I have recently purchased a 10W polycrystalline solar panel with 30A battery clips, a 20A solar charge controller (intelligent regulator with 12V/24V USB display) and a 12V 7Amp lead acid rechargeable battery. Setup seems simple enough but the charge controller did not come with instructions. My concern is that if I hook up the 3 in a circuit that battery will overcharge and gas. I want to charge it in my room (medium size, not large and not small) but I am not sure how to prevent overcharging. What can I do and is there cause for concern? Can I incorporate an LED to burn off excess charge or something like that? Will the charge controller prevent overcharging? What happens when the battery is full and the panel is still delivering energy? Thoughts? Thank you!

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    \$\begingroup\$ I would presume that the charge controller would prevent over charge, but without documentation who knows?! You need to search online using the manufacturer and model number of the charge controller and find documentation. Charging a vented lead acid battery in an enclosed space is not recommended! \$\endgroup\$
    – LsD
    Sep 8, 2017 at 16:28
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    \$\begingroup\$ A 300W or more charger and puny 10W PV may be mismatched for efficiency unless it has features for MPT. \$\endgroup\$ Sep 8, 2017 at 16:35

1 Answer 1


The charge controller will handle the current coming from the panel. As LsD mentioned, it should prevent overcharging, but check the manual via model number online if possible. It's essential you have the instructions on hand to ensure you don't fry the controller when hooking it up.

Typically when the battery charge becomes close to 100%, the controller switches into a trickle charge mode.

Hope this helps.


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