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How often to equalize batteries (flooded lead-acid)


Q:

How often should batteries be equalized? I installed a few systems on a missionary compound in Haiti last year and we can initiate/schedule equalization of the batteries but have not done it just yet. All three systems are identical but the houses have different usage profiles, some loads have been modified since we left. They use big flooded lead-acid forklift batteries that the customer purchased. The customer has some one top off all of the batteries every month with distilled water. And all 3 systems are currently programmed a little bit differently. They are Outback systems that are connected to the ReOptics platform for monitoring and programming which is very beneficial to us being in the US! I can provide more detail about each (PV Capacity, Battery Bank Capacity etc.) but wondering if there is a simple rule of thumb to that they can follow.
1) Operates as a off-grid system. The owner has been running without using the grid for a little bit under a year now.2) Was operating as off-grid but they recently added more loads to the service and they cannot make it through the night using just the battery bank as we installed it. So I have programmed it power the loads using grid power for a few hours of the day to help maximize/maintain charging of the battery bank during the sunny hours.3) Uses grid power except from about 11pm-7am (when there is no grid power). So this system stays fully charged for a good portion of each week.

A:

Hi Nate,

The correct answer to your question about how often to equalize batteries is to ask the manufacturer.

What most people do is something in between 1x per month to never.

What equalization does is stir up the battery to prevent stratification (heavy stuff sinking to the bottom) and to get the lead sulfate crystals that have built up on the lead plates to break free.

Lead sulfate crystals will build up on plates when batteries are left for long periods of time without a full charge. If your batteries get topped off every day, they can last for a longer time without an equalization that a battery that is only getting to 80% charged all winter.

Since you have someone there adding water on a regular basis who is probably not too expensive, I think once per month would probably be good.

Note:  Never equalize batteries that you cannot add distilled water to.

Thanks,
Sean



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