Battery Mystery

[RonM]

I have a couple of camcorder batteries that I think would be good for powering a home built LED flashlight. They are 3.6V, 4050mAh, Li-ion. That's a lot of capacity!

Here's the mystery. When I measure the voltage at the terminals I get 0 (zero), yet they power my Sharp Viewcam just fine. There are three terminals marked: +, C, -. Measuring accross + & - I get no voltage. Between + or - (I forget) and C I get about 1V. What's the deal?

Also, any suggestions for what type of LED would be good for this 3.6V if I can ever figure it out?

Thanks - RonM

 

[The_LED_Museum]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by RonM:
Here's the mystery. When I measure the voltage at the terminals I get 0 (zero), yet they power my Sharp Viewcam just fine. There are three terminals marked: +, C, -. Measuring accross + & - I get no voltage. Between + or - (I forget) and C I get about 1V. What's the deal?

<HR></BLOCKQUOTE>

Best guess?

You probably have to short the (C) to one of the other terminals - probably the combination that registers a flat 0 on your meter (try that combo first, anyway).

The theory I have is that this acts like a safety device, preventing the battery from becoming shorted and starting a fire inside your camera bag or exploding in a bomb of toxic glorp in there.
In order to get a fire or explosion, you would need two complete short circuits to two sets of terminals (+ & C and - & C for example), not just one set.

The camcorder probably has two of these terminals bridged internally, thus completing the circuit and allowing full battery power to be fed to the camera.

Any other opinions on this?

http://ledmuseum.home.att.net

 

[**DONOTDELETE**]

Maybe one of the terminals is used for charging. I know Makita uses a separate charging terminal on their cordless drill batteries- it connects to B+ through a thermostatic relay- when the battery gets warm it opens and shuts down the charging cycle. Also, the later Sony Handycam batteries contain a microprocessor to calculate run time- thus two of the four contacts are used for serial data transmission. It's a bit odd that only one volt is seen between any of the terminals- maybe check it with another meter.
Chet