I don't understand batteries

[Mike OReilly]

My sealed lead acid batteries* sat for two years, eight months (32 months) with no charging. They were already four years old, and they'd seen good hard use over those years.

I fully expected to find these batteries to have gone to battery heaven, but when I put the meter on them a few weeks ago they all registered 12.5v. I charged them, and have been using them for a few weeks now. They seem fine.



How can that be? Shouldn't they have self-discharged completely, and sulphated? They sat through three Newfoundland winters and two full summers with no charging.


Not that I'm complaining, but why are these batteries OK?

*This was not my first choice. It happened...

[rslifkin]

Self discharge and sulfation both happen slower in cold weather. So the winters helped. Plus, AGMs have lower self discharge than flooded lead acid. Add a little luck and somehow they hadn't discharged enough to be much of a problem.

[goboatingnow]

Unless you capacity test them you can’t be sure they are actually ok.

[goboatingnow]

Originally Posted by rslifkin

Self discharge and sulfation both happen slower in cold weather. So the winters helped. Plus, AGMs have lower self discharge than flooded lead acid. Add a little luck and somehow they hadn't discharged enough to be much of a problem.

Who said they were AGM they could just be VRLA

[rslifkin]

Originally Posted by goboatingnow

Who said they were AGM they could just be VRLA

It's possible, but I'll call it unlikely. On this side of the pond VRLA wet cells are rare with any kind of deep cycle label in large sizes. They're most common in very small batteries for UPS systems and as automotive starting batteries. So they're most likely AGM or gel.

[thomm225]

Originally Posted by goboatingnow

Unless you capacity test them you can’t be sure they are actually ok.

Right but a reading of 12.5 volts is a pretty good start and most folks would be satisfied with that.

When the battery alarm lights up and sounds off on one of our UPS units we can usually quickly troubleshoot it just with voltage checks with a meter.

Any battery that reads below 12 volts we go ahead and replace and that usually clears the alarm.

Our UPS Units hold from 24 batteries to 72 batteries. All 12 volts.

[Simi 60]

Originally Posted by goboatingnow

Unless you capacity test them you can’t be sure they are actually ok.

Yep,
Most of our old AGM 220ah batteries register 12.5 and higher after 6 mths sitting but I had to go through a few to find one that had the grunt to start a small Kubota Genset.

[Stu Jackson]

Hey, Mike, so glad you're back in "heaven!" Somebody's been looking out for your batteries, it's that simple. I know you're not complainin'.

[StuM]

Originally Posted by goboatingnow

Who said they were AGM they could just be VRLA

"Sealed lead acid" (SLA) and VRLA are synonymous, so there is no "could" about it, they are VRLA.
But they must be one of the types of VRLA/SLA. There are essentially two types used on boats: AGM and Gel .
(There are a some "VRLA wet cells" but you have to be careful how you handle them since they don't like being bounced around, laid on their side or inverted )
AGM is a reasonable assumption since they are by far the most common VRLA for boat use.

[Mike OReilly]

These are the batteries. My understanding is that they are standard wet-cells, but sealed.

https://royalbatterysales.com/catalo...arine-battery/

I haven't capacity-tested them. But I have run them through their paces, maintaining house loads overnight, discharging and recharging. They appear to be performing as they did back in 2019.

Stu, you're right! I'm definitely not complaining. I'm just in shock. I was certain these batteries would be dead. Yet they appear to be performing as well as when I left them in the fall of 2019.

It's true that cold weather is good for battery storage. But these have also sat through two summers. And while it's not as warm as more southerly locations, NL still sees plenty of heat. And even the winter's aren't that cold here due to being on the coast.

My lay-up practice has always been to fully charge the batteries, and then completly disconnect them. I pull all the leads off so there is no stray currents. This has worked great for over-wintering, but looking at the self-discharge rates, I should have dead batteries.

Definitely not complaining. But I am confused. It seems to go against common battery wisdom.

[goboatingnow]

Originally Posted by StuM

"Sealed lead acid" (SLA) and VRLA are synonymous, so there is no "could" about it, they are VRLA.
But they must be one of the types of VRLA/SLA. There are essentially two types used on boats: AGM and Gel .
(There are a some "VRLA wet cells" but you have to be careful how you handle them since they don't like being bounced around, laid on their side or inverted )
AGM is a reasonable assumption since they are by far the most common VRLA for boat use.

