Accumate causing verdigris on battery - thoughts?
Discussion
OK first off I'll admit I'm pretty disgusted to see this and assure you I spent a few hours this morning cleaning it all up! I last used the car about 3 months ago and put it away in the garage with the Accumate charger connected as usual. This morning I came to get the car out and was confronted with this mess. So, instead of an early morning drive Sunday has turned into a massive get the battery out, clean up all the mess, wash the corrosion with bi-carb, Vaseline the terminals and while at it wash and polish the whole car!
Anyway the point of this post is to ask the question; what's causing such massive build up of verdigris (if that's the correct term) around the earth terminal. The other (neg) post was fine. Once I'd removed the green salts underneath was a hard, dark brown/copper coloured build up, the texture of hardened chalk that I had to chip off with a screwdriver.
It all cleaned up ok although but I think I will get a replacement battery clamp. I baffled as the batteries of the other cars that I use Accumates on don't display this behaviour.
Thoughts anyone?
![](http://thumbsnap.com/sc/YjOqvmtd.jpg[/img]</a> <a href="http://thumbsnap.com/ARCeetcg" Target="_blank">[img]http://thumbsnap.com/sc/ARCeetcg.jpg)
Anyway the point of this post is to ask the question; what's causing such massive build up of verdigris (if that's the correct term) around the earth terminal. The other (neg) post was fine. Once I'd removed the green salts underneath was a hard, dark brown/copper coloured build up, the texture of hardened chalk that I had to chip off with a screwdriver.
It all cleaned up ok although but I think I will get a replacement battery clamp. I baffled as the batteries of the other cars that I use Accumates on don't display this behaviour.
Thoughts anyone?
What had happened was that the build up forced the little crocodile clip off the terminal and it landed on the centre cell. Dodgy I know, but it's all cleaned up ok. Just can't figure it out.
p.s. the green light on the Accumate has been flicking on no trouble and that signifies that it has reached maintenance level I believe.
p.s. the green light on the Accumate has been flicking on no trouble and that signifies that it has reached maintenance level I believe.
Edited by RichB on Sunday 7th June 22:12
You'll fit in well on Pistonheads - nothing to contribute exact a sarcastic remark! 
The "few hours" referred to getting all the corrosion off the clamp with a solution of bi-carb and polishing it with a wire brush, cleaning up the battery also with mild bi-carb, making sure none of the acidic gunk had spilt into the depths of the wing and then washing and polishing the car. Oh and going for a "test drive" as one does.
The "few hours" referred to getting all the corrosion off the clamp with a solution of bi-carb and polishing it with a wire brush, cleaning up the battery also with mild bi-carb, making sure none of the acidic gunk had spilt into the depths of the wing and then washing and polishing the car. Oh and going for a "test drive" as one does.
Edited by RichB on Monday 8th June 11:52
Yes, it's a positive earth. The battery was new about a couple of years ago from Lincon batteries, they make all shapes and sizes in the original rubber cases to suit older cars. http://www.lincon.co.uk/classic_car_batteries.html
I am wondering if the metal or the clamp would have any effect? It looks like it's brass while the negative clamp is steel.
I am wondering if the metal or the clamp would have any effect? It looks like it's brass while the negative clamp is steel.
Wikipedia says...
Corrosion at the battery terminals can prevent a car from starting due to electrical resistance. The white powder sometimes found around the battery terminals is usually lead sulfate which is toxic by inhalation, ingestion and skin contact. The corrosion is caused by an imperfect seal between the plastic battery case and lead battery post allowing sulfuric acid to react with the lead battery posts. The corrosion process is also expedited by over charging. Corrosion can also be caused by factors such as salt water, dirt, heat, humidity, cracks in the battery casing or loose battery terminals. Inspection, cleaning and protection with a light coating of dielectric grease are measures used to prevent corrosion of battery terminals.
