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Battery equalisation

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How often should one equalise a battery bank? I can do it from my inverter using the generator as a power source, but have't done it yet. How often should it be done? 

Best would be to check your specific batteries' datasheet.  I noticed in one of the Trojan datasheets that some battery manufacturers suggest doing it once a month, but Trojan recommends doing it once or twice a year at most.

  • Author

Busy with an equalisation cycle now. The batteries are taking 62V at 10A, I can taste the H2SO4. How long are you supposed to equalise them for? Default on my inverter/charger is 1 hour? 

  • Author

Hmm,, Trojan says this:

 

Equalizing (Wet Batteries Only)

 
Equalizing is an overcharge performed on flooded lead acid batteries after they have been fully charged. It reverses the buildup of negative chemical effects like stratification, a condition where acid concentration is greater at the bottom of the battery than at the top. Equalizing also helps to remove sulfate crystals that might have built up on the plates. If left unchecked, this condition, called sulfation, will reduce the overall capacity of the battery.
 

Many experts recommend that batteries be equalized periodically, ranging anywhere from once a month to once or twice per year. However, Trojan only recommends equalizing when low or wide ranging specific gravity (+/- .015) are detected after fully charging a battery. 

  • Author

And this:

 

3.4.2 Equalizing (deep-cycle flooded/wet batteries only)
Equalizing is an overcharge performed on deep-cycle flooded/wet batteries after they have been fully
charged. Trojan recommends equalizing only when batteries have low specific gravity, below 1.235 or
wide ranging specific gravity, > 0.030 points between cells, after fully charging a battery. Deep-cycle
AGM or gel batteries should never be equalized.

Thanks thats great information.

 

Does the fact that you can only equalize flooded lead acid cells and not AGM or Gell cells mean that they are actually a better choice of battery?

 

Put another way is it a major disadvantage that you cannot equalize AGM and Gell batteries?

Thanks thats great information.

 

Does the fact that you can only equalize flooded lead acid cells and not AGM or Gell cells mean that they are actually a better choice of battery?

 

Put another way is it a major disadvantage that you cannot equalize AGM and Gell batteries?

 

Hi Carl, I cannot comment on the "better choice of battery " statement, but when it comes to gel batteries, you have to prevent the generation of bubbles in the gel, because since the bubble generation is not reversible it reduces the capacity of the battery and shortens its life. Bubble generation typically occurs when you charge or discharge the gel batteries at a higher than recommended rate, or "over-charge" them e.g. while equalizing them.

  • Author

Well, the batteries didn't explode which I take as a good thing. And since the wife and kids where in Joburg last night, there was low power consumption overnight and now at midday the batteries are at float charge stage. When my batteries are at float stage they bubble a bit, so I don't think stratification of the acid is a real risk. as for the sulphation, where does the sulphur come from? If it is coming out of the acid and you bubble it off as H2S or H2SO4 vapour or  whatever, are you not going to weaken the acid over time, and consequently the battery?

So, one shouldn't need to equalize-charge sealed AGM batteries then?

 

I'm using VRLA with AGM tech batteries and the datasheet specifies "Equalization and Cycle Service Charging Voltage", so yes you probably would do it occasionally.  Just don't do it with Gel-type batteries, as per above.

I'm using VRLA with AGM tech batteries and the datasheet specifies "Equalization and Cycle Service Charging Voltage", so yes you probably would do it occasionally.  Just don't do it with Gel-type batteries, as per above.

I currently have Sprinter p6v1700 6V (http://www.exide.com/Media/files/Downloads/IndustEuro/Sprinter_P_XP_en.pdf) AGM VLRA batteries but can't find any decent info on them, so I don't know if / when they should be equalize charged. 

 

Any tips?

I currently have Sprinter p6v1700 6V (http://www.exide.com/Media/files/Downloads/IndustEuro/Sprinter_P_XP_en.pdf) AGM VLRA batteries but can't find any decent info on them, so I don't know if / when they should be equalize charged. 

 

Any tips?

 

If you have a charger capable of performing and equalize charge, then maybe do it once a year. 

 It is probably better to build yourself some Zener regulators. Follow this YouTube thread that was made (for me!) on how to make Zeners and why.

 

Hi Chris, do you mind sharing the link please. I would also like to know more about that.

Hi Chris, do you mind sharing the link please. I would also like to know more about that.

