Keeping batteries in camper over winter?

[Birddude]

There's a lot of advice out there that says the best way to maintain deep cycle batteries over the winter is to remove them from the camper and put them in warm storage. However, I'd like to use the camper occasionally during the winter and it would be convenient to leave the batteries in it if I can do so without damaging them.

The manual for the Progressive Dynamics PD4000 power converter in the camper says it will automatically go into "Storage Mode" and decrease the voltage to 13.2 volts to maintain the battery. Does this mean I can just plug-in the camper power cord over the winter and the batteries will be OK? If not, could I purchase some kind of battery tender or maintainer that would work?

[Kayteg1]

The storage mode is not effective as float circuit battery maintainers deliver.
I am strong believer in maintainers as I had motorcycle-size battery in my PWC.
The battery come weak on season 2, but since I used PWC only once then, I did not worry about it, leaving it for the winter under battery maintainer.
Here comes season 3 and battery works perfectly.
Hard to beat that.

[hedgehopper]

Birddude wrote:
The manual for the Progressive Dynamics PD4000 power converter in the camper says it will automatically go into "Storage Mode" and decrease the voltage to 13.2 volts to maintain the battery. Does this mean I can just plug-in the camper power cord over the winter and the batteries will be OK? If not, could I purchase some kind of battery tender or maintainer that would work?

I leave the PD connected all winter and have done fine. Before I had the PD, I used a temperature compensated BatteryMINDer 2012. That did fine too. I think the BatteryMINDer is the better option because of the temperature compensation. But I'm just guessing. And just leaving the PD connected is easier.

[HMS_Beagle]

Batteries die of heat, not cold.

One thing not mentioned so far, the charge and float voltage of batteries increases at colder temperatures, that is, the temp coefficient is negative. If you are keeping it plugged in, it's best to have a temp compensated charger, and the float voltage will go up as it gets colder, not down. Good AGMs will not discharge enough over 6 months to worry about, and I'd just make sure there were no loads on them. In a camper, there are often things connected directly to the battery, like the CO detector and certain controls and idiot lights. Removing the ground terminal is a sure way to know they are disconnected.

[Kayteg1]

x2 what aruba5er says.
I had 400lb of batteries in my conversion that I had in storage with no power.
When I was taking the engine batteries with me for occasional recharge and other uses, the deep-cycle (cheap golf-cart size) did hold good charge for up to 10 months. Even with switch - the cables can leak some current in dump condition.
Just pull the battery clamp. Most of RV batteries have wing nut for such purpose.
The $46 batteries last me for 10 years btw.

[aruba5er]

charge them fully , disconnect one post so it doesn"t drain { the curcuit that keeps time in your radio or did you remember to turn off the heater strips in your refer? } They will be fine next spring. Trust me, I forgot to disconnect the battery in the boat this last summer and the radio killed the battery. Now have a harbor Freight kill switch on it now.

[Geewizard]

Fixed link for above.

Sandia National Laboratories - PDF

Temperature effects on sealed lead acid batteries and charging techniques to prolong cycle life

[bb_94401]

Storage, aka non-use battery conditions are important to attain maximum battery cycles/life, especially the farther you deviate on either side of ~25C (77F). Self discharge increases with higher temperature and age. Combine that with any parasitic draws if you don't disconnect the battery, and your battery capacity won't last long due to sulfation, if you don't follow the white paper from:

Trojan PDF - Deep Cycle Battery Storage

In the cold, you get the benefit of a 2x slower chemical reaction for every 10 degree C decrease (Arrhenius equation). Sulfation slows down, but nothing is free. The capacity of the battery (a chemical reaction) also decreases, it also takes more voltage to recharge the battery, if you don't have temperature compensated charging. So only a partially charged battery.

So if you aren't monitoring or keeping your battery charged in the winter, in addition to sulfation, the electrolyte freezing point also gets higher, the more discharged the battery. Resulting in a frozen/destroyed battery, if it isn't an AGM.

40% discharged; Freezing point -30F
50% discharged; Freezing point -14F
60% discharged; Freezing point -3F
70% discharged; Freezing point 9F
80% discharged; Freezing point 16F
90% discharged; Freezing point 23F

You can read more about all of the above in:

Trojan - User's Guide PDF

Or if you like even more info:

Sandia National Laboratories - PDF
Temperature effects on sealed lead acid batteries and charging techniques to prolong cycle life

[Camper_Jeff___K]

I have 2 group 31 AGMs. The 80 watt solar is useless during winter months. I keep the TC plugged into shore power and also have a 1000 watt baseboard in there to keep the TC at 60 degrees all the time so I can use it for overflow cooking and refrigeration. Never had a problem.

[JimK-NY]

I have never seen any studies showing that batteries need to be stored in warm conditions. Several people have expressed that opinion. Are there any facts to back up those opinions?

I left my batteries in my RV for 7 years. They had a lot of cycles, lots of temperature extremes and seemed to be as good as new until the 8th year. Moderately cold weather, like down to zero to 10 degrees does not seem to be an issue for charged batteries. High temperatures are a totally different issue. Car batteries rarely last 2 summers in Phoenix, at least for cars used and stored on the streets.

[midnightsadie]

check water level clean post.then charge them ,unhook the ground cable and they should be just fine.

[pianotuna]

LOL Photomike,

Actually for every ten degree C downwards in temperature the speed of a chemical reaction is 50% less. That means the slow dissolving of the positive "plates" is 1/2 as fast.

If nominal is 20 c, at 10 c, it is 50%, at 0 c it is 25%, at -10 c it is 12.5%, at -20 c it is 6.25% and at -30 it is 3.125% as fast.

This is NOT accurate--but just an approximation.

[Photomike]

pianotuna wrote:
Bring batteries into warm areas decreases their life span. It is good to fully charge, leave in place and disconnect.

Having solar to charge is even better than the above.

You just say that because there is no "warm area" where you live :B :B

I have to go shovel snow now :h

[Tom_M1]

I spend 6 months in Florida for the winter. I have a pickup and two motorcycles that are in an unheated garage in Minneapolis. Temps can routinely hit -20F. I make sure all batteries are fully charged then disconnect them. One winter I had a cheap Harbor Freight tender on one battery. It shorted and drained the battery. The battery froze and busted.

[jplante4]

200 watts of solar keeps my 4 GCs up all winter. I disconnect the chassis battery. On my last rig, the little solar panel wasn't enough and the batteries froze. However, the case wasn't compromised (just bulged) and the batteries took enough of a charge in the spring to run a few things to sell the coach.