Batteries not holding charge ???

My last set of Costco (interstate) batteries lasted 8 years. Try a hard charge for 3 hours and cook em off at 15-16v. May help de-sulfate them. Put a kill switch in for storage and put a charge on them every few months. The electronics and propane detectors will draw them down to a low level which causes your problem. Those are very good batteries for what they are. And the price is right. Here is a chart that gives you an idea of charge state. Keep in mind you don’t want to go below 50% of a charge on a flooded battery. Good luck.....

If you let them go two months at a time without charging, it's close to miraculous they last two years. Conventional flooded cell lead-acid batteries can lose about 15% of their charge in a month at 80F. leaving battery in a discharged state cause sulfation to become irreversible.

When you store the trailer, are you plugged into shore power? If not, I think 2 months or less may not be too bad since there are parasitic draws on the system, even if the battery disconnect is switched to off. The CO/LP monitor comes to mind. If there is no power hooked up to them, try disconnecting the batteries and see what happens. Mine is stored hooked up to power so my advice may not be that helpful because I cannot recall how long my batteries have held a charge when not plugged in. Its been years since I was in that situation.

ilvtravln wrote:
I have 2 year old deep cycle Interstate batteries, usually they hold a charge for about 2 months but recently its much shorter than before. Is there a way to check the RV charging system? When I plug into power everything lights up normal. I check the water in the often. I plug into power about every 2 months. Last set of the same brand of batteries lasted 4 or 5 years. I called Costco where I bought them and they said warranty was only for 1 year. Thanks for any help.

My last set of batteries in my previous fifth wheel were over 10 years old ,and still going strong when I sold it .. They were Kirklands from Costco. I leave my fifth wheel plugged in 24/7. Thats something I recommend if possible.

13.19 charging is hopefully in float mode. Disconnect and let them sit a few hours to see what the resting voltage is. You can see what your converter is doing by measuring the voltage at the converter's 12 volt terminals. I have an all in one unit, so I just open the breaker/fuse door and check the voltage on the DC board.

If your talking about a couple Interstate 12 volt group 24's or 27's two months with no charging seems like a bad idea to me. Whats the resting voltage after two months?

If you have a battery disconnect they might be okay for two months. I charge mine once a week while in storage off my generator. If I didn't have a generator I would have a 100 watt or so solar system for battery charging. Then you can leave the batteries on all the time, the solar will keep them topped up. I put a battery disconnect on all my RV's, its a must have IMO if your rig gets stored regularly. Every one of my trailers would have mystery drains, so I have a decent size battery disconnect like you would have in a boat, not those mickey mouse things people put on battery boxes.

If they drop to 12.4 volts or something like that it will take a good number of hours to recharge them 100% and a few hours to hit 90% if your charger is one with the 14 volt initial boost mode.

I've got the same batteries that are 2.5 seasons old and they read 13.5-13.8 when plugged in. I put solar on the roof during the 1st couple months that we bought the trailer so the batteries have always been charging except when the sun goes down. In the winter the trailers plugged in 24/7.

It almost sounds like they need to be bulk charged and the RV's charger's not getting them up to bulk so they can go into absorption mode then into float.

When on solar my batteries float right around 13.8 with nothing on them except the normal parasitic draws.

When all charging is off they sit at 12.7-12.9 or so.

If they've dropped below 50% too many times then you just may have damaged goods.

CA Traveler wrote:
Idiot lights are for the salesman to explain what a great charging system the RV has...

Buy a digital voltmeter for $10-20. With a dishcarged battery the battery voltage at the battery terminals should ramp up to 14.4V (bulk charging), then hold at 14.4V while the amps taper down (absorb charging) and then volts and amps taper down to float mode of 13.6V.

There are many posts on chargers that don't charge correctly especially WFCO and many have replaced that alleged charger.

If the plates are not completely covered with water the batteries are compromised. Have the batteries load tested by a good battery shop, an auto store is not a good battery shop.

Batteries read 13.19V while plugged into power, I check the water on a regular basis, have not load tested batteries yet. Thanks

Ed9824v wrote:
I am sure you checked the water in the batteries?

Yes, on a regular basis. Thanks

Lwiddis wrote:
Solar makes keeping batteries charged so easy. My TT is neither on the 300 watt roof main system or, when covered, on the 30 watt panel on top of my cover.

Good idea, Thanks

2oldman wrote:
It's not unusual for acid batteries to lose capacity much faster than you think. Do you work them pretty hard?

No