on 9/12/03 10:21 AM, John Hudson at 13874@xxxxxxxxxx wrote:
> Not being electronically inclined I do not understand the connection between
> ".......the low level drain of the 4T,..." and
> "......the short[ ] life of" the lithium battery. Is the nature of a
> lithium battery such that it is prone to being drained at a greater rate
> than a silver oxide battery by the same device, in this case the 4T, or is
> the nature of the draining device, the 4T, such that it is more demanding of
> a lithium battery than a silver oxide battery?
Neither. Its the 'nature' of lithium-battery chemistry that when confronted
with continuous but low-level drain (as in the OM-4 circuits) it slumps off
rather faster than silver-oxide chemistry. On the plus side, I think
lithium-chemistry can provide short peaks of high output better than other
chemistrys... so the battery chemistry should be matched to the nature of
the drain, somewhat.
>
> I have used 1.5v lithium batteries in my F280 flash and they have lasted far
> longer than the copper top or pink bunny batteries so am just curious why
> they should avoided in the OM4T.
The type of drain of a flash circuit is that 'short periods of high current
demand' type where lithium chemistry excells, so for this purpose they are
quite satisfactory, if a bit expensive. Alkaline batterys will provide high
current output for short peaks pretty well, but the alkaline chemistry
voltage declines significantly over the life of the cell, so you don't want
them in your OM-4 circuit either. Ni-cad and Ni-MH batterys can output
strong current for short peak demand circuits very well, perhaps better than
other chemistrys. In some cases this current output capability is -too much-
for the circuitry; that is why you aren't supposed to use Ni-cad batterys in
the QA-310 flash I think...
Silver-oxide chemistry holds a pretty flat voltage until just about entirely
exhausted. That will provide the best performance for the OM-4 type of
circuit drain... The best for flat voltage over time was the mercury
chemistry, but you can't get those (new) anymore. Some can be found at a
high price, but the shelf life is getting iffy on those expensive mercury
batterys by now.
>
> John Hudson
--
Jim Brokaw
OM-'s of all sorts, and no OM-oney...
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|