Solar Panel Battery Charge Time

winger
winger Registered Users Posts: 1
in Advanced Solar Electric Technical Forum #1
Hi I'm new to solar power so I hope someone can answer this easily. If you can share the math so I can do it myself in the future I'd appreciate it!

I have deep cycle LiPo model airplane batteries I need to charge. They're typically 12V @ 1-5 amps, and have a 500 Ah capacity. My question is how long would it take to charge this battery with solar panel(s) at X watts (for X=50, 100, 200, 300, 500, 1000). Do I need to hook up to more than 1 panel and use some voltage converter to get some of these higher powers? Any recommendations on panels, converters, connection schemes, or other pieces I need would be great!

Thanks so much in advanced everyone..
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Solar Panel Battery Charge Time

    Welcome to the forum.

    What you and we need to know here is what the battery manufacturer recommends for charge rate & Voltage. Then see if solar can be used as a source to duplicate that need. Chances are it can.

    This bit I don't understand: "They're typically 12V @ 1-5 amps, and have a 500 Ah capacity." A battery is rated in Voltage & Amp hours @ rate (20 hour rate is typically used for RE). What is the 1 to 5 Amps? Discharge rate used or recommended peak charging current? It would be pretty ridiculous to try and charge a 500 Amp hour battery @ 5 Amps as it would take a very long time.

    Some batteries recommend a constant current charge, others a Voltage peak & time charge, and various combinations there of. If this were a standard FLA battery in an RE application you'd want to see a peak current of 5 to 13 (or perhaps higher) percent of capacity, or 25 to 65 Amps which would require approximately 400 to 1000 Watts of panel and a good MPPT type charge controller.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #3
    Re: Solar Panel Battery Charge Time
    Cariboocoot wrote: »
    This bit I don't understand: "They're typically 12V @ 1-5 amps, and have a 500 Ah capacity." A battery is rated in Voltage & Amp hours @ rate (20 hour rate is typically used for RE). What is the 1 to 5 Amps? Discharge rate used or recommended peak charging current? It would be pretty ridiculous to try and charge a 500 Amp hour battery @ 5 Amps as it would take a very long time.

    Just a guess, but since we are talking about LiPO4 and model airplanes, I suspect that the batteries are 500mah not 500Ah. Unless it is a very very large model!
    And a Lithium battery of that size could produce 1-5 amps for a correspondingly short period of time.
    SMA SB 3000, old BP panels.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: Solar Panel Battery Charge Time
    inetdog wrote: »
    Just a guess, but since we are talking about LiPO4 and model airplanes, I suspect that the batteries are 500mah not 500Ah. Unless it is a very very large model!
    And a Lithium battery of that size could produce 1-5 amps for a correspondingly short period of time.

    That would make more sense. :D
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