Interesting Mark, If I remember correctly your chargers are higher current than the 350ma and 1A chargers I will be making?
I have had 350ma on a pack for over 2 days with 12V fan running, with only a 3-4 degree temp rise above ambient.
The pack was in thermal zone at over 170V for the last half day of that test.
For everyday charging,I agree that having the charger run out of volts near the full point should be better than balancing each day.
To assure full balancing, all cells must be full and converting the full 350ma into heat, so I will set the max V to several volts over the max that can be reached just to guarantee that all cells get filled.
Since this is easily adjustable, maybe we raise the V to 175 for the occasional balancing, and leave it at 169-170 the rest of the time.
Of course this max V is a temperature dependent variable, so maybe the pack temp should determine this max V?
I am just getting into the final smart grid charger control system design so lets figure out what features we want to include. The Microcontroller will be reflashable and socketed like MIMA, so we can keep improving the control strategy as we learn more.
I plan on being able to turn off the 1A and also the 350ma charge by computer control, so the hardware max V can be set to 175V, and the charger will simply shut off when a programmable target voltage is reached, the charger times out, the MAX AH is reached, or the PTC strip indicates a hot cell.
Last edited by Mike Dabrowski 2000; 09-02-2010 at 02:26 PM.
|
