A123 Motorcycle Battery?
 

I know using something like a123 cells for a car battery has been discussed, but I wonder if I could make a batt for my zx12r with a123 cells.

Currently I have a agm 14ah 12v battery in there. Not sure what the starting current demands of the engine are (1198cc 4 cyl with 12:1 compression) But I figure a 3-4p setup should work. Not quite 14ah with a 4p (6p would be closer) but I am not sure if I will need the extra capacity as the c rating is much higher on an a123 cell so starting should not be an issue. 4p gives 9.2ah, and at 25c discharge (pretty sure I remember a123 being able to handle that without dropping below 3v per cell) that is 230 amps.

My question is, how many cells in series should I use? 4s sounds about right, 3.3v nominal would be 13.2v and fully charged the voltage would be around 14.4v which is about what a std 12v car battery gets to.

Also wondering if the stator on the bike would cause charging issues? I know a123 cells are pretty good about being charged quickly and discharged low, but can they handle a possible overcharge? Not sure what the stator puts out, but I am sure it is around 12v. I can test this when I get the bike running tomorrow.

Also, a 16 cell a123 pack will be much smaller and lighter than the stock batt, and free up some space. Since the batt is housed in the center of the frame (weird monocoque design ) will I have heat issues with the a123s? Not much (if any) airflow around the batt in the stock location.

So any info would be greatly appreciated, I know we have some diehard a123 users here, so I guess you guys will tell me if I am barking up the wrong tree.

Linc, I have been tempted to make a A123 car starter battery as well.

Well, I charge my A123 packs with 3.8v/cell @ 10amps/2.3Ah... for a 4s pack, that's 15.2 volts, that's roughly what lead acid chargers peak at. You should take some measurements on the road of what the leadacid batt is idling at, if it's between 13.8volts and 14.4volts, you should be good, as that is the recommended charging specs for them. I'm sure they can handle being 'held' at 3.6v/cell for as long as you ride the bike, and anything lower, is better. A 4s4p pack should work just great. That's a 3000watt/4hp pack.

13.8volts is 3.45v/cell, which is the recommended float-charge voltage.

14.4volts is 3.6v/cell, that is the standard charge voltage.

So I think if you are in between that range for stator voltages, you should be golden. Even if 3.45v/cell doesn't charge it to 100% SOC, the pack should have more than enough energy and power to start the bike.

If you build the pack right, that should be the last batt you buy for your bike. no doubt.

Good info ZPB, just what I was looking for. I will get the bike running and check the idle and cruise voltages and see what they are. A 4s4p pack would be 1/3 or less of the size of the current battery... I should be able to score 16 cells up reasonably cheap as well.

4s4p will be the best bet. You won't need much. Here is the tek battery page that does the same thing with an internal BMS http://www.tekbattery.com/Batteries/PricesDoc.html

4s is the replacement for 12v lead acid. It will get slightly undercharged by a lead acid charger too, which makes it last longer.

More good info, thanks JRH. Now I get to search for 16 decent cheap a123 cells.

Ebay... IIRC the guy that sells the 12x a123s for $70 also sells 16x cells for $100 or so

Well to be honest, you COULD even do fine with a 4s3p starter pack... just thinkin because IIRC, a typical car takes between 250 - 300amps to start. So I can't imagine that a bike would be anymore than 150amps? Or are these bike starters of the high speed/high power type?

But, if the same place sells 16x cells for $100, then why not, go for it.

Thanks for posting that too! I am always looking for places that make packs from A123 cells... I like to keep the ideas, and compare them to how I would make mine. That is if and when I make an electric motorbike, and in the future, an ultra light super car.

Linc can I just ask why?

As you mentioned, and as would be my concern, will A123 take a 'dirty' charge directly from the rectifier? And why would you want a messy cluster of a battery.. the new AGM batteries are supposed to be the shiz and cost about the same as a gel cell.

Not to be the skeptic, I'm known for doing odd stuff like this, but what is the objective?

Curious:yes:

....so add some capacitors to the pack, clean the power up IF it were a problem. IMO, you don't need caps.

Redshift, I have 30 55Ah Yellow Tops (AGM spiral wound) waiting to be place in an electric truck conversion. An A123 pack 1/7 the weight has the same punch and power as the best lead acid batt.

A123 starter batts do actually make sense in the long term.

Fair enough zp, weight is waste in a 1:1 conversion (and I would love to do my own) but I'm pretty sure linc's 1200 already has a fairly decent power to weight ratio, just a wild guess:lol:

You that concerned about trying to keep up to a ZX14 James?

Yah, and remember, 1lb. on a car doesn't make a whole heck of alot of difference, but every lb. on a bike does almost 8 times as much as it would in a car.

And heck Linc, if it were ever -40C there, it would still start like a charm... :lol:

Yeah, I just wanted to free up some weight and space. The factory tool kit is in the trunck on the bike, and most of it could be put with the battery if i went a123. I picked up a new agm battery for the bike today. Need to get it running before I do anything else. Might even sell it.

Seems like a great usage for a123 cells. Hows that electric truck conversion coming along ZPB?

And what does ZPB mean?

Zero Point Bug

Well I won't speak for him but Zero Point Energy is probably what ZPB had in mind, free energy, metascience, etc......