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of electrical terms.
The battery is rated at 51.2VDC at 210Ah. An “Ah” is amp-hour, or a rating for battery capacity (electric
charge) which means that it will supply 210 amps of current for one hour. This means that to determine
the capacity that a load will consume we will need to use a few calculations to move the loads of various
power sources to one value.
To make calculations easy, we will use watt-hours or Wh. Watts is a measure of power, and it’s the
product of the current and voltage of a specific load or device, and to determine power, simply multiply the
wattage (in watts) by the time it’s used (in hours). Example:
Coffee pot consumes 12.5A and it connects to the 120VAC outlet. (12.5A) x (120V) = 1500W
To determine the energy use (watt-hours) of the activity, first determine the load in watts and multiply by
the time it’s used (in hours). Example:
Making coffee for breakfast and the coffee pot was on for 30 minutes:
Wh = (1500W) x (.5 Hours) = 750Wh
The battery has 210 Ampere Hours at 51.2VDC, or 10,752Wh of energy available at 100% SOC. Each 1%
of SOC (state of charge) is equal to 2.1A at 51.2VDC, or 107.52Wh (51.2V x 2.1A). To determine current
reserve capacity, in SOC% left after the usage, divide the Wh’s of usage by 107.52Wh to determine the
SOC % that the activity would cost. Then you can compare that SOC percentage from the current SOC
percentage to determine if you want to perform that activity. Continuing our example from above:
Making coffee for breakfast and the coffee pot was on for 30 minutes:
Wh = (1500W) x (.5 Hours) = 750Wh
SOC% = 750Wh/107.52Wh = 6.98%
SOC% Cost for 30 minutes of coffee is approximately 7% SOC
The display will give you current SOC%, and the aforementioned calculations can be used to determine
what loads will cost in SOC, to help determine how long the current capacity can last before recharging.
Recharging uses the same calculations so you simply convert the amps of charging to watt hours, then
SOC%. The only difference is you add from current SOC% instead of subtract. To simplify this, a chart
was comprised of typical loads and charge values, with corresponding Wh and SOC percentage are.
o SOC Quick Reference for discharge: Use the chart below as a quick reference for
typical load SOC percentages to subtract from current SOC percentage for discharge
times, see below:
USAGE (LOADS)(SUBTRACT FROM SOC%
LOAD NAME
384 768 1152 1536 3.57% 7.14% 10.71% 14.29%
100 200 300 400 0.93% 1.86% 2.79% 3.72%
375 750 1125 1500 3.49% 6.98% 10.46% 13.95%
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