Battery equalization

[Rogerh]

Should I remove battery vent caps while equalizing?

 

[kchace]

No

 

[Rogerh]

Hope the answer is yes. Just started equalizing this way.

 

[kchace]

All caps on Flooded Lead Acid batteries are vented - no reason to take them off and plenty of reason to leave them on. They act as a safety feature in case there is a spark so that (hopefully) a flame wont travel into the battery proper. Also keep acid from splashing out during bubbling, also keep dirt etc from falling in.

No reason you can't put the caps back on without interrupting the charge.

Ken

 

[kev_rm]

won't matter. careful not to make a bomb either way :O

 

[Lou_tribal]

May I ask what is battery equalization?

 

[kev_rm]

May I ask what is battery equalization?

https://www.pacificpowerbatteries.com/aboutbatts/Deep Cycle Battery FAQ/dcfaq6.html

and

Interstate Batteries FAQ :: How do I charge certain deep cycle 6-volt, 8-volt and 12-volt batteries?

 

[Lou_tribal]

Oh ok I see the equalization phase during battery charging.
I thought equalizing something between 2 baterries, what the heck

Thank you kev_rm!

 

[High Wire]

Caps or no caps, if the hydrogen gas ignites the whole battery top comes off. Don't ask me how I know.

 

[C lectric]

And if you are really lucky the side of the case splits.
DAMHIK

 

[Ken E.]

Please excuse the slight swerve off-topic, but how often should you equalize? I know it's a function of how many charge/discharge cycles. My Magnum 3.1 kw inverter/charger documentation is vague on the issue. When we are on the hook alot in Alaska with usually two charge/discharge cycles a day, I equalize about once a month. I can see the increased house bank voltage in the morning as a result. Interested in what C lectric and others might have to say on this.

 

[High Wire]

Per the Interstate link above: Equalize every 4 to 8 weeks or when the difference in specific gravity readings vary by 0.020 points or more and always after a normal charge.
The spec sheet for your batteries should specify.

 

[ranger58sb]

Please excuse the slight swerve off-topic, but how often should you equalize? I know it's a function of how many charge/discharge cycles. My Magnum 3.1 kw inverter/charger documentation is vague on the issue.

Reading suggests it depend on the battery maker's recommendations, not the charger.

Some makers don't even want you to equalize, ever (most AGMs, I think, but excepting Lifeline).

-Chris

 

[fryedaze]

I often wonder about the effect on my batteries from having three charge sources. I have a three stage battery charger, two 120 amp alternators with Sterling regulators and 450 watts solar with a Morningstar MPPT controller. Here is an example of the charge characteristics of the boat.
Its at the dock fully charged and floating at 13.5v on the charger. I start out a zero dark thirty and the alts and Sterling regulators fire up and drive to 14.5v absorbtion. After a while the Sterling drops it back down to float at 13.5v. I go back to the dock and plug in to shore power and the battery charger drives back to 14.5v absorbtion and then back to 13.5 float. Now sitting at the dock the solar panels and MPPT controller drive the voltage back up to 14.5 absorbtion voltage every morning when the sun is out. In the winter I have seen 15.1v during absorbtion due to the temperature compensation of the controller.
I wonder if driving voltage to absorbtion voltage multiple time impacts the batteries. So far it appears to be OK. I only water once a month and it only requires about 1.5 pints for 8 6v Crown batts. The SGs remain balanced but I only check about every 3 months. Batteries are 32 months old have seen 1200 hrs of engine time. I have only equalized once and think I should add equalizing to our charging scheme. I am hoping to be one of the lucky ones that gets more than 5 or 6 years out of a bank.

 

[sunchaser]

With so many boat chores to do, equalization is so far down my list that it doesn't seem relevant. But, if I were a full time cruiser and were on the boat all the time it would maybe be different. They are so cheap though --

My first set of T105 house batteries went an easy 8 years without equalization as is, but seem to have a good charging and wiring setup. Fingers crossed.

 

[kchace]

Per the Interstate link above: Equalize every 4 to 8 weeks or when the difference in specific gravity readings vary by 0.020 points or more and always after a normal charge.
The spec sheet for your batteries should specify.

