Charging issues or lack there of!

WillieT · March 2017

First of all I am a Solar newbie. I try to read as much as I can but I'm having an issue that I can't wrap my head around. Any help would be greatly appreciated!

I have a off grid camper on some remote property I own. The system is 12 volt (all wired parallel) with (3)100 watt panels, (usually reading about 21 volts) A fairly cheap 30 amp charge controller (nothing user configurable), (2) 210 ah deep cycle marine batteries (which just tested good and were fully charged at home before installing) and (1) 800 watt inverter. Running off the inverter a small TV, DVD player, and occasionally a fan or two (less than 100 watts). On the 12 volt side the usual camper lighting (all LED) Radio/CD player, camper water pump, and fridge (propane and electricity) . Generally not a big draw on the batteries. The problem is the charge controller doesn't seem to be charging the batteries. The charge controller initially read 13.0 volts on the battery bank. After several hours of as much load as I could muster the battery voltage dropped some and read 12.3 volts. Checking the controller several times with all the stuff running it continued to read 0 amps going to the batteries. Now, after that long winded introduction, my question is "Shouldn't the charge controller have kicked in a started recharging the batteries by then?" The charge controller has no documentation indicating at what voltage it begins charging. I have confirmed via multi-meter, the voltage at the panels, the voltage on the array side of the controller, and the battery bank voltage. All is consistent. I initially thought it was the controller and have replaced it 3 times. All my wiring sizes and runs are within specs. Again sorry to be so long winded but I wanted to anticipate any questions you might have while trying to answer. Any help would be greatly appreciated! Thanks in advance

WillieT
Middle Tennessee

littleharbor2 · March 2017

If you are getting 21 volts and the panels are connected to the controller there is something wrong with the controller or connections thereof. 21 volts is open circuit voltage on 12 volt panels. Are you sure all POLARITY is correct? Verify positive and negative with your multimeter at all points. One backward connected panel will cause problems. Are the panels connected to the solar inputs and not another terminal? Did you connect the batteries to the controller FIRST? Your controller needs to see battery voltage first to differentiate between 12 and 24 volt systems.

WillieT · March 2017

Littleharbor2, Thanks for the quick response! 19 -21 volts (no current) depending on sun, via multi meter I have checked the polarity on the connections and even using one panel at a time, The panels are connected in parallel via connectors/adapters that I bought from the panel manufacturer then to the array terminals on the controller. The batteries were connected first, but the charge controller is 12v only. so does that matter on this system. I've had the same results with 3 different charge controllers. So in a perfect world should it be charging with a battery reading of 12.3 volts at both the controller and directly on the battery bank via multi meter. I had to leave it today, but plan to go back out tomorrow afternoon and see what happened in the morning. Thanks again

mike95490 · March 2017

Maybe it's time to upgrade to a better brand of controller ? Morningstar makes several series in various wattages.

littleharbor2 · March 2017

Connect the panels directly to the batteries and watch the voltage.If you can get it to rise to over 14 volts then the only answer is, Bad controller. Even the most inexpensive controllers seem to do their job. Yep new and DIFFERENT controller.

WillieT · March 2017

I've been thinking about the polarity issue you brought up. I have checked the panels and all the connections multiple times, but it could be possible that the wiring from the array that is in conduit (21ft run) into the camper then to the charge controller could be reversed. When I setup the system I purchased a roll of 6 gauge wire in black and marked the positive wire with red tape. If I screwed up then I reversed the polarity. That would explain everything I'm seeing!. The controller is simply preventing the current to flow from the array to the batteries regardless of the battery charge level because the polarity is backward. Obviously the charge controller is much smarter than me! I'm usually not that careless, getting old sucks! I'll check it out tomorrow and post the results. Thanks again for the help!

littleharbor2 · March 2017

I use the same method of identifying the positive conductors. I had that reversed polarity issue once which drove me nuts trying to troubleshoot. Of course that's right I labeled it positive, NOT. Fortunately the controller and panel strings were forgiving enough that once corrected everything worked correctly. This may not always be the case.

WillieT · March 2017

Well, that was it.... I remember setting up the system and fishing 2 wires through conduit from the array to the camper and the red tape I had used to wrap the positive lead was barely hanging on when it came through the other end of the conduit. Apparently it had come completely off and was hanging on the negative wire. I re wrapped it without checking. Went in this morning checked the voltage coming into the charge controller and the polarity was backward. Switched it around and was getting 14.2 volts and about 10 amps. Had my batteries fully charged in no time. Thanks for the advice "Littleharbor2" you certainly got me looking in the right direction.....

BB. · March 2017

But--Be very careful... Connecting solar panels with the wrong polarity directly to a battery bank will create a dead short through the panels and probably ruin the panels, plus possibly overheat the wiring (especially if no fuses/breakers are present in the battery to panel wiring).

-Bill

Charging issues or lack there of!

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