Corrosion at the battery terminals can prevent a car from starting due to electrical resistance. The white powder sometimes found around the battery terminals is usually lead sulfate which is toxic by inhalation, ingestion and skin contact. The corrosion is caused by an imperfect seal between the plastic battery case and lead battery post allowing sulfuric acid to react with the lead battery posts. The corrosion process is also expedited by over charging. Corrosion can also be caused by factors such as salt water, dirt, heat, humidity, cracks in the battery casing or loose battery terminals. Inspection, cleaning and protection with a light coating of dielectric grease are measures used to prevent corrosion of battery terminals.
RichB said:
Thanks Craig, someone else also said that perhaps the post is not bonded perfectly with the gum case topping. I may try to seal it with some black non hardening rubber mastic.
Good coating of petroleum jelly will prevent the corrosion, assuming the seal between the post and the casing is fairly tight.eldar said:
RichB said:
Thanks Craig, someone else also said that perhaps the post is not bonded perfectly with the gum case topping. I may try to seal it with some black non hardening rubber mastic.
Good coating of petroleum jelly will prevent the corrosion, assuming the seal between the post and the casing is fairly tight.eldar said:
Should help, but is a bit prophylactic maybe. You need to check the battery isn't suffering from a damaged cell or being overcharged.
Regards overcharging, doesn't the fact that the Accumate switches from yellow to green indicate that the battery is at full charge and the charger has switched to maintenance mode? RichB said:
egards overcharging, doesn't the fact that the Accumate switches from yellow to green indicate that the battery is at full charge and the charger has switched to maintenance mode?
Possibly not, if there is a duff cell. Try this.http://www.aa1car.com/library/2003/us20310.htm
I posted this about a year ago on the "Odd Battery Corrosion" thread on this Classic Car forum.
Pay attention at the back Richard B!
But the rest of thread is worth reading even if my contribution is not!
[report] [news] Saturday 31st May 2014
A year ago, having taken note of these advices , I thoroughly cleaned each of the two six volt batteries on my old positive earth Jaguar.
A year later I was horrified to find more corrosion than ever, and the Vaseline was still there in liberal quantities. The white corrosion was within the Vaseline which demonstrates how ineffective it was.
It is probably due to the less regulated charging system with the dynamo, but there is no sign of acid kicking about, and the electrolyte had not boiled away at all and needed no topping up.
I think the answer must be to put plenty of bicarbonate of soda around the positive terminals of the battery as it only forms on those battery posts.
Initially I thought that the reaction needed air to make the corrosion active, hence the Vaseline, but thinking about it further with electrolysis air is probably not needed. (Any chemists out there?)
I suppose that as the terminals are made of brass which is a copper zinc mixture, then the corrosion is a mix of copper and zinc sulphate, hence the whiter appearance . If it was just copper sulphate it would be blue.
Anyone have any better ideas?
Pay attention at the back Richard B!
But the rest of thread is worth reading even if my contribution is not!
[report] [news] Saturday 31st May 2014
A year ago, having taken note of these advices , I thoroughly cleaned each of the two six volt batteries on my old positive earth Jaguar.
A year later I was horrified to find more corrosion than ever, and the Vaseline was still there in liberal quantities. The white corrosion was within the Vaseline which demonstrates how ineffective it was.
It is probably due to the less regulated charging system with the dynamo, but there is no sign of acid kicking about, and the electrolyte had not boiled away at all and needed no topping up.
I think the answer must be to put plenty of bicarbonate of soda around the positive terminals of the battery as it only forms on those battery posts.
Initially I thought that the reaction needed air to make the corrosion active, hence the Vaseline, but thinking about it further with electrolysis air is probably not needed. (Any chemists out there?)
I suppose that as the terminals are made of brass which is a copper zinc mixture, then the corrosion is a mix of copper and zinc sulphate, hence the whiter appearance . If it was just copper sulphate it would be blue.
Anyone have any better ideas?
my latest thinking is that the post isn't sealed but to be honest I might try Lowdrag's approach and simply disconnect the battery in the winter. It's getting tedious now. 
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