This is about the same as Trojan's recommendation.

Ken

 

[foggysail]

Love my East Penns, could not afford T105s. My solar regulator automatically puts my Penns into equalization frequently, could even be daily. I do check all my batteries at least once at the beginning of the season with my hydrometer. I have a total of 7 wet cells and only need to add distilled water once a season and not much at that.

Two 12v batteries I have connected for 24v are entering their tenth year.

 

[BruceK]

We are discussing equalization, without a clear statement of why it is done. As I understand it, it is intended to pulsate and shake any sulphation off the plates, back into solution. In other words, it is not a process primarily to make all cells equal, though it may well have that effect. And it can be physically hard on a battery.
I had my solar chargers set to equalize automatically monthly. I sure need to top up after. Then it struck me that if equalization is aimed at sulphation, and sulphation occurs in (?chronically) undercharged batteries, and my solar keeps my batteries fully charged, usually in float, there should be no appreciable sulphation and no real need to equalize.So I deactivated equalization in the regulator program. The batteries seem fine after nearly 20 months.
I`d like to hear other views. I`m not into hammering my batteries once a month if I don`t have to.

 

[psneeld]

Equalizing Charge For Stationary Batteries – Battery University

BU-404: What is Equalizing Charge?

Know how to apply an equalize charge and not damage the battery.

Stationary batteries are almost exclusively lead acid and some maintenance is required, one of which is equalizing charge. Applying a periodic equalizing charge brings all cells to similar levels by increasing the voltage to 2.50V/cell, or 10 percent higher than the recommended charge voltage.*

An equalizing charge is nothing more than a deliberate overcharge to remove sulfate crystals that build up on the plates over time. Left unchecked,*sulfation*can reduce the overall capacity of the battery and render the battery unserviceable in extreme cases. An equalizing charge also reverses*acid stratification, a condition where acid concentration is greater at the bottom of the battery than at the top.

Experts recommend equalizing services once a month to once or twice a year. A better method is to apply a fully saturated charge and then compare the*specific gravity*readings (SG) on the individual cells of a flooded lead acid battery with a hydrometer. Only apply equalization if the SG difference between the cells is 0.030.

During equalizing charge, check the changes in the SG reading every hour and disconnect the charge when the gravity no longer rises. This is the time when no further improvement is possible and a continued charge would have a negative effect on the battery.

The battery must be kept cool and under close observation for unusual heat rise and excessive venting. Some venting is normal and the hydrogen emitted is highly flammable. The battery room must have good ventilation as the hydrogen gas becomes explosive at a concentration of 4 percent.

Equalizing VRLA and other sealed batteries involves guesswork. Observing the differences in cell voltage does not give a conclusive solution and good judgment plays a pivotal role when estimating the frequency and duration of the service. Some manufacturers recommend monthly equalizations for 2–16 hours. Most VRLAs vent at 34kPa (5psi), and repeated venting leads to the depletion of the electrolyte, which can lead to a dry-out condition.

Not all chargers feature equalizing charge. If not available, the service should be performed with a dedicated device.

Last updated 2016-02-23

 

[sdowney717]

Sulfation and How to Prevent it - Battery University

Interesting battery discussions are here.

I was thinking would using an old style battery charger with the heavy transformer work to equalize cells? They tend to overvolt as the batteries are charged up, seen some go to 16 vdc.

Mine can get to mid 15's from what I recall.

Most of my batteries fail with shorted cells.

I did a battery flush - rinse which managed to remove a short, but the battery still had no power though readin 13 vdc. During the rinse, a lot of rust came out of the battery, which means to me a lot of destroyed plates.

I have never been able to bring back any dead or dieing battery.

 

[foggysail]

Yes, of course it should have been mentioned earlier what the purpose of equalization is, I thought it was general knowledge. Now as to watching for heating during equalization, I find that is not as important as checking for heat during charging at very high current.

