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Charging a 70Ah 12volt battery with solar panels Answered

Hi seen your ads on google very enlightening. Was wondering if you could advise me. I have 2 strip lights that i run off my 1000w invertor poweredby a 12v car battery that dies after a while. My kids bought me 2 x 20w solar panels12v. Can i just join the negs and positives together from the panels and connect straight to the battery neg and pos or is more involved. I also have another battery I can join too,Would i need diodes and a controller also? thanks in advance Dougie

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Downunder35m

2 years ago

You need a deep cycle battery to start with, car batteries are totally useless here - that's why it dies so quick.
For the panels you need a solar charge controller and it would be best to go for one that has 24V input so you can put the panels in series.
Gives you a max of 20W.
If they are protected with a diode you can also use a 12V charge controller and get 40W.
Considering even the 40W would only give you a theoretical max of 3.3Amps 70Ah might be overkill.
If you get 8 hours of really good sunlight you can charge about 25Ah.
If your LED lights use more or run longer you might not be able to fully charge the battery - that is where the controller shuts off to protect the battery if the lights stay on.

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DougieD4Downunder35m

Reply 2 years ago

So deep cycle battery req,d. It was just that I have a couple of spare car batteries laying about. I will have to get one then and diodes too ! Thanks for your help appreciated !