What's the best battery to get for Ebikes in 2008

recumbent

100 kW
Joined
Sep 7, 2007
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Location
Okanagan valley Canada
We still have Nicad packs available, which worked well on my bike for 5 years then died. Nimh is better, and readily available also.
THE lithium manganese on my Bionx is the best I've ever tried so far, but only for a few months.

My first choice: "li-mn" because you don't need BMS circuitry.

Are there better choices?
 
This is the same question I've been asking, and the answer I got 6 months ago is diffrent from now, too. By next aspring, I expect yet another answer.

I think it depends on your application. Lipo is the highest energy density and the highest discharge capacity, but only a medium life expectancy. I've found it as cheap as $1.01 a watt hour

LiFePO4 has a much longer life than Lipo, but its still an infant in the world of batteries, and fitting the technology to a practical aplication is still in the fronteer stages. I've found it as cheap as $1.11 a watt hour

Both of these technologies are better than lithium manganese, though. Higher energy density, lighter weight, longer service life, and lower cost.
 
This chart could help you to make your opinion about that:


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Drbass, thanks for the comparrison graph you supplied. It was a little hard to understand at first but those German words are similar to English. I;m told English is rooted in the germanic language.
Thanks for all the great help with the battery choices, only a few months away.
 
My first choice: "li-mn" because you don't need BMS circuitry.

What do you mean? Why are they different from other types? Wouldn't li-mn cells get out of balance just like others? I have a bunch of li-mn emoli cells in my garage right now, and I'm trying to figure out how to manage them.


Someone please explain this to me.
 
Most BMS don't balance cell voltage that i know of. However, the information about li-mn was from a Bionx video.
 
It depends on on what kind of BMS it is. Some include a balancer and some don't.

Look at this list of BMS available from Batteryspace.
http://www.batteryspace.com/index.asp?PageAction=VIEWCATS&Category=711
 
ALL batteries can use BMS systems, some more than others.

When you pay 150 $ for a battery pack and know how to use/care for it, a BMS that costs as much as the pack is not really cost effective...

But when you spend big $$$ and want to make sure that the pack is not forced into an un-safe and cycle-life killing situation it's an attractive option.

Problem right now is that not many BMS are rugged enough to stand the test of time and abuse tolerance is not a primary factor in their desing.

A bms is supposed to take the human factor out of the equasion by monitoring things for you, if you are well versed in battery tech and understand what repercussions over-discharge and over-charge and over-amp etc can and will do to a packs life.. then you can make due without one.

For those who really.. and i mean really just want to plug and play and not bother with any technical details about their battery.. a BMS is a MUST in my opinion.
 
recumbent said:
We still have Nicad packs available, which worked well on my bike for 5 years then died. Nimh is better, and readily available also.
THE lithium manganese on my Bionx is the best I've ever tried so far, but only for a few months.

My first choice: "li-mn" because you don't need BMS circuitry.

Are there better choices?

Where did you get these NiCads that lasted 5 years from?What are their specifications? How many amps is your controller? Mine are only a few months old and I find the performance worse than lead acid.
 
Johnbear said:
Where did you get these NiCads that lasted 5 years from?What are their specifications? How many amps is your controller? Mine are only a few months old and I find the performance worse than lead acid.

Regular "Sanyo, D size" batteries that were equiped with my Heinzmann 35amp controler with about 30 "D" cells in a rear bike rack package. When i say 5 years that referes to 5 summer seasons in the Okanagan=8 months usage per yr. They heated-up after a 16km ride where the charger wouldn't kick in till an hour or so after they cooled and the thermister signalled ok. Cost a fortune ($300 incl labour to solder) to replace them, but after about 3 years still going strong but don't hold charge as long, time to ballance the pack. Hope i can fix it.

edit: might only lasted 4 yrs, just guessing, long time ago.
 
Thanks for your response. Playing with batteries gets very expensive. I have some liFePo4 on order from Yesa, well see how that goes!
 
Johnbear - I hope you have better luck than me with getting LIFePo4s. I ordered from FalconEV early August, still don't have mine.

When you get them, tell us how it works out, delivery time, costs, any problems, etc.

Gettin cold here in Korea...
 
I will keep you posted! I hope they come within a month. It is not the best riding season now as it is getting cooler. I have a few bikes to keep me busy in the meantime.

I think I will start ripping apart battery packs and picking out the good cells because my nickel packs are not performing well.

I am curious how lithium polymer fare in e-bike applications. A lot of places only rate them for up to 300 discharges. That is not alot. I am more inclined to the higher cycle life like the nicads and hopefully the lifepo4's.

8)
 
300 cycles to 80% is the normal for Lipo technology. Then another 300 cycles to 64%. So thats 600 cycles before it gets down to the efficancy of SLA.

Yeah, thats not a long life, but its 2 to 4 times that of SLA.
Its also normal for Lipo to be rated at 10C. Even cheap Lipo is 5C. I've been researching both Lipo and LiFePO4 for a few weeks now. LiFe wins in just about every way in theory, but I think it will be a year or two before there's a practicle, reliable solution on the market for Ebikes. in the mean time, Lipo is already there.
 
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