Project: low cost NiMh battery

[flecc]

I've placed an item about this in the Battery FAQ section here
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[Ian]

Nice one Flecc, and thanks for a very comprehensive reveiw of the results. It will be interesting to see what capacities AA cells eventually reach.

 

[flecc]

Thanks Ian. Yes, 2800 mAh now and I think some 3000 around, but I chose the 2500 mAh since the slightly larger ones were disproportionately expensive.

It would be good if someone mass produced high discharge capability ones, since they are clearly more efficient in content use, giving a higher capacity to weight ratios than the larger volume D cells.
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[flecc]

A bit of a game has developed for some members with these projects, me laying clues of what I'm up to in advance.

Not many this time, but these are the clues shown as links to where they appeared:

A Schottky barrier diode could be used in series with each battery.


for me it's an NiMh future until something better comes along

It's not a bike, it's not a modification to what I've done before, and it's not the Twist.

Fit the eZee NiMh battery innards, there's probably room, or there's alway my current experimental project.

The project was ready before I had a chance to lay a clue about a certain road rescue organisation.
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[coops]

flecc strikes again! I was so close this time to finding the first clue: I picked up something on your very next post in that thread, though for some strange reason I didn't re-read the previous post... still, a miss is as good as a mile I did suspect a battery project of some kind, but couldn't be certain without finding the clues... still, might've been tough even with an AA clue .

A very interesting test flecc, thanks from me too for your usual thorough write-up ; given the results do you think other "sub-D" cell sizes like C or sub-C may perform well with similarly powerful motors? Though I'm not sure what sort of capacity they come in or how well they may fit a case sizewise - I once looked into 12V "sticks" of 10 sub-C cells end-to-end, but only about 3.5Ah I think and around £70 for 3, so not high capacity or very cheap either, but I've not checked recently. I think they were possibly intended for RC use, but since many RC enthusiasts now use lithium batteries they may now be cheaper? (or possibly unavailable/discontinued too!).

Stuart.

 

[flecc]

Sub C and C would be better Stuart, C come as large as 5 Ah and sub C, 4.5 Ah, but they're still far too expensive to be worth bothering with so I ruled them out. There are a few "sell-off" lines, but quality and age unknown, and still much dearer than the AA cells.

Also, 64 C cells wouldn't fit in the case. AA works because the smaller the circumference, the better the space utilisation. So 256 AAA cells? I think not!
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