Charging NiMH batteries with solar panels

Discussion in 'The Projects Forum' started by duhdave, Mar 15, 2013.

  1. duhdave

    Thread Starter New Member

    Dec 6, 2010
    Hi guys. I'm looking to charge 6 x 1.25V NiMH D batteries in series using a small solar panel such as this one:

    Is this possible? The panel doesn't need to get the batteries anywhere close to fully charged, rather, it only needs to supplement their charge (these batteries are going to be part of a portable USB charger.

    If this is possible, what circuitry is involved? Thanks.
  2. tindel

    Well-Known Member

    Sep 16, 2012
    Of course it's possible. I use the LT1510 for many of my SA projects requiring NiMH batteries. That solar array is probably perfect. 250mA is adequate out of your SA. You'll need two of them to charge using the LT1510 though. The 1510 is a buck converter so if your input voltage is below your battery current it won't work properly. A buck-boost converter would probably be better for your application if you just want one SA panel, but 1.5W panel is adequate.

    NiMH should be current controlled until the voltage starts falling, then it should stop charging. A secondary means of stopping charging should be implemented, as well, this is usually done with a temperature threshold on a NiMH cell.

    Whatever you do - don't just put your SA on your battery cells.
  3. mortonc

    New Member

    Jun 6, 2014
    Does the lt1510 stop the battery from charging once it's full?

    Also does that end up wasting a lot of energy?