Winter solar battery charging when you can't add water?

[Buckshot_Bill]

We have a solar panel on the roof of our travel trailer that keeps our two 6 volt batteries charged when we're boondocking.
This winter we're leaving the trailer in an RV park in the mountains at 6900 ft. elevation, and, as this is 180 miles from where we live, I can't add dist. water when the batteries need it.
The batteries will be un-attended for 7 months and temps will go down to zero or below.

I've been told to just dis-connect the neg. connection and not worry about the batteries, or

should I leave them connected with the solar charger running as usual
or

should I take them with us and hook a trickle charger to them?

Sorry to be so long winded about all this, but I'm really confused about which way to do this.
Thanks for any suggestions, BB

[time2roll]

Secure them well in the truck bed.

[3_tons]

Removing the batteries and then replacing only once in seven months thus having no morning after sickness ($$)...Sorry, what was the silly question??

[pianotuna]

Hi,

The colder the better so long as they are fully charged. Mine winter nicely and we do get to -40. I do have solar.

[Buckshot_Bill]

Thanks for all your different replies.
The rig in question will be in the White mountains of Eastern Arizona at 6900 ft. elevation- Show Low, Az. area- for those of you familiar with that "neck of the woods" (in an RV park and not out in the boonies,) so it'll be SOMEWHAT more secure, but I'm leaning toward the "put them in the back of the truck and take "em home" side too.
I'm mostly concerned about not being able to add H2O if they need it, and the variables about different loads, the cold killing them,etc.
Much obliged,I sure appreciate everyone's help.
Bill

[JeepCB]

Take them home. Better safe that sorry. You might want to take propane tanks too! Man if both were gone..................just sayin'
Good luck!

[mena661]

smkettner wrote:
I would leave them on solar. No water should be needed for at least six months.

X2

[RJsfishin]

What make you think the batts will still be there when you get back ?
Too many risks, take them w/ you while you can.

[MEXICOWANDERER]

Diapered Horse Trots Up...

A lot depends on what the charge controller is capable of or more importantly what it isn't capable of.

Myself I like BFL's answer.

Spring arrives. You drive all the way up there -ooooooops ---- happens. The panel got covered with three feet of snow. Oops, something, a load turned on when it shouldn't have. Oops, the controller got a sudden case of PMS.

You find all this out not in your driveway but way the hell and gone back in the sticks. Where does it leave you. Up el creeko is where.

I like to weigh decisions like this using the "Risk Benefit" ratio. IMHO the teeter-totter with the take-them-home side is jammed to the ground.

[landyacht318]

If the solar controller has adjustable setpoints, lower ABSorptionVoltage to lower 14's and duration should be no more than 30 minutes.

lower float to manufacturer recommendations for expected temperatures.

Disconnect all loads on battery.

If batteries self discharge to 'zero' in winter, with all loads disconnected, then they are done for anyway and it does not matter what you do.

[time2roll]

Cold battery also has a much slower self discharge. Yes disconnect all loads if snow can linger for a few days or more.

[TucsonJim]

"As the state of charge in a battery decreases, the electrolyte becomes more like water and the freezing temperature increases. The freezing temperature of the electrolyte in a fully charged battery is -92F. At a 40% state of charge, electrolyte will freeze if the temperature reaches approximately 16F." I'd take them with me.

Source of information "Trojan Battery Company"
Trojan Battery Company Website

[CA_Traveler]

smkettner wrote:
I would leave them on solar. No water should be needed for at least six months.

I conditionally agree. If the OP is referring to lower winter snow area (he lists Meza, AZ in his profile) then leave the batteries connected to solar.

Second condition is that ALL RV loads/wiring are fully disconnected from the batteries.

[BFL13]

In theory you can arrange it right to leave them on solar and all will be well. OR for no nail- biting for seven months, you can take them home and know they are all right.

[westend]

Leave on solar, set float voltage on controller, save your back for other tasks.