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VertaMax User Manual
Revision 3
4
0.204 (5.19)
0.249
1210 lbs
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0.258 (6.54)
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1930 lbs
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2430 lbs
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4.4 B
ATTERIES
4.4.1
Battery Life
The VertaMax can draw lots of amps from your battery when operating. If you are using it for
extended periods of time, you will want to recharge occasionally to maintain the charge in the
battery. In addition, the power inverter will also draw a small current, less than 600mA, when
turned off and not operating. Therefore, it should be disconnected from your battery if it will not be
used for more than a day. The following chart shows typical operation time for typical batteries for
various loads.
Power Usage
Current @ 12V
50A/h Battery Operating
Time
100A/h Battery
Operating Time
100 watt
9 Amps
5.5 hours
11 hours
200 watt
19 Amps
2.6 hours
5.2 hours
500 watt
47 Amps
1 hour
2 hours
*All Values are approximate
4.4.2
Battery State of Charge (SOC)
You can measure battery state of charge with a hydrometer or approximate state of charge with a
voltmeter. Using a digital voltmeter that can display tenths or hundredths of a volt, measure the
battery when it has not been charged or discharged for several hours.
For a deep-cycle battery at 77º F (25º C), use the following table:
Battery Voltage
State of Charge
12.7 – 13.0 V
100%
12.5 – 12.6 V
80%
12.3 – 12.4 V
60%
12.1 – 12.2 V
40%
11.9 – 12.0 V
20%
4.4.3
Actual Battery Current Draw
Approximate 12 volt current draw is the AC load in watts divided by 10. Thus a 60 watt light bulb
plugged into the inverter will cause the inverter to draw 6 amps (60 / 10 = 6) from the 12 volt
power supply (e.g. battery).
Batteries are rated in several different ways:
•
Peak cranking amps - This has little to do with how long an inverter can supply power,
so it is not a useful number for inverter operation.
•
Battery reserve capacity - This number shows how long a battery can supply a given
current, typically 25 amps, before the battery voltage reaches a low voltage. Therefore,
a battery rated at 200 minutes reserve can deliver 25 amps for 200 minutes before it is
discharged. Ampere-hour capacity - This rating indicates how many amps a battery can
deliver over a period of time, typically 20 hours. Therefore, a 100 amp-hour battery can
deliver 5 amps for 20 hours (5 x 20 = 100).
Actual operating time from a battery will depend upon the current draw from the battery. A battery
will deliver less total power (energy) as you draw higher amps. A 100 amp-hour battery can
deliver 5 amps for 20 hours (100 amp-hours) but it will only deliver 50 amps for 1 1/2 hours (50 x
1.5 = 75) or 75 amp-hours at the higher rate.
Also remember, battery life is decreased if the battery is discharged fully. Lead acid batteries
have the longest life, if they are kept fully charged.
