Making a Battery Pack

noexit

noexit

Been Around the Block
In this thread, there was a link to the SpeedCell 120A battery pack.. It's $160, which I can't afford, so I thought, how about making my own?

Here we go. A 3.3v LiFePO4 cell with a max discharge rate of 120A for $18.

LiFePO4 batteries have a very high discharge rate, high charge rate, and a 2000 charge cycle life, so they seem perfect.

Wire four together and I have a battery. Seems like a good idea, eh?
 
What bike is it????? electric start ::) or kick?? search the archives and there are plenty of ways to hide a lead acid battery,,and make sure it conforms to your alternator output,,,,you'll boil it, if its too small,,,,, one last thing ,Im still using the original yuasa sealed battery in my 00 sv650s,,,50k on the bike,,,,,,(keep them charged ::)),,,,,,,tell the clan if it works :D
 
The only question that I have, which I'll probably have to ask at an RC or electric vehicle forum, is whether or not I need some kind of charge balancing and overcharge protection circuity.



Edit: Learning as I research. Removed some incorrect info.
 
Wee Todd said:
What bike is it????? electric start ::) or kick?? search the archives and there are plenty of ways to hide a lead acid battery,,and make sure it conforms to your alternator output,,,,you'll boil it, if its too small,,,,, one last thing ,Im still using the original yuasa sealed battery in my 00 sv650s,,,50k on the bike,,,,,,(keep them charged ::)),,,,,,,tell the clan if it works :D
Click to expand...

It's a CB400F that I'm cafe-ing. I'm kind of waffling about taking out the electric starter. My only starts with the electric start if it's already warm, and the kick start is so easy anyway that I don't really see a reason for keeping the electric start. I'm about ready to seal the engine case halves together, so I need to hurry up and decide. I'm at the point now where I need to start mocking things up, and I'll be making my own wiring harness. Having a battery that's 3x2.5x.75 inch sitting under my seat sounds really nice.
 
Here is a link to another motorcycle site where someone made a pack like I'm considering. He used 3 parallel sets of 4 batteries in sequence to get enough cranking capacity to start his large sport bike. I think this is putting me on the right track.
 
I'm not sure about LiFePO4 batteries. I use LiPo batteries (Lithium ion polymer) on my airplanes and they require a special charger or else they will explode. LiPos can not be charged by a bike's alternator.

I plan on welding a plate to the bottom of the frame rails under my seat and then finding the thinnest AGM battery I can to sandwhich inbetween the plate and the seat pan. I will use two in parallel if necessary.
 
Flugtechnik said:
I'm not sure about LiFePO4 batteries. I use LiPo batteries (Lithium ion polymer) on my airplanes and they require a special charger or else they will explode. LiPos can not be charged by a bike's alternator.
Click to expand...

According to what I've been reading, LiFePO4 can take a lot more abuse than LiPo. Short circuits, overcharge or other damage does not cause them to explode. They can also be charged with a much higher current and tolerate overcharge better than other batteries.

[quote author=Wikipedia]LFP batteries are gaining popularity now in the world of hobby-grade R/C, due to the benefits over the ever-popular LiPo batteries. They can be recharged much faster and for more cycles, are not prone to catching fire or exploding while recharging, and are more robust than the LiPo type.[/quote]
 
More learning. I think this thread, again from another bike site, has be convinced that this is the route I'm going to go.

The poster shows a 4 cell 2.3Ah pack that he's made for his bike, running a total loss system. But what really has me convinced is that he's been running an 8 cell pack, two sets of four for a total of 4.6Ah, in his car. Charging with an alternator and everything.

Battery problem solved. On to next bike problem...
 
so 4 cell 2.3h and your kick only and its going to work and charge fine? Pics when your done :)
 
Actually, I think I can use the electric start and it will crank over fine. The SpeedCell Super Sport is only 2.3Ah, but they call it a 120Amp because that's how much it can put out over 10 seconds, more than long enough to start a bike. For a larger bike, like a CB750, you'd probably have to use 8 cells, with two sets of four in parallel. When running them in parallel, you might want to use some equalizer circuitry like the RC people use, but the guy on the 1000RR forum doesn't, and he says his works fine, even using it as a replacement for his car battery.

It will be a while before I get my bike running off this battery. CB400F project is here.
 
Ran accross some interesting info on these batteries. Thought you might be interested. I am also planning on running one of these in my 750. Seems do-able. I was just about to buy the batteries and do the soldering myselfbut the guy selling them might be able to supply them complete with wire and connectors. I told him to give me a price on quantities of 1, 5 and 10 in case people are interested ina group buy.

anyways heres the link
http://www.slkelectronics.com/DeWalt/index.htm
 
Wee Todd said:
What bike is it????? electric start ::) or kick?? search the archives and there are plenty of ways to hide a lead acid battery,,and make sure it conforms to your alternator output,,,,you'll boil it, if its too small,,,,, one last thing ,Im still using the original yuasa sealed battery in my 00 sv650s,,,50k on the bike,,,,,,(keep them charged ::)),,,,,,,tell the clan if it works :D
Click to expand...

Where do you live?
Battery life is considerably shorter where its 'warm' (over 75 deg F) and/or batteries are not put into service correctly when new

PJ
 
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