Friday, October 10, 2008
If you’ve been shooting with a flash for a while, I’m sure you had some battery problem or another at least once. Like when one of four batteries goes bad and quickly discharges the other three. Or when it’s cold and the batteries don’t hold their charge so well anymore. Wouldn't it be nice if you could have a more reliable source of power? One that virtually lasts for ever (well, not forever, but for a darn long time). This is probably on the wish list of anyone who is shooting off shoe and don't care much about weight, but do care about recycling time and number of pops that can be squeezed in a session.
Konstantin Sirotkin describes how to make a Flash mod that will allow you to connect your flash to an external power source.Yes this is an external power source, no mater how bomb-like it looks.
Four full alkaline batteries connected in series will give you about 6V total voltage. Four fully charged NiMH will net you about 5V. A fully charged sealed lead-acid battery (SLA) is about 7V and it eventually goes down to 5V as the battery discharges. As you see, a fully charged SLA is slightly above the rated voltage for the flash, but in practice I’ve never had a problem with that. I believe that the logical electronics in the flash works on 3V from a regulated supply (i.e. with a higher input it would just generate a bit more heat) and the step-up converter that produces high voltage doesn’t really care about its input as long as it’s DC and above 4V.
Here's another example.