John asked :
>>
I do have one question if someone has used one of these things before. The
dryfit appears to charge properly and the flash operates
flawlessly. However, the dryfit battery is not new; it's about four years
old. When plugged into the flash handle and turned on after a full
charging cycle, the red light on top of the battery slab box next to the
power switch blinks. Is this "normal" operation, or is indicative of
something else?
<<
The Led is a self flashing LED that just indicates the low voltage power is on.
It flashes more
erratically if the cell voltage drops a lot under load at end of discharge. I
have had good look
at the electronics of these units, so am very familiar with them. The age of
the cell is not so
important as whether it has been left discharged for extended periods. The
cells can be bought
back a bit by putting the cells through a number of full charge-discharge
cycles **provided they
are only modestly sulphated**. But it is rough on the flash to use it as a load
by flashing. Use a
power resistor and discharge to ~1.8V/cell (5~5.4V) at about 1A (6 Ohm). It is
much better for the
batteries to leave them on float charge for an extended period (>18hrs)rather
than disconnect
immediately the charging light goes off, otherwise you may "cycle down" the
cells. The batteries
can be safely left on float charge for an extended period, it is a voltage
regulated design at a
safe float level (2.3V/cell). If you don't want to use a resistor to
discharge the cells, just
leave the flash on rather than trigger it repeatedly, as it has a fairly high
standby current
drain and this is less stressful than flashing at full power.
Regards,
Tim Hughes
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