Disconnected Battery Lifespan

[MarTer]

Hi,

I was unable to return to my boat last year due to illness. This means she has been stored ashore in Germany with the 2 engine & 4 leisure batteries disconnected for two years.

I was told by a battery supplier today that they will be useless even though they are only just over 12 months old! I have regularly left my batteries disconnected for 12 months with no ill effects.

I have a new Sterling Pro 50A battery charger installed. Is there nothing I can do to recover them?
TIA

 

[Plevier]

Batteries left for too long will lose all their charge and will suffer from hard to shift sulphation and other ills. Just how bad depends on the particular battery, the storage conditions (cooler is better) and random variation!
Most batteries are OK for 6 months without recharge provided they then get a good conditioning charge before returning to service.
Some pure lead ones claim 12 months storage is OK. I'm a bit dubious about this (based on several years working for one of the manufacturers who claimed this).
After 2 years, whatever your batteries are, they are going to be pretty low on charge and to have suffered some damage.
You may find you can get them back to a usable state but I would expect substantial loss of capacity.
On the black side they may have developed internal shorts and be useless.
Try to recharge them, watch out for any heating or swelling, bad signs.
They may be reluctant to take any charge initially. Once they do start, make sure they are charged thoroughly, several days at 13.8V after the initial fast charge if possible. Don't cut corners.
If you get them working reasonably, they may improve further over a few weeks if kept well charged.
A few deep cycles may help recover capacity now at the expense of shortening future life.

 

[savageseadog]

I've stored deep discharge batteries without charging them for 2 years without a problem. It will depend on the exact situation and battery technology though

 

[No Regrets]

Hi,

I was unable to return to my boat last year due to illness. This means she has been stored ashore in Germany with the 2 engine & 4 leisure batteries disconnected for two years.

I was told by a battery supplier today that they will be useless even though they are only just over 12 months old! I have regularly left my batteries disconnected for 12 months with no ill effects.

I have a new Sterling Pro 50A battery charger installed. Is there nothing I can do to recover them?
TIA

How come your batteries are just over 12 months old, but left disconnected for two years?

just asking like....

 

[Plevier]

I've stored deep discharge batteries without charging them for 2 years without a problem. It will depend on the exact situation and battery technology though

Quite seriously, not being flippant, how do you know?
Unless you have done an accurate capacity test, you can't know if they have been damaged.
It's highly likely that they have lost significant capacity and that the life has been shortened - but you can't really tell!

 

[savageseadog]

Quite seriously, not being flippant, how do you know?
Unless you have done an accurate capacity test, you can't know if they have been damaged.
It's highly likely that they have lost significant capacity and that the life has been shortened - but you can't really tell!

I have a battery conductance tester. There's a good correlation between a good CCA reading (compared to previous reading or spec) and capacity.

 

[MarTer]

How come your batteries are just over 12 months old, but left disconnected for two years?

just asking like....

They were just over 12 months old when they were left disconnected for 2 years. Apologies for the confusion.

 

[nimbusgb]

I was told by a battery supplier today that they will be useless even though they are only just over 12 months old!

And he wanted to sell you replacements.

Without testing them he can have no idea of how knackered they are. I accidentally left a battery connected to the car in a greek yard for 5 months with alarm and interior light on. The battery sat in 30 degree plus heat for most of a Greek summer. I thought I'd give it a trial charge before buying a replacement. 2 years later I sold the car with the same battery still in it.

One catastrophic deep discharge may well shorten the life and reduce the capacity of a battery but before buying a few hundred quids worth of replacements I'd try a few things!

 

[Plevier]

There's a good correlation between a good CCA reading (compared to previous reading or spec) and capacity.

I'm afraid I wouldn't agree with that. When I was in the battery industry we did quite a lot of work looking for a quicker way of assessing industrial battery installations and never found a a meaningful way of measuring capacity other than a test discharge at realistic rate. High rate performance and low rate capacity are governed by quite different factors.

 

[Bajansailor]

I have a similar question re disconnected battery lifespan, so rather than start a new thread, I hope it is ok to ask it here.

I have a couple of 6V deep cycle golf cart batteries that are a couple of years old - I got them from another boat.
I intend to use them, but not for another 18 months or so (as realistically, it will take at least that long to finish the slow refit on our boat).
Hence I would like to 'lay them up' essentially.
I was thinking that if I just kept them charged steadily then this would be the best plan, but I have been told by an electrician here that it would be better to empty the acid out of the batteries and store them 'dry', and then re-fill with new acid (or filtered old acid to get the bits out?) when I want to resurrect them again.
Troubadour, if you were in this situation what would you do (I see you are on line)?

 

[Plevier]

Absolutely do not empty them! You can't do that to a commissioned battery. Dry charged ones ex factory are a different matter.
Best you can do for them is lay them up somewhere as cool as possible and give a refresh charge every 3 months or so and isolate them in between charges.
Use a good regulated charger at say 13.8V (for 2 x 6V in series) for at least 24 hours.

 

[Bajansailor]

Thank you very much Mr T - I must admit that even though the advice mentioned earlier (re emptying the acid out of the batteries) came from a very self confident marine electrician, I had my doubts, hence thought it better to ask on here.
I shall keep them in my living room, and keep an eye on them, and give them a good charge every few months or so (or maybe earlier if the voltage is dropping).