Solar NiMH AA Charger

[slackwarelinux]

Its a slow weekend and I feel like building a Solar NiMH charger and I want some advice.

I have two 16ma 3 volt solar cells, and I am going to try to hook them up in parallel to some NiMH AAs to charge them. I am thinking about adding in some sort of diode to prevent discharge at night. According to my calculations, this means it will take about two weeks to charge a pair of 1600ma AA batteries (I don't get much daylight in Alaska).

Anyways, I just thought I should get a sanity check and make sure none of this would blow up in my face. I am also hoping that some people with formal education in Electrical Engineering will have something insightful to say. Any ideas?

 

[imported_rod]

To charge batteries like that, it is best to supply them with a constant current, of upto about 0.1C (which means 10% of their total capacity - in this case, 160mA)

You sure they're 16mA, that seems small, even for solar cells.

If you put a diode in series with the batteries, it will drop the panels output by 0.6V (to about 2.4V) Also, remember that niMH and NiCad batteries discharge at about 10%-20% per month.

RoD

 

[Jiggz]

Originally posted by: slackwarelinux
Its a slow weekend and I feel like building a Solar NiMH charger and I want some advice.

I have two 16ma 3 volt solar cells, and I am going to try to hook them up in parallel to some NiMH AAs to charge them. I am thinking about adding in some sort of diode to prevent discharge at night. According to my calculations, this means it will take about two weeks to charge a pair of 1600ma AA batteries (I don't get much daylight in Alaska).

Anyways, I just thought I should get a sanity check and make sure none of this would blow up in my face. I am also hoping that some people with formal education in Electrical Engineering will have something insightful to say. Any ideas?

I doubt it will blow in your face. But if you are not getting a lot of sun in locale why bother building a solar powered battery charger? Dude, just get the regular charge and plug it in. It'll probably cost cheaper than the solar cells!

 

[vailr]

A quick froogle.com search on "Solar NiMH charger" found:
UNIVERSAL SOLAR BATTERY CHARGER W/ METER + 4 BATTERIES -- $20.75