>
> 1. They have lower internal resistance, so they can deliver higher
> currents for faster recharge times.
>
A few months ago, when I was rebuilding the battery pack in a T45 flash, I
researched my battery options and spent a lot of time on the technical
issues involved in battery technology. The T45 battery packs are NiCd, not
NiMh. I considered converting the pack over to NiMh and modding a charger
for it.
I stayed with the NiCd batteries for several reasons. For one thing, the
charger modification was going to be a bear, but secondly, I calculated the
current draw the T45 has and it was high enough to actually damage the NiMh
batteries. (The T45 is in the "extreme" draw category--fuses need not
apply).
Both battery types have low internal resistance, but when applying large
draw (near short) to the batteries, NiCds will deliver the current without
internal damage to the cells. NiMh cells will succomb to internal filiment
problems and other nasties when "cooked" in this manner. NiCds are more
likely to suffer "memory effect" but unlike NiMh cells, do not deteriorate
through charge-discharge cycles.
Another interesting thing I learned about NiCd cells is that they charge
cold, but once peak recharging has been reached they quickly warm. (This is
why smart NiCd chargers usually used thermal sensors). NiMh cells charge
warm. Learning this is a way I charge the T45 pack. I start out by time
(knowing how much I've used it) and then check the pack every 15 minutes or
so until I feel it going warm.
Just a side-note, I have yet to completely drain the T45 pack. I have no
idea just how many flashes I can get out of it as it has far exceeded my
requirements for any event shoot.
Now, all that said, spend the money for the Sanyo Enerloops for the FL50R.
Best general-purpose AA rechargeables around.
AG
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