i have a 15w panel and i want to split the output to go to two or three controllers to charge seperate vehicles. is that possible?

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Originally Posted by mlrff i have a 15w panel and i want to split the output to go to two or three controllers to charge separate vehicles. is that possible?

No not really. unless you are talking about a few AA batteries for a pen light or MP3 player. You need a couple hundred watts at least. A 15 watt panel is barely enough to even power a charge controller, not even close for 2 or 3 of them.. You need at least a 100 watt charge controller, and a 100 watt panel to feed three small auto batteries to make even a Trickle of Maintenance charger out of it.. You need a lot mo Money to do what you want to do.

Now with a 15 watt panel and a $10 toy controller made for that wattage panel, or a 50-cent diode you can make a Trickle charger for an auto battery. But no way would it ever charge a auto battery not to mention 3 batteries. It is just not physically possible. At 15 watts @ 12 volts you only generate about C/50 (1-amp) of a 50-amp-hour battery which is a Trickle charge to over come self discharge rates. To make a charger you need C/10 or 5 amps for a single small auto battery of 50 AH.

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Dereck, PE, MSEE
Moderator

according to the manufacture i can charge(trickle) up to four batteries.....if i put them i series.i thought that if i split the incomming wires and ran them to seperate controllers that i could charge more than one battery at a time

What kind of battery are you referring too?

Are you talking auto 12 volt batteries? If so you cannot wire 4-12 volt batteries in series (48 volts) and charge them with a 12 volt charger. You can wire them in parallel and charge them, but a 15 watt panel isn’t going to do very much.

A Trickle Charge is anywhere from C/300 to C/50 rate, where C= the Amp-Hour rating of the battery. A car battery ranges in 50 to 150 AH’s. So if C =50, then 50/50 = 1 amp

Ok a 15 watt panel @ 12 volts can only deliver about 1-amp of current and no more. So a 15 watt panel can only Trickle charge 1, 2, maybe 3 small auto batteries assuming they are fully charged to begin with, but 4 is a stretch of imagination realistically.

Anyway to do this all you need is one charge controller with the batteries wired in parallel. One note of caution here, all the batteries must be in good shape and fully charged. Otherwise the strongest battery will discharge into the weaker ones until they all equalize, and this small of a panel could take months to recharge them if ever at all.

A better approach is use a much higher wattage panel like 50 watts per battery and let the charge controller float charge the batteries. That way you have both a charger and Trickle charger.

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Dereck, PE, MSEE
Moderator

i'm sorry i should have said parallel ...yes they are 12v i should have explainedt exactly what i want to do. i have two vehicles that i don't use all the time so i just
need a trickle charger to keep the battery charged. i don't want to have to pull them out of the vehicle. i thought if i split the power coming out of the panel i could go to seperate controllers.will i get the same output if i do that?

Yes actually you will get more power using just one controller because you only have to power up one controller. Besides I don't even know if you can connect two controllers to a common solar panel array output.

I assume you have an inxepensive shunt of PWM type controller. Those types are very inefficient and will burn 20 to 40% of you solar power.

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Dereck, PE, MSEE
Moderator