egilbernt
Sweden
Asked
— Edited
Hello.
Got a 9.6V battery i use for my ez-B. If I shall charge the batterypack with a solarpanel, how much voltage should i go for? Should I use a solar panel with 10v? or more? And what about the ampere? Is it okay with a solar panel with 0.2amp for a 0.7amp battery?
And would I need a charge regulator, or simply just a one-way diode on the positive site?
Thank you,
Hey there Egilbernt!
Just to confirm that your 9.6V battery pack is NiMH or NiCd type correct? If either of these is the case you can definitely use a Schottkey Diode from Solar panel '+' to Battery '+' as you were saying. You would use a schottkey because they have a low forward voltage drop and as such would not take much voltage away from the solar panel. And yes you would want a solar panel that is probably around 12-16V because you will likely not seem ideal light conditions all the time so you'll want to get a panel that can provide you with a voltage higher than 10V (9.6V + Diode foward voltage: 0.36V = 9.96V) on average during the day. As for current (measured in amperes) you can always use a low current as your panel can provide, just be aware that the higher the current rating the faster you'll charge the battery pack.
A couple of these in series might do the trick for you.
As an aside if you were to trickle charge a Lipo battery with a solar panel you will need a Lithium polymer charging circuit
Good luck with the solar charging!
Thank you very much! But if I charge the battery with a solar panel who have 4-5v higher than the battery pack it wont damage the battery? And can it always stay connected? It wont overcharge the battery?
Thank you,
I wouldn't worry about over charging cause solar panels have a hard time keeping up with charging anyway. I have a Solarbotics PumLantern that I have running with that type of circuit which charges daily and has been Pumming at night for more than a year now with the same batteries. As for damaging the battery, you won't have to worry about that because you have a 9.6V battery that means 8 cells at a nominal 1.2V a piece. 5V/8 = 0.6V so you are charging each battery at 1.8V a piece which is fine because that extra 5V will be under ideal light conditions. Each battery is usually charged at 1.4V-1.6V a piece and I'd say that the majority of the time you will be within this range, as you won't always have direct light on you panel(s) all day long.
Yes, you can leave the diode/solar panel combo hooked up permanently as the diode blocks voltage from escaping from the batteries through the panel, the panel will always try charging the batteries when there is enough light.
Hope that helps. :)