Lead-acid battery equalization

[phorvati]

Has anyone done the equalization of their lead acid batteries. I have the Xantrex XAR regulator which has an equalization program. I set mine to 15.8V and various times like 2.8h or 2.1h. I am a bit puzzled with the output. According to Nigel Calder you should keep the current down to < 5% of the AH rating so 5 amps for each 100AH. This way you don't cook the batteries. During equalization, voltage never gets to 15.8, its more like 15.4 but only after I increase the RPMs to 1000, and then the current is more like 45amps, too much for my bank. The battery seems a bit hot, its bubling, but the battery temp sensing switch never shuts off the regulator. So i can only assume that the batteries are not 125F yet. Anyway, specific gravity in my two oldest batteries is not moving beyond 1.230. At idle RPMs the voltage is 15.2 and current 25A. Should I force the voltage to beyond 15.2 and even beyond 15.4 by increasing the RPMS to 1500 and then have higher amps flowing in. The risk is overheating but would that make the specific gravity get higher to where it should be like 1.265? All my batteries are torjans SCS225 and the two older ones have uniform 1.230 reading across. The two newer ones have 1.250 reading, and bubble less. I equalize them all at the same time.
Thanks,
Petar

[Jon D]

I spent the summer working on getting all the cells in my batteries up to par. In the end a two hour equalization is not long enough. What I would suggest trying first is try a 4-6 hour equalization at the 15.4V. So after the unit resets itself after a 2 hr cycle start another cycle. Do not depend on the unit to shut itself off to prevent an overtemp scenario. I would pick up an infrared thermometer so you can accurately monitor temp. My batteries took several 4-6 hr equalizations over 2 months to get the cells all to 1.26 or so.

[Fishspearit]

Over time the lead sulphate ,PbSO4, will break off of the plates of the discharged battery falling to the bottom. This is what often shorts out the plates of the battery ending it's life. The other problem with it is that it can no longer be turned back into Sulpheric acid, H2SO4, once it has broken off which is why the older batteries won't reach as high of a specific gravity. One of the biggest causes of the lead sulphate active material breaking off of the plates is by applying too high of a current to a discharged battery and by too much bubbling/gassing during the equalization period. Hence the need for low current while raising the voltage above 15V. You want some bubbling going on, but not too much. I would recommend keeping the current down low and just realizing that your older batteries are going to drag down your good batteries while charging and discharging.

[Rick]

First in this discussion please refer to the article in Electrical: Batteries etc. posted on 05/01/05 regarding "How Fast You Can Relaibly Charge Batteries" in order to separate fact from "rumor" and so-called "rules of thumb".

Once a battery has been charged using a proper regimen (which requires reaching at least a minimum acceptance voltage for a suffucient time) AND allowed to rest for 24 hours on a proper float voltage THEN one can equalize the battery. So far the discussion in this thread has not indicated just how proper equalization is performed.

Equalization refers to the method of bringing a set of series cells into convergence with respect to cell-to-cell specific gravity. Because cell voltage is directly related to specific gravity one could also refer to equalizing the cell-to-cell voltages.

Flooded-cell lead-acid batteries may never have had their fluids "matched" from the beginning and, therfore, the cell-to-cell voltages may never become equal. For example, if one cell was low in fluid and you later fill it up to a reference mark with water then that cell will not have the same specific gravity when "full" as the other cells if they were full in the beginning.

An equalization cycle begins with applying a constant current equall to 2 to 7% of the Amp-hour rating number until the voltage reaches 2.7 to 2.8 Volts per cell. Should any cell begin to gas excessivly then the process is terminated which is why equalization is not an "automatic" process...it must be observed manually. Different battery construction dictates whether or not to use a 2% rating current or a 7% or something in between. The process may take up to 16 hours or more, sometimes less. Obviously this process does not lend itself to the use of solar or engine power and is most often relegated to the shop where a constant current source may be available (do you have such a supply, I doubt it!).

One reason that those of you who have read my contributions regarding battery charging "know" me to be such a proponent of attempting to follow "Amp-hour law" charging is that when using such a regimen, on a cycle-by-cycle charge/discharge basis, the necessity for having to apply a true equalization cycle becomes minimal over time, if at all.

By using elevated acceptance voltages with the use of so-called three-step chargers that can be varied a reasonable approximation to the Amp-hour-law charging regimen can be obtained. In this case acceptance voltages around 14.7 V will be applied (at temperatures near 70 deg. F).

It is not the applied voltage that one needs to be concerned about, it is the applied current that EXCEEDS the number of Amp-hours "missing" applied for an excessive time (so as to excessively gas or cause an excessive temperature rise) that is important. Understanding the limits of the Amp-hour-law explains just how important it is to have a "real" battery monitor capable of telling you how many Amp-hours have been removed or added to your battery (with an underlying measurement of true energy:AmpsXVoltsXtime).

