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Battery Sulphating on Negative terminal post
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userHymerVan
Posted: 11 September 2019 9:51 AM
Subject: Battery Sulphating on Negative terminal post
 


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I have just discovered that the Banner Leisure battery in my van has heavy crystalline sulphating on the negative terminal post. Mr Google says this is a sign of undercharging however the van has two solar panels and the voltage indicator shows a voltage of 13.2v and both batteries (leisure and vehicle) seem to be in good condition.

Is there another explanation for sulphating ? The electrolyte level looks OK. So apart from carefully cleaning off the terminal post and adding a touch of vaseline is there anything I should be worried about and/or does anyone have any advice ?
userOcsid
Posted: 11 September 2019 10:48 AM
Subject: RE: Battery Sulphating on Negative terminal post
 
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Under what conditions are you seeing 13.2 volts and was that with a meter you are confident in its accuracy?

Thirteen point two is good to see if it is in the night before the solar panel(s) are doing anything, and if the batteries are fully charged during the day and the solar controller has backed off trying to push any more in.

If the system is trying to recharge the batteries then 13.2 Volts is too low to do so.
userHymerVan
Posted: 11 September 2019 11:20 AM
Subject: RE: Battery Sulphating on Negative terminal post
 


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Thanks Ocsid. 13.2 is the reading on the main (Sargent) panel when the solar is contributing something but I didn't pay enough attention to exactly what the solar was doing.

I know from experience that the voltage taken directly from the battery (using a multimeter) is pretty much the same as the the voltage shown on the main panel and also on the Votronic Voltmeter and computer which I had installed as part of a Solar Charge controller upgrade which Alan Evans kindly helped me specify and Dave Newell fitted (because Alan had come out of the solar market even though he still helped me).

So I think what you are saying is that there may be a charging issue even if the voltage is relatively high. I will check the voltage across the terminals with the negative terminal off i.e. not getting anything from the solar and post it. I need to finish cleaning off the terminal post anyway as I didn't have a small wire brush in the van. The van is in storage so it may be a few days before I can repost

Edited by HymerVan 2019-09-11 11:34 AM
userOcsid
Posted: 11 September 2019 1:12 PM
Subject: RE: Battery Sulphating on Negative terminal post
 
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I am saying that 13.2 Volts on a battery that one is trying to charge is too low to achieve any additional charging.
That leaves open the real possibility it is already well charged and the smart solar regulator has simply stopped trying to over charge it.
It could also mean that the charging system has either a fault or simply inadequate solar energy being received to charge it, despite it needing further charging.

A check is to drain the batteries somewhat, no need to stupidly deplete them, just get off them possibly being at 100% SOC, then with a sunny day is the voltage considerably higher than 13.2 Volts. It needs to exceed 13.4 but ideally above 13.8 probably up around 14.4 Volts.
userHymerVan
Posted: 11 September 2019 3:25 PM
Subject: RE: Battery Sulphating on Negative terminal post
 


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Thanks again. I have actually got a hydrometer so I can check the battery "the old fashioned way".
Would that be useful ?
I can also get some idea of the cumulative output from the solar from the "Computer".

As I said I will post again once I have visited the van but that may not be before Saturday 14th.
usersteveandlisa
Posted: 11 September 2019 6:36 PM
Subject: RE: Battery Sulphating on Negative terminal post
 


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Disconnect the leads and give the battery terminals a good clean. Boiling water is the best and quickest way to remove the sulphating from the leads, it will dissolve the crud instantly and leave them looking brill. Refit the leads to their correct terminals and give them a good smearing of Vaseline or copper grease to help prevent further corrosion, job done and should last quite a long time

Steve
user747
Posted: 11 September 2019 7:45 PM
Subject: RE: Battery Sulphating on Negative terminal post
 


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A Banner battery?

Chances are that it is as dry as a bone inside.
userOcsid
Posted: 11 September 2019 8:07 PM
Subject: RE: Battery Sulphating on Negative terminal post
 
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747 - 2019-09-11 7:45 PM

A Banner battery?

Chances are that it is as dry as a bone inside.


Yes quite likely if you had not realised it was not sold as a maintenace free battery, like batteries of that type they need water.
usercoach2000
Posted: 11 September 2019 10:41 PM
Subject: RE: Battery Sulphating on Negative terminal post
 
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Can you tell me where you got the information from that 13.2 volts is too low to add a suitable charge as I have never heard this before.

Clive.
userHymerVan
Posted: 12 September 2019 8:16 AM
Subject: RE: Battery Sulphating on Negative terminal post
 


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747 - 2019-09-11 7:45 PM

A Banner battery?

Chances are that it is as dry as a bone inside.


No its definitely not dry as a bone there is electrolyte visible (I removed all six caps) but when I revisit the van (see above) I will take a torch just to make sure I am seeing it properly that the electrolyte is covering the plates.
userspirou
Posted: 12 September 2019 8:22 AM
Subject: RE: Battery Sulphating on Negative terminal post
 


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coach2000 - 2019-09-11 11:41 PM

Can you tell me where you got the information from that 13.2 volts is too low to add a suitable charge as I have never heard this before.

Clive.


13.2 is just above resting voltage for most lead batteries and usually considered maintenance charge i.e. not letting the battery discharge but also not charging much.. You'd have to wait a really long time to recharge a battery using 13.2V
userOcsid
Posted: 12 September 2019 9:04 AM
Subject: RE: Battery Sulphating on Negative terminal post
 
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coach2000 - 2019-09-11 10:41 PM

Can you tell me where you got the information from that 13.2 volts is too low to add a suitable charge as I have never heard this before.

Clive.


I have no recollection where I got to know about charging lead acid batteries as that knowledge goes back now some 60 years ago to my apprenticeship days.

However, just this sort of info is readily available on the internet from well regarded sources.
Here is one, see figure 3.

https://batteryuniversity.com/learn/article/charging_the_lead_acid_battery
usercoach2000
Posted: 14 September 2019 11:38 PM
Subject: RE: Battery Sulphating on Negative terminal post
 
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Thanks for that. Very informative link.

Clive.
userHymerVan
Posted: 15 September 2019 7:18 AM
Subject: RE: Battery Sulphating on Negative terminal post
 


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Returned to van yesterday. Inspected each cell with a torch. Electrolyte level fine.
The solar computer was showing a small output from the solar but that the leisure battery was fully charged at 14.2 volts (available charge not being applied to battery).

Checked that voltage with multimeter after disconnecting the negative battery clamp 13.8v. Thoroughly cleaned the terminal post and clamp and applied vaseline rechecked voltage still showing 13.8 and retightened.

So it looks although battery itself and charging circuits are all fine which leaves unanswered the question of why the terminal post was sulphated in the first place.

The battery has been in use for 30 months.

Incidentally the Sargent EC 238 panel was showing a (varying ) voltage for the leisure battery even though the negative terminal post was connected to nothing and no subsidiary connections or anything from this source.
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