Battery charger constant current value ?

Go To Last Post
4 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I have made a basic battery charger with a LM317.
What is the best constant current value I should use ?
(using NiMh)

Also if I charge the batteries in serie, should I multiply the charge current by the number of batteries in serie ?

Thanks for your enlightment ;-)

Chris.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

No, don't multiply the currents.

The current depends on how fast you want to charge the batteries, usually something like C/10, where C is the nominal capacity divided by ten. E.g. 2500mAh batteries are charged with 250mA and charging takes 10 hours (actually a bit more because the charging efficiency isn't 100%).

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Note that you can't leave the battery to the charger forever unless you are using low mainentance charge only (C/300). You must stop the charge after the battery is full, otherwise the battery won't like, will degrade, and it may get damaged and damage people if it explodes.

I suggest you read the Wikipedia article on NiMH batteries

- Jani

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Before plugging in the batteries, I suddenly thought that I was doing something wrong...

You just confirmed it ;-)

I'm a bit smarter now, thanks !