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[OM] Re: TSA: Safe Travel with Batteries and Devices

Subject: [OM] Re: TSA: Safe Travel with Batteries and Devices
From: Tim Hughes <timhughes@xxxxxxxx>
Date: Wed, 2 Jan 2008 21:29:57 -0800 (PST)

--- Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx> wrote:

> I also meant to mention that when you buy a Quantum Turbo "CZ" power 
> cable for Canyon flash units it comes with a power saver dummy AA 
> battery.  Apparently the control electronics of the flash must be able 
> to run on about 3 volts so the 4th battery is not really required when 
> running with a high voltage supply.  Perhaps the same is true of other 
> flash units but the best is the T-32 and some Sunpaks which don't need 
> any AA's when running on high voltage.  It helps same some weight but I 
> leave all the batteries in anyway just in case the high voltage supply 
> fails at an inopportune time.

If you were to leave the 4th cell in the unit, then the turbo and the 4cells 
charge the hi-v cap
in parallel (faster), but the 4 cells get depleted at a relatively rapid rate. 
Dropping the
voltage by one cell means the 3cells don't contribute much to charging the 
hiv-v cap and so not
only do you "save" one cell, the remaining cells stay fresh and last a longer 
time in supplying
the control electronics and so keep the unit running longer on the external 
turbo pack.

> Chuck Norcutt wrote:
> > For some reason I thought there was at least one Metz flash that could 
> > accept either 4 alkaline AA's or 5 NiCad or NiMH such that the flash 
> > always saw 6 volts.  But if it exists I couldn't find it.  

I have never heard of that but the Metz T45's have a different holder pack for 
the NiCd's vs the
Alkaline (still 6cells) (You are not suposed to use  NiCd's or NiMh's in the 
Alkaline holder) The
holders connector attaches at a different point in the circuit, so providing an 
optimum tap on the
invertor transformer, to get the best performance from the niCd's.

>> Some of the 
> > bigger Metz and Sunpak units take 6 AA's which I think is just for 
> > additional capacity.

Actually it is not only capacity it is more of a rate issue, as many of those 
units (except the
very largest) have about the same energy as the T32. The 6 cells can charge the 
capacitor much
faster and more consistently than the T32 can with 4 alkaline cells, but at a 
weight cost.  The
T32 struggles to charge fully in anything like it's specified time because the 
maximum energy rate
extractable from the 4 cells is a lot less than 6. If it had been optimised for 
just NiCd (or
NiMh,if they had existed then) then they could have more easily achieved the 
specs. The T32 on
it's booster handle actually is much,much more consistent than it is on it's 
own, because like the
sunpaks it then also has a hi-voltage feedback regulator that the simpler T32 
on it's own lacks,
however it was also designed for alkalines and you can't extract energy from 4 
alkaline C cells a
whole lot faster than from 4 AA cells, although it takes much longer before 
they really start
wilting as badly!  Unlike Alkalines,most rechargeable's have a rate capability 
that scales with
size so it is easier to design for them alone. Of course in an OM when using 
TTL everything
usually works fine, even if the flash is not fully charged. It's the manual 
settings that suffer
consistency, if the cap is not fully charged.

Tim Hughes

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