Adding water to a flooded cell battery

[Donald]

I know the proper way to fill a flooded cell battery is to fill each cell to the "full" mark. But some fill it to the bottom of the tube to when it "pops". That would mean the battery acid is slightly more diluted than designed. But also longer interval between the battery needing additional.

In boats where due to the location, checking a battery is a PIA so a longer duration between when the battery needs water to be added is a plus.

So what are the pros and cons of filling to the bottom of the tube?

 

[partspro]

We were taught by Johnson to fill each cell individually till it just topped over the plates,

 

[billt460]

"Back in the day", (and perhaps even now with some models), you filled wet cell batteries with ONLY distilled water, to a split ring that was located well above the plates. This was pretty much a standard. Filling just to the plates doesn't offer much of allowance for evaporation, or electrolyte loss. The plates should NEVER be exposed.

 

[Donald]

"Back in the day", (and perhaps even now with some models), you filled wet cell batteries with ONLY distilled water, to a split ring that was located well above the plates. This was pretty much a standard. Filling just to the plates doesn't offer much of allowance for evaporation, or electrolyte loss. The plates should NEVER be exposed.

I used water generically. Of course distilled water.

 

[mk378]

The issue with overfilling is that acid can come out through the vents. It doesn't affect battery performance. Batteries designed for long life (at a slight loss of capacity) for example for backup of telephone systems have a weaker acid solution from the factory.

 

[Pequod]

NAPA sell battery fill jugs that are designed to fill to correct point.

 

[Kira]

That would mean the battery acid is slightly more diluted than designed.

I was told that "water only" (nothing is 100%) is driven off and the resulting lower level is thus more concentrated and that the added distilled water brought the battery's acid back to normal concentration.

edit: What does, "pops", refer to in the OP?

 

[wpod]

"Back in the day", (and perhaps even now with some models), you filled wet cell batteries with ONLY distilled water, to a split ring that was located well above the plates. This was pretty much a standard. Filling just to the plates doesn't offer much of allowance for evaporation, or electrolyte loss. The plates should NEVER be exposed.

Filling the battery to the [ring] makes a bigger mess.

 

[2heeldrive]

Make sure you only add (distilled) water to a fully charged battery. Water level changes with charge level. The water level in an undercharged battery will be lower than a fully charged battery. Overfilling is bad, it will dilute the acid and may run over.

 

[circuitsmith]

Fill to below the ring.
The ring is there to reduce capillary action; sulfuric acid likes to "creep".

 

[Snagglefoot]

I’ve always filled to the ring where your reflection will “invert”. My boat battery is five years old being filled this way and is fine. Maybe the answer is it doesn’t matter as long if you keep it above the plates.

 

[Donald]

I’ve always filled to the ring where your reflection will “invert”. My boat battery is five years old being filled this way and is fine. Maybe the answer is it doesn’t matter as long if you keep it above the plates.

The reflection inverting is what I meant by "pop".

If you look into a cell with a flashlight as you slowly add water you will see what I mean.

 

[billt460]

I’ve always filled to the ring where your reflection will “invert”. My boat battery is five years old being filled this way and is fine. Maybe the answer is it doesn’t matter as long if you keep it above the plates.

Same here. Always filled to the split ring, and never had a problem or a, "mess".

 

[Dave9]

I was told that "water only" (nothing is 100%) is driven off and the resulting lower level is thus more concentrated and that the added distilled water brought the battery's acid back to normal concentration.

You've never seen corroded battery terminals or what looks like crusty salt deposits on top of a battery that failed from low water level? Definitely not near 100% water.

 

[Donald]

Another puzzling question is when you add water to a battery that was a little low the battery typically needs some charging.

So does that mean after adding water and charging that the battery has more stored energy than one that was fully charged but a little low in water.

I mean the additional charging has to be stored in the battery as energy.

 

[billt460]

You can also purchase battery electrolyte from most auto parts stores. If your battery is low on water, you can check your battery with a hydrometer. And if it gives a low reading, (diluted electrolyte), you can then add electrolyte instead of just water. Then fully charge the battery. I've "brought back" several flooded lead / acid batteries this way over the years.

Do You Need To Replace Electrolyte in Your Car Battery?

Do You Need To Replace Electrolyte in Your Car Battery?

www.popularmechanics.com

https://www.autozone.com/batteries-starting-and-charging/battery-acid?filterByKeyWord=battery+electrolyte&fromString=search&isIgnoreVehicle=false

 

[Donald]

You can also purchase battery electrolyte from most auto parts stores. If your battery is low on water, you can check your battery with a hydrometer. And if it gives a low reading, (diluted electrolyte), you can then add electrolyte instead of just water. Then fully charge the battery. I've "brought back" several flooded lead / acid batteries this way over the years.

Do You Need To Replace Electrolyte in Your Car Battery?

Do You Need To Replace Electrolyte in Your Car Battery?

www.popularmechanics.com

https://www.autozone.com/batteries-starting-and-charging/battery-acid?filterByKeyWord=battery+electrolyte&fromString=search&isIgnoreVehicle=false

Unless it spills I think people should always use distilled water only.