Charging NiMH batteries with Solar Panel?

I'm looking at charging a set of 3 Nimh batteries in serial (= 3.6v) that I'm using to power an Arduino Pro. What would be the easiest design to charge these batteries using a 5v solar panel?

Google returned over a million possibilities when I ask "nimh charger ic".
Paul

Thanks, I have run this search as well

  1. I saw one mention that you only need a diode I believe but there were no exact specs - pardon my ignorance with electronics.
  2. Wondering if anyone here has built something similar specifically for 3xAA batteries and 5v solar panel and could share the details

For 3xAA NiMH and a 5V solar panel, you need just a diode, which prevents the batteries from discharging through the solar panel at night.

NiMH batteries can be "trickle charged" for long periods of time with little or no damage, but to learn the gory details, consult batteryuniversity.com

For example, start here: BU-203: Nickel-based Batteries - Battery University

1 Like

Thank you - this is exactly what I was looking for. I will have a look at the at the BU. For the diode, would any Schottky diode work? 1N4001? Anything to take into consideration to keep my circuit at low power?

What voltage will the Arduino see in full sun? The 5V solar panels I've used have an open circuit voltage close to 6V. If you're powering directly, with no regulator, then maybe a 1N4001 would be the safest way to go.

1N4001 is fine.

Forum members would be better equipped to offer advice if you would measure the open circuit voltage and short circuit current of your solar panel in full sun, and post that information.