Equalize your deep cycle batteries

Have you noticed your deep cycle batteries need recharging more often? Before replacing them, try equalizing them. If a deep cycle battery isn't discharged and charged very often, lead sulphate crystals can form on the plates, effectively reducing the plate area and thereby reducing the effective capacity of the battery. Another thing that can happen is that the specific gravity of the electrolyte stratifies i.e. its value varies at different heights within a battery cell.The sulphate crystals can be removed and the specific gravity de-stratified by a process known as equalization.

If you have a hard-wired inverter/charger it's probable that it has a built-in equalization feature, but you'll need to initialize it manually through the control panel.

The equalization process, which should only be done on flooded wet cell batteries, involves applying a controlled over-voltage (14-17V) to the batteries while limiting the current. The batteries should be fully charged before initiating the equalization process. To help prevent the loss of battery capacity, you should perform equalization periodically. The "correct" interval is a matter of debate, but can be anywhere between one and six times a year.

One caveat - disconnect any sensitive DC loads before intiating the equalization process because they may be damaged by the over-voltage.

Check your battery manufacturer's instructions and your inverter/charger manufacturer's instructions for the correct procedure in your situation.

I believe there is an aftermarket device that can be connected across the batteries that delivers a periodic spike of voltage to the batteries, thereby breaking down the continuous build up of sulfite within the cells...the reason for equalization.

Is this product still available?? I recall seeing it sold by Cummins dealers at FMCA rallies as an accessory.



Some additional bits and pieces from my factoid library on equalization:

Charge at 16 VDC while amperage is limited to max 5% of amp/hr cpacity of battery.

Only lead acid batteries can be equalized...not maintenence free batts.

Should be done when low or wide ranging specific gravities (+- .015 are detected after fully charging a battery

Temp should not exceed 100 deg F or excessive gassing or ejection of electrolyte could indicate a short circuit.

Inspect breather holes to ensure no blockage exists

In addition, Trojan Battery has some worthwhile maintenance tips HERE.? Of special interest might be the "battery watering diagram" at the bottom of their list on the right of the page.

Is that aftermarket device automatic Steve? If so, how do you prevent the voltage spikes from damaging sensitive equipment?

Tom,

There are aftermarket devices available (around $70) or you can build your own for about $5. Does it work? I'm highly sceptical. Passing a high voltage pulse to correct electrolytic capacitor shorts and tv picture tube shorts has been used for many years with the caveat that you may ruin them completely by trying this last ditch effort. Not a problem with storage batteries tho'; they can handle the meager pulse these units put out. To see if it really works would require a truly dead (by sulfation) battery, and see if it would bring it back to a state where it could accept and hold a charge, but most of us would have replaced them a long, long time before they got that bad.

Proper fluid level and charging are the keys to long life, as is periodic equalization - when required and only to the point where s.g. levels have been restored. These devices would do nothing to prevent/cure stratification which requires the electrolyte be 'boiled' (read:bubbling), which equalization does.

The high voltage pulses would PROBABLY not cause any problems because the virtual short of the battery would absorb almost all of it - unless the battery is completely dead; but then you wouldn't be powering anything with it anyway. ;D

Tom said:

Is that aftermarket device automatic Steve? If so, how do you prevent the voltage spikes from damaging sensitive equipment?

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Yes, its biggest market was last time I checked with the railroads who were installing them across thier fleet. I haven't looked at them for quite a while and can't remember name. I may still have the advertising folder in my file at motorhome. I will look for it tomorrow when I go ovver to load some clothes. Cummins Distributors did sell it for awhile but it was not something Cummins per se had any involvement in it.

Karl

I'll let you into a secret ...... I don't remember to equalize until the efficiency of the batteries has fallen off enough to be noticeable i.e. they don't hold their charge very long. This happened on Friday night when the voltage of my golf cart batteries dropped low enough to cause the inverter to shut off in the middle of the night. Saturday I ran the generator all day to recharge and then equalize the batteries. Bingo, they came back to normal capacity.

Thanks Leo.

Tom,

That's pretty much the way you tell when to equalize. Battery seems to run down quicker without much change in usage habits. Also, s.g. when supposedly fully charged will not be correct.

I've been doing it the same way on this set of batteries for the last 5 years  ;D

BTW how do you know if the SG has stratified? I can't get SG readings at different depths in my batteries 'cos the plates are in the way.

