Measuring and Calculating Battery Capacity "Wasted" or Remaining

[TinselKoala]

This is important information for anyone experimenting with devices that use or charge batteries while running.

How much energy capacity in a battery? How can you tell how discharged a battery is, or to put it another way, how much useful energy is there remaining?

Dave at EEVBlog shows us how:

http://www.youtube.com/watch?v=1hs_9vx9APw

[Pirate88179]

This is important information for anyone experimenting with devices that use or charge batteries while running.

How much energy capacity in a battery? How can you tell how discharged a battery is, or to put it another way, how much useful energy is there remaining?

Dave at EEVBlog shows us how:

http://www.youtube.com/watch?v=1hs_9vx9APw

I really like Dave and have learned a lot from watching his videos.

Bill

[MarkE]

This is important information for anyone experimenting with devices that use or charge batteries while running.

How much energy capacity in a battery? How can you tell how discharged a battery is, or to put it another way, how much useful energy is there remaining?

Dave at EEVBlog shows us how:

http://www.youtube.com/watch?v=1hs_9vx9APw

It is a well done video.  I have a couple of objections, but they are minor and he addressed one in his overlay comments.  People who experiment with batteries should pay attention to the need to actually test remaining capacity by discharging the battery into a load until it is effectively dead.

[TinselKoala]

I think that the video contains some information that may help recycling, charging pulse-motor builders understand how their run batteries can show little or no voltage drop on a multimeter while the motor runs for so long. The voltage when the pulse is _off_ is essentially the noload terminal voltage of the battery. But the voltage when the pulse is _on_ drops, and it drops more and more as the battery's capacity is used up. So while the no-load voltage curve is still relatively flat, the loaded voltage curve drops off more steeply.
The multimeter displays the average voltage fairly accurately even of a pulsed voltage. So with the very short _on_ duty cycles that these motors use, the average battery voltage shown on the DMM will be close to the no-load voltage and will remain fairly constant even as the loaded (pulse on) voltage drops off.