Because equalization can only occur with fully charged batteries, their current acceptance is low. Mine are usually in the 5-10 ampere range for two pairs of East Penn golf carts connected series and paralleled. Maybe one could equalize a low charged battery but the currents will be huge because the battery's internal volt and resistance in this condition is low. The batteries will get hot! The charging current from a stiff voltage source is

I(charge) = (V(source) - V(battery))/(battery's internal resistance)

As the battery's internal voltage increases, the current will decrease with other things being equal. My equation is simplified and certainly overlooks wiring resistance and the internal resistance of the charging source other than to say the source is 'stiff'. I did not show any chemistry impacts.

 

[foggysail]

Sulfation and How to Prevent it - Battery University

Interesting battery discussions are here.


I have never been able to bring back any dead or dieing battery.

I have not had any good results either. Really better off preventing failures than trying to rejuvenate them. I have never had a shorted cell, how old were your batteries for that to happen?

 

[kev_rm]

I often wonder about the effect on my batteries from having three charge sources. I have a three stage battery charger, two 120 amp alternators with Sterling regulators and 450 watts solar with a Morningstar MPPT controller. Here is an example of the charge characteristics of the boat.
Its at the dock fully charged and floating at 13.5v on the charger. I start out a zero dark thirty and the alts and Sterling regulators fire up and drive to 14.5v absorbtion. After a while the Sterling drops it back down to float at 13.5v. I go back to the dock and plug in to shore power and the battery charger drives back to 14.5v absorbtion and then back to 13.5 float. Now sitting at the dock the solar panels and MPPT controller drive the voltage back up to 14.5 absorbtion voltage every morning when the sun is out. In the winter I have seen 15.1v during absorbtion due to the temperature compensation of the controller.
I wonder if driving voltage to absorbtion voltage multiple time impacts the batteries. So far it appears to be OK. I only water once a month and it only requires about 1.5 pints for 8 6v Crown batts. The SGs remain balanced but I only check about every 3 months. Batteries are 32 months old have seen 1200 hrs of engine time. I have only equalized once and think I should add equalizing to our charging scheme. I am hoping to be one of the lucky ones that gets more than 5 or 6 years out of a bank.

I don't think pushing a charge on top is ideal... What I try to do is let them discharge at least a bit by disconnecting early and let the fridge and inverter draw them down a bit. Don't know technically if it helps. Some solar charges can also not be smart about detecting a full charge too.

 

[sdowney717]

I have not had any good results either. Really better off preventing failures than trying to rejuvenate them. I have never had a shorted cell, how old were your batteries for that to happen?

More than 5 years old, and on up to 10 years is the most I can get.

Typically, the shorted batteries I notice they get warmer, and also acid shows up on the outside. These shorts I eventually get are just small drains, and charger is working harder. They are not dramatic massive internal arcing failures.

 

[foggysail]

More than 5 years old, and on up to 10 years is the most I can get.

Typically, the shorted batteries I notice they get warmer, and also acid shows up on the outside. These shorts I eventually get are just small drains, and charger is working harder. They are not dramatic massive internal arcing failures.

Thanks, I will see how my 8+ year olds (2 for 24v) are doing when I launch this spring. I really do not want a surprise with these two batteries because they power my windlass plus provide some ac for a tv.....via an inverter of course.

 

[BruceK]

Equalizing Charge For Stationary Batteries – Battery University....

Stationary batteries are almost exclusively lead acid and some maintenance is required, one of which is equalizing charge. Applying a periodic equalizing charge brings all cells to similar levels by increasing the voltage to 2.50V/cell, or 10 percent higher than the recommended charge voltage.*...

An equalizing charge is nothing more than a deliberate overcharge to remove sulfate crystals that build up on the plates over time. Left unchecked,*sulfation*can reduce the overall capacity of the battery and render the battery unserviceable in extreme cases. An equalizing charge also reverses*acid stratification, a condition where acid concentration is greater at the bottom of the battery than at the top.

Experts recommend equalizing services once a month to once or twice a year. A better method is to apply a fully saturated charge and then compare the*specific gravity*readings (SG) on the individual cells of a flooded lead acid battery with a hydrometer. Only apply equalization if the SG difference between the cells is 0.030.

