Re: Roundshot charger?

[Willem-Jan Markerink <w.j.markerink@xxxxx>]

On  4 May 99 at 20:50, Alan & Shari Kafton wrote:

> Dforth617@xxxxxxx wrote:
> > 
> > I just received a new charging unit for my 35s Roundshot, I dropped the
> > original one and it ceased to function.  I have a question to anyone out
> > there that knows  something about electricity.  The original charging unit (
> > the dropped one) was a 9V  DC at 500ma output and the new one is 6VDC at
> > 300ma.  Why the difference in voltage output from one unit to the next?
> > Natural assumption would be that all 35/35s charging units would all be the
> > same ??
> > 
> > Don
> 
> 
> Don,
> 
> My Roundshot 35 charger, made by Calrad, is also rated at 6 volts @
> 300mA.
> 
> I should add, however, I doubt your old charger would make much
> difference!  
> 
> While my charger is labled 6 volts, the actual OPEN CIRCUIT voltage is
> 9.6 volts, and when it is plugged into the camera for charging, the
> terminal voltage drops down to about 3.9 volts.  Basically the battery
> becomes a current sink on the dc charger, loading it down until it's
> output voltage equals the battery's terminal voltage.
> 
> Primitive, but given the substantially overdesigned battery source built
> into the Roundshot (i.e. 100 roll charge capacity), who cares if
> capacity is degraded somewhat by so-so battery management.
> 
> By the way, the best thing you can do to extend the life of your
> batteries it NOT TO OVERCHARGE THEM!  The manual says nominal charging
> time is 12 hours, but I measured the charging current on my camera, did
> some rule-of-thumb calculations, and for my camera believe a full charge
> from a completely discharged state is 8-9 hours!
> 
> I also don't charge it everytime I go out and shoot....I've had the
> camera more than 2 years, never replaced the batteries, and haven't been
> caught short on charge yet....

I don't know the capacity of the rechargeable pack, but it would be 
wise to invest US$100-150 in a smart charger, the ones used for RC 
construction models. Technology keywords are delta-peak switch-off, pulsed 
charging, and if possible even 'reflex-charging' (though this you'll 
find mostly on heavy chargers, perpaps too much for small packs).
This gives you many nice features, like very fast charging without 
any damage, easy topping-off [*], the actual capacity of the pack 
(takes a charge/discharge cycle, all built in)

You didn't mention what Roundshot charged (pun intended) you for the 
OEM charger, but I doubt it made you happy, especially not given the 
crude technology....8-))
 
[*] forget everything you learned about the memory effect; it is a 
collective name for various types of abuse, and charging without 
discharging is one of the least likely....it's close to an urban 
myth....more about this on my homepage:

http://www.a1.nl/phomepag/markerink/mainpage.htm

--                 
Bye,

Willem-Jan Markerink


      The desire to understand 
is sometimes far less intelligent than
     the inability to understand


<w.j.markerink@xxxxx>
[note: 'a-one' & 'en-el'!]