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charging 24vdc battery with solar panel

Thread starter #1
I bought the harbor freight 45watt, 12vdc charge controller solar kit.
Can I charge my two 24vdc batteries with this kit?
Do I need to buy a 24vdc charge controller?
Can I build a DIY step-up converter (12vdc to 24vdc)?


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Can you connect them in parallel during charging?
Thread starter #4
Thanks for the info. I'll post for a DIY circuit on building a 24vdc charge controller. Hope you're safe in CO, heard about the fires.


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Wouldn't that just double the amps and voltage would still be 24vdc?
If you connect your two 12V batteries in parallel, + to+ and - to -. you have created a 12V battery with double the Ah capacity. Your panel will be charge that just fine, but it will take twice as long.

You will have to disconnect the charger before connecting the batteries in series again to power your load. A DPDT switch could be used to do that. Do not leave the 12V solar charger connected to only one of the two batteries while drawing a load off the two connected in series.

You could also buy a 24V panel, buy a 12V to 24V step-up charge controller, buy a second 12V panel...
Thread starter #7
Connecting batteries in parallel

See the attached block diagram of my solar panel system with batteries. Is that what you meant about connecting the batteries (24vdc each) in parallel? Also, where would I connect the DPDT switch?


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New joiner's attachments are checked by Moderators before the membership will see them.

I misunderstood, I thought you have two 12V batteries in series to make 24V, but you actually have two 24V batteries.

Short of using a step-up switch-mode power-supply/charger to convert 12V to 24V, there is no way for you to use a 12V panel.
Thread starter #9
Thanks Mike. The two 24vdc batteries came with a 24volt battery charger, have you heard of anyone changing the battery charger to an inverter? It stands to reason that in a battery charger you take the 110 a.c. input to charge (output) the 24volt battery. Therefore, is it possible to modify the battery charger and make it an inverter? I'm recycling some of my STUFF to stay 'green' at the same time.


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Can you post a url link to your charger?

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