Winter battery storage / maintenance??

[TJPOLSIN]

Greetings,
How does everyone store and maintain their trailer batteries over the winter - when your RV is stored?

do you leave them on the trailer and pretty much ignore them?
do you leave them on with the trailer connected to shore power and assume they will trickle charge all winter?
do you take them off store them out of the elements?

I've done all of that in the past and am not sure my battery life was affected one way or the other.

I live in the Puget Sound area and winters rarely get below freezing.

I'm just looking for other options.

Tim

[Flyer15015]

When I park the coach in the barn for the winter, I disconnect the house and chassis batteries, check their water levels and hit each with a dumb charger for a day and walk away.
Mine sits for 4 months here in Colorado and temp's can get down to -20F.
Never had a problem with my 6-year-old batteries.

Mike in Colorado

[Bob K4TAX]

I leave the batteries mounted on the A frame and in a battery box. The trailer sits outside next to my shop. I keep shore power connected, using a dedicated 30A RV circuit. I let the converter take care of the batteries as it is designed to do. I do check the electrolyte level and fill as necessary in the batteries before winterizing our trailer.

Bob

[TeJay]

Tim, Wet cell batteries once they are placed into service begin to deteriorate. They usually do have a limited life basically because the activity happening inside these batteries is constantly fluctuating.

The charging and discharging is kind of a constant never ending process. That does not mean we can't do something to keep the battery in a decent state of charge so we can get the maximum amount of usage from them.

What can we do??? Any battery will discharge over time. We keep the RV battery's charged but not over charged almost constantly by keeping it plugged into a charging source.

Take for example your riding lawnmower. Depending on where you live and how often you cut the grass we can do this. If your cutting season is 6 months long driving it during those 6 months will keep the battery charged. During the 6 month off season I usually charge the battery every month. I use a slow charge which stops when the battery reaches its full charge. If the battery sets for 6 months with no charging it will shorten its life. A discharged battery may sulphate if not charged once a month.

One needs to assure that your charging system does a slow charge and reduce its charge once the battery is fully charged. In other words you need a smart charger. Most chargers are considered just that, "Smart chargers."

Slow charging is always the best. The charging process occurs at the molecular or cellular level so the slower the better. When done slowly the charge is more complete. In fact I've brought back to life several batteries using slow charging.

I keep a charger connected to our RV during the winter months for about 2 weeks each month. I know the charger will reduce its charge rate when it's fully charged. Very seldom do I have to add water to a cell. If I do need to add more water than normal maybe the battery is getting older and beginning to fail. That shows up wen one cell needs double or triple the water than the others. That usually means a shorted cell.

We have a covered metal building right next to the house. It's very easy to service the batteries. If I had the RV stored away from home I'd probably take the batteries out and keep them in the garage at home so they could be charged every month until the next RV season.
1. Any wet cell battery will discharge over time if it is not charged on a monthly or bi-weekly time period. If it stays in a low state of charge to long it may not recover very well.

2. Charging any wet cell battery on a time schedule will extend the life of the battery. The older chargers probably did not automatically lower the charging rate so once charged they over charged the battery which would cause the water to boil leave the battery exposing the plates to air which was not good. I'm almost positive all chargers these days are considered smart chargers.

I have 2 chargers I use. They both allow me to choose a 2-amp or 4-amp or 6-amp charge rate. The slower the better. Now if I'm trying to jump start a battery to get my vehicle running then a fast charge is needed. A slow charge takes 24 to 48 hours.


TeJay (Tim)

[chopity]

Originally Posted by TJPOLSIN

I live in the Puget Sound area and winters rarely get below freezing.

These are flooded wet cells?

Fully charge and disconnect them. No need to leave them on the charger 24/7. The batteries are not going to self discharge in a couple weeks or a month. Worse things you can do are:
1. Purposely give them a very low charge rate. (you want to be around 10-13% of C20. The batteries need to bubble during charge to keep the plates clean)
2. Leave a battery at float voltage for many months when it could just be disconnected. Only exception is if the batteries are in very low freezing temps.
3. Never perform an equalization charge. (look it up, you want a high charge voltage to purposely boil the batteries a couple times a year)

[SailorSam]

For you in the Seattle area, assuming you have a lead/acid battery, probably the best option is to fully charge the battery, completely disconnect it, give it a bath to clean grease and dirt off the top, and leave it on the trailer in the battery box.
These recommendations come from information provided by the US Army Corp of Engineers:
"Batteries should be stored in a cold place, say, about -15°C, although when fully charged to a specific gravity of 1.280 or greater they can be stored at -1°C indefinitely without deteriorating. Batteries, particularly those conditioned for arctic use, should not be stored in warm places.
In addition, all batteries experience some degree of self-discharge during storage. This can be greatly reduced by storing them at lower temperatures."

Rate of self discharge falls as temperatures drop. If your temperatures are mostly above 40F, then you can expect some self discharge Fully charged batteries won't freeze until temps are below -40F.
Only reason to remove it from the trailer is concern about possible theft.
Leaving it on the trailer eliminates all risk of damage to the battery or yourself when you move it.

If you decide to put the battery on any type of charger, check it regularly to monitor water level.

