Hi guys,
I am new, i have few 3.7V batterys (2000mah)
and i am trying to connect them in series(with 3 batteries).
I am not sure how to select the solar panel that charge them.
9v or 12 V solar panel?
or how many watts i need for the solar panel to charge the batteries.
Thank you for helping
To charge a battery you need a voltage that is higher than the battery voltage but not so high as to damage the battery.
Since you say 3.7v I assume you refer to LiPo cells which are certain to explode if they are overcharged. That means that you MUST use a suitable charger for safety. Even then I would not charge them unattended unless they are in a container that will withstand and contain a fire or explosion.
When you get a suitable charger it will probably tell you what input voltage and current it requires.
If you were charging lead-acid batteries things would be very much simpler.
Have a look at the Battery University website.
...R