Cause of verdigris on battery terminal?
Discussion
I cleaned the earth terminal on the Aston today. Over the winter it had built up a really bad case of verdigris but more interestingly under the usual salty green deposits was a hard solid dark red build up. I was able to chip it off and clean up the terminal but does anyone know what it was, causes this and how I can prevent it?
The car is on an Accumate and I always clean the terminals and apply a smear of Vaseline on them before fitting them back but it always seems to return.
The car is on an Accumate and I always clean the terminals and apply a smear of Vaseline on them before fitting them back but it always seems to return.
This is like "Science lesson" at school. I always wondered myself: Interesting info I found.
Sulfation occurs when a lead acid battery is deprived of a full charge. This is common with starter batteries in cars driven in the city with load-hungry accessories. A motor in idle or at low speed cannot charge the battery sufficiently.
What is sulfation? During use, small sulfate crystals form, but these are normal and are not harmful. During prolonged charge deprivation, however, the amorphous lead sulfate converts to a stable crystalline that deposits on the negative plates. This leads to the development of large crystals, which reduce the battery’s active material that is responsible for high capacity and low resistance. Sulfation also lowers charge acceptance. Sulfation charging will take longer because of elevated internal resistance.
There are two types of sulfation: reversible (or soft sulfation), and permanent (or hard sulfation). If a battery is serviced early, reversible sulfation can often be corrected by applying an overcharge to a fully charged battery in the form of a regulated current of about 200mA. The battery terminal voltage is allowed to rise to between 2.50 and 2.66V/cell (15 and 16V on a 12V mono block) for about 24 hours. Increasing the battery temperature to 50–60°C (122–140°F) further helps in dissolving the crystals. Permanent sulfation sets in when the battery has been in a low state-of-charge for weeks or months. At this stage, no form of restoration is possible.
There is a fine line between reversible and non-reversible sulfation, and most batteries have a little bit of both. Good results are achievable if the sulfation is only a few weeks old; restoration becomes more difficult the longer the battery is allowed to stay in a low SoC. A sulfated battery may improve marginally when applying a de-sulfation service. A subtle indication of whether a lead acid can be recovered is visible on the voltage discharge curve. If a fully charged battery retains a stable voltage profile on discharge, chances of reactivation are better than if the voltage drops rapidly with load.
Several companies offer anti-sulfation devices that apply pulses to the battery terminals to prevent and reverse sulfation. Such technologies tend to lower sulfation on a healthy battery but they cannot effectively reverse the condition once present. Manufacturers offering these devices take the “one size fits all” approach and the method is unscientific. A random service of pulsing or blindly applying an overcharge can harm the battery in promoting grid corrosion. Technologies are being developed that measure the level of sulfation and apply a calculated overcharge to dissolve the crystals. Chargers featuring this technique only apply de-sulfation if sulfation is present and only for the time needed.
Sulfation occurs when a lead acid battery is deprived of a full charge. This is common with starter batteries in cars driven in the city with load-hungry accessories. A motor in idle or at low speed cannot charge the battery sufficiently.
What is sulfation? During use, small sulfate crystals form, but these are normal and are not harmful. During prolonged charge deprivation, however, the amorphous lead sulfate converts to a stable crystalline that deposits on the negative plates. This leads to the development of large crystals, which reduce the battery’s active material that is responsible for high capacity and low resistance. Sulfation also lowers charge acceptance. Sulfation charging will take longer because of elevated internal resistance.
There are two types of sulfation: reversible (or soft sulfation), and permanent (or hard sulfation). If a battery is serviced early, reversible sulfation can often be corrected by applying an overcharge to a fully charged battery in the form of a regulated current of about 200mA. The battery terminal voltage is allowed to rise to between 2.50 and 2.66V/cell (15 and 16V on a 12V mono block) for about 24 hours. Increasing the battery temperature to 50–60°C (122–140°F) further helps in dissolving the crystals. Permanent sulfation sets in when the battery has been in a low state-of-charge for weeks or months. At this stage, no form of restoration is possible.
There is a fine line between reversible and non-reversible sulfation, and most batteries have a little bit of both. Good results are achievable if the sulfation is only a few weeks old; restoration becomes more difficult the longer the battery is allowed to stay in a low SoC. A sulfated battery may improve marginally when applying a de-sulfation service. A subtle indication of whether a lead acid can be recovered is visible on the voltage discharge curve. If a fully charged battery retains a stable voltage profile on discharge, chances of reactivation are better than if the voltage drops rapidly with load.
