Estimating Battery Requirements
Calculating Battery Size
Step 1: Compute Amp-hours
For each appliance, compute the number of
1.Obtain the wattage. If the wattage is marked on the nameplate rating, use that. Otherwise, multiply the marked voltage and amperage:
WATTS = VOLTS × AMPS.
2.Obtain the
WATT-HOURS = WATTS × HOURS.
3.Obtain the
BATTERY AMP-HOURS USED = AC WATT-HOURS÷10
For example, a 100 W light bulb that is used for 4 hours will use 400
40 Ah from a
4.Enter this information on the blank calculation worksheet (page 56).
Battery Information
Step 2: Calculate Battery Size |
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5. Complete the rest of the worksheet; see Table 5, “Battery | only. | |
Sizing Example” on page 54 for an example. | ||
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Size the batteries at approximately twice the estimated total amp- | personnel | |
hour usage. Doubling the expected | ||
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batteries will not be overly discharged and extends battery life. |
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Do not skip this doubling step. More capacity is better since you | qualified | |
will have more reserve capacity, be better able to handle large loads | ||
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and surge loads, and your battery won’t be discharged as deeply. |
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Battery life is directly dependent on how deeply the battery is | by | |
discharged. The deeper the discharge, the shorter the battery life. | ||
use | ||
Troubleshooting If you find that the system shuts down when | ||
for | ||
appliances with large motors are started, the problem may be that | ||
this motor is too much for the battery. Even though you calculated | guide | |
the | ||
motor makes high demands on the battery. You may find that adding | ||
more | This | |
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a bigger battery) solves the problem.
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