corrosion on negative terminals

[mtbandy]

Fistly apologies if this has been covered before, but I didn't have much luck finding any info!

I have several 86Ah Yuasa SLA batteries that I keep indoors, but I'm getting this horrible corrosion growing on the negative terminals (see pic). Does anyone else have similar problems, and what can be done to prevent it? I keep brushing it off, but it goes everywhere! The mess in the pic took about 2-3 weeks to 'grow'. The batteries have mostly just been sitting there fully charged, with about 13 volts on the terminals. Room is dry, temperature averages about 22*C. Thanks

[spinningmagnets]

I am very experienced working on old cars, but not experienced at all with large home RE battery packs, so take this with a grain of salt...

Ever notice the only vertical surface in your home that collects dust is the face of the TV? The invisible electromagnetic field draws the dust.

A cars battery is vented for when it get hot, and the battery terminals weak and invisible field draws the sulphuric vapors to the post, causing corrosion. Lead will be whitish, and copper will be greenish.

I take the clamp off, clean everything thoroughly, re-attach, then smear grease over both the posts. It works for me (on old car batteries).

I have heard from old heavy equipment mechanics that they have poured Karo syrup over the post, which dries into a crust, but I have never tried this.

"Now I know why tigers eat their young"! -Rodney Dangerfield in "Caddyshack" when observing the bosses son.

[kurt]

i have used this stuff http://www.pleasureboatmarine.com/crcbateprcr.html it is like a spray varnish that coats the battery termanals and keeps them from coroding. i have also used electrically conductive grease you just smear it all over the battery connections and put a thin layer between the mating serfices of the lug and post when you make the connections. you can buy eather product at most auto parts stores

[mtbandy]

Thanks for the replies

I have actually heard the batteries venting, so it looks like this is the root cause. They seem to vent when they hit 14.4 volts, and my charge controller has been set for 14.2. Strange thing is the batteries vent ever so slightly when just sitting, I can sometimes hear them. Probably this is caused by the room temperature variation?

For now I will spray some PCB coating over the terminals to try and prevent the corrosion, but I should probably try and do something to stop the venting. Thanks again

[Flux]

Corrosion is more common on positive terminals, but the venting is making it worse.

Clean and grease or coat with other things as advised.

Go to Yuasa site and look up the float voltage for your batteries, I am sure 14.2v is too high to sustain on a VRLA for any significant time, may be ok for a short equalise but those things don't like much in the way of equalising.

Definitely don't let them go up to 14.4v

Flux

[mtbandy]

They state 13.65 volts for float, and the batteries are actually 'designed for standby use'.

I've been charging them as I would for cyclic use, although to be honest most of the time (or at least during the day) they just sit there floating, maybe with the odd 10-20% discharge. Maybe I should only charge them to about 14v?

All the terminals are about 13.1 volts at the moment, even after just sitting for weeks.

[Flux]

I would be inclined to set the limit at 14v. For indefinite float then the 13.68 may be correct. Normally with normal use they are happy at 13.8, if you limit to 14v and spend most of the time below this then it should be ok.

I think they will have vented each time you reached 14.4 for a significant time. If you sustained this voltage for long periods you would have dried them out. You are lucky that your use hasn't let it happen very often.

Flux

[AbyssUnderground]

I always set my batteries to hit 14.2v maximum. Mine doesn't vent or bubble. It used to when it was new 8 months ago but after 2-3 months it stopped making noises (which was the odd squeal when charging/discharging). Mine seems quite happy at 14.2v and it gets a better absorption period.

[ghurd]

Those 99 cent, red & green felt washers work wonders.

Really.  I didn't believe it either, but they do work.

G-

[SparWeb]

Another choice for anti-oxidant grease is called "IN-OX-ID".  It's recommended on the terminals of my GNB batteries.  I'm currently tracking down where to find a tube of the stuff.  Maybe any sort of grease would work, actually...

I'm just guessing by the computer cable and wall baseboard in the picture that you don't have the battery bank in a closed container.  If so, you could also cover the terminals with a rubber boot (or something equivalent) to prevent metal things from being dropped on the exposed terminal.  I was very wary of unscrewing my battery terminals until I realized that I could just wrap my wrenches with black tape when I used them for battery connections.

[Waterlogged]

The hardest part of a battery to seal is where the lead terminal comes through the plastic case. It only takes a small crack for the vapors to escape, and corrode the lead. (What a stupid idea it was for General Motors to put this hard-to-seal spot below the acid surface level?) This is what the felt rings are made to protect against. Many people use grease, but grease is not a good idea. It gets hot, and oozes into the connection. Most grease doesn't conduct electricity. Spray paint is the best sealer for battery terminals. It won't ooze into the connection, and can be color coded for safety.

Rod.

[jimjjnn]

I use the red and green washers and the spray in the blue can (forgot the brand name) from auto parts stores.

I drove last car 150k miles without having to touch the cable clamps to the battery. Neighbor is still driving same car with same battery. That battery is now 8 years old. My new vehicle has a gel cel battery. Don't know how long it will last. Red and green washers on it. I sprayed it with NAPA battery terminal protectant.

[spinningmagnets]

You may want to wear clothes that you don't care about when cleaning batteries. No matter how careful I am, I always get a tiny bit of the acidic corrosion on me, and then my clothes develop holes!

Use the work pants and shirt your wife keeps throwing away, and you keep digging out of the trash and hiding in the garage.

"Never ask a barber if you need a haircut" -Will Rogers

[zeusmorg]

Do not use standare lubricating grease to coat battery terminals! I worked as an auto mechanic for years and i saw a lot of battery failures caused by improper connections at the terminals caused by grease oozing in between the connector. The best bet is to use a spray coating specifically sold (see above post)for coating terminals. Make sure your connections are clean and solid before applying , of course. Remember these batteries ain't cheap! take care of them. Also the little felt pads do help in neutralizing the acid, but do not take care of the problem forever.