harbor freight solar controller

[danlaurajacobson]

Sorry, posted this before in wrong forum...

I have the solar kit set up and I am just trying to figure out the controller. After some significant time on hold with the "technical questions" people, I gave up and figured someone here would know.
The panels charge the battery during the day, but seem to discharge the battery as the light fades. I was thinking that the controller prevented this, but yesterday the battery began the day at 11.7v and reached 12.6v during the afternoon. Then, as the sun got lower, the voltage dropped down to 12.0 and stopped there. This is well below the 13 to 14.5v that the instructions say indicates full charge.
It does appear that the controller stopped the discharge at 12v, but this is lower than I want, right? Does this mean that the controller should be switched off when the battery is at peak voltage (afternoon) so that it does not discharge every evening?
thanks!

[admin note: this duplicate thread is closed. To view the active thread go to <a href="http://www.loghomebuilders.org/harbor-freight-solar-controller">http://www.loghomebuilders.org/harbor-freight-solar-controller</a>]

[donjuedo]

I wouldn't be too sure the controller is discharging the battery. I would expect the voltage to be a little higher while current is running into the battery, but that does not represent the true battery voltage The best way to measure is when zero current is going in or out of the battery.
You could ensure no current flows from the battery into the solar panels by adding a diode, but that also represents a power loss when the solar panel is supplying the battery.
Of course, the controller could still be a poor design, and indeed be discharging the battery. What make and model is it?
You probably already thought about the load, but didn't describe it. Is there a load? If so, when is it connected and when is it not?
Have the measurements been repeated, day by day?

Peter

[danlaurajacobson]

wow, I accidentally got two threads going here. The solar kit is a harbor freight 45watt kit. The results have repeated for several days. There is no load on the battery. It is simply a battery connected to the solar controller and the solar array.

[slrrls]

I have read some guru's that said this controller is a good replacement for the harbor freight 45 watt system.
http://www.ecodirect.com/Morningstar-SunGuard-SG-4-12-Volt-4-5-Amp-p/morningstar-sunguard-sg-4.htm

[lilbluehonda]

With only 45 watts you probably don't even need a charge controller it's more like a trickle charger unless your charging a little battery

[lilbluehonda]

You could go here http://sunelec.com/index.php?main_page=product_info&cPath=47&products_id=1504 and by a 46 watt panel for 61.64 ,or an 80 watt panel for 95.20