Xantrex Technology 1000i, 1800i owner manual Battery Size

7.2 Battery Size

Just as important as the type of battery selected for use with your Xantrex Prosine Inverter is the subject of battery size (capacity). There are a number of different standards for rating battery capacity. Automotive starting batteries are normally rated by cranking amps. This is not a relevant rating for continuous use. Deep cycle batteries are rated either by reserve capacity in minutes or by amp-hours.

Battery reserve capacity is a measure of how long a battery can deliver a certain amount of current—usually 25 amps. For example, a battery with a reserve capacity of 180 minutes can deliver 25 amps for 180 minutes before it is completely discharged.

Amp-hour capacity is a measure of how many amps a battery can deliver for a specified length of time— usually 20 hours. For example, a typical marine or RV battery rated for 100 amp hours can deliver 5 amps for 20 hours. (5 amps x 20 hours = 100 amp hours)

You can expect performance from the inverter to suffer with the use of a small, low amp-hour rated battery (for example, 50 Ah). Even if your battery is in excellent shape and fully charged you will likely experience poor surge power performance and unsatisfactory operating time with anything but a small AC load. Xantrex recommends a minimum battery size of 200 Ah for moderate loads (less than 1000 W) and greater than 400 Ah for heavy loads.

To determine how large a battery or battery bank you require for equipment running from the inverter, simply add together the power requirements for all electrical devices that you will be running multiplied by their approximate running times in hours between battery recharges. Each device will be rated in either watts, volts and amps, or VA. For this calculation, all three of these ratings are equivalent (i.e. volts x amps = watts

=VA). The following example, based on battery recharging every three days, illustrates the calculation:

1Power Consumption x Operating Time

Convert the watt hours to amp hours by dividing total watt hours by 10:

1495 watt hours/10 = 149.5 amp hours

A 150 amp hour battery is required to supply enough power for the above loads, and become completely discharged. Ideally, you normally want to discharge your battery to only 50% capacity, so for the above loads, you would require about 300 amp hours of battery capacity.

When sizing your battery, be generous. More capacity is better since you will have more reserve capacity, and your battery will not be discharged as deeply. Battery life is directly dependent on how deeply the battery is discharged. The deeper the discharge, the shorter the battery life.

As your power requirements increase, to obtain sufficient battery capacity, you may need to use more than one battery. Two identical batteries can be connected positive to positive and negative to negative in a parallel system that doubles the capacity and maintains the voltage of a single battery. It is not recommended to connect batteries from different manufacturers or with different amp-hour ratings or with different battery electrolytes in parallel. Decreased battery life may result.

Load	Power		Operating Time	Watt hours1
	Consumption
TV & VCR	115	W	3 hrs	345
			(1 hr per day)
Coffee	750	W	1 hr	750
Maker			(20 min. per day)
Microwave	800	W	0.5 hrs	400
Oven			(10 min. per day)
			TOTAL	1495

Xantrex Prosine Inverter Owner’s Manual English 15