Tired of waiting for your undersized charger to finish?
Have you made the mistake of buying an undersized charger? Either trying to save a few dollars or not being quite sure of the math’s and thinking ‘she’ll be right’,… only to find yourself waiting around for it to finish so you can get on with your work day?
Sizing your battery charger
Choosing a Battery Charger for your Electric Forklift can be a confusing task. The typical day in the life of a single shift forklift will be 8 hours of use, 8 hours of charge and then 8 hours of cooling. But how do you ensure your battery charger is the correct size to complete it’s charge cycle within 8 hours?
The #13 Rule
All you need to remember is the #13 Rule, which is:
Charging Current = 13% of Battery Capacity
Consider the example of a 48V 600Ah lead acid battery. If you wanted to know what size charger you need just apply the #13 Rule:
Charging Current = 13% of 600 Ah = 78 Amps
Whilst 13% is the target to fully charge a depleted battery in 8 hours, it is suitable to go as low as 9% (but full charge will take longer at 10.5 hours) or as high as 20% (full charge completed quicker in just 6.5 hours). Charging at rates over 20% are also achievable, however extra precautions need to be taken, which is a discussion for another day…
So in our 48V 600 Ah battery example the battery charger output current could range between 54 Amps (9% of 600 Ah) and 120 Amps (20% of 600 Ah), with the sweet spot being 78 Amps.
A common charger size is 80 Amps so in this example we would recommend the GME-H10 48V 80A, which is the GM Electric H10 model, with rated DC output of 48 Volts and 80 Amps.
Flip the script
Another way to approach the calculations is if you have a charger in mind simply divide it’s output current in amps by your battery size in amp hours and see what percent it is:
80 Amp Charger / 600 Ahr Battery Capacity = 0.133 = 13.3%
13.3% is within the ‘Ideal’ range of 10% to 16% so yes this charger is suitable.
Buyers Guide
To make selecting your next battery charger even easier we have done these calculations for every charger in our range and put the results together in a single reference chart.
Simply compare your Electric Forklift Battery Capacity (Ah) at the top of the chart with your Battery Voltage (24V, 36V, 48V or 80V) on the side of the chart to determine your required Battery Charger model.
Light green indicates that the charger is ‘suitable’ and dark green indicates that the battery charger is ‘ideal’ for your particular electric forklift.