Solar Battery Charger Question

[80 Cruiser Rod]

I bought one of those Thunderbolt Solar Battery Chargers from Harbor Freight. It's only rated for 1.5 Watts. I've taken out the 30 amp fuse so nothing is inadvertently left on inside of the camper. The instructions state that it should not be used w/o a regulator, inverter, and/or charge controller. Is that really necessary? I've used these in the past and never had a problem.

[Les7h]

I would monitor my battery very closely because your panel is so small it may not keep up with the self discharge rate of the battery ( even with nothing connected ) can you return it for a larger panel? Les

[PlayersZ28]

I would say it's no different than the 1A wall wart chargers you can buy (have a couple here) that will keep charging a battery forever. They don't know when it's full though so will just keep going.

Is this for maintaining the battery in storage? If it's a week or so then probably OK but for a long term I'd just bring the battery home rather than use something like that.

[80 Cruiser Rod]

Originally Posted by Les7h

I would monitor my battery very closely because your panel is so small it may not keep up with the self discharge rate of the battery ( even with nothing connected ) can you return it for a larger panel? Les

I have monitored the battery. When I was connected to shore power the battery was over 13 volts and while it has been on the 1.5 W solar battery charger it has come down to @ 12.3 volts but has maintained that for well over 2 weeks now.

[bankr63]

I would say that yes, you should have a controller. According to the product details, the panel is actually 24v (most panels are more than 12v output). So you should be regulating the voltage down to about 14v, which will actually up the charging current (although the overall power will remain at 1.5w).

[Mustang65]

Another issue with the cheap SOLAR battery maintainers that do not have a charge controller is that at night, if it does not have a "BLOCKING RESISTOR", or it is not working, the SOLAR panel becomes a "LOAD" at night or when there is not enough sun light.

The 1.5 amp output of the SOLAR panel is measured at PEAK sun only. So, maybe 2 or 3 hours a day you will hit that max, and as each cloud passes over, well you guessed it... a minimal amount of energy going to the battery.

If you park in a partially shaded area, you might as well skip the 1.5 watt SOLAR solution.

The very minimum for a 1 battery system that I would recommend is a 50 watt SOLAR panel with a SOLAR charge controller. That at PEAK sun will give you about 4.5 Amps for those 2 or 3 hours a day.... and the SOLAR panel needs to be in clear sun light all day.

If I were adding SOLAR for maintaining my battery investment, I would go with a 100 watt system. Even on cloudy days you will get enough power to keep the batteries topped off. The SOLAR charge controller will maintain the voltage properly and an occasional visit to check the battery water level is all that is needed.

Don
My Registry

RVing with SOLAR

[bdreinv]

Are first try at Solar was a Harbor Freight 3 panel portable unit $149.95.Worked fine was a little cumber-son for storage.Thanks