Dud battery, or just not enough sunlight? (1 Viewer)

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I was wondering if anyone has experienced something that has (maybe) recently cropped up.

I'm currently running about 200W of panels via a mppt controller, with a flooded lead acid aux battery (under the hood) and my fridge is the main load.

Since the start of the year, the whole system has been chugging along and no known issues. My fridge is on 24/7.

I went camping for the first time this year, and in the middle of the night noticed my fridge was going into low voltage alarm. I monitored the voltage and when the fridge was off it was sitting at about 12.5V, and when the compressor kicked off it was dropping to 11.5V.

Firstly that voltage sounded low. I was a bit surprised by that as I was driving 3hrs out to camp. The afternoon was pretty overcast, and I was parked in the forrest so I could forgive the battery not being fully charged, but I surely a 100Ah battery should be able to manage a fridge for 24hrs.
And then I was very surprised to see such a big voltage drop on fridge start up. Is that normal? Or does it point towards a possible issue with my battery?

I have been lazy and not been monitoring my battery acid levels, and it was looking low, but the plates were still flooded. So I gave it a drink.
The little dot thingy was saying that the battery needs charging, but after a day of charging it hasn't changed. I figured that its probably not a reliable indicator, so is it worth getting one of those turkey baster testers?

I've also read around the traps that it could also be a dead cell in my battery. Is there a simple way I can test that?

What I do want to test is pick up a tong test and measure the amps off the panel, to make sure the controller is still charging the battery properly when the fridge is running.

Or was it just a matter that its too cold at 2degC that evening?
 
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Put it on a real charger (wall plugged) and monitor the voltage across the battery as it charges fully. Then load test the battery. Though it does sound like a dropped cell.

cheers,
george.
 
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What fridge ? Did the solar charge controller show input from solar during this event ? I realize you noticed it at night but the day before had you noticed if solar was working at some capacity ? The drop to 11.5 from 12.5 when running is what my cheap socop/danfoss fridge would show, FWIW, it did have a larger drain than the engel does but with 200w of solar you should have been o.k., what type & size fridge ? what are you using as a plug or connection for fridge power ?
 
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A few quick answers, its a Kick Ass 75L dual zpne fridge. I'm running the bigger chamber at 4degC, and the smaller chamber at -13degC. Everything is connected via anderson plugs. Only the fridge is on the load side of the mppt controller with all the other stuff (lights mainly) directly connected to the battery, and the aux battery is connected to the battery side of the controller.

I picked up a tong tester today so that I can do some proper measurements of where all the power is going. I want to check how much power is really coming off the panels, and doing some checks to make sure its all sized correctly. Its possible there is far less power coming off the panel than I'm assuming.

After leaving the panels on charging all day yesterday (and the fridge off) it was back up over 13V which is encouraging. But then today, with the fridge running all day, by about 90mins after sunset it had already dropped below 13V.

I might also pop into the battery place to get them to check it out, as its still under 12 months old. I'm sure they will also have an opinion about my setup.
 
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I can tell you from personal experience that a 75l with a secop/danfoss comp will kill both batteries with no solar in a day / day and 1/2 depending on conditions, amount opened, shaded, etc. With 75+ watts of solar operating at say 75% with decent sun you should be able to run stand alone indefinite until you lose sun. I have 100w on a engel 45qt and it easily rep[laces what the fridge uses at night and keeps the system at charge. Ran the #'1 years ago on the engel with measured voltage use not whats printed and found that it requires a min of 68 watts of solar at optimum perf. to keep up with fridge on a 90 + day & replace nightime usage. With your 200watts even at 50% it should keep both batts between 12.3 & 13.1 is what I have measured. I believe the voltage drop is due to ambient temps and connections of system although testing shows same voltage throughout when checked at different points. I was referring to Batt connections. Keep an eye on the charge indicator on the solar controller and verify activity during different conditions then you'll know when your solar is not producing, i.e., how much shade cuts it out. Mine produces when you swear it wouldn't.
 
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I agree with you without solar. When I first put in the fridge, with my dodgy old aux battery, I would get about 2 days and then it was done. Which is why I put in the panels.

I also agree with you about panel sizing, and part of the reason I went with 200W of panel. I'm sure in reality on most days its probably on making about 10A at best, but even that should be more than enough to power my fridge and fully charge the battery.

I'm a bit suss that the mppt controller has broken or not performing well, but a thorough amp survey should answer that.

For reference, I dropped to about 12.1V overnight last night. Even though it was about 2degC, so it shouldn't have been running hard.

I'm also banking on taking it back to the battery shop, and seeing if they can swap it over. I paid the premium price because they offer national wide support, so time to see if they deliver.
 
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I would not at all be suprised by a drop to 12.1 at night with that fridge. FWIW I check panels alot and get 18 to 21V , with 200watts your system should recover very quickly in the morning. I would be most suspect of a bad battery.
 
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The shop tested my battery and its testing okay. But doing some online research, and talking with the guy at the shop, he recommended NOT putting my fridge on the load side of the controller, rather connect it to the battery directly, and still use the panel/controller to charge the battery.

