Based on that 1mA. Even the big ones (4.5x10) give about 50uA with artificial light, and ~300uA with the indirect light of the day. Sunlight is like 6 times more powerful. Even when the ambient light seems to be about the same as 2x100w LED (each about 1000 lumens)

So any options beside using several NiMH batteries in parallel?

 

So any options beside using several NiMH batteries in parallel?

I used 2 of the bigger cells (means ~ twice 300uA) and they seem to be giving enough power. Time will tell. They either prolong the single NiMH battery or hopefully keep it charged. I also tested it and it uses 310uA. I measured the battery's voltage and it is 1318mV. will keep track of the change to see which way it goes. Fingers crossed

 

I used 2 of the bigger cells (means ~ twice 300uA)

it uses 310uA

That means the solar cell will need to charge at least 12 hours/day to maintain the battery charge.

Obviously you won't need any charge control circuit as the battery will never be overcharged.

 

That means the solar cell will need to charge at least 12 hours/day to maintain the battery charge.

Obviously you won't need any charge control circuit as the battery will never be overcharged.

Just an update after testing for a few days. The battery swings between 1298mV to 1293mV. Seems like mission accomplished. Thanks