[Soppy]

I make sure my batteries are fully charged, then disconnect them.They will sit in the cold winter with temps getting down to -30° . My RV sits in storage for 6 tp 8 months. When I take it out of storage and reconnect them , the voltage is around 12.7v. My batteries are only charged before or after a trip , or if plugged into shore power at a campground while camping. My batteries are 15 yrs old and still last days boondocking. I do the same with all my heavy equipment , and never had a problem. Storing batteries in cold temps will extend their life as the chemical reactions are slowed by the cold.

[phoneguy99]

I remove my 2 6 volt batteries from the trailer and keep them on a shelf in the garage. I check the water and trickle charge them every copy of months til spring. 6 years old no problems yet....

[Buckmountain]

Everyone's post above assumes wet cell batteries, which will have a much higher self-discharge than AGM at a given temp. Since you have a new trailer, check to see what the dealer installed. If AGM, the self-discharge rate is about 3% per month and can go for several months in storage with no concern for charging and no need to check electrolyte levels since they are sealed. If wet cell, follow the guidance above.

[TimtheToolGy]

Originally Posted by chopity

These are flooded wet cells?

Fully charge and disconnect them. No need to leave them on the charger 24/7. The batteries are not going to self discharge in a couple weeks or a month. Worse things you can do are:
1. Purposely give them a very low charge rate. (you want to be around 10-13% of C20. The batteries need to bubble during charge to keep the plates clean)
2. Leave a battery at float voltage for many months when it could just be disconnected. Only exception is if the batteries are in very low freezing temps.
3. Never perform an equalization charge. (look it up, you want a high charge voltage to purposely boil the batteries a couple times a year)

As far as item 1. Some good chargers will raise voltage for brief periods of time and then drop to voltage somewhat less than 13.2 to exercise battery and keep plates clean. In this situation even a 1A charger attached all the time works well. The low sleep voltage significantly reduces acid loss. This method is much easier and as effective as charging once a month. It also reduces need to equalize after storage.

Ideally the battery is disconnected from camper in case there is a permanent loss of power driving charger.

[chopity]

What voltage does it raise to? You got me curious now. My first thought is a 1amp charge wont be able to raise voltage very high, if at all. On something like 210ah of flooded batteries. Will test it for fun. I have a charger i can set to 14.7v charge and limit it to 1a. I would be surprised if it raises much higher than the 13.6 its floating at. Very roughly speaking when ive checked before i left my batteries floating for several days with no load and it was around 1.6a to maintain the float. Batteries are 4 years old though so maybe this is an internal resistance issue.

[TimtheToolGy]

Originally Posted by chopity

What voltage does it raise to? You got me curious now. My first thought is a 1amp charge wont be able to raise voltage very high, if at all. On something like 210ah of flooded batteries. Will test it for fun. I have a charger i can set to 14.7v charge and limit it to 1a. I would be surprised if it raises much higher than the 13.6 its floating at. Very roughly speaking when ive checked before i left my batteries floating for several days with no load and it was around 1.6a to maintain the float. Batteries are 4 years old though so maybe this is an internal resistance issue.

I have four-year-old two 6V 210Ah Interstate GC2 AGM connected to NOCO GENIUS1 and it seems like the maximum current to maintain the batteries was about .4-.6A and that included having the batteries connected to the TT, so driving some devices in TT, but main switch off. Voltage peaks were at 14.8 and maybe higher when cold out due to temperature compensation. Voltage measured through Victron BMV 712 BMS. When the batteries were not fully charged the NOCO would fully charge them but was slow, of course.

To your point, open cell lead acid batteries of this size likely take more current to reach maximum voltage than more efficient AGM.

[chopity]

Do you think a solar controller hooked up to an AGM in storage would be a similar action? Battery is fully charged. But still every morning the Solar CC will do a 14.4 or 14.7v charge at whatever amps it takes to get there.

Back around 2017 i got a trailer. It had 2 AGM marine batteries. Trailer was stored with the battery disconnected from the trailer but hooked to solar. Went camping and noticed the batteries were toast. Didnt have much capacity it seemed.

Went on the internet. I think it might have been the older rvnet forum. It took several people there to teach me how the constant float and low charge current from solar killed my AGM batteries that were only a year or 2 old.

I accepted their fate and bought 2 GC batts from costco. Kept the original AGM batteries and would charge them a couple times a year.

I thought both those AGM were toast. But a month ago i brought 1 of those AGMs camping to use as my generator starting battery. Its a 5500w Onan. Camped for 5 days straight. That battery started the genny maybe 20 times without charge. Made me wonder if indeed those original batteries were damaged from the low amp charge like the smart battery guys had told me. I believe they said the low amp charge doesnt keep the chemicals inside happy. I dont read much about AGM so its hard to remember.

I do see the difference in how the charger above will reduce to a lower voltage float. That is a pretty sweet feature. Its too bad chargers cant turn off completely. Without doing a "dumb" charger on a basic timer.

[1stimerveer]

I have my 2 six volt deep cycle golf cart batteries connected to shore power year round.
Normally when I check, they are maintained at 13.2 volts and at 5 years old seem to be holding up very well.

It would not normally be noticeable as we only occasionally boondock, but we get the better part of 2 full days out of them before they need a recharge. This includes refrig, lights, heater fan, tv, & water pump use.
We always bring a generator when boondocking but use it only when necessary.

One time, when we didnt bring the generator, I used the connector to my tow vehicle to top them off, and was surprised that in 45 minutes they had accepted enough charge for another days use.

Safe travels and all the best..