Battery winterization

[prestonjr23]

Is it recommended to remove the coach batteries (flooded lead acid) during the winter months to prevent freezing?

[Milford 47]

No need to if they are charged and no load exist, so that they stay charged

they should be clean as well

[powercat_ras]

Table below of what temp battery fluid freezes at vs. state of charge.

If you store with batteries well charged then they won't freeze unless they discharge during storage. You can disconnect the battery ground cable from both coach and chassis batteries to make sure the only discharge is due to self discharge. In many RVs there are "vampires" that draw current, even if you have a coach and chassis battery disconnect switch you have operated, that may cause slight discharge each week. Some examples on my Winnebago Vista are:

- Kwikee Entry Step Control Board
- Battery Isolation Manager Module
- In-dash electronics always on function that maintains clock time, etc.

If batteries are clean and there's no leakage current between + and - terminals, they may lose up to 20% of their charge due to self discharge during 12 weeks of winter climate storage with average storage temps of 40 F or below.

State of Charge Freezing Temperature
100 -92.0°F
92 -71.3°F
85 -62.0°F
62 -16.0°F
40 + 5.0°F
20 +19.0°F

[prestonjr23]

Thanks for the information!

[Griswald One]

Originally Posted by prestonjr23

Is it recommended to remove the coach batteries (flooded lead acid) during the winter months to prevent freezing?

Your owners manual will also likely indicate the need to exercise both the Engine and the Generator. The owners manual for my new rig indicates every two weeks, which is probably more then needed. But with my previous RV I went up to storage every 35 days (my work schedule) and ran both the engine and genny for an hour. Following that schedule I never saw by batteries dip below 90% and the motorized parts got their exercise.

Also make sure you either put in fuel stabilizer or ethanol free fuel during your winter storage to prevent things getting gummed up.

[Mark_K5LXP]

My brother worked at a car dealer when I was a kid. We lived in Wisconsin where it got cold from time to time.

Got to see first hand how the battery freeze thing worked. If your battery was charged enough to start the car in sub zero temps it was fine. But, forget to to turn the headlights off (pre-computerized car days...) and the battery would drain to the point where the electrolyte would freeze. Normally a battery can be revived if run dead that way above 32F, but once it's frozen it's pretty much done for.

Mark B.
Albuquerque, NM

[prestonjr23]

Great info, much appreciated!

[MN_Traveler]

Does anyone know just how much leakage current can be generated from”dirty” (ie not clean) batteries? Also, what is best way to clean the batteries? Just maybe sweep them with a brush? Water? Solvent of some kind?

[SgtJac]

Originally Posted by powercat_ras

In many RVs there are "vampires" that draw current, even if you have a coach and chassis battery disconnect switch you have operated, that may cause slight discharge each week.

Very well put..

[ken64k]

Ok, I'm new to the RV world but I was a boater for more than 40 years in New England. The only thing I ever did for winter battery storage was make sure they were fully charged and I would disconnect the negitive terminal. The batteries were always good in the Spring when I put the boat back in the water. Note: most of my boats were big cabin cruisers.
It is also a good idea to keep them clean. A little soap and water than wipe them dry.

[Griswald One]

Originally Posted by ken64k

Ok, I'm new to the RV world but I was a boater for more than 40 years in New England. The only thing I ever did for winter battery storage was make sure they were fully charged and I would disconnect the negitive terminal. The batteries were always good in the Spring when I put the boat back in the water. Note: most of my boats were big cabin cruisers.
It is also a good idea to keep them clean. A little soap and water than wipe them dry.

The difference is you will have prepped your boat engine by draining and fogging it for winter storage. The truck engine and generator both require frequent exercise during the winter months. You could disconnect the negative to prevent vampire drains but that means reconnecting them for each start up. If you are doing your scheduled engine maintenance and operating the battery disconnect switches then they should stay well charged all winter long.

If you want to go a step further... Install true disconnect switches right after the batteries to prevent the vampire draws as well.

[twinboat]

You don't need to, or want to, start your engines during long term storage.

Fuel injected, shut them off. Carburated, run the gas out or drain the bowl and leave it.

Read the manuals for long term storage.

[bobmac]

Onan recommends you run the generator for 30 minutes monthly to maintain it - with a significant load. Your batteries will get charged when this is done. Running the genset produces heat and can displace any moisture build up in your generator so it is your best interest to follow the Onan recommendation. Good luck.

[twinboat]

Originally Posted by bobmac

Onan recommends you run the generator for 30 minutes monthly to maintain it - with a significant load. Your batteries will get charged when this is done. Running the genset produces heat and can displace any moisture build up in your generator so it is your best interest to follow the Onan recommendation. Good luck.

I guess you didn't read the " Long Term Storage " section.