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Re: Q: Sony NP-F960 requires Sony BC-V615 ?

From:
Date: Fri, 5 Jan 2001 13:09:43 -0800

KPJ wrote:

> I have a Tri-M HE-104 PC/104 power supply with a BC104 battery 
> charge option. I would like to be able to use the HE-104 to 
> charge Sony NP-F960 batteries

Unless you know exactly what you are doing (in which case
you would not be asking these questions), please don't 
try chargining lithium-ion batteries using anything but 
the chargers that are made for them. Inside the NP-960 is
a little computer that monitors the battery and talks to 
the charger, indicating when it is SAFE to charge and 
when to STOP charging. Bypassing this circuitry is very 
dangerous. If you can get the protocol info and talk to 
the internal battery monitor in the same way that the 
traditional chargers do, that's a different story, but I 
have never heard of anyone who has done that.

> 0. Is this possible?

Possible? Yes. Safe? No.

> which really boils down to
> 0.1. Does the battery have special requirements (like charging
> voltage curve form, etc.)?

Lithium Ion is volatile and can explode if over-charged. 
This is why you CAN'T buy l;ithium-ion cells as a consumer,
you can only buy battery packs wih the monitoring/charging
circuitry integrated into the packs (which talk to the 
charger). You CAN get the necessary components from maxim
and other suppliers, but you need to know exactly what you
are doing. 

> Does the Sony NP-F960 batteries require the Sony BC-V615 ?

Not sure but I assume the answer is yes.

> 0.2. What happens if the battery is charged when already 100 % charged?
>    = Does it handle it gracefully (or does it become damaged)?

Worse, it is very volatile and could explode!  I suggest that 
you leave li-ion charging to the experts. If you want to use 
the battery charging facilities of HE104/BC104 I suggest that
you stick with nickel cadmium or nickel metal-hydride batteries,
which are not volatile and are therefore much safer than li-ion.
BTW one other postential (although futuristic) alternative is 
lithium-ion polymer, which has better energy density than the
li-ion (circular) and is much less volatile. Here is an 
example of lithium polymer cells that have an energy density
of 130 Wh/kg!

http://www.ultralifebatteries.com/polymer.html

When compared with the energy density of other batteries:

   Lead Acid      30  Wh/kg
   Ni-Cad      40-60  Wh/kg
   NiMH        60-80  Wh/kg
   Li-Ion      90-100 Wh/kg
   Li-Poly    130-150 Wh/kg

The other interesting things about li-poly batteries is 
that they can be shaped. Traditional Li-ion batteries 
use electrolyte solution that must be contained in a 
solid circular reservoir. Lithium Polymer uses a plastic
electrolyte (hence the polymer name) that can be made 
into any shape. This means the case for a device (say 
handheld or cell phone) could actually be the batteries! 
Too bad it's not as simple as opening a can of silly 
putty ;-)

Your goal of charging with the BC104 is admirable but 
it's really not safe with Li-ion cells. You might want 
to consider using the new Sanyo 4500mah 1.2 volt NiMH 
cells instead. Energy density is not as good as Li-ion,
but it's not too bad. 

  -- Doug

------------------------------------------------------------
  Grow your own Wearables: http://wearables.los-gatos.net
 What I'd like is to have you call me and my jacket answers
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