iconoclastica wrote:why not just use a strobe since a separate power supply kind of negates the speed light advantages of small size and portability[/code]
There's two arguments for that, both non-technical:
- - The speedlight + PS was made from scrap parts, whereas the strobe I was looking at just now costs 780 pounds;
- - I work in studio only, so size and portability are - for me - not prime considerations.
Am I mistaken to think that a 15W PS would charge the speedlight 5x faster than the present 3W PS?
The strobes I mentioned are about $109 US. The Adorama and Godox are the same I believe (I only have the Adorama), but the Adorama comes with a Bowens mount reflector, whereas the Godox does not (requires a separate purchase).
I recall that the initial current draw for a quality speed light can exceed 10 amps from the batteries. To be safe I would think a power supply would need to be able to supply this peak current for maybe ~1 second, then slowly taper off.
If you consider the energy supplied by the flash as FE, the battery voltage VB, the battery current I and the overall average recharge efficiency as Eff (energy out/energy in), then a very crude estimate of the recharge time is:
Time to recharge = FE/(VB*I*Eff)
So for FE =60WS, V =6 volts, I = 10 amps, Eff = 25%
Time = 60/(6*10*0.25) or 4 seconds.
Of course this assumes full 60WS recharge, battery with no internal resistance (no voltage drop), constant 10 amp recharge current and 25% overall efficiency.
First off the current isn't constant (probably a tapering off exponential decay), the battery has a internal resistance or voltage drop and so on. So a very very crude estimate indeed, but an estimate nonetheless.
Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike