Hi guys,

Please guide me what to do with a contaminated electrolyte in the lead acid battery .

My jeep is having a week lead acid battery,which rest on a 12.3v. Thought of using a desulphator.

I have noticed that, there is some contamination inside the cells.Which look like some white grains and tiny black rod, kind things resting on top of the plates.

Do i have to drain all the electrolyte and fill it with distilled water or acid?

Regards & Thanks
Thomas.

 

First consideration, is the age of the battery... these things happen in older units...

Secondly, nix the jeep, and focus on the battery... AAC does not allow automotive topics.

 

The white stuff is lead sulfate. The extent of its coverage across the plates indicates the level of damage to the battery. If you see lots of it. More than 50% coverage, replace the battery. Otherwise remove it and place it where the off gas will not get in your house and charge it. Start with a fast charge and then leave it on a trickle charge for at least one full day. If the white stuff has not decreased in coverage then the battery is no good. Replace it. Have a shop or parts store test your alternator. It is probably not working correctly.

 

Otherwise remove it and place it where the off gas will not get in your house and charge it.

If i drain the battery, is it ok to fill it with distilled water instead of acid?

Have a shop or parts store test your alternator. It is probably not working correctly.

When idling, I am able to measure a 13.5v on the battery. So i hope my alternator is fine?

 

More important is what is the battery voltage when the engine is running at above idle speed, say 1500rpm? It should be ~14.2V to 14.7V. If it stays at 13.5V, that is the root cause of your battery failure.

The battery is badly sulphated, likely from being chronically undercharged. You can sometimes recover it by using a constant-current power supply set to ~3A and charging the battery for 24 hours. This is called an equalization charge.

During this last ditch effort to revive the battery, the battery voltage may go as high as 16V, and it will get warm to the touch. Add distilled water (only) to keep the plates always covered with liquid, but do not overfill the battery.

Disconnect it from the charger, let it sit for 24hours, and then measure the open-circuit voltage. If it is greater than 12.7V, chances are you can get a few more months out of it (provided you fix the charging system).

 

If i drain the battery, is it ok to fill it with distilled water instead of acid?

No, this won't work... The battery fluid, is a specific dilution of sulfuric acid, which makes the battery do its thing... Plain water will not take or hold a charge.

 

It seems like the plate itself is mechanically damaged.
Maybe you could try to drain all of the acid into a container and see if there's any more similar particle. If it does, then the chances are, the battery couldn't survive as the active material disintegrated.

If things looks good;
I would suggest to first cleanse it with distill water, cycled several time, then, fill it with fresh acid.

 

For what it's worth:

Depleted battery acid is ~1.1 S.G. This is a 15% solution of sulfuric acid, almost 3M (molar). It's conductivity is 568 mmho/cm at 25°C.

Charged battery acid is usually less than 1.28 S.G. This is a 37% solution of sulfuric acid. It's conductivity is 787 mmho/cm. That's just 39% higher than the discharged solution.

 

How old is the battery? If it's more than 3 years old is may be at the end of it's useful life.

 

If i drain the battery, is it ok to fill it with distilled water instead of acid?
?

A fully discharged battery will have as close as it gets to distilled water (all the acid is in the plates) - in a fully charged battery the acid will be as strong as it gets.

The problem you have with a sulphated battery is guessing how much of the acid is crystalised into lead sulphate.

Increasing the acid concentration above the specified specific gravity will make the battery sulphate (even more) a whole lot easier.

Weigh up the cost of a new battery compared to calling out a recovery truck to the middle of nowhere in a foot of snow.

 

A fully discharged battery will have as close as it gets to distilled water (all the acid is in the plates) - in a fully charged battery the acid will be as strong as it gets. /QUOTE]


Please explain...

How does the acid, that is in solution with water, morph itself into the plates, and leave the water behind...

Lead, is not able to act as a sponge that I ever heard...

 

A fully discharged battery will have as close as it gets to distilled water (all the acid is in the plates) - in a fully charged battery the acid will be as strong as it gets. /QUOTE]


Please explain...

How does the acid, that is in solution with water, morph itself into the plates, and leave the water behind...

Lead, is not able to act as a sponge that I ever heard...

It's called electro-chemistry:
http://www.av8n.com/physics/lead-acid.htm

 

A fully discharged battery will have as close as it gets to distilled water (all the acid is in the plates) - in a fully charged battery the acid will be as strong as it gets. /QUOTE]


Please explain...

How does the acid, that is in solution with water, morph itself into the plates, and leave the water behind...

Lead, is not able to act as a sponge that I ever heard...

Porous lead does.

Actually its a chemical reaction, the H2SO4 combines with the lead to become lead sulphate, as long as you recharge the battery promptly, the chemical reaction is reversible - if you let it develop into the crystalline form, it pretty much insulates the plates.

It was very common in yesteryear, but you can still buy them in some auto accessory shops - the specific gravity meter; a pipette with a rubber bulb and a calibrated float inside. Squeeze the bulb and dip the end of the pipette in the electrolyte to draw some up, if the float is heavy relative to the SG of the electrolyte and tends toward sinking - you have very nearly distilled water and a flat battery - if the electrolyte SG is heavy relative to the weight of the float, it sits high in the fluid, this indicates a high SG 9strong acid) and a good state of charge.

Perhaps this is a test you should try before messing with the electrolyte!

 

It's called electro-chemistry:
http://www.av8n.com/physics/lead-acid.htm

Dang nice article !!

And that will be my " something new for today " Because if one cannot learn something new every day, the day is poorly used...

 

More important is what is the battery voltage when the engine is running at above idle speed, say 1500rpm? It should be ~14.2V to 14.7V. If it stays at 13.5V, that is the root cause of your battery failure.

At higher RPM i am able to measure a 14.25v from the battery.

The battery is badly sulphated, likely from being chronically undercharged. You can sometimes recover it by using a constant-current power supply set to ~3A and charging the battery for 24 hours. This is called an equalization charge.

For the equalization charge, what should be the charging voltage level.And how often i have to do this.

Regards,
Thomas.

 

For the equalization charge, what should be the charging voltage level.And how often i have to do this.
...

I use my lab supply for equalization. With the supply unloaded, I first set the voltage control to ~1V. I then short the supply output terminals, and set the current limit control to 3A. Then I remove the short, and set the voltage control to >20V. Finally, I connect the supply to the battery.

Several hours into the equalization process, you can expect the battery voltage to reach ~16V. The supply is running as a constant-current source during the entire equalization process (it is always current-limited; the battery determines its own voltage).

If while running the engine at cruise rpm the battery is getting to 14.7V and the vehicle is driven frequently, it shouldn't need equalization during its lifetime. If it is setting around a lot without being driven, even if it is being float-charged, it might need equalization once per year.

 

A fully discharged battery will have as close as it gets to distilled water (all the acid is in the plates) - in a fully charged battery the acid will be as strong as it gets.

The problem you have with a sulphated battery is guessing how much of the acid is crystalised into lead sulphate.

Increasing the acid concentration above the specified specific gravity will make the battery sulphate (even more) a whole lot easier

Thanks for the information, I had never played with acids much. Thinking of flush the electrolyte and clean it with distilled water.And fill it with fresh electrolyte if it is available as is in the market.

.

Weigh up the cost of a new battery compared to calling out a recovery truck to the middle of nowhere in a foot of snow.

True but, i will try my max to make it work at least for one day.

Regards,
Thomas.

 

Thanks for the information, I had never played with acids much. Thinking of flush the electrolyte and clean it with distilled water.And fill it with fresh electrolyte if it is available as is in the market.

.........................

Unless the battery is fully charged you don't want to add electrolyte since you don't know how much acid to add. Better to fully discharge the battery so the electrolyte is basically water and then flush the battery with water. Then fill it with distilled water and fully charge the battery.

 

Better to fully discharge the battery so the electrolyte is basically water and then flush the battery with water. Then fill it with distilled water and fully charge the battery.

At what discharge voltage level, the electrolyte become water

Thanks,
Thomas.

 

At what discharge voltage level, the electrolyte become water

Thanks,
Thomas.

Zero volts



By the way, a bottle of acid will cost about $15 to $20 online. Unfortunately, any reputable company will charge $30 in shipping because of the fedEx, UPS and USPS have a very high hazardous materials shipping surcharge.

Any companies (or individuals) shipping acid without the hazMat shipping fee means you and the shipper are at risk of lawsuit from the carrier and fines from the DOT. Mostly the shipper is at risk if mailed from the US, and you are a risk if mailed from overseas (you become the importer of record).

I doubt you can find 3Molar acid at the local hardware store. If you can, it is not diluted with distiller water so it is not good for batteries.

I would put my $50 towards a new $75 battery. Costco and Walmart seem to have the best prices on batteries.
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EDIT: By the way, you will likely splash some acid droplets as you do this so add the cost of a new shirt and new pair of jeans, possibly reprint anything else the acid splashes on.