Portable Solar Panel, hook direct to batteries temporarily?

[crcr]

I have a small solar system I put together, and when I sold the TT that I had installed it on, I removed it. We bought a larger TT, but I did not have time enough before the start of the camping season to install the solar system on the larger TT. And for the duration of the camping season, we keep our TT at a storage lot a couple miles from the campground we frequent all summer, 120 miles from home. So I won't be able to install the full solar system until winter.

We have one camping trip coming up of 4 nights where we won't have hookups. I will be taking our 120 Watt folding portable solar panel. In full sun, it puts out 7 amps or slightly more. Our TT has two Sams Club golf cart batteries, totaling I believe 220 amp hours. We will supplement as needed with a Honda eu2000i generator.

Since I don't have my Morningstar controller wired in as yet and don't really care to try to patch it in for a single 4 night camping trip, I am thinking to just hook the solar panel direct to the batteries, and keep an eye on it and disconnect the panel for awhile should the batteries get fully charged and/or start to bubble. I don't really expect to get in an overcharging situation, as we will have to use the OEM propane heater some at night and early mornings, and we all know what power hogs those are. And I run an antenna booster all day and a laptop quite a few hours a day along with the normal 12V load of a modern TT. My question is, do you think I can get by this way one time only for 4 nights without damaging the batteries if I am careful?

Second question, is it OK on occasions when I am running the generator with the TT plugged into it, to also continue to let the solar panel pump amps into the batteries?

Thanks for any expertise on these questions from our knowledgeable solar folks here!

[ken_white]

A Solar Panel acts like a constant current source, so it will assume a particular load voltage based on the battery's condition and the solar irradiance received.

Monitor the battery voltage and disconnect when the SG is acceptable.

[crcr]

Thanks to all for your responses.

Yes, it is a 12V solar panel.

[doughere]

If this is a 12 volt panel (puts out 19 to 21 volts open circuit) tied to two GC's it will probably never get near 15 volts unless you are at 100% SOC. Watch the voltage at the battery, and if it looks like you are going to go over 15 volts (I seriously doubt it) just lay the panel down.

Have a great trip,
Doug

[2oldman]

RoyB wrote:
Having 19VDC or higher might start blowing incandescent bulbs and other low current 12VDC devices..

This is a good point I didn't think of. You may not want that voltage also appearing in your coach...especially at the refrigerator.

[RoyB]

I have not experienced this but if it was putting out 19VDC and higher at 5-6AMPS I don't think I would like to do that. It could be the battery will load it down somewhat...

If it is a 12VDC type solar panel no problem...

Having 19VDC or higher might start blowing incandescent bulbs and other low current 12VDC devices...

This if course is the reason you should be using a SOLAR CONTROLLER to regulate the DC output to the proper setting for your battery bank...

Most panels produce the higher DC VOLTAGES to allow the solar controllers to output a good steady selectable DC VOLTAGE OUTPUT that you need.

just my thoughts...

Roy Ken

[2oldman]

crcr wrote:
do you think I can get by this way one time only for 4 nights without damaging the batteries if I am careful?

Second question, is it OK on occasions when I am running the generator with the TT plugged into it, to also continue to let the solar panel pump amps into the batteries?

Yeah, I think that'd be fine.

Without the controller? I don't know how smart your converter is, but with a higher voltage from the uncontrolled panel, it may not charge at all. With a controller.. pretty much same answer. Every system is different.