12 NiMH C cells replacing 12V SLA - good idea?

KevinL

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Jun 10, 2004
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OK, I'm kinda unsure where to post this so if it needs to be moved, please do, thanks /ubbthreads/images/graemlins/smile.gif /ubbthreads/images/graemlins/stupid.gif because it involves a spotlight (spot/HID forum), a 55W incan, batteries (electronics) and it's about modifying the spot's batteries (modified).

I'm thinking about leveraging NiMH's flatter discharge curve to drive a 55W H3 automotive bulb and at the same time, gain more capacity. Amondotech is selling some C-cells with tabs and a reasonable capacity, I'm thinking of buying a dozen and rolling my own pack. 14.4V should provide a nice overdrive to the thousands-of-hours lifetime bulb, too. And it's cheap, a dozen will run me less than $40.

You guys tell me why it's a bad idea /ubbthreads/images/graemlins/wink.gif
 

Ginseng

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Feb 27, 2003
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I do it. Sway does it. Bwaites does it. You get better voltage delivery with no loss in current capability.

For example, the Aurora runs on only 11 4/5A nimh cells. It is brighter than my converted Vector 2MCP SportSpot which runs the same Osram 62138HLX bulb on a 3.3Ah SLA. Doesn't run as long, but if I used 11 1/2 Ds, it would be brighter and run longer.

I can get a 12 x 1/2D nimh pack into the space of a 6V lantern battery and it delivers mega-oomph. 15.3V at 9A+.

Wilkey

Be wary of those C-s delivering good voltage under load. 5A probably ok. 9A, maybe not.
 

Sway

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Aug 25, 2003
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North Carolina
Ditto what Wilkey said and let the pack rest after a charge your hot voltage with 12 cells will be over 17.5 volts it's easy to flash a lamp like this. Some times 11 cells can be the sweet spot depending on how much push the lamp will take and the amount of current you cells are able to deliver.

Later
Kelly
 
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