Several companies offer anti-sulfation devices that apply pulses to the battery terminals to prevent and reverse sulfation. Such technologies tend to lower sulfation on a healthy battery but they cannot effectively reverse the condition once present. Manufacturers offering these devices take the “one size fits all” approach and the method is unscientific. A random service of pulsing or blindly applying an overcharge can harm the battery in promoting grid corrosion. Technologies are being developed that measure the level of sulfation and apply a calculated overcharge to dissolve the crystals. Chargers featuring this technique only apply de-sulfation if sulfation is present and only for the time needed.
But that is talking about sultfation on the plates. I'm getting a red hard build up on the earth terminal which is brass. It's the consistency of chalk but harder and dark red.
In 40 years of owning classics I've never seen this before hence my curiosity.
The charger it lives on is an Accumate so should be fine.
Eta bloody iPad is determined not to let my type sulfation
In 40 years of owning classics I've never seen this before hence my curiosity.
The charger it lives on is an Accumate so should be fine.
Edited by RichB on Sunday 18th May 16:02
Eta bloody iPad is determined not to let my type sulfation
Edited by RichB on Sunday 18th May 16:02
I remember reading a while back on a battery suppliers website that (ordinary) modern made car batteries do not require anything like Vaseline on the battery posts as they now use a different material on the posts
could it be the way you clean the post or clamps, have you overdone it perhaps, stripped the surface(s)
for decades I've used Copper Ease on the inside and outside of the battery clamps with no ill effects other than the thorough wipe clean before disconnecting to save the dirty copper grease getting transferred everywhere else including my clothes
as has been said already if the battery is venting over itself or mixing in with something else on the battery that might do something
possibly it might be from the environment the car is kept in or something having an effect on that particular area of the environment
obviously keeping a car sat still for long periods can throw up oddities and lack of use issues
as you've got one of these (marvellous???) iThings a posted photo might help especially if unlike many phone users you have the focus of the photo on the subject rather than blurred and sharp background
could it be the way you clean the post or clamps, have you overdone it perhaps, stripped the surface(s)
for decades I've used Copper Ease on the inside and outside of the battery clamps with no ill effects other than the thorough wipe clean before disconnecting to save the dirty copper grease getting transferred everywhere else including my clothes
as has been said already if the battery is venting over itself or mixing in with something else on the battery that might do something
possibly it might be from the environment the car is kept in or something having an effect on that particular area of the environment
obviously keeping a car sat still for long periods can throw up oddities and lack of use issues
as you've got one of these (marvellous???) iThings a posted photo might help especially if unlike many phone users you have the focus of the photo on the subject rather than blurred and sharp background
nta16 said:
...as you've got one of these (marvellous???) iThings a posted photo might help especially if unlike many phone users you have the focus of the photo on the subject rather than blurred and sharp background
Not possible as I've cleaned it all up but next time I'll get a few snaps. I'll try copper ease instead of Vaseline. As for the venting, don't know. It's a period looking black rubber top battery I got from Lincon Batteries so each cell has a vented cap. Maybe I just need to continually clean the croc clip on the Accumate throughout the winter before any build up happens. RichB said:
It's a period looking black rubber top battery
blast, I put ordinary in brackets for battery and meant to go on to traditional/traditional looking/old style batteries - all bets off for those with methere are a couple of good John Twist vids on batteries, IIRC rubber case is mentioned in at least one, if they're the old fashion construction you need trays under them and all sorts, unless you're in concours get modern made, traditional looking if you must
if you can't start the car you can't drive it, then it truly enters the realms of concours
this vid is a bit old and grainy now but is still relevant and shows the battery post isolators that might(?) help in your case and correct- http://www.youtube.com/watch?v=UnbQ2G5K2zI
I think this vids tells you about rubber case batteries but I didn't check - http://www.youtube.com/watch?v=_Uk53AYZ_2o
ETA: if the battery posts and the crocodile clips are protected by cooper grease at points of contact then that will take car of anything that might have been coming off the posts
you could fully coat the posts and crocodile clips in coper grease to protect them but that wouldn't help to resolve how this thing happens as you've eliminated all areas of possible build up
Edited by nta16 on Sunday 18th May 23:33
BT didn't like silicone grease on their terminals - but that was back in the day when they actually had qualified time served engineers so all might have changed now
how about this - http://contralube.com/contralube-770/
how about this - http://contralube.com/contralube-770/
nta16 said:
RichB said:
It's a period looking black rubber top battery
if you can't start the car you can't drive it, then it truly enters the realms of concours...<clip?>
The car starts perfectly, the battery holds its charge perfectly. I've not said anything is wrong with the battery just curious about the red copper oxide. Lincon Batteries near Southend, look them up, very good, look the piece and work perfectly. Being an old codger like you I've had my fill of flat batteries over the last 40 years
p.s. I've moved the +ve croc lip away from the battery and put it on the earth isolator switch about 12" away so let's see if that helps.
