Batteries - charging ahead

2nd of December 2016
Batteries - charging ahead

How important is a battery’s ability to take a charge quickly and efficiently in the productive running of a machine? Does the type of charger used make a difference to the running costs and performance of a cleaning machine, or is it relevant what type of charger is employed? Trojan Battery writes for ECJ.

To achieve maximum performance of floor care machines, it is important to understand what impacts the ability of the battery to operate at peak performance. Two things are required: (1) proper battery maintenance which includes watering the batteries for flooded lead acid types, making sure the posts are clean, and ensuring terminal connections are tightened, as well as (2) proper charging by ensuring the use of the correct charge algorithm for the battery types and correct charging frequency.

If both maintenance and battery charging are being performed as required, the battery will be in the best possible condition to accept a charge. The amount of time it takes to recharge a battery is dependent on its state of charge, or SOC. If batteries are not fully charged after each daily use, the batteries will be at a low SOC and possibly completely discharged when the charging process begins.

Limit DOD

This is not ideal, since the lower the SOC, the more sulphate is present on the surface of the plates which requires more time for it to be removed during the charging process. Ensuring you limit the depth of discharge (DOD) by charging the batteries after each daily use will help the battery’s ability to accept a charge.

The important thing to remember with selecting a charger is to ensure the charger contains the proper charge algorithm specified by the manufacturer of the batteries being used in the equipment. Some chargers are designed for flooded batteries only, while others can be used for either flooded or VRLA (Valve Regulated Lead Acid) batteries such as AGM or Gel. Therefore, it is important to know what type of batteries you are charging.

Type of charger

In addition, the output or size of the charger can impact the amount of time it will take to recharge a battery. Be sure that the starting current, also known as bulk current, does not exceed what is specified by the battery manufacturer. While a higher charge current can reduce overall charging time, too high of a current can damage the plates inside the batteries, which will reduce performance and life.

The overall operating costs of a floor machine, from the charging perspective, is determined by the size of the charger (wattage) and the depth of discharge (DOD) of the batteries. The deeper the DOD, the longer the batteries will take to charge, which increases amount of electricity needed to charge the batteries.

Charging algorithms

If proper battery maintenance and charging practices are followed, batteries will deliver maximum performance and life.  The use of the proper charging algorithm cannot be overstated, because
each charge algorithm is developed to meet the overcharge requirements determined by the battery manufacturer based on its own design.

Remember, deep-cycle batteries need to be overcharged to ensure adequate mixing of the electrolyte to avoid stratification, therefore it’s critical that the charger be allowed to complete its full charge cycle. For example, if 30 AH (amp hours) is used during the daily operation of the machine, and only 30 AH is returned to the batteries during charging, there is not an adequate amount of mixing of the electrolyte and stratification would start to occur. Continuing this type of charging will result in undercharging and severely impact battery performance and life.

On the other hand, if excessive overcharging of the batteries occurs, there would be increased electrolyte loss, which will concentrate the specific gravity in the cells and deteriorate the plates.
This also will result in decreased performance and life. Most OEM chargers today come programmed to ensure controlled overcharging.

Electrolyte temperature

Battery temperature also is important to consider when charging batteries.  When flooded lead acid batteries are cold, ie, electrolyte temperature not ambient temperature, they have a lower charge acceptance in comparison to a warm battery.  Therefore, it will take longer for them to charge.

AGM batteries accept charge better than flooded or Gel batteries because they have lower internal resistance. Batteries with high electrolyte temperatures will accept charge faster, but the higher electrolyte temperatures will accelerate positive grid corrosion. Therefore, the most effective charging is temperature compensated to ensure the proper charging of batteries.

The ability of the batteries to provide maximum performance and life, depends mainly on proper maintenance and charging according to the battery manufacturers specifications. By gaining a clear understanding of the importance of battery charging ensures that batteries used to power floor cleaning machines will function at peak levels of performance and reliability.


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