During equalizing charge, check the changes in the SG reading every hour and disconnect the charge when the gravity no longer rises. This is the time when no further improvement is possible and a continued charge would have a negative effect on the battery.

The battery must be kept cool and under close observation for unusual heat rise and excessive venting...

Last updated 2016-02-23

The article is a good find.
How many people keep their batteries under constant surveillance during equalization? Those doing it manually may, but many equalizations are regulator programmed with the owner likely absent.
How can SG be regularly checked during the process? Stop the process, wait, test, restart, and repeat? It doesn`t sound practical.
A high charge is applied, usually with pulsation, to force or vibrate sulfur off the plates back into solution, and to mix the solution. That takes some force, I`m not sure batteries were built for those forces.
Under my previous regime of automatic monthly equalization I began to see bits of separator floating loose in the batteries. They were decent LA Marine batts. I suspect,with no certainty, equalization had a hand in their demise. I`m not doing it with the replacements, wondering how it will turn out, an informal test I suppose, in solar maintained batts.
I`m not saying equalization is bad, but it needs to be understood as a relatively violent process batteries were not necessarily designed for, and some discretion exercised.
Is anyone aware of control tests, identical batteries in identical use, one equalized monthly, one not, over an extended period ? We have electrical guys on TF, what do you say?

 

[Ken E.]

I wondered what Interstate Batteries might have to say on equalizing. At their website in the FAQ section, they say you should equalize every 4 -8 weeks, with the caps on. No warnings or disclaimers of any adverse effects of equalizing and it looked like a normal maintenance procedure.

While I have no specific gravity or other technical data to provide, my experiences with equalizing have been beneficial, doing it about once a month during the summer when we're on the hook most days. I have a house battery bank of 8 golf cart batteries for 1000 AH @12 volts. All are 2 years old. Aside from hotel loads, I have two refers and freezer, all 120 volt ac, that are the big power consumers. No air conditioning. After equalizing, I typically see around 12.5 volts in the morning at anchor, 12 hours since the last genset battery charge. After say 4 weeks, voltage in the morning is down to around 12.2 volts. At the next marina stop while on shorepower, equalizing again restores morning voltage to 12.5. And so it goes. Hence, I'm a fan of equalizing and don't see a downside in doing it. There certainly would be a downside to letting gunk continue to build up on the battery plates and not burning it off by equalizing. IMO.

 

[psneeld]

I don't think there is any "force" applied or vibration to the batteries...just pulsing voltage.

My batteries are vibration free and quiet during the equalization with all the battery chargers I have owned lately.

Now at the microscopic level...maybe bubble formation and explosion causes tiny vibrations like cavitation erosion in engines...but it is not discernible to me at the macro level.

The batteries in my boat live a great life compared to the ones in my truck when it comes to violent motion, vibration, etc...

 

[foggysail]

The article is a good find.
How many people keep their batteries under constant surveillance during equalization? Those doing it manually may, but many equalizations are regulator programmed with the owner likely absent.
How can SG be regularly checked during the process? Stop the process, wait, test, restart, and repeat? It doesn`t sound practical.
A high charge is applied, usually with pulsation, to force or vibrate sulfur off the plates back into solution, and to mix the solution. That takes some force, I`m not sure batteries were built for those forces.
Under my previous regime of automatic monthly equalization I began to see bits of separator floating loose in the batteries. They were decent LA Marine batts. I suspect,with no certainty, equalization had a hand in their demise. I`m not doing it with the replacements, wondering how it will turn out, an informal test I suppose, in solar maintained batts.
I`m not saying equalization is bad, but it needs to be understood as a relatively violent process batteries were not necessarily designed for, and some discretion exercised.
Is anyone aware of control tests, identical batteries in identical use, one equalized monthly, one not, over an extended period ? We have electrical guys on TF, what do you say?

Bruce-- I would not be concerned about batteries under equalization. They will not accept much current after they have reached full charge therefore....should not have a heating problem. I never take notice when mine are being equalized via solar.