julesa
10 kW
- Joined
- Jun 23, 2008
- Messages
- 950
The post below is what I've come up with while shopping for batteries (I'm still saving up my money)
so any corrections/suggestions/pointing-out-misconceptions are VERY welcome.
Lead acid deep cycle AGM batteries can be found for around $0.20 per rated watt hour which, when you factor in the Peukert effect, works out to more like $0.40 per real watt hour at an average 10-20 amp load. They are heavy and will probably only last, at best, half as long as any other battery, and a lot less than LiFePO4 provided you have a good BMS on your LiFePO4 pack. On the plus side, if you don't need your e-bike to go very far (less than 10 miles, or farther if you pedal a lot), lead acid batteries can give you plenty of current for a low price. With cheap 2c continuous rated batteries, you'll need to buy 20Ah or bigger to give you enough current to get you up that nasty hill on your commute.
NiCd can last almost as long as LiFePO4 if treated carefully. It weighs about half as much as lead-acid, and about twice as much as Lithium.
5c rated NiCd packs go for about $0.90 per watt-hour at http://www.ebikes.ca
3c rated NiCd packs there are $0.63 per watt-hour.
2c rated NiMH packs there are $0.76 per watt-hour
Not sure why anyone would buy those NiMH packs with the lower current output and higher price, and NiMH has a shorter cycle life than NiCd so they will go dead sooner... ??? I'm assuming the c-rates above are a measure of max continuous current. Ypedal pointed out that NiMH packs are smaller then NiCd for the same amount of energy... but if volume was that important to me I'd just buy lithium anyway.
NiMH packs are also available at batteryspace.com for $1.12 per watt-hour.... again, doesn't seem like a good deal - max continuous current is 3c:
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2538
Ping LiFePO4 packs -- he's charging about $0.63 per watt-hour if you e-mail him and order a custom-size pack directly from him. This price doesn't include shipping, which is probably $120-$150 for an average pack. Many reports of good customer service can be found -- probably the most reputable seller on ebay. Comes with BMS and a 2A charger.
According to StevenR the BMS high current cutoff is actually 60A on the 48v 20Ah pack.
Contact Li Ping at: pingping227@hotmail.com
http://stores.ebay.com/PingBattery
Headway 48V20Ah LiFePO4 pack -- $620 = $0.65 per watt-hour. Like Ping's batteries, they come with BMS and charger, but shipping them from China is expensive (around $150 per pack?) so it's more like $0.80/wh shipped to your door. There are conflicting reports on how the quality of these batteries compare with Ping's. According to Headway, "The continuous discharging current of our existing pack of 48v20Ah is 60A, and the max. peak discharging current is 80A." That says to me that I'm less likely to hit a BMS cutout on a steep hill than with Ping's packs. Hopefully it doesn't mean I'm more likely to shorten the pack's lifespan by stressing the cells. This seems like the best bargain if you don't need DeWalt/LiFeBatt/PSI/etc. high current output. Anyway, from what I've read so far, 60A continuous should be plenty for a general purpose e-bike.
The charger provided with the pack is 3 amps, made by B&R Industries. I haven't seen any reports from people who have bought Headway's pack but some have bought loose cells and have gotten good customer service from Victoria (She's responsive, there were a couple bad cells in one of the orders but they were replaced at no charge).
Contact Victoria at: market@headway-cn.com or chcj55@hotmail.com
http://headway-cn.en.alibaba.com/pr...48v20Ah_LiFePO4_lithium_ion_battery_pack.html
FoxxPower LiFePO4 -- $0.86 per watt-hour, BMS is included, charger is not. They're in the US so shipping isn't as much as Ping/Headway. These look like Thundersky cells, but if I remember correctly, Zane claims they're not. Recommended working current is 3c, so these cells are probably pretty comparable with Headway's and Ping's. Contact Zane at: zane@foxxpower.com
http://www.foxxpower.com/tech.html
Toolpacks:
Power tool batteries are pretty much guaranteed to put out as much current as you would want, so the advantage there is that you only need to buy as much battery as you need range, though this will shorten their life if you're pushing the edge of their capabilities. With a Ping pack, you've gotta buy 20Ah or more just to give you enough current to get up a hill. But that same pack will probably take you 40 miles or more, which is more than some people need. On the other hand, toolpacks are more expensive. Also, you'll need to either buy multiple toolpack chargers (and maybe even carry them all with you now and then), or build/buy a custom BMS and charger.
Note: LiMn cells will probably weigh a little less and be a little more compact per watt hour than LiFePO4, but LiMn batteries available right now usually have a cycle life around 1000 charges or less; LiFePO4 will last you twice as long or more before you need to replace it.
Canadian Tire Yardworks LiMn 20v 6Ah at $110 each = $0.92 per watt-hour
Yardworks batteries can put out up to 5c (30A/pack) - a little less than some other toolpacks are rated, but still pretty good for the money.
