Has my battery gone Toes Up?

How old is it?

 

You could try defulfating it --- The onboard charger doesnt' seem to do a great job, but the CTEK seemed to do better. My battery (I _Flat_ emptied it 2 or 3 times now) is damaged. This spring, I was testing a 220 watt solar panel I purchased, and I found the CTEK actually improved the batteries life by a noticeable mount...

Hopefully you're 5 days inside the warranty period and get a free replacement --- I don't know if Walmart is pro-rated or not...

 

Ken,

6 years is a lot to get out of the AGM when using the fridge. I am guessing the battery is coming to end of life. The fridge is the big factor here, it increases the depth of charge/use cycle which adds a more substantial count to the cycle life of the battery. I see lots of fridge users get only 3.5-4.5 years out their batteries.

Load test for sure is the next logical step.

Cary

 

Not too bad. Prices are up slightly but generally available.

Cary

 

You'll get absolute and concrete results using a battery test meter. Something like this - a volt meter alone isn't beneficial here. You can still get 12 volts on a battery which is 'unhealthy'. If you don't have a test meter (and don't want to buy one) most car parts and battery shops will test the batteries for free hoping to sell you a new battery if you need it.

If you want to geek out a little on battery health, this video gives an excellent 6-minute lesson on the true culprit...internal resistance.

 

EDIT: I identified the wrong pinout originally --- Updated to hide my shame

If the battery tests OK, then the charge pin is your next logical only choice. If you start the car, you should see 13.8+ volts coming off the alternator....what battery isolated are you using? Mine is the ctek 205...it takes a few minutes to realize the voltage is high enough to charge before it starts...but you should see charge voltage (13.8+) on the battery shortly after the car starts...if you aren't seeing an charging voltage then the charge pin is the logical choice.

You can check this with a volt meter; just look for 12 volt+ on the on the tow vehicle side of harness on the charging pin. (EDIT: See @SethB update below for details on which pin that is). If you have to charge voltage there, check for voltage at the battery isolator...in my case the CTEK 205....which isolator do you have in yours?

 

Great test procedure Sweeney, but I think that’s the wrong diagram in the attached image. The 6 pins are a dead giveaway! I think that on the TV side one finds +12v upper right on Pin 4, and ground lower left on Pin 1.
View attachment upload_2023-5-25_7-52-9.png

 

WOOPS! What I get for 'working' while goofing off Thanks for the catch!

 

I can't speak to yours but I don't think I ever got even 5 years on a battery using the fridge. Got tired of replacing them every few years and got a Renogy Li battery that I'm delighted with. Now I run the fridge directly from that and never plug it into the trailer. I also added their 40 amp DC-DC charger to my vehicle and use that to keep the Li battery charged as necessary if solar is insufficient, which is not often. It gives me much longer life for the fridge than the AGM and I don't have the problem of the fridge cycling off when the fridge load cycles on, momentarily dropping the voltage after the battery has been depleted some over a weekend.

 

Not going to lie, I think having a separate LiFe battery with a display showing state of charge that you can discharge to 0% makes using the Dometic way less stressful.

 

The CTEK has a great setup. Using the 220watt solar (18volt @ 220 amps) I get a really fast charge and after letting it charge a couple days, my battery health improved. According to the manual, desulphation is the first 4 hours of the charge cycle. So you are probably just fine in that department.

Good luck -- I've always stuck with the cheap lead acid batteries. $95 at walamrt. Friday night through Sunday been fine as long as I am careful about not charge too many laptops

The CF35 and the new CFF35 both seem to be similar in that department. Keeping it out of the sun helps.

 

This thread got me curious. I have flatlined my batter three times now. I'm talking so low a light wouldn't even glow.

I decided to test my battery. Thanks to amazon points, I bought a tester and emptied the storage bin. The 1 1/2 year old battery that has been abused tested out perfectly healthy. Perhaps the deep-cycle batteries are more resistant than I have assumed.