regarding batteries


Thread Starter


I work for a Research and Development company in India. In one of my projects there is need for me to use lead acid batteries in the configuration explained below. Can you please clarify me with suitable inputs and suggestions regarding this . I am much oriented towards electrical engineering and I am not much experienced in the chemical processes behind the batteries.

Your inputs will help me a lot .

Kind regards,
Veda, India .
[email protected],[email protected]

A. I plan to use a lead acid battery with sulphuric acid electrolyte filled up to the recommended level marked. Above the electrolyte column it is filled with high viscosity silicone oil up to a few inches height.

I presume the following to happen during the charging and the discharging process.

1. When charging in a normal pace or slow pace the hydrogen and the oxygen generated in the either plates recombine to form water inside the electrolyte column itself and hence no gassing and loss of water is likely to occur.

2. When overcharging or rapid charging is done, of the hydrogen and the oxygen generated a portion will undergo recombination in the electrolyte itself, whilst the rest of the oxygen and hydrogen in the form of bubbles proceed towards the top of the water column and stay at the oil water interface. But as the diameter of the bubbles generated is very small they cannot get bubbled through the oil interface so easily and they wait there to grow in size so that they get enough size and get bubbled through the oil column. During the resilient period of stay in the interface region ,the oxygen and the hydrogen recombine back to water and get mixed with the electrolyte itself, which is similar to the phenomena happening in the portion above the electrolyte column in a sealed /VRLA battery.

3. During slow discharge there is no chance for the hydrogen and the oxygen to get generated. Even if they are generated they undergo the same process as indicated in point 2.

Will there be any deviation in my presumptions in point 1 , 2 and 3.

B. I plan to pressurize the air column above the electrolyte somehow by external means and start charging the battery rapidly and the discharging the battery.

I presume the following to happen.

The possibility of the generation of the hydrogen and the oxygen is reduced due to the high hydrostatic pressure acting on the electrolyte column. Under such circumstances,

1. How far the charging and the discharging characteristics will be affected?
2. In case of any deterioration in the charging and discharging capacity as anticipated due to the created operating conditions, how this can be measured in situ and what parameter is to be measured? (like measuring the battery impedance using impedance meter ... or comparing the experimental charging and discharge curves with the normal discharge curves etc….)

Can you clarify /suggest anything regarding the above points A.1, A.2, A.3, B1, B2.

Phil Corso, PE

Veda, you have posed a doozy of a query! It certainly piqued my interest because for the first half of my career I was always told, "Never ever use anything but distilled water!" And for the last half, "It's OK to use ordinary tap water (in most cases)!"

I know that given enough time, and especially with temperature changes a myriad of chemical reactions can occur in a battery. Furthermore, the VRLA battery is supposed to eliminate water evaporation in normal operation. Then, I found a caveat dating back to the '20s in an early edition of A.E. Knowlton's, "Standard Handbook for Electrical Engineers". It pointed to a USA Federal Specification, O-A-111, that imposed limits on "impurities" in the electrolyte! But no specific mention of oil. A web search produced an article by the American Chemical Association "Rapid Discrimination of Counterfeit Gas-Oil Prepared by Mixing Fuel Oil with Sulphuric Acid..." Still no real answer to your query.

So, I asked two of the biggest Horses' Acid battery manufacturers (I know, its a lame pun)... Johnson Controls in the USA and VARTA (inventor of the VRLA battery) in Germany. The JC rep said that he had heard of some testing about 15 years ago, but had no recollection of any conclusion.

VARTA, has not responded. Perhaps your research facility has enough clout to extract a reply from them!

Until you get an answer, I won't be putting any oil (except oil of Vitriol) in my battery!

Regards, Phil Corso, PE ([email protected])