Solar Panel for an RV does it need a controller?

[gary350]

I have an Rpod 179 camper trailer. It has a 2 pin plug on the side for connecting solar panels.

I have 135 watts of solar panels. Load voltage about 18 volts.

Do I need a controller? Prices have jumped to $90. Instructions says, prevents battery from discharging into the solar panels after dark, regulates the power, Limits current to the battery, prevents battery from over heating.

135 watts / 18 volts = 7.5 amps I don't think that will damage the battery a battery charger puts out 10 amps on LOW charge.

Will the battery really discharge into the solar panels after dark???????????????????

I think a diode in the circuit will stop battery from discharging into the solar panels.

Lead acid batteries are self regulating the deader the battery is the more amps it pulls. If battery tries to pull 50 amps it can only get 7.5 amps. When battery gets near full charge it will only take 1 amp of the 7.5 amps that are available.

I can parallel 10 1a diodes to get 10 amps or use a 35 amp diode to stop battery from discharging into the solar panel. I'm not sure that really happens but I will find out tomorrow night after dark when I have it hooked up to see what the meter says.

The dealer says, there is a built in controller it is part of the circuit in the circuit box that charges the 12v battery with 120v at the camp site and powers the 12v lights in the camper. If I had a circuit drawing I would know for sure.

What do you think???

 

[Nigel Goodwin]

Will the battery really discharge into the solar panels after dark???????????????????

I think a diode in the circuit will stop battery from discharging into the solar panels.

Yes to both, some solar panels have such diodes built-in.

 

[debe]

135W solar panel without a regulator will definitely damage your battery. Once the battery is fully charged the current will start droping & the voltage will keep rising destroying your battery.

 

[Dr_Doggy]

i just bought a solar panel with charge controller from canadian tire(the junk store)...
but the controller holds things at 12volts!!! not enough volts to charge my car battery!!>???

afaik solar controllers are more for keeping things at 12volts when the panel voltage goes higher than that....


... just to complain a little more
i also bought a weed wacker from them where the motor swivels for edging which is a very cool feature... problem is that they got their left and rights mixed up so that if you swivel it to edging mode there is a wheel that blocks the button to swivel back to weed wack mode.... so now when i talk to any sales agent i ask "does it work?" I still dont trust anything they say...

 

[Adrainsmith]

Not always, but usually. Generally, there is no need for a charge controller with the small maintenance, or trickle charge panels, such as the 1 to 5-watt panels. A rough rule is that if the panel puts out about 2 watts or less for each 50 battery amp-hours, then you don't need one.

 

[NsrMagazin]

135W solar panel without a regulator will definitely damage your battery. Once the battery is fully charged the current will start droping & the voltage will keep rising destroying your battery.

Also it will damage your solar panel and possibly your RV.

Try to get it second hand from somewhere if possible. They should be sold on local classfield sites, but the quality on those sites is junk in my country. Everyone sells there their junk. You can risk if you want. According to my opinion the price will be rising and reach 130-150 USD or more.