Milwaukee LiMn 28v 2.6Ah at $99 each = $1.36 per watt-hour
Bosch 36V 2.0Ah packs at $80 each = $1.11 per watt-hour
DeWalt nano LiFePO4 36v (actually ~33v) 2.3Ah at $140 each = $1.85 per watt-hour
Or if you want loose cells but you don't want to take the pack apart yourself you can buy them from johnrobholmes for $15.50 each = $2.04 per watt-hour:
http://holmeshobbies.com/product.php?productid=135&cat=22&page=1
LiFeBatt/PSI raw LiFePO4 cells seem to go for around $40 each, or about $1.25 per watt-hour delivered to your door. This is probably the best deal if you want/need high current output (these are rated at 12c continuous!?!). If you're racing, need to go fast but not far, or carry a very big load up a short steep hill, LiFeBatt and DeWalt/A123 will be able to handle anything you can throw at them. But you need to come up with your own BMS -- Edit: A BMS kit should be available soon here for somewhere around $90: http://www.tppacks.com/products.asp?cat=26
LifeBatt LiFePO4 packs -- includes high quality BMS - about $1.96 per watt-hour
Edit -- updated 10/21:
Elite Power Solutions seems to have a decent product for a good price, and you don't have to pay the shipping from China. They have 20Ah cells, so the choice is simply between 24v, 36v, and 48v packs, unless you want to buy individual cells.
NOTE THERE IS NO BMS. No low voltage cutoff, no cell balancing, though EPS says their charger will not overcharge the pack, I would still expect problems when the cells eventually get out of balance. If I was going to buy one of these, I'd do it intending to buy a BMS and install it on the pack myself. It would still cost about the same as you'd spend on a Headway 48V 20Ah pack including shipping.
As for the quality of the cells, EPS claims a peak output of 13.7 hp for the 48v pack, lessee... 214 amps. Just noticed on their web site the cells are rated 3c continuous, 10c peak. So these cells are probably pretty close to Headway's -- while they may be capable of more, you probably don't want to take them over about 4-5c (80-100A) if you can help it, but that should be more than enough for almost all e-bikes.
I do like the fact that these prices (around $0.65/wh) include a 6 amp charger:
Subtracting $79 (their price for the included 6A charger) it's about $0.55/wh.
24v 20Ah - $331 plus shipping (USPS from Arizona)
36v 20Ah - $477 plus shipping
48v 20Ah - $623 plus shipping
so any corrections/suggestions/pointing-out-misconceptions are VERY welcome.
Lead acid deep cycle AGM batteries can be found for around $0.20 per rated watt hour which, when you factor in the Peukert effect, works out to more like $0.40 per real watt hour at an average 10-20 amp load. They are heavy and will probably only last, at best, half as long as any other battery, and a lot less than LiFePO4 provided you have a good BMS on your LiFePO4 pack. On the plus side, if you don't need your e-bike to go very far (less than 10 miles, or farther if you pedal a lot), lead acid batteries can give you plenty of current for a low price. With cheap 2c continuous rated batteries, you'll need to buy 20Ah or bigger to give you enough current to get you up that nasty hill on your commute.
NiCd can last almost as long as LiFePO4 if treated carefully. It weighs about half as much as lead-acid, and about twice as much as Lithium.
5c rated NiCd packs go for about $0.90 per watt-hour at http://www.ebikes.ca
3c rated NiCd packs there are $0.63 per watt-hour.
2c rated NiMH packs there are $0.76 per watt-hour
Not sure why anyone would buy those NiMH packs with the lower current output and higher price, and NiMH has a shorter cycle life than NiCd so they will go dead sooner... ??? I'm assuming the c-rates above are a measure of max continuous current. Ypedal pointed out that NiMH packs are smaller then NiCd for the same amount of energy... but if volume was that important to me I'd just buy lithium anyway.
NiMH packs are also available at batteryspace.com for $1.12 per watt-hour.... again, doesn't seem like a good deal - max continuous current is 3c:
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2538
Ping LiFePO4 packs -- he's charging about $0.63 per watt-hour if you e-mail him and order a custom-size pack directly from him. This price doesn't include shipping, which is probably $120-$150 for an average pack. Many reports of good customer service can be found -- probably the most reputable seller on ebay. Comes with BMS and a 2A charger.
According to StevenR the BMS high current cutoff is actually 60A on the 48v 20Ah pack.
Contact Li Ping at: pingping227@hotmail.com
http://stores.ebay.com/PingBattery
Headway 48V20Ah LiFePO4 pack -- $620 = $0.65 per watt-hour. Like Ping's batteries, they come with BMS and charger, but shipping them from China is expensive (around $150 per pack?) so it's more like $0.80/wh shipped to your door. There are conflicting reports on how the quality of these batteries compare with Ping's. According to Headway, "The continuous discharging current of our existing pack of 48v20Ah is 60A, and the max. peak discharging current is 80A." That says to me that I'm less likely to hit a BMS cutout on a steep hill than with Ping's packs. Hopefully it doesn't mean I'm more likely to shorten the pack's lifespan by stressing the cells. This seems like the best bargain if you don't need DeWalt/LiFeBatt/PSI/etc. high current output. Anyway, from what I've read so far, 60A continuous should be plenty for a general purpose e-bike.
