Fridge, CTEK, Batteries. Somebody is not happy

[Raingler Nets]

Hey all! Just got to a point with no success after days of troubleshooting and rewiring batteries and charging boxes after all great and good for a year in the RAM 2500. Need some help or testing ideas.

2016 RAM diesel rig set up with a Snowmaster 67L, Renogy 160w panel, dual Northstar AGM27F batteries92 a/h (in parallel. One is 4 y/o and oher is 2 y/o. The older battery does only test at 780cca whcih I know if down from original performance) and CTEK 250S Dual and the smartpass 120S. All worked great for a year and then at the BC Overland Rally the Snowmaster popped it's 15A fuse. I replaced the fuse but ever since then the CTEK 120S flashes (says battery guard activated) the non critical consumer + output and provides no power. I put the power directly to the + for the batter charge output on the 120S and the fridge runs. Until the battery finally drops down to 10v where I have the Snowmaster to auto shut off. As long as the truck runs or the solar is charging, all good. The 120S continues to show flashing even with the consumer output disconnected.

I got a replacement 120S from CTEK and yep, same problem. I've pulled the batteries and had them tested and taken it to just a single consumer battery (the 2 y/o 932 cca) to try to eliminate battery or connection points being an issue. Could it be excessive draw from the Snowmasterthat triggered the original blown fuse? The Snowmaster did have the control panel replaced not too long ago due to a replacement remote (that's another ongoing problem! lol) It's fine as long as I'm driving; or the suns nice and bright, but I'd sure like to get back to the performance that I'd gotten used to originally where I could leave the truck parked for multiple cloudy days and fridge still nice and running cold.

Sure like some testing ideas before I start to throw new batteries or parts at it. Thanks in advance!

 

[jonyjoe101]

I suspect your draining the batteries too low and they aren't getting back up to full. 10 volts is too low for agm's. Once the batteries start going below 11 volts they start losing capacity, they will still charge back up to 14.4 volts but once you start putting loads on them they don't last long. If they charge back up to full too quickly thats a sign they lost capacity.

Next time your charging the batteries measure the voltage at the battery terminals with a multimeter and see if they are reaching 14.4 volts. With solar its more than likely not getting to 14.4 volts, I encountered that many times due to voltage drop.
Also a fridge will slowly drain your batteries on very hot days where solar wont be able to keep up with it. About 2 years ago when the weather was very hot, even with good sunlight the fridge I had drained my 220ah lifepo4 down to about 10 percent, it took about a week to do it. And I had a 240 watt solar panel but it wasnt enough to run the fridge and swampcooler I had.

Its the first thing I would check, maybe a very good charge on the batteries will get them back up to a good condition. IF the charging system aint getting your batteries to 14.4 volts (at battery terminals) replacing the batteries will do no good.
The battery guard flashing is probably a sign the battery is getting too low. For lead acid/agm 12.1 volts is where you don't want go below.

Also check what the max voltage on the northstars can handle and charge them to the max. My start battery is a fullriver agm and requires 14.7 volts to fully charge, I have to topped them off every once in a while since the alternator only goes to 14.4 volts. If I dont top them off I get slow cranks.


I would also look at getting a coulombmeter to count amps going in/out of the battery. I use one on my lifepo4 but they will also work on lead acid. These read the voltage directly from the battery terminals so it will give you a good reading of what the voltage is reading. If you use 20 amps on monday then on tuesday you have to put at least 20 amps back in, With lead acid/agm you have to make sure your reaching max voltage everyday and it needs to stay there for several hours to fully charge.

 

[Raingler Nets]

hey thanks a bunch! FInally had a chance to get out and do some testing. I do also have the CTEK dash mounted monitor. https://baintech.com.au/product/ctek-system-monitor/
I get between 16v - 19.3v from my solar panels at the charging input connection. Just on solar charge, the service battery is maxing it's charge at 12.2v (confirmed also at moniter up front). The max output from the CTEK charger is 13.5v stable with nothing connected to it. Charge to the starter batteries is 12.6v from the CTEK. Turning on the fridge drops the consumer output (and same for consumer battery) from 12.2 to 11.8 within a minute or two of the fridge running which shuts off the fridge now that I've raised it's shutoff voltage point to highest position : 11.8v. It seems that the running alternator brings the voltages up on both alternator and consumer connections to 13.5v (immediately at float level) but still not close to the 14.7 you reference.

EDIT: as truck was driven more, voltage did finally climb to 14.3. It would appear that I will have to likely replace these batteries at some point and more immediately get a home charger to step up the charge to the 14.7. Thanks again for the leads (pun intentional)!

 

[Trestle]

Check the max solar input on the CTEK. Should be in the manual somewhere. You will probably have to do some math to calculate it. For mine, it is either 120 or 125 watts worth of solar, with the max solar panel being below a certain voltage. Anything over that (volts or watts) and it shuts down the solar charge is it is not rated. You mentioned you have a 160w panel, and I suspect that is the issue why you are OK to charge from the B2B, but not from the panel.

