Mppt charge light doesnt come on

[Colin Hughes]

I recently purchased a 120w solar panel kit, panel, cables, mppt controller. When I set it up, the load and battery lights come on when I connect the battery but when I plug the solar panel into the mppt, the charge light doesn't come on. I sent the first mppt back and they sent another out but it's the same. What am I doing wrong. When should I expect to see the barge light. I would think it would come on as it is saying the battery isn't showing fully charged - yellow light on mppt. Any help appreciated.

 

[dwh]

MPPT works by finding the exact crossing point of voltage and amperage where the solar panel is putting out the most watts at this particular moment. Then it adjusts the load on the panel to keep it most efficiently loaded. That "Maximum Power Point" changes as the light on the panel changes, and as the panel temperature changes.

So, let's say your panel puts out a Vmp (Voltage Max Power) of 15v and you're battery is at 14.4v and the MPPT logic decides that at this moment, the most efficient load on the panel is 14.4v.

In other words, MPPT is making no difference. A lot of MPPT controllers, use the indicator light to indicate that the MPPT is actually providing an extra "boost" (it isn't really a boost, but "boost" sounds good to the marketing guys). If the situation of the solar panel and battery at this moment is such that the MPPT isn't doing anything, then the "MPPT Boost" light isn't going to come on.


As for the charge light. If the battery is already charged when you hook up the solar gear, then what is the solar gear going to do?

Nada. The battery is already charged so there's nothing for it to do.


This is all of course, just remote guesswork, since I don't know if your battery was charged or not when you hooked up the solar. Your post doesn't say.


Who made the controller?
Did you check the solar panel to make sure it's actually putting out power?

 

[Colin Hughes]

Thanks for the reply. Yes the battery is charged, I have a battery separator which charges my second battery once my starting battery is fully charged. The idea of the solar panel is to keep the second battery charged to run my ARB fridge when I'm camped for more thana few days. Before I shipped the original mppt back, the battery was reading around 12v and the panel was reading 17.8 v, measured at the battery and at the mppt for the panel.

 

[dwh]

Hrmm...

What I'd do, is run the battery down some overnight and then stick the solar panel in some good strong sunlight the next day and check it then and see what happens.

You didn't answer, "who made the controller"?

 

[Colin Hughes]

I have another deep cell battery that has almost run down. I'll try it tomorrow as its going to get very hot and sunny. See if the light comes on. The controller came with the kit, made in China, I'll check tomorrow and see if it has a brand name on it. It looks like a smaller version of the one I had before made by Wellsee.

 

[dwh]

http://www.wind-sun.com/ForumVB/sho...ons-on-cheap-chinese-mppt-controllers-on-ebay

See post #6. Solar Guppy is a guy who ran an independent lab and got paid to test charge controllers. Also, I think he's got some MPPT patents as well.

There are quite a few of those Chinese units with different brand name decals on them. They all basically look the same though.

 

[Colin Hughes]

All is good The controller is speaking to, well they are winking at each other, the battery. Looks like I'll have cold milk for the duration of my trip.