Failing/weak Battery??

We have a 2017 550, with the original Marinco charger built in. Put in a new Enersys
DataSafe 70ah AGM battery in it two years ago. Always plugged in while not in use.
Now, this year, if I unplug the charger, voltage is at 13 v, but if it sits for 12 hours, voltage drops to 12.4 (80%).
It does this whether the main disconnect is on or off. I checked parasitic draw, and it is 4 milliamps or .004 amp, that is not the issue.

AGM batteries are running over $200 now, so I don't want to replace unless I know it is the problem.
However, if it needs to be changed out, I'd rather do it at home than try to find one on the road.
Does this sound like a normal battery function?

 

$200? Walmart near me is selling a Group 24DC (deep cycle) for $75. Johnson Controls is currently making them if I am not mistaken --- they aren't a bad battery.

It sounds like the battery is probably done for but possibly repairable. You may want to try a "desulfinating" charger --- Noco Genius5 is what I use. Once the battery is "fully charged," you put the charger into "repair" mode. I have heard of some success but also accusations of snake oil.

At $60, it's probably worth the gamble. Especially if you have lawn mowers and such with batteries

I would pull the battery entirely from the trailer when repairing, but at the very least disconnect the battery leads or throw the "disconnect" switch...I'd hate to zap any electronics board.

I have used this charger on mine, and I have no ran completely flat twice...

 

I have a NOCO Genius 5. Nothing to lose by trying to 'repair'.
Getting that battery out is a real bear though. Need suction cups to get it to start it sliding out.

 

I'm curious if there was a difference in model years.

My battery has a few wood screws, and the panel comes off. The battery is right there, and it slides out relatively easily. A suction cup would make it easier but not required.

Just remove shore/AC power, and flip the master switch off before you begin. Disconnect negative first, and connect negative last when reassembling...

The one thing to make sure if is you know which battery wire is positive and negative --- they use a single color of wire and I can see how it might be an easy mistake to make if aren't careful.

 

AGM's are well over $200 everywhere. It came with an AGM, so I put another in in 2020. Should I consider a normal deep cycle battery??

 

"repair mode" is in progress. We shall see what happens.

 

Group 24 marine deep cycle batter would not fit without mods to cavity, or battery, or both.
Would prolly have to cut lead posts off top of battery as it is too high, and saw plastic handle slots off end of the battery itself, as it is too long.

 

No. Camp-Inn’s design has a closed battery compartment, which requires an AGM.

The reason is that a conventional lead-acid battery may outgas hydrogen sulfide, a little poisonous and a lot flammable. They require a ventilated battery compartment. An AGM doesn’t outgas, and doesn’t require ventilation.

Note to future readers: NEVER put a conventional or deep-cycle battery in a CI battery compartment. ONLY use an AGM, a type of Sealed Lead Acid battery (SLA). Or, if your charger, expected camping/charging temps, and/or Lithium Battery Management System (BMS) will accommodate it, a Lithium battery.

 

Well, tried the 'repair' with the Noco Genius 5. It still dropped to 12.4 from 13volts in 12 hours, where it seems to sit.
Looks like a new battery is in the cards, as I've really lost half of the usable power that battery should provide.
I say that because one should not drain these agm batteries below 50%, and if I leave home with 75-80%, that is half of its usable capacity. Don't know why this one is that far gone after 2 years. Two years of TLC at that.

 

Lipster,

I should point on something on battery voltage. The "full" battery voltage of that AGM battery is 12.2-12.3v. Anything above that is float voltage and sort of free power. When using a capacity meter like the TriMetric that first 20% is the float voltage which you need to use in a first day or so to gain any advantage to it.

So, a AGM battery dropping to 12.4v withing 12 hours is completely normal and sounds like a healthy battery.

Cary

 

Cary - I would defer to you with this, as I would with most things....and I hate to sound like I am challenging. But what you are saying isn't in agreement with other sources I've read.

12.7 volts is the 100% I see on the published charts I commonly use, and 12.4 is in the 60-75% range. Dropping from 100% down to 75 with no load overnight sounds like a pretty high rate of self-discharge. If there's a better source of information, I'd love to know it.

Thanks in advance...

-S

 

Cary, thanks for the prompt info.
I don’t have a TriMetric meter, just use the chart for AGM voltage many of use. I will forstall buying a new AGM and see how this one hold up on the trip next week.
One thing of note: When the the present battery was new, it took 13 hours to go from 13v to 12.4v, with a 1.37 amp load.
Now it takes 12 hours to get there with no load. Free indeed!