Edited by RichB on Monday 19th May 22:51
Edited by RichB on Monday 19th May 22:52
RichB said:
sorry Nigel, you're barking up the wrong tree.
I was think of possibly the next stage if you get the build up again, the vids were to give general info and about those old rubber batteries if you had one (and it was in the vid) RichB said:
p.s. I've moved the +ve croc lip away from the battery and put it on the earth isolator switch about 12" away so let's see if that helps.
not a bad idealong as it was -ve clip
ETA: you're quite right, even in my sort life I soon got fed up with a flat battery or car that didn't start, one of my pet pevs is a car that won't start, if it starts often you can limp it back, for many, many years I've made a good battery with it and the connections in good condition a priority because of previous experiences
Edited by nta16 on Tuesday 20th May 13:17
I just posted on the "odd battery corrosion" thread and NTA very kindly pointed out this thread.
"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?"
A few more things
The XK120 has two 6 volt batteries which are contained under a cover behind the seats with no ventilation. The car is used only occasionally and has a Ctek conditioner.
The corrosion is only on the positive terminals and is equal in quantity and the brass clamp has been eroded to the same degree on each one. So it does not seem to be the fault of one particular battery.
Very interesting that Rich finds this to be a problem this year. I have had the car since 1998 with little problems before and have other positive earth cars with enclosed unventilated batteries and no problem at all. I was genuinely horrified at the amount of corrosion that had taken place since I last checked, which may have been last Autumn, before she was put to sleep for the Winter. Especially since I had put liberal coatings of Vaseline on the posts.
"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?"
A few more things
The XK120 has two 6 volt batteries which are contained under a cover behind the seats with no ventilation. The car is used only occasionally and has a Ctek conditioner.
The corrosion is only on the positive terminals and is equal in quantity and the brass clamp has been eroded to the same degree on each one. So it does not seem to be the fault of one particular battery.
Very interesting that Rich finds this to be a problem this year. I have had the car since 1998 with little problems before and have other positive earth cars with enclosed unventilated batteries and no problem at all. I was genuinely horrified at the amount of corrosion that had taken place since I last checked, which may have been last Autumn, before she was put to sleep for the Winter. Especially since I had put liberal coatings of Vaseline on the posts.
Edited by Vanin on Sunday 1st June 09:00
I still have the same battery I had 11 years ago on the positive earth E-type. I don't use battery conditioning nor ordinary chargers at all, despite this being a dynamo and not alternator charged car. I just use a simple thing called a spanner and disconnect the battery when I know the car will not be in use, such as winter. I've never had any corrosion problems - ever.
RichB said:
I cleaned the earth terminal on the Aston today. Over the winter it had built up a really bad case of verdigris but more interestingly under the usual salty green deposits was a hard solid dark red build up. I was able to chip it off and clean up the terminal but does anyone know what it was, causes this and how I can prevent it?
The car is on an Accumate and I always clean the terminals and apply a smear of Vaseline on them before fitting them back but it always seems to return.
Because it's brass the obvious thought is that it is cuprous oxide that is forming as this is the red oxide of copper but if you're getting verdigris also it suggests that it isn't. Verdigris usually forms from cupric oxide, not cuprous, and if that is being formed I can't imagine that cuprous would be also. Although, the cuprous form likes to convert to cupric oxide in moist air so may explain the verdigris on top. The car is on an Accumate and I always clean the terminals and apply a smear of Vaseline on them before fitting them back but it always seems to return.
lead tetroxide is a candidate. Brass often contains lead to make it more malleable.
If your terminals are made by turning the brass then this will have brought a lot of the lead to the surface. 'Leaching' is the term I think.
However, I can't think of a non industrial process that would create it.
Easiest way to test it is to stick some under a blow torch. It you get lead globules then you have your answer almost certainly one way or another.
Other than those two I can't think of a red oxide or sulphide that you could get from brass in a conventional RT&P sort of scenario but it's over twenty years since I should have known what it is and how it was formed.
Blimey, that's a bit of a science lesson and thanks, it's fascinating. In the mean time I seem to have cured the problem by moving the earth croc-clip away from the battery terminal and clipping it on a bare bit of the earth lead where it connects to the isolating/kill switch which all Feltham Astons have in the footwell. 
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