In my head that makes sense as it removes the voltage drop when the current is flowing backward from the battery to the fridge via the controller.

I'm going to give that a whirl as a quick fix.
 
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^ What brand/model MPPT controller do you have. I use a Victron unit and have my fridge on the load side. No issue, voltage drop is minimal (more drop in the wiring). I like it on the load side since the Victron shows how energy usage by the load and of course energy coming from the solar. Let's me decide if I have net gain or net loss.

You should measure voltage at various points of your wiring/system - use a decent meter. That will give you facts versus hearsay :)

cheers,
george.
 
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Just a cheapy at the moment that came with the panel. I reckon my cheap tong tester will tell me just as much as a controller.

One thing I did consider as I lay in bed last night is to check my resistance across the plugs. I might have developed a bad earth over winter.
 
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FWIW my less expensive fridge with the secop/danfoss comp will sometimes show the E1 code and if I pull the cig. lighter plug and replace it clears and shows 12.5V, I do feel that any connections can be suspect, I have also been trying to get an answer from anyone as to wether the low voltage cut off systems check voltage all the time, this would explain why it randomly goes into low volt protect, I think the low voltage prevent checks voltage all the time and if system is at say 12.5 and it kicks on the voltage could be below the 11.4 momentarily and the dang thing cuts out due to the low volt protect even tho the low volt condition was momentary. This is what I suspect, have not experienced that with the engel.
 
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Since I love data and trends, I cant help but look at the trends when commissioning.
Its looking like the battery is settling into a voltage of about 12.6V overnight, which still feels low, but bearing in mind this is the voltage the fridge sees via the controller.
And then when the fridge cycles it gets hammered on the volts and drops down below 12V. That sort of lag makes me feel like its a resistance/wiring issue. I actually have a recollection that the load terminals of the controller are quite small, so I think bypassing that will give it more omph.

Screenshot_20220915-081758_KA Products Main.jpg
 
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FWIW my less expensive fridge with the secop/danfoss comp will sometimes show the E1 code and if I pull the cig. lighter plug and replace it clears and shows 12.5V, I do feel that any connections can be suspect, I have also been trying to get an answer from anyone as to wether the low voltage cut off systems check voltage all the time, this would explain why it randomly goes into low volt protect, I think the low voltage prevent checks voltage all the time and if system is at say 12.5 and it kicks on the voltage could be below the 11.4 momentarily and the dang thing cuts out due to the low volt protect even tho the low volt condition was momentary. This is what I suspect, have not experienced that with the engel.
I would agree with that being a symptom of power supply sizing issues such as undersized cables, or earthing issues. Basically the start up current sucks the line out, voltage drops, then fridge freaks out. This is basically what I was seeing at 2am when I was camping. Low enough to go into warning, but not low enough to cut power.
 
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Cheap "MPPT" that came with the panel.... Well, if it's the typical cheap from China and came with the panel, then it's quite likely not an MPPT, regardless of what they quote. Most are PWM and they put an inductor in there to pretend it's MPPT.

So, I'd be looking carefully at that charge controller with a very skeptical eye.

cheers,
george.
 
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I use a sunforce 8 amp with just idiot lights, I am not a big fan of the fridge control units that the fridges with secop/danfoss comps use, they are junk IMO, ever look inside the compressor/control box , connections are lacking, packaging is suspect and you should check the coil mounting, they shake loose.
 
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Cheap "MPPT" that came with the panel.... Well, if it's the typical cheap from China and came with the panel, then it's quite likely not an MPPT, regardless of what they quote. Most are PWM and they put an inductor in there to pretend it's MPPT.

So, I'd be looking carefully at that charge controller with a very skeptical eye.

cheers,
george.
Everything comes from China. Its just a function if you buy something good or bad.
 
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My point is that whatever charger comes with a panel is more than likely not what it seems. There's a reason it's thrown in for essentially $0. A real MPPT charger has quite a bit of electronics, well beyond 'free'.

And yes, I've been to Shenzhen multiple times for products that we manufacture. They can do good work if well supervised and the path well laid out. In that case the product is not $0 or thrown in...

And China isn't the only manufacturing center in the world. A heck of a lot of good stuff is manufactured/assembled in Malaysia, Philippines, Thailand, Taiwan etc - as far as the far east is concerned.

cheers,
george.
 
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I agree with you that a Kings mppt controller isnt going to match a Renogy or better. Which is why I'm putting that high up the queue for potential issues, especially considering I have it mounted behind the panel which is always out in the open. I'm betting the IP rating on it isn't great.

As an Asian guy, I get a bit disappointed by all the "China = s***" rhetoric I hear still. People said the same thing about Japan 50 years ago, and now we all drive Landcruisers because they're the most reliable!
 
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Problem solved! Well, at least its looking solved.
Re-routed the cables so that everything is now on the battery side of the controller. So at night time its directly drawing from the battery, and during the day it should be charging and power the fridge in parrallel. I'll see how the voltage at the battery goes today, and I'm still interested to see the amps.

But the voltage trends are barely budging now, so it must have been the voltage drop back through the controller.

Screenshot_20220916-083151_KA Products Main.jpg
 

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