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BrianG · 05.06.2010, 05:49 PM

By CC dropout, I mean: The CC source circuit will consist of a voltage regulator configured as a CC source, and it has ~1.5v dropout, coupled with the V drop on the current programming resistor of 1.25v. The extra voltage is just a little extra to prevent the pass transistors from saturating when the cells are close to 3.6v (which would reduce the current) and to account for any deviation in supply voltage. Transistors by themselves could be used as a CC source, but their values do change with temperature and current, so a V reg is a better idea for consistent operation.

And actually, I made an error on the previous post. That 15lb transformer would actually be good for closer to 20A. So, you could either use that at 20A, or use a smaller (and lighter/cheaper) transformer for 10A. But as you said, the "base station charger" will probably stay in one place so moving it around is irrelevant. And for a small 2A on-bike charger, a similar idea could easily be made under 5lbs that will do the same thing.

Sure, you can use a Duo or whatever, but unless your charging station is located where the bike is (my R/C stuff is in my basement and my bike would be in the garage), it will be a PITA to move the charger, PS, and assorted cables around. Not to mention the charger/PS setup will be substantially more expensive.

	(#78)
BrianG RC-Monster Admin Offline Posts: 14,609 Join Date: Nov 2005 Location: Des Moines, IA	05.06.2010, 05:49 PM By CC dropout, I mean: The CC source circuit will consist of a voltage regulator configured as a CC source, and it has ~1.5v dropout, coupled with the V drop on the current programming resistor of 1.25v. The extra voltage is just a little extra to prevent the pass transistors from saturating when the cells are close to 3.6v (which would reduce the current) and to account for any deviation in supply voltage. Transistors by themselves could be used as a CC source, but their values do change with temperature and current, so a V reg is a better idea for consistent operation. And actually, I made an error on the previous post. That 15lb transformer would actually be good for closer to 20A. So, you could either use that at 20A, or use a smaller (and lighter/cheaper) transformer for 10A. But as you said, the "base station charger" will probably stay in one place so moving it around is irrelevant. And for a small 2A on-bike charger, a similar idea could easily be made under 5lbs that will do the same thing. Sure, you can use a Duo or whatever, but unless your charging station is located where the bike is (my R/C stuff is in my basement and my bike would be in the garage), it will be a PITA to move the charger, PS, and assorted cables around. Not to mention the charger/PS setup will be substantially more expensive.