Charge controller thinks battery is 24v - it's 12v?

rooduJardin

Hello all

A simple 12vdc system only running led external lights. Assembled the system on a bench, all good. Installed it and now the controller is treating the battery as 24v. Of course all paramaters now reflect that of a 24v battery and cannot be changed to reflect a 12v battery. Result is now a non-functioning system.

Anyone experienced this or can offer an explanation?

Thank you.

Tecnodave

Please define your system a bit better, what brand of controller, model, etc. takes a lot of guessing out of it, just a test...remove DC power from controller, wait about 5 minutes, reconnect. ?? Same or it's starting new and sees a 12 volt battery

littleharbor2

It is vitally important that you connect the battery bank first. All 12/24 volt charge controllers need to see the battery voltage to determine whether it is 12 or 24 volts. As Technodave suggests, disconnect solar and batteries. Connect the batteries first ,give the controller a chance to boot up before connecting solar.

mcgivor

The auto detect will see the array voltage if connected first and assume that is the nominal voltage if greater than say 20V , always connect the the battery first to get a reference of the nominal voltage.

BB.

Check the battery bank voltage with a meter.

The controller is expecting around 9.5 to 18.0 volts for a 12 volt bank. If outside that range, the controller may not auto configure correctly.

Bill

rooduJardin

https://forum.solar-electric.com/discussion/comment/396732#Comment_396732

Already tried this but same result. The controller is a noname mppt 30amp. I changed it over to an old, very cheap pwm controller and now no problems. I think I'll stick with this, behaving perfectly. The mppt had issues.

Thanks all for replies.

littleharbor2

https://forum.solar-electric.com/discussion/comment/396820#Comment_396820

Many no name MPPT controllers aren't MPPT at all. Any chance you can post the model or pics of it?

What voltage were you running into the controller?

DaangeroussDan

Yeah,, you probably got a fake mppt. If it was less then 100 bucks,, its a fake. As stated above, always hook up your charge controller to the battery bank first, then the pv. here is my quick guide to hooking up mppt vs pwm. https://www.youtube.com/watch?v=1oAi44IAQwQ

here is an explanation of why pwm sucks, and true mppt will save you bank in the long run https://www.youtube.com/watch?v=v0eztArZsBE

Look at the input from a cheep Chinese knock off of the "Make Sky Blue" 60 amp MPPT solar charge controller on a cloudy day. Its amazing output compared to pwm https://www.youtube.com/watch?v=4pHUt2x46Xw

if you click on my youtube name icon, you will come to my youtube page , then click "videos" or "uploads" to see a dozen helpful videos.

Estragon

Mppt CAN be better, but it really depends. IMHO, pwm don't "suck", they're just the right tool for a different job than mppt.

In many cases, for example, using a single 60 cell panel (or multiples in parallel) with mppt to a 24v bank could be problematic.

DaangeroussDan

https://forum.solar-electric.com/discussion/comment/396860#Comment_396860

LOL,, why would you do that? Just to be able to spend extra money on wire? Solar panels are 80 cents per watt now. And if your running multiple panels in parallel when you have a 24 volt battery bank, [not needed. -BB]. Just run groups of 2 in series.

DaangeroussDan

This is 4 groups of 2-12v panels(800 watts) on an MPPT charge controller on a stormy day. 24 volt coming in to 12 volt battery bank (could easily make it 24 but that would be dumb) https://www.youtube.com/watch?v=4pHUt2x46Xw

You will never get that kind of performance from pwm, not in your wildest dreams.

Photowhit

@DaangeroussDan , The advantage is about 10% for MPPT type charge controllers if you are using panels in the proper vmp range to charge a battery voltage. Since MPPT are more expensive and 72 cell panels are common. There are some configurations that PWM are more cost effective. Indeed many MPPT type CC have difficulty being configured for 48 volt systems in cold climates.

mcgivor

MPPT will have an advantage in climates which experience seasonal changes in temperature 10-15%, however in hot tropical regons the advantage is reduced dramatically due to consistently high temperature. So it's best not to assume they will be way more efficient in all circumstances, the added cost of MPPT may be better directed to additional array, in low altitude tropical applications. Morningstar explain this here https://www.morningstarcorp.com/whitepapers/traditional-pwm-vs-morningstars-trakstar-mppt-technology/

Estragon

https://forum.solar-electric.com/discussion/comment/396865#Comment_396865

Why parallel multiple panels? Say I'm setting up an RV and want to maximize pv on limited roof. There's unavoidable shading from vent stack or whatever which will partly shade panel(s) part of the day. The short run from pv the combiner means wiring cost is minimal, but parallel means a shaded panel doesn't take down a whole string. Just one example.

mike95490

Multiple parallel panels will need combiner boxes when you get more than 2 panels. That adds complexity, wires and routing issues,

Estragon

True. Just saying there are different tools for different jobs.

rooduJardin

https://forum.solar-electric.com/discussion/comment/396828#Comment_396828

Pic attached - running 18 volts into the controller for a 12 volt battery. The controller cost the equivalent of AU$15. The pwm I swapped in cost AU$8. Most Chinese knock offs around this price range in Thailand.

Tecnodave

18 volts in just might be a bit too low for that controller, normally you need 24-30 volts for a MPPT controller to function properly. I am not impressed with the looks of the unit at all. Those are the worst terminals that I have ever seen on a solar controller, no barriers between terminals, no short protection. hoakie! Chinese copy of a Chinese copy! Is it really a MPPT controller, many are not they say MPPT on the front cover but inside is a PWM controller

Tecnodave

Right.......Its made by MPPT SOLAR......

littleharbor2

Absolutely, positively another fake MPPT controller. I'm finding many on eBay for $12,49 a piece. I don't care how cheaply the Chinese can make stuff, you're not going to get an MPPT controller for $12.49

Here's a snippet of text I pulled from one of the listings,

1: What is MPPT?

Automatic aggregation tracking charging.

 

Q2:Why the product manual shows "Fully 3-stage PWM charge management"?

Thanks to the kind buyers for reflecting this issue to us, we are very sorry for our unqualified quality inspection work! We only pay attention to the quality of the product itself, but ignore the accuracy of the manual.

We have verified with the supplier that the manufacturer has adopted an universal manual for different types of solar controllers, which has caused buyers confusion. The supplier has promised to replace the new manual.

Since there is still a batch of goods in our warehouse (with inaccurate instructions), in order not to affect the delivery time, we will still send the goods and provide accurate electronic version of the instructions.

In addition to the problems of the manual, if there is any problem with the product itself or logistics, please contact us and we will solve any problems for you.

littleharbor2

You are running 18 volts, (which is typical voltage from a 12 volt panel into your not MPPT controller. It should be operating as a normal PWM controller.

If after rebooting the controller and still acting as a 24 volt controller you have one choice in my mind. Throw it in the trash and if you want a real MPPT controller spend the money on a real one. Verify it is real before spending your money.

One thing I'm confused about. how is it acting as a 24 volt controller with a 12 volt panel connected?