Tom,

Good point. You don't know - another reason to equalize. I suppose you could suck up some electrolyte in the hydrometer and squirt it back towards the side of the battery case where there is space between it and the plates several times to mix things up, but I doubt that would be adequate. A low reading after full charge (less than 1.277 (adjusted to 80 degrees F) indicates a cell's health starting to decline and/or sulfation and/or stratification.

Alll seriousness aside, a sure way to get a good reading is to take each battery out, turn it upside down a few times, shake well to mix the electrolyte, and then take your readings!? Builds good upper arm strength and possible hernias ?Ladies, don't try this at home ;D

Another argument for AGM batteries. ?Most people won't, or can't, take the trouble and effort to properly monitor their battery condition and perform the needed equalization procedure to keep their batteries in good shape. ?I know I didn't so I switched to AGMs when my flooded cell batteries wore out, partly through neglect.

I'm skeptical of the need for equalization as a routine procedure.  Sulfating does not seem to occur in every battery, though I have never seen a description of the conditions that produce it.  And stratification probably occurs mostly in batteries that are little used (in the electrical sense) or in rigs which are not driven around much, i.e. shaken up.  I suppose it does no harm to do a routine equalization, but it is a nuisance to do properly and a waste of time if not done properly.  I'm one of those who doesn't bother with equalizing and seldom have battery problems. I got  6 years on my last set of golf carts and they were still going strong when we traded the rig. Got 3 years on the current set.

There is an add-on charging device called The Battery Minder that supposedly prevents/cures sulfating. It's available for $39.95. See http://www.batteryweb.com/batteryminder.cfm

Gary,

Sulfation occurs mostly under two conditions: when a battery is left for extended periods in a disharged condition or is frequently discharged below the 60% level, and when the s.g. is too high due to low water level or someone adding acid to the cells, which should never be done. The "pulse" devices we talked about earlier are left connected across the battery and use the battery power for operation. The device you mention needs 120V power to operate.

Ned

I've been promising myself I'll buy AGMs when these golf carts eventually give up. They're in the old tub and there's 10 of them. I also replaced 4 8Ds with AGMs and they've essentially been maintenance-free ever since.

I've read contradicting advice on whether AGMs should or should not be equalized. Intuitively I'd think not, because  the elctrolyte is absorbed in the mat and it's not possible to get the boiling/bubbling action you get when equalizing flooded batteries. Presumably, the SG doesn't stratify.

Meanwhile, each time I add water to my flooded golf cart batteries, aren't I stratifying the SG? Why is that not harmful i.e. why doesn't it cause the batteries to lose their charge quicker? I've been adding water to batteries for many years, but have never correlated that action with loss of battery capacity

Tom,

Normal driving will cause the water to mix with the existing electrolyte. That's one of the reasons battery mfg's. tell you not to overfill them. Also normal charging will cause some bubbling which takes care of the problem. AGM's should NOT be equalized and will only cause excessive heat within them. Because the mat holds the minimum amount of electrolyte distributed evenly, sulfation will not (should not) occur.

AGM batteries should never be equalized.  As they are sealed, there is no way to relieve the pressure that will build up.  Also, the design of the AGM battery precludes the conditions that cause the need for flooded cells to be equalized, as Karl said.

AGM batteries are truly maintenance free.  Just don't overly discharge them and don't overcharge them.  I keep my maximum discharge to no more than 50% of capacity and have my charger set to not overcharge.  For maximum life, a 3 stage charger should be used with AGMs and the charger should have an AGM profile setting.  You can use a flooded cell profile but there will be a slight overcharge in that case.  My charger has an ambient temperature setting and setting that 10F higher than ambient corrects the charge profile to prevent the overcharge.

Agreed Ned. The reason I asked the question is because of incorrect stuff like this AGM Battery Equalization Procedure that's out there.

Tom said:

Agreed Ned. The reason I asked the question is because of incorrect stuff like this AGM Battery Equalization Procedure that's out there.

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Tom

I have AGM batteries and have never equalized them. That said, the most well known distributor of AGM batteries, Lifeline, does offer an equalizing procedure, as you linked, and does recommend equalizing when appropriate.

Bernie

Although that article references a Lifeline equalization procedure, I couldn't find it on the Lifeline web site.