NFU Mutual Smallholding Insurance

Author Topic: battery sulfation  (Read 464 times)

Charlie1234

  • Joined Feb 2017
  • Powys
battery sulfation
« on: July 04, 2017, 01:07:30 pm »
Hi All
I live off grid 1800ft up the cambrian mountains,mid-wales.Been here 3 years and mainly use a small wind turbine to charge our battery banks but also have a few solar panels.Recently noticed the batteries were not charging great so ordered more Bat-aid tabs they do work but can anyone recommend anything that works better/quicker ?

Did buy one of those battery desulfating devices that connects to the battery but it didnt seem to do anything really.

Batteries were new when we moved here + I top them up weekly.

5 Dogs,5 cats,40 chickens,2badger faced sheep + a full freezer

mab

  • Joined Mar 2009
  • carmarthenshire
Re: battery sulfation
« Reply #1 on: July 04, 2017, 10:39:48 pm »
The bat-aids are basically EDTA (a chelating agent) which helps remove sulphate from the plates. The sulphates form a barrier between the plates and the electrolyte, so removing them lowers battery internal resistance. The problem with the EDTA is that it doesn't break up the sulphate crystals and return them to solution, but instead binds to them, removing them from the plates, then settles to the bottom of the battery. so you are still losing the lead off the plates and the sulphate ions from the electrolyte which reduces your battery capacity over time.

the electronic desulphators are not scientifically proven to work though some folks swear by them - I don't think much of them myself, though the theory behind them is plausible.

To answer your actual question: Rolls batteries suggest a 'recovery charge' to desulphate their batteries which is kind of an extreme equalisation:- you push the voltage up to ~17v (for a 12v battery - 2.85vpc IIRC) until the current stabilises or the battery gets too hot - this help break down some of the smaller PbSO4 crystals (i.e. desulphates) but if they've formed into larger crystals even this won't help a lot.

It does sound like you are suffering a lot of sulphation considering your battery is only 3 years old, which suggests you're too deeply discharging the battery too often, or you are leaving it in a low state of charge too long, or you need to equalise it more often (unless it's the whole battery that's suffering and not just a few cells). The best way to deal with sulphation is to avoid it in the 1st place  :) - not that that helps you at this point.

Charlie1234

  • Joined Feb 2017
  • Powys
Re: battery sulfation
« Reply #2 on: July 05, 2017, 12:12:18 am »
Cheers Mab  :thumbsup:
5 Dogs,5 cats,40 chickens,2badger faced sheep + a full freezer

mab

  • Joined Mar 2009
  • carmarthenshire
Re: battery sulfation
« Reply #3 on: July 05, 2017, 12:30:17 am »
no worries. I feel I should advise caution in using the recovery charge method - as the word recovery suggests it's to be used in extremis when a battery has been allowed to get badly sulphated and not as a routine procedure as it is quite hard on the battery in itself.

I can't find the reference to that procedure now but have found this:-

http://www.rollsbattery.com/wp-content/uploads/manuals/Rolls_Battery_Manual.pdf

which refers to a corrective equalisation on page 19 and is perhaps a safer procedure to follow.

Also interesting to note they don't recommend the use of EDTA (pg21).

Charlie1234

  • Joined Feb 2017
  • Powys
Re: battery sulfation
« Reply #4 on: July 05, 2017, 11:25:33 am »
Very interesting reading,took a few attempts as the concentration level aint what it was lol.

Both banks of batteries rarely fall below 12.5v as we are 1800ft up and the turbine is always moving. we have a big wind farm just across the fields from us so we must be in a good area for wind + the solar puts a lot into them to the point that the dump load heats plenty of water.

All our household items are extra low energy including our modern twintub washing machine which is only 150w. kettle etc is boiled via propane cooker so never any big power usage and batteries are topped up religiously.


Phoned the company we had the batteries from and they are coming out to run some tests so maybe they will find something.
5 Dogs,5 cats,40 chickens,2badger faced sheep + a full freezer

Possum

  • Joined Feb 2012
  • Somerset
Re: battery sulfation
« Reply #5 on: July 18, 2017, 10:27:52 pm »
Hi Charlie,


Did the tests produce any useful results?

Charlie1234

  • Joined Feb 2017
  • Powys
Re: battery sulfation
« Reply #6 on: July 21, 2017, 11:44:51 pm »
Hi Charlie,


Did the tests produce any useful results?

Hi Possum
I had a family funeral to attend so didnt get to see the engineer. He had to change the charge controller as it was faulty and not allowing the correct voltage through resulting in Under charging. He also  added a product called Thermoil Battery de-mister,supposed to help with desulfating whats already on the plates. Hadnt heard of it before but what I`ve read since sounds interesting. Has anyone tried it ??
5 Dogs,5 cats,40 chickens,2badger faced sheep + a full freezer

 

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