Solar charger for NIMH batteries.

General project discussion / help
Did you make a robotic coffee pot which implements HTCPCP and decafs unauthorized users? Show it off here!

Moderator: phalanx

Post Reply
infernoprime
Posts: 15
Joined: Thu Mar 02, 2017 4:20 pm

Solar charger for NIMH batteries.

Post by infernoprime » Mon Dec 31, 2018 5:06 pm

I have revised my original idea to this as it is the closest thing I can find to my idea that is affordable.

Here is the project :https://www.allaboutcircuits.com/projec ... batteries/

I have a few questions about this design if anyone sees this post.

1.I don't want to have the 12v output. Can I safely remove that or is it hardwired to the point where it can not be removed.

2.I would like to know if I could use my 5v 500mah solar panel. Because at most I will only charge 2 batteries at once which I am sure will take a while.

PS I have tried posting on other forums but for some reason I just can't get a response.

Thanks.

jremington
Support Volunteer
Posts: 2339
Joined: Fri Jun 15, 2007 9:41 pm
Location: Eugene, Or

Re: Solar charger for NIMH batteries.

Post by jremington » Mon Dec 31, 2018 5:57 pm

The design you linked is for a 22 V solar panel and is way overkill for a single AA battery. It won't work at all with a 5V panel.

In full sun, your 5V, 500 mA panel will charge 2 AA NiMH (2200 mAh) series connected batteries in about five hours. All you need is a diode to prevent the panel from discharging the cells after dark. Of course, you would have to monitor the charging process and disconnect the batteries when fully charged.

infernoprime
Posts: 15
Joined: Thu Mar 02, 2017 4:20 pm

Re: Solar charger for NIMH batteries.

Post by infernoprime » Mon Dec 31, 2018 8:02 pm

Can I introduce an led to help me to know when they are full or not ?.

jremington
Support Volunteer
Posts: 2339
Joined: Fri Jun 15, 2007 9:41 pm
Location: Eugene, Or

Re: Solar charger for NIMH batteries.

Post by jremington » Mon Dec 31, 2018 8:36 pm

Of course you can, but that requires circuitry to know when the batteries are fully charged.

Look around for some other charger designs. 30 seconds of googling turned up this 5V USB charger, which might work with your panel: http://www.stefanv.com/electronics/usb_charger.html Or, buy a cheap USB AA charger with auto shutoff, and power it with your panel.

You would need to add a diode between the panel and the charger, to prevent malfunction in case of darkness or cloudy skies.

infernoprime
Posts: 15
Joined: Thu Mar 02, 2017 4:20 pm

Re: Solar charger for NIMH batteries.

Post by infernoprime » Tue Jan 01, 2019 3:21 pm

This does look like it would work with my panel. Do you have any other suggestions ?.

infernoprime
Posts: 15
Joined: Thu Mar 02, 2017 4:20 pm

Re: Solar charger for NIMH batteries.

Post by infernoprime » Fri Jan 04, 2019 4:41 pm

I need some help on getting the thermistor for this project. It says I need a 10kΩ @ 25°C thermistor, approx. 3.7%/C° NTC the closest one I can find is this one :https://www.digikey.com/product-detail/ ... -ND/769408

Post Reply