How to test the solar panel output and some other questions.

[Bbasso]

I'm used to seeing up to 15 amps coming from my two 100wt renogy panels, connected to the ecco-worthy charge controller which feeds my two 155ah (each) agm batteries. But now that I'm back mobile and in Florida again, I haven’t seen over 8.5 amps...

So what is the best way to test everything to make sure all is functioning correctly?

I understand that if the batteries are (near) full they will draw less but I have a feeling there is something wrong.
Thanks for your time and advice

 

[LeishaShannon]

Can you isolate/unplug each panel to check the input each is providing?

 

[Bbasso]

Sure I can, what am I looking for? I have a decent multimeter...

 

[dwh]

Park in the sun. Put like a 20a load on the batteries.

That will consume all that your solar can produce plus a bit more, and then you can see exactly how much the solar produces when maxxed out.

 

[Bbasso]

What's the best way to put a 20a load?
Everything I use is very efficient lol

 

[dwh]

Um...

Got an inverter?

 

[Bbasso]

Nope... everything is 12v.

 

[dwh]

Got a split-charge relay or ACR?

 

[DaveInDenver]

I have a stack of surplus power resistors I use for first powering of new supplies, tuning up radios, bringing up power amps, that sort of thing. I get them at ham swaps and electronics junk stores. At work we had some 300W monsters and I got some as big as 50W at home. You can find them on eBay and stuff in the large sizes, too. Put a couple or three 8 ohm loads in parallel, that will get a load that should in theory draw the max a 100ish watt panel would produce.

An alternative is to use a whole bunch of 3W resistors in parallel suspended in a mineral oil bath. I made a 250W 50 ohm dummy load in a paint can like that. That barely heats up.

http://www.ai4ji.com/projects/dummyload.htm

 

[dwh]

Engage the split-charge relay by turning on the key without starting the engine. Turn on everything in the truck - headlights on high beam, radios, heater fan, etc. That should probably be enough load to soak up all the solar can produce.

With an ACR, force it on with the engine off and do the same thing.

 

[Bbasso]

Sounds like a good plan, but my blueseas 7622 ACR switch has been acting funky llately and I can't force connect. I look into the manual switching it.
Thanks!

 

[jonyjoe101]

8.5 amps sound about right for 200 watts of panels and this time of year. You might get 15 amps on rare occasions when the sun is straight overhead and your batteries are below 50 percent and brand new.

I got the same ecoworthy controller connected to a 240 watt panel, in the summer I max out at 12 amps, and right now in the winter with the sun lower in the horizon I'm only getting 9 amps at mid day. I have seen it go as high as 15 amps but its extremely rare, usually only happens when the sun comes out from behind a cloud and only lasts for a few seconds.

On the ecoworthy you can press a button that does a mppt check, on mine it will shoot up the amps to show what the max amps you can get with the sun you have. By looking at the lcd screen you will see the amps peak at there maximum then return back to charging your battery. And also like they pointed out by running loads on your battery, the controller will pump all the amps it can into the battery to keep the voltage up. Myself I got a roadpro 12 volt lunchbucket type cooker, it uses 11 amps when I plug that bad boy in, it maxes out the solar system.

After having the ecoworthy for almost 4 years, I'm confident thats about as many amps as I'm going to get from it, I havent cleaned my panel in years, so i might be able to squeeze an extra amp out of it. I think you can get about 1 amp for ever 20 watts of panels in the best sun conditions. With a 120 watt panel I used to max out at 6 amps.

 

[AndrewP]

I agree. In the best of conditions, you get a bit over 5 amps @12 volts from each 100 watt panel. So with the sun low in the sky, like now, 8+ amps seems about right. I doubt you ever saw 15 amps @ 12 volts from 200 watts of panels.

I think you are worried about nothing. But if you want to be sure, run down your batteries by using a compressor, or leaving the lights on or whatever, and then retest. But 5 amps per panel is the best you're going to do at this time of year and so 8 amps for 2 panels sounds pretty good.

 

[Bbasso]

Just a random pic I took in August... I might even have the 14+ amp pic somewhere too...

 

[Bbasso]

Hrmmm...
I found a 12v heater/fan and it seemed to draw more than I've seen in a while.
Here are the results from 3 mins ago