Evolution of the Electric Bike?

[Miles Hellon]

Re. A123:

There's been several threads about this on the Power-Assist group - see, for instance: Yahoo! Groups

I'm still using Wickes 18v Ni-Cads, for testing - I cut up their rechargeable torches to get the connectors/mounts. I use 2S,2P.

Miles

[coops]

Thats a good idea - do you mean this one Miles?

2s2p of 18V 2Ah batteries, that'd be.... 36V 4Ah? Not to be sniffed at!

I got an 18V cordless drill on special in my local Netto, included 2 Nicad batteries of around 1.5 Ah I think, and I was wondering how they could be mounted onto a bike for testing, as you say... but your idea is miles better!

I can see a new thread topic - sources to scavenge cheap ebike batteries from, lots of Nicad ones too I bet!

Stuart.

[Miles Hellon]

Yes, that's the one Stuart.

I'll post a "how to" on mounting them, when I have a moment...

Miles

[coops]

Thanks Miles.

I'm trying to do the figures on what sort of range they'd give, with a quite powerful motor, say at 300-400W - anything more than the 5 miles or so for flecc's trial 36V 5Ah AA cell NiMH for instance?

Nicads don't get discussed much here and are probably vastly underrated & overlooked as a good ebike battery, aren't they? Do you happen to know which cell size make up the 18V packs, by the way, and the approximate weight of each 18V 2Ah pack?

Modular batteries for ebikes - select how many to mount to the bike according to your desired range, I like it!

Would make charging a bit more complex, but carrying spares easier?!

Stuart.

[Miles Hellon]

Stuart,

To be honest, I haven't paid much attention to the batteries, themselves - I've been using them for static motor tests.

Whilst the Ni Cads don't have a great energy density, they do have a reasonable power density.

The Wickes 18V weigh 1.063 kg and the cut-off torch bases 0.1 kg.

Miles

[coops]

Thanks for the information Miles .

ADDED: If I've understood correctly, you're saying that while NiCads may not be particularly light for their energy capacity, they can supply current rates relatively high for their size? i.e. the opposite of what's observed of some lithium batteries which are lightweight (high energy density) but fall short at high discharge rates .

I think I've read here that NiCad are good for ebike use, though there's the toxic cadmium element & limitations on their use now makes them a less attractive proposal...

Still, maybe useful for small, high power ebike batteries for e.g. short burnout rides on dirt tracks if you have some knocking around?

Stuart.

[flecc]

Infinitely high if they can be kept cool enough Stuart. NiCads can literally dump their entire content in seconds, and when first introduced destroyed many consumer products designed before NiCads existed. Capacitor discharge flashguns were particularly vulnerable, their last flash being their electronics burning out!

Great for maximum output on ebike motors under any load conditions though.
.

[Miles Hellon]

Yes, as flecc says...

The faster you grab it, the less you get in total, of course...