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Old 06-18-2009, 04:58 AM   #3 (permalink)
dcb
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Quote:
Originally Posted by wjdennis View Post
dcb, if you're reading this thread, I'd like to hear more about why you think lithium is inefficient when using constant current as I've described. I've certainly never heard that before.
Unknown battery x is assumed inefficient, it was not clear you were using lithium. Most of the DIY crowd here is still pretty low-tech on the batteries so that where where I am coming from.

A constant current is a fairly trivial circuit (basically a glorified voltage regulator) so using a complete motor controller would be a bit of overkill that still needs a fair bit of thinking over to make it into a charger. But there is a charge profile typically applied to lithium ion, i.e. if cell voltage is low, and to prevent runaway, so a processor (i.e. avr) is probably approproate to condition the applied charge (and discharge) to suit the needs of the specific batteries.

Of course there are still losses in conditioning the transfer to a "constant current", they can be reduced by using a switching instead of dissapating approach, though this will introduce ripple, if that is an issue.

What batteries #s are you using?
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