My vehicle is a e-bike, so feel free to move this post to that forum, but I figure this was more of a battery specific question that was somewhat vehicle agnostic so I would post it here.
After buying a pair of those cheap 48v 1000w direct drive hub kits off ebay I was initially planning on buying SLA batteries... they were cheap (at least upfront) and the weight savings, while important, was not important enough to me personally to pony up 3x as much for a lithium based battery. After doing more research I started reading that some chemistries can have 5x the cycles. Other articles indicated that a 12AH SLA would provide less range than a 12AH Lithium counterpart. I figured AH was AH regardless of the source, but I'm no expert in this and still learning. These two factors change things a lot, because if one can truly expect 5x (or more) cycles and/or if the same capacitance in Li based batteries does provide more range then it makes sense. Coupled with the weight and form factor advantages it becomes all but a no brainer.
The initial outlay for these batteries is quite steep though and I'd be concerned if I'm investing so much into batteries that is the right battery. I use LiPo all the time for RC, but never in sizes like this. But I have enough experience to know that it is not uncommon with the value oriented (and sometimes with the more expensive ones) to get failures, puffy packs, etc - at least in LiPo and especially in the foil flat packs. At $5 - $20 its cheap enough to retire without being too annoyed. At $200, $300 or $500 that would be painful. And since I have two bikes to power I would hate to think about replacing buying another pair any time soon.
A lot of what I've read suggests LifePO4 is still currently the best battery in terms of value and performance, at least for an application like mine, would that be correct? Or would you suggest looking for another type of chemistry or technology? There seems to be a lot of really good cells out there also, and I'm not opposed to building my own packs as I've done a lot on smaller scales, but I see a lot talk about fake or subpar cells and I can't seem to find retailers selling certain cells at prices some are claiming. As much as I would like to have the time to buy recycled laptop batteries and build a pack I just don't think I have the time or fortitude to test all the cells and have the confidence in them being stored in my motorhome while I am sleeping.
At this point in time the best priced battery has been one on ebay (albeit from China) for a 48v 12AH for $230, and is only described as a ebike Li-Ion, so I would hope it was LifePO4 as opposed to LiPo, but who knows.
I guess the ultimate question is, for someone making their first battery purchase at this point in time, which solution has the best watt/dollar ratio over the course of the lifetime, and can anyone recommend any suppliers that have good prices and quality? If there was a quality pack available that had the 1000 cycle life I see claimed at under $2 per watt hour that would be a pleasant surprise, but everything I've seen so far makes me believe it is wishful thinking. :?
Thanks!
Bobo