little cheap charge controller

[omegaman66]

Hello,
I am looking at a small cheap charge controller that comes in a package with a 30 watt solar panel. The charge controller can only handle 10amps.

Similar charge controllers cost about 10-20 dollars. This one is not mppt. I don't see the company name in the package. Just wondering how much power these tiny cheap charge controllers consume in a 24hr time frame.

extra unimportant info: Off grid, 2hours from home, to power a super small load once a day. I am going overboard with the battery and even having an solar panel in this application is rare. It just sucks to drive two hours to find out the battery is dead and I would prefer that never happens again. The 30 watt panel is way to big but this location is shaded so I won't get close to 30 watts ever.

 

[mikefitz]

much power these tiny cheap charge controllers consume in a 24hr time frame.

The only specification I have for a generic PWM, ( the units with USB), is not more than 10mA, so 240 mA hours per day. A 30 watt panel has a maximum current output of around 1.7 amps. In practice say 5 amp hours per day with sun. If shaded, much less depending on shade pattern and duration. If serious continual shading the project may fail. On site testing for panel current delivery would be useful.

 

[omegaman66]

The only specification I have for a generic PWM, ( the units with USB), is not more than 10mA, so 240 mA hours per day. A 30 watt panel has a maximum current output of around 1.7 amps. In practice say 5 amp hours per day with sun. If shaded, much less depending on shade pattern and duration. If serious continual shading the project may fail. On site testing for panel current delivery would be useful.

Thanks I will test the panel when I get it under harsher conditions that I think it will face when I actually use it. Thank You

 

[omegaman66]

Update and question

I have the panel and charge controller. The panel puts out 20v in full sun. It is suppose to have protection that will not allow the panel to drain the battery. I do not know how it does this if it does it at all. I assumed it would be via a diode.

So I get it with cloudy weather conditions. Output 10 VOC. I hook it up and the volts to the battery fluctuate all over the place. 5,7,8,6,9 etc! After a short while disconnect the battery and battery voltage is lower than it was minutes before.

I then hooked the solar panel up lawnmower the next day but did it directly, no charge controller. The battery is holding good voltage hours after the sun has set. So it was draining the battery 100x faster with low light conditions than it does with the solar panel hooked directly to the battery.

So does anyone know what is going one?
Q1: Why is the voltage to the battery jumping around so much?
Q2: Can solar charge controllers prevent solar panel backfeed some other way besides a diode?


(extra info: Yes I knew it wasn't going to charge. I was testing to see if it would drain the battery when the sun isn't out and if so how fast. Well it was way to fast. To use it this way imagine I could put a diode in line myself. This is probably a 10 dollar charge controller. Pwm)

 

[MakeMePower]

i have the mppt unit your talking about, it pulls its power from the solar panel, not the battery, there should be 0 load when the sun is down

 

[omegaman66]

It is PWM not MPPT.