Equalizing your battery bank.

NOTE: DO NOT EQUALIZE GEL OR AGM BATTERIES! EVER! AS IN NEVER EVER.

The process of equalizing your battery or battery bank can be a daunting and frightening effort if you've never done it before. Simply put, you are going to shove so much voltage into your battery bank that you will be very nervous the first few times you do it. When you see the voltages required you will quake, your feet will sweat and your computer may crash just from reading about it. 

But, no worries, done right it will eliminate the need for a desulfator, extend the life of the bank and keep everything up to snuff. What you are going to do is use the charging process in a controlled over charge to cause the sulfate crystals to break free from the lead plates instead of vibrating them with a desulfator. The equalizing process takes 3 to 5 hours, a equalizer takes up to 3 weeks. Also, what I've found (see the table of voltages below) is that it may take 2 or 3 equalizing charges over a period of 12 to 24 hours (with a battery rest period of several hours between equalizing) to break the sulfates loose from the lead plates.

What equalizing does is well, equalize the cells in the batteries. It is a controlled overcharging of the battery bank and is easier to do on an entire battery bank (or part of one). When to do it varies greatly depending on how you use your bank. If you discharge your bank every night (smaller banks or heavy loads) then you'll want to do it once a week. If you use the bank occasionally, then once a month to even six months is okay.

Equalization is basically a controlled overcharge that extends your battery life by knocking deposits off the lead plates via a boiling process. Keeping any eye on the electrolyte is very important in this process. Do NOT fill the cells with distilled water before starting. The process generates heat and causes the electrolyte to expand. Fill AFTER charging only!

Here's a handy chart. Just use a piece of paper and write down all your own charging figures. As you can see, the capacity increased with each charge cycle. I did not put a load on the batteries, only let them rest for 12 hours between chargings.

It's usually easiest to do this with a generator or a fully manual battery charger (I prefer Schumacher chargers - I have one that I bought in 1975!). Charge the batteries using your normal charging procedure, via solar panels, wind generator or a fuel powered generator. 

Once it's at a indicated full charge, remove all loads, chargers, disconnect any other devices. Keep charging for 2 or 3 hours longer. Monitor the process,  take specific gravity readings 30 minutes apart and continue the process until the readings stop increasing. A sensitive hydrometer is recommended for this part.

An equalizing charge is an overcharge cycle that performs several actions within the battery bank. During equalization, the voltage is raised to approximately
2.7 volts per cell, or about 16.2 volts for a 12-volt battery! 16.2 volts is a lot!

This is the part about doing this on a battery bank instead of on a single battery. You want the amperage to be 5% or less of the total bank amp hour size.

 In other words, a 200-amp hour battery bank should be charged at no more than 10 amps of current. The purpose of limiting the amperage is to prevent overheating. 

The equalize cycle is timed to be between 4 and 8 hours depending on the features
of the charging source, but the cycle can always be terminated early if necessary. 

The battery manufacturer's recommendations for equalization time should be followed.

This elevated voltage results in a vigorous charging action to take place within each cell that does several things to the battery bank. 

First, much of the residual sulfate is forced to re-combine with the
electrolyte in the form of sulfuric acid. 

Crystallized sulfate that will not recombine is broken loose
from the plates and falls harmlessly to the bottom of the battery. Remember that part in the "Revive a dead battery" page about washing out the battery? Well, this is where that comes in. Deep cycle batteries have additional space beneath the plates intended to collect this material. This cleans the plates exposing fresh lead to the electrolyte and restores battery capacity.

After 20 to 30 of these equalizing charges, there will be a lot of crap in the bottom of the batteries. 

The vigorous bubbling action that occurs during equalization stirs up the electrolyte and restores it to a consistent mixture of acid and water. The equalizing process also causes all cells in a battery to reach their maximum idle potential of 2.1 volts.

It is a good practice to equalize batteries after every 10 or 12 deep discharge and re-charge cycles. For batteries in constant discharge and recharge usage, this would mean about every two weeks.

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