[CSY Man]

I equalized my house bank last month (4 Deka Golf Cart) with the Xantrex 40 Amp AC charger.
First I let them sit for a day, then used the equalization program on the charger while monitoring fluid level and battery temp.
The temp never got too high, but after the 6 hour cycle I read on the Battery Monitor that 63 more amps have been pumped into the bank during the equalization process.

Is this about normal, or any indication of anything at all?

(Hey Rick, don't tear into me for being ignorant, I am just a regular guy, not an electro-pro like yourself )

[Rick]

Yo CSY Man,
I cannot overemphasize that NO existing charger offers a true equalization protocol. Read again the process and compare with your charger specs and you will observe that what is called "compliance voltage" is no where near 17 Volts or more which is required to perform a nominal 12Volt lead-acid battery equalization protocol. So, therefore, what you have is a bastardized process that is neither "text book" nor necessarily even "good enough" to be considered a replacement. The Xantrex process, like most so-called "equalization" modes are designed to avoid litigation from inadvertent use where someone creates a dangerous situation that could happen with a proper compliance "end of process" voltage. Such dangers could be spewing out of acid into the surrounds that effectively could require abandonment of the spaces.

Pay attention to your battery monitor (again, let us discuss "Amp-hours" not "Amps" as you might do so that we are speaking in common terms). The number of Amp-hours delivered during the pseudo-equalization process applied by your Xantrex charger IS some indication of something yet it is not what one specifically lingers on when attempting to bring into convergence the various cell-to-cell voltages. One observes the cell-to-cell voltage variance (or specific gravity if you will) after the process is complete and the battery is left standing for 24 hours with no charge source or load. Sometimes as many as three cycles are required to complet the process with proper constant-current sources. Lucky if you arrive at the end with equalized cell voltages with your existing equipment if your battery exhibited a wide variance of cell-to-cell parameters before the attempt.

[Vasco]

Thanks Gord and Rick, thought it was too good to be true. Hope you're not going to tell me the STP I put in my 66 Mustang was a waste of money.

[GordMay]

Sorry Rick - anyone who buys “mouse milk” (a flavour of “snake oil”) gets an automatic “A” in Professor P.T. Barnum’s introductory class, titled, “There’s a sucker born every minute.”
The fact is aftermarket lube additives, such as STP & others, are totally useless, and in many cases actually detrimental to your engine.

Beginning about a decade ago, the Federal Trade Commission (FTC) mounted a long-term attack on false, misleading and unsubstantiated performance claims made by manufacturers of “Mouse Milk”, or Aftermarket Lube Additives (ALAs),

In 2000, Dura Lube settled and paid a 2 million dollar fine, and Motor Up settled, after agreeing not to make claims it could it could not scientifically support, and not to misrepresent tests, studies or data on its product’s performance.
In 1999, Prolong (Motor Up) settled without a fine, also agreeing not to make unsupported claims.
Earlier, in 1995, First Brands paid a $888,000 fine settle what the FTC said were misleading claims for STP Oil Treatment (for “Scientifically Treated Petroleum”).

Each of these companies continues to market “Mouse Milk” ALAs.

As far as I know, EVERY engine manufacturer discourages or prohibits the use of aftermarket additives.

For those:
- looking for simple solutions to complex problems
- - who prefer bumper-sticker slogans to boring facts
- and etc.
Let me introduce & offer:
Gord’s “Whiffle Dust”
Introductory Offer for CF Members Only $19.99 each.
“Whiffle Dust“ Makes you feel good about everything – As good as heroin, but cheaper.

[FrankZ]

Originally Posted by GordMay

For those:
- looking for simple solutions to complex problems
- - who prefer bumper-sticker slogans to boring facts
- and etc.
Let me introduce & offer:
Gord’s “Whiffle Dust”
Introductory Offer for CF Members Only $19.99 each.
“Whiffle Dust“ Makes you feel good about everything – As good as heroin, but cheaper.

After watching football today I will take some if you promise it really, really works.

[Celestialsailor]

I was wondering during all this discussion of equalization if one could not just hook up 1, 50 watt solar panel to the battery bank unregulated? Hence, higher voltage, lower amps.

[Rick]

Yes, a properly sized unregulated pv panel may be used to equalize a battery. Mostly alternative energy applications lend themselves to such a solution whereas a two-battery bank system is designed to provide long life energy.

The two-bank battery system works when the two banks are alternated. The fully charged bank is switched into the load and the discharged bank is then FULLY charged and left to stand for 24 hours and then either equalized using a dedicated pv panel for such a purpose, if needed, or then swithced into the load and the cycle is repeated.

Two bank battery systems do not, in general, make sense in small cruising boats because the second bank must be the same capacity, size and weight as a single bank system and, therefore, not practical AND few small cruising boats have the ability to completely recharge the alternating bank before allowing a 24 hour recover standing time.