You were looking at the efficiency at the end of charge, a pack that is discharged to 20% can be down in the 130-140V area.
If the supplies are set at 170V,and the pack you try to charge is down to 130V, there will be 40 volts across the 33 ohms, the pack will try to draw 1.2A, and the supplies will go into foldback regulation. If the supplies could put out the current. You would dissipate 47watts in the resistor alone.
The constant current switcher keeps the current the same throughout the charge, and will do so with the pack at any voltage between 127 to 170V.
Just seems like a better solution to me?
Last edited by Mike Dabrowski 2000; 08-13-2009 at 11:40 PM.
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