Your dream battery (well, dry cell)

[badnewswade]

F type batteries:

http://www.eurobatteries.com/sitepages/ ... 20%20Li-on

I reckon 30 of these could power my moped /pedal scooter. If they weigh about the same as AAs then the reduced weight will solve the machines performance problems pretty much for good!

Sadly even with bulk discounts 30 of them would cost a little over £300, (which I still think is a bargain) but I'm not ready to throw that much money at it, but if anyone else is looking for a new power source and they have lots of cash, it looks like this is it unless I'm very much mistaken.

[badnewswade]

More on the "F" type from a US distributor (note the lower prices and lack of international shipping, grrr!)

http://www.all-battery.com/index.asp?Pa ... tegory=230

Is this the fabled NiMH invented by Professor Stanford R. Ovshinsky, the one they put in the EV-1? It certainly seems like it.

[EVguru]

All battery types other than Lead acid (and Lead acid in many cases I would argue) need a management system. NiMh is trickier to charge than NiCad, which in itself in not particularly easy. Most NiCad chargers were prone to causing the FALSE memory effect (actually depressed discharge voltage and caused by overcharging) and the only reason NiMh don't suffer from it is beacause that amount of overcharge will damage or destroy the cell, so the chargers were forced to improve.

With your bicycle you're fighting the fact that it's designed to comply with the 'Electrically Assisted Bicycle' laws. Extra range; Fit a bigger battery ,except that you may have problems if the battery is much heavier. Better acceleration; Higher current limit in the controller, but you risk overheating the motor (can happen fast) and will reduce range if you use the extra performance. More speed (Ignoring legal requirements); Change the gearing, but acceleration will suffer unless you increase the current limit (more load and more current, fast overheating!), or increase the voltage; Needs new battery and controller.

I wouldn't start from where you are!

[badnewswade]

You're right, the real problem with this bike is something far more fundamental - a design flaw if you will.

Without the approx. 12 kilo weight penalty of the wet cells, this bike will really move - possiblyt even up to the point where I might derestrict the speed and register it with DVLA!

NiMH (or if _very_ cheap, NiCD) cells seem to be the stablest and best dry cells - although obviously I'll want to build some kind of cooling system as they'll get hot - and I reckon I can make a pack out of about 200 high capacity NiMH AA batteries that'll go fast (that said, it's still in the conceptual stage, though NiMHs certainy SEEM to be lighter per watt).

Oh and I've found out more about the F Cells - they're just super-sized "D" cells. Still, they do come in up to 14 amps and they have been used in e-bike battery packs, so if you've got the cash they're your batts.

http://www.batteryspace.com/index.asp?P ... rodID=2538