 

[Oka 374]

You need more solar especially if the panel you have is laying flat. A 160 watt panel won't keep up with a fridge so you are slowly draining the batteries, anything below 12.2 or thereabouts is starting to kill them and as others have said they don't come back if down that low at 10v for long.

 

[Trestle]

Did a little research, as I had more time, and it seems your panel is likely compatible with your setup. Open Circuit, and total wattage look like they should be good if the Renogy specs I pulled are similar to your actual panel. I have an older CTEK, so mine must have much lower capacity.

I run a Snowmaster 67 liter off of a 105 amp AGM with the CTEK B2B and a 120 watt panel (when stationary) without issue, so 160 should be plenty unless lots of cloud cover, etc. You could get some degradation over time, but that is more a symptom of batteries getting old than system capacity when new. Most people have to oversize their panels due to a number of factors that make systems inefficient.

I'm leaning into Dusty Xavier's camp, thinking that between pairing an old and new battery, combined with the age of the system (one battery 4 years old) that the batteries are the issue. I also think if you're going to replace them, simply get two matching and do it up right vs. replace one and have the same issue in 2 years.

One other thing to think about. Take a look at where the CTEK setup is. It should be as close to the house batteries as possible. Two reasons. Some like to put them in the engine bay. They tend not to last as long there. The main reason though, is that voltage is lost over wire distance. Place the CTEK close to the starter batteries, and you have a potentially long run to the house batteries. CTEK output is at X voltage (probably close to ideal), but house batteries never see ideal...they see X minus voltage loss. Place them close to the house batteries so that your ideal charge voltage "X" suffers little to no voltage loss, and the way a B2B system works is that they will compensate for the voltage loss FROM the starter battery thus that loss is less of a detractor.

Be sure to update us once you figure this out, so that it can serve as a reference for others who may need this at a later date.

 

[Raingler Nets]

Check the max solar input on the CTEK. Should be in the manual somewhere. You will probably have to do some math to calculate it. For mine, it is either 120 or 125 watts worth of solar, with the max solar panel being below a certain voltage. Anything over that (volts or watts) and it shuts down the solar charge is it is not rated. You mentioned you have a 160w panel, and I suspect that is the issue why you are OK to charge from the B2B, but not from the panel.

Good idea on that and I had thought that might be a concern. The CTEK does allow up to 23v on solar input.

 

[Raingler Nets]

Did a little research, as I had more time, and it seems your panel is likely compatible with your setup. Open Circuit, and total wattage look like they should be good if the Renogy specs I pulled are similar to your actual panel. I have an older CTEK, so mine must have much lower capacity.

I run a Snowmaster 67 liter off of a 105 amp AGM with the CTEK B2B and a 120 watt panel (when stationary) without issue, so 160 should be plenty unless lots of cloud cover, etc. You could get some degradation over time, but that is more a symptom of batteries getting old than system capacity when new. Most people have to oversize their panels due to a number of factors that make systems inefficient.

I'm leaning into Dusty Xavier's camp, thinking that between pairing an old and new battery, combined with the age of the system (one battery 4 years old) that the batteries are the issue. I also think if you're going to replace them, simply get two matching and do it up right vs. replace one and have the same issue in 2 years.

One other thing to think about. Take a look at where the CTEK setup is. It should be as close to the house batteries as possible. Two reasons. Some like to put them in the engine bay. They tend not to last as long there. The main reason though, is that voltage is lost over wire distance. Place the CTEK close to the starter batteries, and you have a potentially long run to the house batteries. CTEK output is at X voltage (probably close to ideal), but house batteries never see ideal...they see X minus voltage loss. Place them close to the house batteries so that your ideal charge voltage "X" suffers little to no voltage loss, and the way a B2B system works is that they will compensate for the voltage loss FROM the starter battery thus that loss is less of a detractor.

Be sure to update us once you figure this out, so that it can serve as a reference for others who may need this at a later date.

Will definitekly update! And hopefully that 6 pack that is on it's way to someone in near future will be nice and cold lol.

 

[ChasingOurTrunks]

Lots of info here that is excellent, far beyond what I know, but I do have a question: Why did your fridge blow the fuse to begin with, and might that give some info as to what's going on?

 

[Raingler Nets]

Lots of info here that is excellent, far beyond what I know, but I do have a question: Why did your fridge blow the fuse to begin with, and might that give some info as to what's going on?

I've been curious as to that too. I've replaced with another 15A and has not blown since. It was really hot, perhaps just overworked compressor? I had replaced the controller panel about a month earlier after my remote was stolen. Todd@snomaster said that they were matched to each remote and the remote I had was on backorder. Unfortunately this did not seem to work as I still don't have a working remote even after programming procedure. I may try to put the original back in but can't fathom it's got anything to do with the power issues.
Remote for bed mounted fridge. Kinda nice feature you don't really appreciate until you DON'T have it!