I am an idiot - comes from trying to do 3 things at the same time (one of them being drinking my first cup of coffee  :) )

https://www.youtube.com/watch?v=yoUxq_BseOo. Work has been slow and EBE has made a couple of videos in response to discussion on one of his other YouTube posts.

I am an idiot - comes from trying to do 3 things at the same time (one of them being drinking my first cup of coffee  :) )

https://www.youtube.com/watch?v=yoUxq_BseOo. Work has been slow and EBE has made a couple of videos in response to discussion on one of his other YouTube posts.

 

I like these! :)  The reasoning behind it (http://www.evdl.org/pages/hartregs.html) makes sense.

That's quite an interesting concepts. Have you built some yourself?

Where do we get "Thermally conductive epoxy filler"?

 

I want to. The components are definitely not available in Graaff-Reinet. Received my Victon battery monitor today so will install that and then start looking at Zeners. I think you could add Zinc oxide to ordinary silicone.gel I plan to mount my Zeners on old CPU heat sinks outside my battery box.

Having installed the Victron battery monitor today and done midpoint measurements, I discover there is a variation in my battery bank that I have recently installed (26.7V (right 2) versus 27.6V (left 2)). So where can I order the components to make Zener regulators from?

Having installed the Victron battery monitor today and done midpoint measurements, I discover there is a variation in my battery bank that I have recently installed (26.7V (right 2) versus 27.6V (left 2)). So where can I order the components to make Zener regulators from?

 

Hi Chris

 

I don't know if there are any suppliers close to you, but the other option would be to buy it online.  You can try:

http://www.communica.co.za

6.2V 5W zener: http://www.communica.co.za/Catalog/Details/P3817820928

6.8V 5W zener: http://www.communica.co.za/Catalog/Details/P1448942910

3.9ohm 2W resistor: http://www.communica.co.za/Catalog/Details/P2189489296

56ohm 1/8W resistor: http://www.communica.co.za/Catalog/Details/P0260544498

3mm Green LED IF=25mA: http://www.communica.co.za/Catalog/Details/P0746445897

 

or

http://www.mantech.co.za

6.2V 5W zener: http://www.mantech.co.za/ProductInfo.aspx?Item=14M0720

6.8V 5W zener: http://www.mantech.co.za/ProductInfo.aspx?Item=72M0777

3.9ohm 2W resistor: http://www.mantech.co.za/ProductInfo.aspx?Item=72M4411

56ohm 1/8W resistor: http://www.mantech.co.za/ProductInfo.aspx?Item=14MB132

3mm Green LED IF=30mA: http://www.mantech.co.za/ProductInfo.aspx?Item=72M0979

 

or 

http://za.rs-online.com/web/ 

6.2V 5W zener: http://za.rs-online.com/web/p/zener-diodes/0463795/

6.8V 5W zener: http://za.rs-online.com/web/p/zener-diodes/0463818/

3.9ohm 2W resistor: http://za.rs-online.com/web/p/through-hole-fixed-resistors/2141620/

56ohm 0.4W resistor: http://za.rs-online.com/web/p/through-hole-fixed-resistors/0151195/

3mm Green LED IF=30mA: http://za.rs-online.com/web/p/visible-leds/8154394/

  • 2 weeks later...

Hmm, I won't equalise VRLA batteries, unless you have the manufacturer's data sheet that gives the voltage. Narada batteries I know doesn't like equalisation, but most VRLA batteries recombines the hydrogen released, so that the battery stays sealed. This is also why you can use VRLA batteries in an enclosed space without having to create vents and ways to get rid of the hydrogen. Equalising them runs 15v through the battery, much higher than the recommended charge rate of 13.8 - 14.1 for most VRLA batteries. 

 

This causes hydrogen buildup, since the recombining process cannot keep up. It also shortens the life of your batteries, as it causes them to dry out. It can cause the sealed batteries to burst / crack / explode. Only equalise flooded lead acid batteries. 

  • Author

I was using 3/8th of my battery bank yesterday to crank start my generator, which was putting it in an unequalised/unbalanced state. Next thing I notice is my Microcare charge controller had detected that and was busy equalising the batteries. Smart unit! 

I was using 3/8th of my battery bank yesterday to crank start my generator, which was putting it in an unequalised/unbalanced state. Next thing I notice is my Microcare charge controller had detected that and was busy equalising the batteries. Smart unit! 

How does it sense this?

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