Batteries sat for 5 months without charge

[Gjac]

I post this for a data point because many on here ask the question about how long a battery can sit without a charge. In Oct I winterized the MH and fully charged the batteries, hit the disconnect switch on the house batteries and removed the negative cable on the chassis battery. Today I checked the voltage readings and the 12v chassis battery read 12.55 v and the 2 6v GC batteries read 12.48 v. That is very little self-discharge for 5 + months. Of course, in cold weather the self-discharge is less.

[mgirardo]

We camped seasonally for a few years and always disconnected the battery before leaving for the season. We always made sure it was fully charged before leaving for the season. When returning 7 months later, the battery was usually at around 12.5 - 12.6 volts.

At the end of the 2019 camping season, we moved our TT off-site to my parents' house because we knew we wouldn't return the following year and disconnected the battery cables. We expected to sell it in the spring. We did sell it in the spring, but because of the Pandemic (mom is high risk), not until the spring of 2021.

When I finally got to the TT 18 months later, the battery was sitting at 11.97 volts. I was expecting to have to buy a new battery before selling it, but it took a charge just fine.

-Michael

[StirCrazy]

Veebyes wrote:

StirCrazy wrote:
I just leave them plugged in year round with a good charging unit in the rv.

And risk the charging unit failing & perhaps failing & overcharging the battery bank, trashing the batteries? No thanks.

If the unit is stored at home where you keep a constant eye on it then fine, leave it on if it makes you feel better. If it is stored remotely where you don't get to it for weeks, months even, better to disconnect & leave the unit completely dead for storage.

No risk of the charger failing that way.

I get to see my unit for the first time since last October in three weeks time. It has been stored completely dead since then. With the exception of a little self discharging over winter, I expect the battery bank to be just fine & will be 100% in a half hour or so of power being restored to it.

Much is made of leaving batteries on trickle chargers by RVers, but look around. Farmers leave equipment for months without use, no chargers. Boaters leave boats on moorings for months unused, no chargers. Construction equipment sits unused for months, no chargers. All kinds of other vehicles sit for months in lots unused. No chargers.

RVs can certainly do the same.

I do store it at home, but I also change out the charger as soon as I buy the unit and throw the WFCO in the garbage... I think one of them I use to run a winch in my garage.... 35 yers now I have been doing that, never had an issue, my last set of GC batteries lasted me 16 years. but I do understand for people that have to store there unit remotly.

Steve

[time2roll]

Gjac wrote:
> Batteries sat for 5 months without charge

Commonly the same as when the battery was bought new.

[Mike134]

Watching and listening. Have to be honest sounds just like the 5-6 guys along the bar at the campground debating what is best.

Cheers!!

[Veebyes]

StirCrazy wrote:
I just leave them plugged in year round with a good charging unit in the rv.

And risk the charging unit failing & perhaps failing & overcharging the battery bank, trashing the batteries? No thanks.

If the unit is stored at home where you keep a constant eye on it then fine, leave it on if it makes you feel better. If it is stored remotely where you don't get to it for weeks, months even, better to disconnect & leave the unit completely dead for storage.

No risk of the charger failing that way.

I get to see my unit for the first time since last October in three weeks time. It has been stored completely dead since then. With the exception of a little self discharging over winter, I expect the battery bank to be just fine & will be 100% in a half hour or so of power being restored to it.

Much is made of leaving batteries on trickle chargers by RVers, but look around. Farmers leave equipment for months without use, no chargers. Boaters leave boats on moorings for months unused, no chargers. Construction equipment sits unused for months, no chargers. All kinds of other vehicles sit for months in lots unused. No chargers.

RVs can certainly do the same.

[Gjac]

wa8yxm wrote:
On a guess I'd say your batteries are
1: Fairly new
2: Still very good.

Self discharge will increase over time

And the advice to all who have batteries which may have sat a bit longer than they are comfortable with.

Charge 'em up and see how they perform.. Worst case. they need replacement. Best case. they don't. IN FLOODED wet cells check if they need Distilled water added first and add to about 1/4 to 1/2 inch BELOW the bottom of the filler tube (Split ring) not to the bottom of it.. over fill they tend to Spit at you. they spit acid.

On the contrary my batteries are 15 years old. 95% of my camping is dry camping. Only charge by alternator or when I get home but never leave on constant charge when home always disconnect. I believe leaving them on constant charge eats away the plates faster than just recharging when they reach 80-90% SOC.

[StirCrazy]

I just leave them plugged in year round with a good charging unit in the rv.

[wa8yxm]

On a guess I'd say your batteries are
1: Fairly new
2: Still very good.

Self discharge will increase over time

And the advice to all who have batteries which may have sat a bit longer than they are comfortable with.

Charge 'em up and see how they perform.. Worst case. they need replacement. Best case. they don't. IN FLOODED wet cells check if they need Distilled water added first and add to about 1/4 to 1/2 inch BELOW the bottom of the filler tube (Split ring) not to the bottom of it.. over fill they tend to Spit at you. they spit acid.

[Boon_Docker]

Lwiddis wrote:
You were lucky. Batteries appear to have survived. Low self discharge is one Lithium advantage.

It's not luck, it's the way batteries behave.
I do the same with my batteries, 6 months disconnected through the winter and lose less that 10% charge. Present set of batteries are 9 years old and still going strong.

[Gjac]

Trackrig wrote:
My batteries in my hunting rig only get used in September. At the end of Sept they're fully charged, hit the disconnect switch and they're good until next Sept after sitting in the rig as far down as -60F during the winter. The last set of Interstates I changed out after 7 years and I expect to get the same out of this set.

What is the state of charge after sitting for a year? Cold weather definitely helps.

[2oldman]

I do this with my car, left at home for winter. Pull the negative cable. Starts right up 5 months later.

[rhagfo]

Once I installed the total disconnect switch on out 5er never had an issue with discharged batteries. While ours never sat for five months, it has sat for two months. During that time I did do some work on it, and would use just the battery to run the slides out and in.

[Veebyes]

Standard MO for battery long term storage has been to disconnect battery bank at the post & leave for 5-6 months untouched. Been doing this for 14 years. 12 of those 14 using AGM batteries. 1 of those years 10 months with no attention.

9 years life out of first AGM. Second one still going strong.

[garym114]

I never use a trickle charger or my inverter/charger when my motorhome is not in use.
I just disconnect the ground cable from the house and chassis batteries. when it is time to go the batteries are always ready.