Battery charging advice needed...

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grpark20
grpark20 Registered Users Posts: 16 ✭
in Solar Beginners Corner #1
Along with many other projects I need your opinion on this. I'm looking at purchasing a 5 watt and under solar battery maintainer. Also know as a solar trickle charger. The specific model I'll looking at is Pulse Tech SP-5 (http://www.batterystuff.com/solar-chargers/SP-5.html ). My question is will this maintainer maintain more than one battery at a time if wired parallel? I have a battery rated at 6 amp hours at 10 hours and another rated at 12 am hours at 10 hours (ATV batteries). If those are wired in parallel with the solar maintainer mentioned will it do enough to maintain both batteries. Both batteries are fully charged and will be stored for a long time without use. Or, would I better off just getting 2 separate maintainers. They're pricey but I'm a believer in you get what you pay for.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
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    Re: Battery charging advice needed...

    In isn't a question of "will it maintain more than one battery at a time if wired in parallel?" it's a question of "will it maintain a battery of 'X' Amp hours?"

    5 Watts is not a lot of power" 5 /12 = .4 Amps.
    You have 6 Amp hours + 12 Amp hours = 18 Amp hours. The most charge rate you'd get is 2%. Technically that would work for maintaining.

    But there's another problem; the two batteries aren't the same size by a factor of 2. In charging this would be a problem even for small batteries. For maintaining it is not as much of an issue.

    However, this thing is advertised as a "desulphator". This probably means some type of PWM controller on the panel. Don't expect it to do much; opinions are mixed on the effectiveness of these sort of devices. A 5 Watt panel is worth about $30 http://www.solar-electric.com/so5wamusopa.html A small PWM controller about $30 http://www.solar-electric.com/sg-4.html

    For the $140 they want for one of those things you can buy the equivalent of two from our host, with change leftover.
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  • grpark20
    grpark20 Registered Users Posts: 16 ✭
    #3
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    Re: Battery charging advice needed...
    Cariboocoot wrote: »
    In isn't a question of "will it maintain more than one battery at a time if wired in parallel?" it's a question of "will it maintain a battery of 'X' Amp hours?"

    5 Watts is not a lot of power" 5 /12 = .4 Amps.
    You have 6 Amp hours + 12 Amp hours = 18 Amp hours. The most charge rate you'd get is 2%. Technically that would work for maintaining.

    But there's another problem; the two batteries aren't the same size by a factor of 2. In charging this would be a problem even for small batteries. For maintaining it is not as much of an issue.

    However, this thing is advertised as a "desulphator". This probably means some type of PWM controller on the panel. Don't expect it to do much; opinions are mixed on the effectiveness of these sort of devices. A 5 Watt panel is worth about $30 http://www.solar-electric.com/so5wamusopa.html A small PWM controller about $30 http://www.solar-electric.com/sg-4.html

    For the $140 they want for one of those things you can buy the equivalent of two from our host, with change leftover.


    That was an easy one. I'm going with 2 separate panels to maintain those batteries. Next question....I have a 50 cent piece of junk fan that draws 1.6 amps at 12 volts DC. Can I hook this fan up directly to a panel that doesn't produce more than 1.5 amps max. I know the panel will have voltage spikes but what do you think. I only need the fan to run in the day time. If that's a no go what if I throw a junk battery (12 volt battery thats dead) on a controller and hook the fan up to the battery. Will a controller regulate the voltage and send the voltage to the fan through the junk battery. What do you think?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
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    Re: Battery charging advice needed...

    Something I thought of later: considering how small those batteries are, why not just two of these? http://www.solar-electric.com/bssoelpa1wa1.html
    grpark20 wrote: »
    That was an easy one. I'm going with 2 separate panels to maintain those batteries. Next question....I have a 50 cent piece of junk fan that draws 1.6 amps at 12 volts DC. Can I hook this fan up directly to a panel that doesn't produce more than 1.5 amps max. I know the panel will have voltage spikes but what do you think. I only need the fan to run in the day time. If that's a no go what if I throw a junk battery (12 volt battery thats dead) on a controller and hook the fan up to the battery. Will a controller regulate the voltage and send the voltage to the fan through the junk battery. What do you think?

    Panel current is a function of the amount of light on it and what it's hook too. In other words, if the fan doesn't have low enough resistance to draw full current from the panel it won't do it. DC motors usually don't have any problem with varying Voltages, even going a bit above the rated Voltage.

    Some people on the forum already drive fans direct from panel - no battery involved. Usually the fan is enough to pull the Voltage down to "normal" levels and the current takes care of itself. Your fan is about 20 Watts. Got a 20 Watt panel about? Chances are it will work fine; the fan speed varying with the amount of power the panel is capable of producing.
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  • grpark20
    grpark20 Registered Users Posts: 16 ✭
    #5
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    Re: Battery charging advice needed...
    Cariboocoot wrote: »
    Something I thought of later: considering how small those batteries are, why not just two of these? http://www.solar-electric.com/bssoelpa1wa1.html



    Panel current is a function of the amount of light on it and what it's hook too. In other words, if the fan doesn't have low enough resistance to draw full current from the panel it won't do it. DC motors usually don't have any problem with varying Voltages, even going a bit above the rated Voltage.

    Some people on the forum already drive fans direct from panel - no battery involved. Usually the fan is enough to pull the Voltage down to "normal" levels and the current takes care of itself. Your fan is about 20 Watts. Got a 20 Watt panel about? Chances are it will work fine; the fan speed varying with the amount of power the panel is capable of producing.

    Would I need a solar controller with those 1 watt panels? I'll roll the dice with the 20 watt panel. Thanks for all the help so far.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #6
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    Re: Battery charging advice needed...
    grpark20 wrote: »
    Would I need a solar controller with those 1 watt panels? I'll roll the dice with the 20 watt panel. Thanks for all the help so far.

    No controller needed. Those particular ones have a built-in blocking diode to prevent reverse current flow at night. The peak current being 0.075 Amps it's about a 1% rate max on the 6 Amp hour battery. Should work fine for maintaining purposes.
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