Deep cycle battery

How does a battery lose all its acid.

I have a 4 year old interstate deep cycle battery that came in my boat. Has been changed many times with a onboard charger. Checking things out for a trip I find the battery only has 5 volts so I changed it. Never would get above 10.5 volts. So I put my big charger on it and bring it up to 12.5 volts but it is back to 10.5 volts after 12 hours.

So I start taking things apart so I can dig this battery out from the cubby hole it is stuck in. When I get it out I find the water is not only low but very low. This is supposed to be a good maintenance free battery.

I filled it with water and will try charging it again. I sure hope I have not destroyed this expensive battery.

Take it back and explain that it is in fact not (aparently) maintenance free.

Here's some reading and examples
https://batteryuniversity.com/learn/
I suspect this is called shedding
BU-804: How to Prolong Lead-acid Batteries
Explore what causes corrosion, shedding, electrical short, sulfation, dry-out, acid stratification and surface charge

A lead acid battery goes through three life phases: formatting, peak and decline (Figure 1). In the formatting phase, the plates are in a sponge-like condition surrounded by liquid electrolyte. Exercising the plates allows the absorption of electrolyte, much like squeezing and releasing a hardened sponge. As the electrodes activate, the capacity gradually increases.


Cycle life of a battery

Figure 1: Cycle life of a battery.

The three phases of a battery are formatting, peak and decline.

Courtesy of Cadex


Formatting is most important for deep-cycle batteries. They require 20?50 full cycles to reach peak capacity and field usage does this. During breaking-in, manufacturers recommend going easy on the battery. Starter batteries are less critical and do not need priming. The full cranking power is available from the beginning, although CCA will go up slightly with formatting in early use. (See also BU-701: How to Prime Batteries.)

A deep-cycle battery delivers 100?200 cycles before a gradual decline begins. Replacement should occur when the capacity drops to 70 or 80 percent. Some applications allow lower capacity thresholds but the time for retirement should never fall below 50 percent as aging may hasten once past the prime.

To keep lead acid in good condition, apply a fully saturated charge lasting 14 to 16 hours. If the charge cycle does not allow this, give the battery a fully saturated charge once every few weeks. If at all possible, operate at moderate temperature and avoid deep discharges; charge as often as you can. (See BU-403: Charging Lead Acid.)

The primary reason for the relatively short cycle life of a lead acid battery is depletion of the active material. According to the 2010 BCI Failure Modes Study, plate/grid-related breakdown has increased from 30 percent 5 years ago to 39 percent today. The report does not provide reasons for the larger wear and tear other than to assume that higher demands on the starter battery in modern cars induce added stress. The organization conducts a study every 5 years to determine the failure modes of batteries that have been removed from service. (BCI stands for Battery Council International.)

While the depletion of the active material is well understood and can be calculated, a lead acid battery suffers from other infirmities long before plate- and grid-deterioration sound the death knell. These conditions are found under: Corrosion, Shedding and internal Short, Sulfation and How to Prevent it, and Water Loss, Acid Stratification and Surface Charge. Most of these can be reduced by proper handling.



Summary
As battery care-giver, you have choices in how to prolong battery life. Each battery system has unique needs in terms of charging, depth of discharge and loading that should be observed. The following papers summarize what batteries like and dislike.

BU-415: How to Charge and When to Charge?
BU-706: Summary of Do?s and Don?ts
BU-806a: How Heat and Loading affect Battery Life



Last Updated 2019-02-06
https://batteryuniversity.com/learn/

I have interstate deep cycles in my boat,they are not maintance free.

I would add acid rather than water. Water will dilute the acid & charging will try & boil it away again to get the SG up.

Putting a big charger on a battery that will not charge is a bad idea.

Might consider going to AGM type.
It's hard to recommend anything because I've had good and bad in all of them. My walmart combos lasted a real long time but I took care of them constantly and was careful to follow recommended guidelines (like watching electrolyte levels)

I've had AGM batteries taken out of communications back up buildings older than dirt continue to perform stellar.(ly)
and another for my motorcycle that lost a cell like the crap I was trying to get away from.
2yr AGM at west marine

Each cell is worth 2.2V, appears you have a shorted cell. Not much to do but replace. I have good luck with pulsed hi frequency charging and have personally used
schumacher and progressive dynamics power converter. Adding acid is pointless unless the battery wall was damaged and repaired.

Fully charged, the battery plates are lead and the electrolyte is acid. As the battery is discharged the acid converts to water and the lead is dissolved/converted to lead sulphate which collects onto the lead plates. The sulphate is brittle and easily flakes off and once removed from the plates represent a loss of capacity. If enough flakes off and collects in the bottom, the cell shorts out. Pulsed hi frequency charging is more effective in breaking the sulfur bond and can be viewed as forcing the sulfur into water and back to acid. Taking a hydrometer measurement of the acid strength in each cell will give you an idea of relative cell capacity/health.

1. Avoid fully discharging the battery.
2. Slowly recharge. 5 amp for first 50%, 1-3 amp to finish (up to a 4D)
3. Use a battery maintainer with hi frequency pulsed DC
4. When a cell is shorted, game over.

It was explained to me one time about my car battery:
LOW maintenance, NOT no maintenance.

How do you mantain a seeled battery that has no caps.

When I put a non-automatic charger on my deep cycle batteries, they would boil and leak acid if I left the charger on too long.

Look for the vent, that will lead back to the fill caps. You may have to pry out a one or two long caps that cover multiple cells.

You can't add water to a maintenance free battery because AGM batteries are sealed.
If you want a powerful AGM battery check out the battery used in a Cadillac XT5.
An AGM batteries may stand up better in a ruff riding boat.
You are less likely to have oxidation on battery terminals with an AGM battery.
Some boats require 3 12v batteries. One for the boat engine and two for trolling, 24vdc. Its best if you have one of the 2 batteries needs replaced, replace the pair. Use the good battery in something else.
geo

Hello john in La,

Sounds like one cell is not showing any voltage. If you add 2.1 volts to that 10.5 you would have 12.6-volts.

I will go out on a limb here and say that, if you topped the cells off and give it a slow charge, it will come back to life,

Guido.

I sold interstates for 35 years I tried them once in my boat I went back to AC Delco battery's. I was also in a fishing club interstates never held up well in a boat : (.. Maintenance free means they have enough electrolyte to last a normal life...

Up until last year I always thought you needed to charge your stock every now and again I beached to AC Delco about the battery's they deliver low in voltage. This is the reply a new one on me...

High heat, extended float charging intervals above 12.6V and any system voltage over 13.8V

I have two sump pumps with battery back up system hooked to them. The system works, and they require deep cycle batteries. They have a little trickle charger on them all the time. AND, they are always low on water!!!!😜

its been my experience when charging a deep cell battery I use a battery maintainer that charges at 2/3 amps. it seems the slower you charge them the better they charge and will hold charge better. not sure why but it does for me.

My deep cycle boat, RV and golf cart batteries are usually low (top of plates) every year. I add one ounce of hydrogen peroxide to each cell and top off with distilled water. I average about 10 years per battery which is great, because iv have 13 of them. I put the hydrogen peroxide in all 40 of my batteries annually unless the are permanently sealed. My luck is about 50-50 on batteries as low as yours. Put the peroxide in them and put on a 2/6 amp charge and see what happens. The peroxide helps de-sulfate them. Usually the cells will start to bubble when you add peroxide.