The charger provided with the pack is 3 amps, made by B&R Industries. I haven't seen any reports from people who have bought Headway's pack but some have bought loose cells and have gotten good customer service from Victoria (She's responsive, there were a couple bad cells in one of the orders but they were replaced at no charge).
Contact Victoria at: market@headway-cn.com or chcj55@hotmail.com
http://headway-cn.en.alibaba.com/pr...48v20Ah_LiFePO4_lithium_ion_battery_pack.html
FoxxPower LiFePO4 -- $0.86 per watt-hour, BMS is included, charger is not. They're in the US so shipping isn't as much as Ping/Headway. These look like Thundersky cells, but if I remember correctly, Zane claims they're not. Recommended working current is 3c, so these cells are probably pretty comparable with Headway's and Ping's. Contact Zane at: zane@foxxpower.com
http://www.foxxpower.com/tech.html
Toolpacks:
Power tool batteries are pretty much guaranteed to put out as much current as you would want, so the advantage there is that you only need to buy as much battery as you need range, though this will shorten their life if you're pushing the edge of their capabilities. With a Ping pack, you've gotta buy 20Ah or more just to give you enough current to get up a hill. But that same pack will probably take you 40 miles or more, which is more than some people need. On the other hand, toolpacks are more expensive. Also, you'll need to either buy multiple toolpack chargers (and maybe even carry them all with you now and then), or build/buy a custom BMS and charger.
Note: LiMn cells will probably weigh a little less and be a little more compact per watt hour than LiFePO4, but LiMn batteries available right now usually have a cycle life around 1000 charges or less; LiFePO4 will last you twice as long or more before you need to replace it.
Canadian Tire Yardworks LiMn 20v 6Ah at $110 each = $0.92 per watt-hour
Yardworks batteries can put out up to 5c (30A/pack) - a little less than some other toolpacks are rated, but still pretty good for the money.
Milwaukee LiMn 28v 2.6Ah at $99 each = $1.36 per watt-hour
Bosch 36V 2.0Ah packs at $80 each = $1.11 per watt-hour
DeWalt nano LiFePO4 36v (actually ~33v) 2.3Ah at $140 each = $1.85 per watt-hour
Or if you want loose cells but you don't want to take the pack apart yourself you can buy them from johnrobholmes for $15.50 each = $2.04 per watt-hour:
http://holmeshobbies.com/product.php?productid=135&cat=22&page=1
LiFeBatt/PSI raw LiFePO4 cells seem to go for around $40 each, or about $1.25 per watt-hour delivered to your door. This is probably the best deal if you want/need high current output (these are rated at 12c continuous!?!). If you're racing, need to go fast but not far, or carry a very big load up a short steep hill, LiFeBatt and DeWalt/A123 will be able to handle anything you can throw at them. But you need to come up with your own BMS -- Edit: A BMS kit should be available soon here for somewhere around $90: http://www.tppacks.com/products.asp?cat=26
LifeBatt LiFePO4 packs -- includes high quality BMS - about $1.96 per watt-hour
Edit -- updated 10/21:
Elite Power Solutions seems to have a decent product for a good price, and you don't have to pay the shipping from China. They have 20Ah cells, so the choice is simply between 24v, 36v, and 48v packs, unless you want to buy individual cells.
NOTE THERE IS NO BMS. No low voltage cutoff, no cell balancing, though EPS says their charger will not overcharge the pack, I would still expect problems when the cells eventually get out of balance. If I was going to buy one of these, I'd do it intending to buy a BMS and install it on the pack myself. It would still cost about the same as you'd spend on a Headway 48V 20Ah pack including shipping.
As for the quality of the cells, EPS claims a peak output of 13.7 hp for the 48v pack, lessee... 214 amps. Just noticed on their web site the cells are rated 3c continuous, 10c peak. So these cells are probably pretty close to Headway's -- while they may be capable of more, you probably don't want to take them over about 4-5c (80-100A) if you can help it, but that should be more than enough for almost all e-bikes.
I do like the fact that these prices (around $0.65/wh) include a 6 amp charger:
Subtracting $79 (their price for the included 6A charger) it's about $0.55/wh.
24v 20Ah - $331 plus shipping (USPS from Arizona)
36v 20Ah - $477 plus shipping
48v 20Ah - $623 plus shipping
), but he said they got too hot at that level, but that 10C to 3v is fine. I had to take it down to 2.5v 'cause I couldn't figure out how to take into account voltage sag at the start of the CBA test! :lol: At 7C it would sag below 3v and shut off the test before recovering back up above 3v. Doh.
