Electric Bikes - lithium manganese vs nickel metal hydride

I know there is already a thread about batteries here, but I need an answer to a specific question. The Bionx kit gives me the choice between lithium-ion (lithium manganese combination) battery vs. nickel metal hydride battery.

The lithium ion gets better performance, longer range, and less weight, but I am utterly terrified by the explosion risk. I've read various things about the lithium ion battery being unstable unless it a lithium phosphate combination, which Bionx is currently not offering. So, I'm leaning towards the nickel metal hydride. It weighs abouyt 6 lbs more, but it may be worth the weight to not have a lithium battery explode in my house while charging or, even worse, explode between my legs while riding.

Any information on the lithium manganese combination out there? (All that I could find was that it was more stable than the original lithium cobalt combos. It didn't indicate that it wouldn't explode. ...My fears are raised by the fact that I got a product recall on a rechargeable battery drill earlier this year. They cited hazards due to the lithium battery.)

In my limited experience, I would go with the lithium. I tried two NiMH batteries in succession and had really poor luck with them. The two types behave quite differently, and now that I have lithium battery I find it delivers more consistent power, and has less variability in terms of range. That's my 2 cents, but I couch it with saying that I know many people are perfectly satisfied with the NiMH. I don't know about the risk of explosion... mine has not exploded, or even gotten warm during recharging.

I haven't heard of a full on explosion, but many in the lithium-ion batteries have had "thermal incidents." Basically, the battery overheating to the point where it will burn you if you touch it

I also have only heard of thermal incidents rather than explosions. I have also heard of fires while charging.

I've been using NiMh rather than Lithium and I'm quite pleased so far. I will change to lithium when these expire.

However, if I was "utterly terrified" as you describe, I would never be comfortable with lithium.

I have also heard of fires while charging.


That's something I could do without, especially since it will be charged inside my house, and most likely will be done while I'm sleeping. ...I think I'll take your advice to stick with the nickel for now.

...So, I'm looking at adding about 22 lbs to the bike, including motor and battery. Does anyone have any idea how much that will slow the bike down when I pedal on my own? (I've read that it's less of a big deal on a recumbent, except when taking on hills.)

Lithium manganese batteries are typically more stable than their Lithium Cobalt brothers. Additionally, good producers will rigorously test their batteries before shipping them out. Here's an excerpt from a local store here, whom i've personally seen testing these batteries.

http://ca.itselectric.ca/category_s/51.htm

We have 2 Nickel-Manganese-Cobalt batteries in our house here at 48v/10.5ah, and both have performed safely. I would consider asking BionX themselves as to what the specifics of their lithium battery is, but so long as the company is reputable and knows their product (which I believe BionX does), and that you take care not to expose the battery to very high heat, all should be well.

...take care not to expose the battery to very high heat, all should be well.

What temperature would be considered very high heat?

Being able to cook eggs?

Being able to cook eggs?

Oy! We're actaully able to cook eggs on the sidewalks in Phoenix. One year druing a heat wave, a guy made fudge on his porch--pure solar energy without the panels. The lithium business might not be too safe for me.

What temperature would be considered very high heat?

Its typically around 55-60 degrees Celsius.

That's 130-140 degrees farenheit. Although the air temperature here usually won't get beyond 120 F (I think 122 is the record), I think it could get hotter inside the battery case.

I'll probably need to just haul the heavier battery. I have contacted Bionx to get their info and recommendations, too.