In Europe AGMS would be specifically labelled so. By far the most common is sealed wet acid both in cars avs on boats

[goboatingnow]

Originally Posted by Mike OReilly

These are the batteries. My understanding is that they are standard wet-cells, but sealed.

https://royalbatterysales.com/catalo...arine-battery/

I haven't capacity-tested them. But I have run them through their paces, maintaining house loads overnight, discharging and recharging. They appear to be performing as they did back in 2019.

Stu, you're right! I'm definitely not complaining. I'm just in shock. I was certain these batteries would be dead. Yet they appear to be performing as well as when I left them in the fall of 2019.

It's true that cold weather is good for battery storage. But these have also sat through two summers. And while it's not as warm as more southerly locations, NL still sees plenty of heat. And even the winter's aren't that cold here due to being on the coast.

My lay-up practice has always been to fully charge the batteries, and then completly disconnect them. I pull all the leads off so there is no stray currents. This has worked great for over-wintering, but looking at the self-discharge rates, I should have dead batteries.

Definitely not complaining. But I am confused. It seems to go against common battery wisdom.

Definitely standard sealed wet acid

[StuM]

Originally Posted by Mike OReilly

These are the batteries. My understanding is that they are standard wet-cells, but sealed.

https://royalbatterysales.com/catalo...arine-battery/

Yep, those are "maintenance free flooded" batteries all right.
You're lucky they have lasted. They are a classic example of the el cheapo so called "deep cycle marine" batteries. The fact that they list Cranking Amps (and a high number at that) is the giveaway that they are actually "dual purpose" batteries and not true deep cycle. A "real" deep cycle battery will not have a CA rating.


They are intended for smaller power boats where they generally only have the one battery which is required to start the engine(s) and support small house loads for a limited time.


I would never use them for house loads on a cruising sailboat.
I'd stick with either true deep cycle wet cells or AGM.

[Mike OReilly]

Originally Posted by StuM

Yep, those are "maintenance free flooded" batteries all right.
You're lucky they have lasted. They are a classic example of the el cheapo so called "deep cycle marine" batteries. The fact that they list Cranking Amps (and a high number at that) is the giveaway that they are actually "dual purpose" batteries and not true deep cycle. A "real" deep cycle battery will not have a CA rating.

They are intended for smaller power boats where they generally only have the one battery which is required to start the engine(s) and support small house loads for a limited time.

I would never use them for house loads on a cruising sailboat.
I'd stick with either true deep cycle wet cells or AGM.

Yes, I know all this. Which is all the more reason to ask: why are they still alive, and so far, performing fine?

[goboatingnow]

Originally Posted by StuM

Yep, those are "maintenance free flooded" batteries all right.
You're lucky they have lasted. They are a classic example of the el cheapo so called "deep cycle marine" batteries. The fact that they list Cranking Amps (and a high number at that) is the giveaway that they are actually "dual purpose" batteries and not true deep cycle. A "real" deep cycle battery will not have a CA rating.


They are intended for smaller power boats where they generally only have the one battery which is required to start the engine(s) and support small house loads for a limited time.


I would never use them for house loads on a cruising sailboat.
I'd stick with either true deep cycle wet cells or AGM.

I only use these types of cells for domestic deep cycle usage , with solar the days of very deep discharge are over anyway

All my charge sources are setup to charge sealed wet acid , it’s works well


Most cruisers around me use the same cheapie batteries mine were €100 each for 2 140Ah batteries, generic batteries made in Turkey

I’ll get about 4 years , but but that a cost of €50!a year. Very few are AGM , the majority are sealed wet acid. ( Bosch and Varta being popular )

My starter battery is even cheaper !! € 50

Unless you fully understand why, never buy more expensive batteries then you need.

AGMs are not a good fit for boats and Gel is even worse , AGMs are regularly damaged by boat charging practices and Gels are completely unsuitable in my opinion

All batteries can be “ deep discharged “ good deep discharge batteries can and are designed for high current discharges and recharges likec traction motor usage. This type of usage profile is very uncommon on a standard modern yacht.