Solar Panel

[kbarlow]

I have a mini solar panel, max 5 watt output, that is mounted on top of the air conditioner. If I turn the RV battery switch "off" every thing is disconnected from the batterys - BUT - after about 2 days there appears to be a small charge building in the system without the batterys in the loop. Is there any potential damage being created in this configuration. Thanks Guys

Ken

 

[CCutshaw]

The charge controller regulates the output from the solar array. With the batteries disconnected and no load from the 12 volt system in your RV, there should be no output from the controller.

Calvin

 

[Gary - K7GLD]

Short answer - at least as far as any "damage" to the battery(s) - no, 5 watts applied only during daylight hours is actually a GOOD thing as to keeping them topped off and in top charge condition...

 

[kbarlow]

I should have said "When I turn the batterys OFF" every thing is disconnected from the batterys - BUT - after about 2 days there appears to be a small charge building in the system without the batterys in the loop.

There is no controller in the system.

Thanks Ken

 

[Gary - K7GLD]

I should have said "When I turn the batterys OFF" every thing is disconnected from the batterys - BUT - after about 2 days there appears to be a small charge building in the system without the batterys in the loop.

There is no controller in the system.

Thanks Ken

I understood your post - but figured you were concerned that stray charging voltage was somehow trickling back into the batteries - not very likely if they are totally isolated from the solar panels, nor is harm likely even if they were. I frequently use a 30 watt solar panel connected 24/7 to our 5er - keeps the batteries (2 golf car types) in full charge condition and ready to go at any time.



The only potential problem with removing the batteries from the circuit with the solar panel connected, is that those panels CAN develop voltages up near 20 volts without the batteries to act as a buffer - and some trailers have devices like smoke detectors, refrigerator thermostat controls, etc, that might be damaged by excessive voltages.

 

[kbarlow]

The only potential problem with removing the batteries from the circuit with the solar panel connected, is that those panels CAN develop voltages up near 20 volts without the batteries to act as a buffer - and some trailers have devices like smoke detectors, refrigerator thermostat controls, etc, that might be damaged by excessive voltages.

That's my concern. Sorry I didn't explain correctly. I think if the voltage gets to high in some of those capacitors it could damage the boards. I turn a closet light "on' and that seems to reduce the voltage. That's the only quick fix I can think of.

Thanks Ken

 

[Todd T]

pull the fuse out of the solar charger. it should be located in the filter section of your AC unit. or better yet wire in a toggle for it and mount it right there on the AC grill.



the only problem i see with your closet light theory is My pea brain would forget and then run the battery dead once i turned it back on.

 

[Todd T]

FYI mine only generates about 5-6 volts during direct sunlight with the battery off.

 

[kbarlow]

the only problem i see with your closet light theory is My pea brain would forget and then run the battery dead once i turned it back on.

I don't have to worry about that, I'm PERFECT. It's the rest of the crew around here I have to watch.

Cheers Ken

 

[Gary - K7GLD]

FYI mine only generates about 5-6 volts during direct sunlight with the battery off.

WOW, that IS weird - mine easily hits 19+ volts in direct sunlight, open circuit voltage with only a digital VM across the leads - and a 12 volt system usually runs a charge voltage up around 14+ volts to fully charge a 12 volt battery...

 

[CCutshaw]

Ken, If your array only puts out 6 volts you don't have enough voltage to charge your battery. That's why you need a charge controller to regulate the output from the array to 13. 8 v to charge your battery. The controller is a DC to DC converter. The voltage output from the array depends on how many solar cells there are in series. The PV array we use on our solar house has a open circuit voltage of 88 volts. We use a RV Power Products, Solar Boost, maximum power point tracking charge controller to regulate our buss voltage.



Calvin

 

[kbarlow]

Ken, If your array only puts out 6 volts you don't have enough voltage to charge your battery.



Calvin

I am going to take a reading today. I'm guessing it will be above 15 volts.

 

[Todd T]

that was ME, Calvin. I checked again today and with my battery turned off the Monitor panel and CO2 detector dont turn off completely or they draw on the solar panel somehow while the battery is off. it will only hit 5-6 volts like that. with everything turned on it'll hit 13. 5-14 volts.



FWIW Ken, your trailer's inverter/charger should shuttle the battery charge and keep it at maximum capacity without boiling the water out of it. I would advise you keep the trailer plugged into 110 while not in use to maintain the battery better or at least put one of those battery tenders on it. Mine has a 3 stage inverter/charger setup.