Mineral oil additive to lead acid batteries

[Chuck Losness]

Another forum that I frequent has brought up putting mineral oil in lead acid batteries. I did a little online research and found that the early battery inventers put a layer of mineral oil on top of the electrolyte and that Thomas Edison even sold mineral oil for batteries. The bottles are collector's items. The railroads used it in their batteries and a lot of RV's are starting to use it. I also found a US Bureau of Reclamation paper on the maintenance and care of lead acid batteries that specified putting a 1/4" layer of mineral oil on top of the electrolyte.
Does anyone here have any real life experience with this?

[Ike]

Never heard of it.

[charmc]

Never heard of it either, but I found the references to Edison's use and RV use. It appears to be used primarily as a barrier to reduce evaporation of water, actually acid. The RV users claim that battery compartments remain clean and free from corrosion. The Edison national historical site in NJ describes its use by Edison to both reduce evaporation losses and prevent contamination of the battery acid. Early lead acid batteries were more "open" in construction, so its use makes sense.

One question I would raise for marine use concerns rough water conditions, storms, etc., which could agitate and emulsify the oil and water, possibly degrading battery performance.

[Chuck Losness]

I thought about the emulsification issue also. But trains and RV's bounce around just as much as boats due at times. So I don't think this would be an issue but I don't know.

[MattZ]

It used to be used in days gone by, but no really solid references as to why it was used. The only explanation, the origin of which I don't recall, is this: Battery acid is hygroscopic, in other words it absorbs moisture from the atmosphere, so a battery in long term storage in humid environments can actually have an increase in electrolyte level. So the mineral oil will prevent the electrolyte from coming into direct contact with the atmosphere.

[Chuck Losness]

Thanks Mattz for your post. I am going to try it out just to see what happens. I will be adding 4 oz's to each cell in my battery bank (4 six volt golf cart batteries). I'll post any results that I get next summer after I put the boat away for hurricane season.

[Chuck Losness]

Well it has been almost a year since I added mineral oil to my batteries. Adding the mineral oil does not appear to have caused any problems. It also did not prevent water from evaporating from the batteries. But it did reduce corrosin to almost nil. If I discover anything else, I'll let you know

[mark775]

Corrosion of what, Chuck? You mean the surrounding area? connectors and whatnot?

[Chuck Losness]

The typical corrosin that you get on battery terminals and the connectors

[Redtick]

From Automotive Storage Battery Care and Repair by O.A. Witte

"Oil in the electrolyte, if allowed to get into the pores of the plates, will fill them and lower the capacity very much. It affects negative plates much more than positives. Probably the only remedy in this case is new plates."

[BTPost]

You folks are mixing Apples and Oranges here... Mineral Oil was used in Edison Cells as described here, HOWEVER these were NOT Lead/Acid Cells, but WERE, Ni/Fe Cells that had Potassium Hydroxide as Electrolyte. Different Chemistry, different Cell types. These are still in use in the Telco Industry for Battery Backup... 1.25 Vdc/Cell... Long Charge Times... Not very efficient... but Very Good Longevity, as the plates don't deteriorate over time, and easy to service. You can put a Full Charge on them, which returns the Plates to pure Ni and Fe, and then replace the electrolyte with New Stuff and you rejuvenate the Battery.

[pistnbroke]

I agree with BT post ..I have long experience of lead acid batteries and always told people not to use mineral grease on the terminals as it reacts with the acid to produce the white clag on them ....the acid leaks up past the lead terminal posts as the plates expand and contract whilst charging/discharging . The french however did put oiled felt rings under the terminal clamps to stop acid reaching the clamps on there Citroen models

[Landlubber]

yes, but they used lanolin as a grease, no worries.

[pistnbroke]

I think by 1985 it had de generated to engine oil....

[gonzo]

My father use to make felts soaked in oil for batteries. They worked really well