Charge controller for 4.8volt system?

Roostorf
Roostorf Registered Users Posts: 2
in Solar Beginners Corner #1
I'd like to design a simple solar system for a 4.8volt cordless screwdriver battery/motor. The manual says not to overcharge the battery and was thinking I'd need a charge controller to keep from burning the battery up but they all seem to be made for 12 volt batteries. Any advice?
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  • tons001
    tons001 Solar Expert Posts: 71 ✭✭
    #2
    Re: Charge controller for 4.8volt system?

    You are probably better off designing a simple 12v system with an inverter to charge those drill batteries using the wall wart and charger that came with it.
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  • n4wff
    n4wff Solar Expert Posts: 48 ✭✭
    #3
    Re: Charge controller for 4.8volt system?

    Just something to think about, USB phone chargers are 5v. Measure the voltage from your wall wart charger and compare it to a USB phone charger.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #4
    Re: Charge controller for 4.8volt system?

    There are many different chemistry for electric tools... Older ones were NiCad, newer ones were NiMH, and the newest are Lithium Ion of some sort...

    All have different charging requirements. And, some like various Li-Ion are very easy to damage if improperly recharged.

    As said above, your best bet is to use the supplied charge controller (typically 120/240 VAC) and setup a solar array+charge controller+battery bank+AC inverter to supply energy to your AC battery charger.

    You can see, this is not a "cheap" project... But does give you the ability to use the tools during the day and recharge at night (because of the lead acid battery in your solar power setup).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • jcheil
    jcheil Solar Expert Posts: 722 ✭✭✭
    #5
    Re: Charge controller for 4.8volt system?
    tons001 wrote: »
    You are probably better off designing a simple 12v system with an inverter to charge those drill batteries using the wall wart and charger that came with it.

    I can't remember which kinds, but many of those cordless tool battery chargers will damage the batteries if used with a modified sine wave inverter so you would need a pure sine wave inverter; although in this case you could get by with a VERY small one.
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
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  • tons001
    tons001 Solar Expert Posts: 71 ✭✭
    #6
    Re: Charge controller for 4.8volt system?
    jcheil wrote: »
    I can't remember which kinds, but many of those cordless tool battery chargers will damage the batteries if used with a modified sine wave inverter so you would need a pure sine wave inverter; although in this case you could get by with a VERY small one.

    I picked up the Morningstar SureSine and have been very happy with it.
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  • Roostorf
    Roostorf Registered Users Posts: 2
    #7
    Re: Charge controller for 4.8volt system?

    I'm not using it as a drill, I was gonna take it apart and use the motor and battery.. I can probably just get a 12v drill battery for $10 and that would probably be a cheaper option.

    BB. wrote: »
    There are many different chemistry for electric tools... Older ones were NiCad, newer ones were NiMH, and the newest are Lithium Ion of some sort...

    All have different charging requirements. And, some like various Li-Ion are very easy to damage if improperly recharged.

    As said above, your best bet is to use the supplied charge controller (typically 120/240 VAC) and setup a solar array+charge controller+battery bank+AC inverter to supply energy to your AC battery charger.

    You can see, this is not a "cheap" project... But does give you the ability to use the tools during the day and recharge at night (because of the lead acid battery in your solar power setup).

    -Bill
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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #8
    Re: Charge controller for 4.8volt system?

    I'm working on a charge controller for 4V system. It's pretty much designed, I will be posting the progress in this thread.

    I looked at Li-ion batteries. They're certainly different from FLA/SLA. They may explode if they go below 20% SoC or above 80% SoC. I was going to do constant voltage charger to keep them at 70% SoC all the time. But they don't really work below freezing.

    So, I decided to buy SLA batteries. The ones I bought were rated to -40C. But the constant voltage charger at an upper float setting should work. However, they need temperature compensation.

    Other chemistries will have different requirements. So, you need to start from finding out what kind of battery is that. Should be printed on the label.
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