What resistor to simulate a 2CR5 under load (homemade battery tester)?

Hello, and Happy New Year to everybody.

My battery tester uses a (too weak) 10mA load for its 6V test.

I'm guessing that a 2CR5 Photo Lithium battery should be tested at
150mA, under load.

Any electronics geniuses out there? What type/size resistor should I
connect to the battery, while testing with my battery meter, to
simulate a Canon SLR's load, and provide me with an estimation of the
usability of my 2CR5 (and other 6V lithium) batteries?

I also have a DMM.

Thanks for all advise and tips.

 

40 Ohms (or about) will work. 2-W is a good power rating.

 

Assuming:
1) your camera represents a 1500 mA load
2) the battery has a 6 volt potential

Then R = V / I, so that R = 6 /1.5 =4
Then W = V x A. so W = 6 x 1.5 = 9

You would need a 4 ohm, 9 watt minimum resister load.

If the load is a factor of ten lower (150 mA), then the resistance would be
40 ohms at 1 watt.

Kevin

 

Digicams are really tough on batteries. I would guess that a camera with
the LCD screen on, would probably draw 1,000mA.
So, I would connect a 6 Ohm, 5-10 Watt resistor across the battery
terminals while measuring the voltage. I'd leave the load on for 5-6
seconds and see how much the voltage drops in that time.
For a fresh Lithium Battery, I'd expect the voltage drop to be no more
than about 0.2-0.3V
Bob Williams

 

Google for "2CR5 specifications" and you'll find manufacturer's pages
that have electrical specs for the battereies that include
voltage/current/time graphs.

 

I find a light bulb works pretty good at the right voltage and wattage as
you can see the drain. so a 6V 10 watt should work or an equivalent 12V
should work fine.

Wayne

 

( R = E/I ) = ( 6V /.150A ) = 40 OHMS

( P = I * E ) = ( .150A * 6V ) = .9W


A 40 ohm, 2 watt resistor will provide the correct load.


THO,
It might be better to go to your local RadioShack,
get a;

6v, 100ma bulb
and a
6v 150 ma bulb

for your tester.
That way, you'll have a quick "visual"
re the state of your battery.

( I'm thinking 100ma load should be adequate for tests )

<rj>

 

A light bulb initially provides close to a dead short across your
battery because the tungsten starts off relatively cold. I wouldn't
do this to my camera battery. I think using a resistor as others have
suggested, is the better plan.