 

[ChasingOurTrunks]

I've been curious as to that too. I've replaced with another 15A and has not blown since. It was really hot, perhaps just overworked compressor? I had replaced the controller panel about a month earlier after my remote was stolen. Todd@snomaster said that they were matched to each remote and the remote I had was on backorder. Unfortunately this did not seem to work as I still don't have a working remote even after programming procedure. I may try to put the original back in but can't fathom it's got anything to do with the power issues.
Remote for bed mounted fridge. Kinda nice feature you don't really appreciate until you DON'T have it!

That's definitely odd; fuses usually don't blow up unless there was something, somewhere that was unusual. But perhaps the issue that is causing everything also blew the fuse. It could also be two things messing up at once in an unrelated fashion - stranger things have happened!

I hear you on the remote thing - I have a Unique fridge I got at Costco (I cannot find them anywhere now though Home Depot used to sell them too) and it has a Bluetooth remote built in so I can use my phone. It's one of those "I don't really need that..." but now I use it on almost every trip at least a few times and wouldn't get one without it!

 

[Raingler Nets]

I am not a expert by any means, but I have some knowledge.

Since you have 2 batteries disconnect one and charge it up seporate from the other. Then do the same with the second battery. Keep them seporate from each other and NOT wired together. Charge then seporate. Let them set for a hour and check the voltage of each. If they still are the same then use one at a time and connect them to the fridge. Check the voltage of each after 5 minutes.

Now
If one drops down to the 11.8 volts it has a bad cell. If the other stays at closer to the 12.7 volts that battery is better shape.

If they both drop down then that leaves a couple of problems could exist. The bad battery could have killed the other. (Note; you said that one battery is 2 years old and the other is 4 years old). You never want to mix a old battery with a new battery. If the old battery is worn out that will ruin the newer battery by constantly bringing it down to the 11.8 volts.

Old school electronics is a process of eliminating one piece of the pie at a time.

So if you have a 12 volt battery (a starter battery) from a different vehicle or another 12 volt battery that you can use for a test. Hook it up to the fridge and see what it will do.

If it runs and stays up for 30 minutes then it is probably a good fridge. What we have done is shown that the batteries are the problem.

Dump both batteries and get 2 new batteries.

If you are to cheap to do that then buy a new one. Now keep the seporate from each other. Charge then one at a time and hook them up one at a time to run the fridge. When it gets low then switch them and the charged one will run the fridge as you charge the other.

This is why the system may have failed after a year the bad battery took and died.

This information is worth what you paid for it, but it may work.

Now if this works you owe the next overlander you see a 6 pack of Beer or Soda. The rules are not a relitave but a stranger. Now if it did not work drink the 6 pack and try something else.

This was some good trouble shooting advice. I charged both batteries independently. Newer battery read afterwards 13.6v and older at 12.99v. Hooked up each separate and ran fridge 5 mins under load as the fridge was trying to get to temp. The newer battery showed 12.7v and the the older one held 12.4v. I've got a trip next week on San Juan Island so I decided to just hook them up both again and noticed as I checked the voltage at CTEK with fridge still running under load that the voltage was holding at 12.6v (solar connected) but fridge was showing 11.9v (just above highest cut off point). Long story short, corrosion inside the main system ground terminal as I spotted just a little bit of fuzzy green peeking out of end by ring. Cut, replaced terminal. And also found a questionable solder joint in the power line where the cable had been extended to the battery box and power distribution fusebox. CTEK pieces and both batteries are in a NOCO HM462 Dual L16 Commercial-Grade Battery Box with about 7 feet of power and ground cable to the fridge. And we have 12.6v on the fridge meter now!
Fridge has been running fine about an hour now, sun is getting low so I'll check it a few times and update. Seems like voltage drops in the power and ground system at this point. It's mostr always something simple that's just overlooked (and hidden). Assorted chilling beverages in fridge. Stop by if on the islands overlanders!

 

[Raingler Nets]

Again, I am not a expert by any means, but I have some knowledge.

Could it be that with the lower voltage that the running of the compressor pulled more amps then the fuse could handle. When the fridge/freezers are run at 24 volt the amps is much smaller then at 12 volts. With the 12.7 volts being down at 11.8, it may draw over the 15 amps through the fuse. That in turn may have been what blew the fuse.

I think the voltage drop in the solder joint was the culprit here. Will update aftr some use. Thank you for the idea to dig into this more!

 

[Raingler Nets]

You need more solar especially if the panel you have is laying flat. A 160 watt panel won't keep up with a fridge so you are slowly draining the batteries, anything below 12.2 or thereabouts is starting to kill them and as others have said they don't come back if down that low at 10v for long.

Ive glued the Renogy to the top of my Alu-Cab. It's getting a bit of whitening now so I'll have to watch for something with more wattage when it's due to replace but I'm certain it's just a "slowing down" of the battery drainage.

 

[PeterChang]

You'd better not over-discharge the battery many times, otherwise, the battery may not be awakened. Fully charge the battery respectively, and try to do a battery capacity test for the electric water heater, electric heater.