Dan Baker wrote:
Thank you everyone for the replies so far- as hoped lots of fantastic info! So it sounds like Cor's idea and Marco's drawing are my best bet. So I guess my only other question would be around this charging scheme is would I need to regulate the charge control once the EV pack reaches full charge (i.e. prevent overcharging)? Would I have to implement a timer? Cor, please yes send me info and pricing on your brick DC/DC module.
Cor's solution is a good one. The DC/DC can boost the voltage so the destination pack can reach "full" even if the source pack isn't full.
You will need to decide what charging algorithm you want to use. Then provide hardware to do it.
The simplest algorithm is just a constant voltage charger. You would wire the control input of the DC/DC to hold the *total* voltage applied to the destination battery at something like 2.25v/cell (13.5v per 12v battery; 54v for a 48v pack). That will work, but could take a day or more to reach full charge.
Or, you can set the DC/DC's output to charge as fast as it can, until the destination battery reaches something like 2.5v (15v per 12v battery, or 60v for a 48v pack). Then hold the battery at this voltage until a) the current falls under 2% of its amphour capacity, or b) the current stops falling, or c) some period of time has elapsed (1/2 to 4 hours). This would take a lot more effort to set up, but would also reach full charge much faster.
-- Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius, and a lot of courage, to move in the opposite direction. -- Albert Einstein -- Lee Hart's EV projects are at http://www.sunrise-ev.com/LeesEVs.htm _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
