teojim@xxxxxxxxxxxxxx writes:
<< What type of charger is used for the lead acid battery?
Has anyone successfully made a power pack for thier flash? >>
Warning OT engineering stuff follows.
Simple chargers for lead acid cells work quite well and are easier to make
than for NiCd's. You need to apply a constant voltage of 2.30V/cell if you
float the cells for long periods. In the case of Hawker(Gates) the older
cells need more like 2.35V/cell for float. The newer cells can be a little
lower. The cells recharge to about 80 apacity very quickly and then take a
long time for the last 20%. It depends on the vendor what the maximum charge
current allowed is For Hawker(Gates) you can use a very high current supply
and the cell handles the high current. For other vendors limit current to
something like C/3 Amperes where C is the capacity in AmpHours of the cell.
If you want to rapidly charge to full capacity (so called cycle use) use a
voltage regulator with a voltage of 2.4-2.5V/cell and the same current limit.
However the cells will overheat and could be damaged if you leave them on
charge too long at these voltages.
The common LM317 regulators work well in this application and that
is what is used in some Quantum Battery packs. With a 317 regulator and a
supply capable of at least 1A the Hawker "D" cells will recharge to 80 0n
about 2Hours at 2.35V limit. It will take another 16Hours or more to fully
recharge at 2.35V. At 1A/2.5V the same cells will recharge fully in about
3hours and then start getting hot and eventually venting. Older Hawker cells
will be seriously damaged at this stage but current production may take this
abuse quite well. Other vendors cells may eventually bulge and crack and will
vent even more. A good compromise is to use a cell voltage between 2.35-2.4V.
Regards,
Tim Hughes
>>Hi100@xxxxxxx<<
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