Electric bike battery question

[msmith1199]

I have a pair of electric bikes that I bought for my wife and I probably over 10 years ago. We almost never used them and they sat in the garage so they are practically brand new. Now I have more time and I want to start using them again, but the lead acid batteries are shot on them. So I'm doing some research on trying to get new batteries, but I wanted to upgrade to a Lithium Ion battery for both of them. They are more expensive, but a lot lighter and carry a better charge.

I stopped by a local bike shop that does electric bike conversions and talked to a young kid there. I told him what I had and what I wanted to do and he didn't think I could do it, but couldn't tell me exactly why. He didn't think you could use a Lithium Ion battery on a motor designed for Lead Acid. I'm no electrician so I have no idea if that's true or not. Anybody here with knowledge on this? The motor is a 24 volt .5 HP Currie motor. Currently it uses two lead acid 12 volt batteries linked together to make one 24 volt battery. Can I just get a 24 volt Lithium Ion battery and use it?

[SlowBro]

I wish I could confirm what MrWizard said. I used to know all this stuff -- in fact I've had two motorized bikes -- but there's a little hole in the back of my head where memories escape. However, there is an excellent electric bicycle forum where I think you'll get a more solid answer:
http://endless-sphere.com/forums/

[StevenH]

What he is saying is not just any 24v Lithium battery will work.

For example a stack of 16 D flashlight batteries (16 x 1.5v =24v) won't work. Two 12v car batteries would because they have enough capacity.

You will have to find one designed to provide the current the motor requires.

Lithium battery will need a different charger than the one for lead acid battery that came with the bike. You need one designed for lithium charge curve.

A lot of expense probably better staying with lead acid, maybe going to a gel or AGM.

[msmith1199]

cdevidal wrote:
It sounds like you have a Currie eZip. They sell lithium ion batteries for those.

Two more advantages: You get many more charges for your battery life, and faster charging. The only real disadvantage is cost.

Nope don't have the eZip. That is their new stuff, what I have now is over 10 years old and isn't made anymore. Currie gave me a "probably" answer because I think they are leary of giving any advice about changing anything on their older stuff. Afraid of the lawyers.

[msmith1199]

I found this: Dakota Lithium Battery

The current batteries I have are not listed on the compatibility chart, but the manufacturer of the bike motor is, Currie. The current batteries I have are replacement batteries so I don't know what the bike originally came with. These lithium batteries look similar to the lead acid ones I have now.

Think they will work?

[SlowBro]

It sounds like you have a Currie eZip. They sell lithium ion batteries for those. Edit: Here they are for sale on Amazon.

Two more advantages: You get many more charges for your battery life, and faster charging. The only real disadvantage is cost.

Edit: If money is an issue, here are replacement lead-acid batteries.

[msmith1199]

Can you translate that to English? 🙂 I just called the manufacturer of the motor and they gave me a definite probably as an answer.

[MrWizard]

it comes down to finding a battery with the equal or better discharge characteristics, something that will handle the motor surge current
and it will very likely require a NEW charger for the battery

as far as the motor, if it can get 24v with enough amps, it doesn't care what the battery chemistry is
that 1/2 hp motor is 373w or approx 16amps at peak power on 24v