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7E
Battery Selection
Example
75 DC Amps × 5 Hrs. Runtime
× 1.2 Inefficiency Rating = 450 Amp-Hours
Select Auxiliary Battery Type (if any)
Select “Deep Cycle” batteries to receive optimum performance from your Inverter/Charger. Batteries of either Wet-Cell (vented) or Gel-Cell
/Absorbed Glass Mat (sealed) construction are ideal. 6-volt “golf cart”, Marine Deep-Cycle or 8D Deep-Cycle batteries are also acceptable.
You must set the Inverter/Charger’s Battery Type DIP Switch (see Configuration section for more information) to match the type of batteries
you connect or your batteries may be degraded or damaged over an extended period of time. In many cases, the vehicle battery may be the
only one installed. Auxiliary batteries must be identical to the vehicle batteries if they are connected to each other.
Match Battery Amp-Hour Capacity to Your Application
Select a battery or system of batteries that will provide your Inverter/Charger with proper DC voltage and an adequate amp-hour capacity
to power your application. Even though Tripp Lite Inverter/Chargers are highly-efficient at DC-to-AC inversion, their rated output capacities are
limited by the total amp-hour capacity of connected batteries. If your vehicle has a heavy duty alternator(s), the battery capacity is less important.
• STEP 1) Determine Total Wattage Required
Add the wattage ratings of all equipment you will connect to your
Inverter/Charger. Wattage ratings are usually listed in equipment manuals
or on nameplates. If your equipment is rated in amps, multiply that number
times AC utility voltage to determine watts. (Example: a piece of equip-
ment listed at 2½ amps. 2½ amps × 120 volts = 300 watts.)
Note: Your Inverter/Charger will operate at higher efficiencies at about 75% - 80% of nameplate rating.
• STEP 2) Determine DC Battery Amps Required
Divide the total wattage required (from step 1, above) by the battery voltage
(12) to determine the DC amps required.
• STEP 3) Estimate Battery Amp-Hours Required (for operation
unsupported by the alternator)
Multiply the DC amps required (from step 2, above) by the number of hours
you estimate you will operate your equipment exclusively from battery
power before you have to recharge your batteries with utility- or genera-
tor-supplied AC power. Compensate for inefficiency by multiplying this
number by 1.2. This will give you a rough estimate of how many amp-hours
of battery power (from one or several batteries) you should connect to
your Inverter/Charger.
NOTE! Battery amp-hour ratings are usually given for a 20-hour discharge rate. Actual amp-hour capaci-
ties are less when batteries are discharged at faster rates. For example, batteries discharged in 55 min-
utes provide only 50% of their listed amp-hour ratings, while batteries discharged in 9 minutes provide as
little as 30% of their amp-hour ratings.
• STEP4) Estimate Battery Recharge Required, Given YourApplication
You must allow your batteries to recharge long enough to replace the
charge lost during inverter operation or else you will eventually run down
your batteries. To estimate the minimum amount of time you need to
recharge your batteries given your application, divide your required battery
amp-hours (from step 3, above) by your Inverter/Charger’s rated charging
amps (see Specifications section).
NOTE! For Tripp Lite Inverter/Chargers over 1000 watts used in mobile applications, Tripp Lite recom-
mends you use at least two batteries, if possible fed by a heavy-duty alternator anytime the vehicle is run-
ning. Tripp Lite Inverter/Chargers will provide adequate power for ordinary usage within limited times
without the assistance of utility or generator power. However, when operating extremely heavy electrical
loads at their peak in the absence of utility power, you may wish to “assist your batteries” by running an
auxiliary generator or vehicle engine, and doing so at faster than normal idling.
450 Amp-Hours ÷ 55 Amps
Inverter/Charger Rating = 8 Hours Recharge
900 watts ÷ 12V = 75 DC Amps
Ambulance/EMS Vehicle Equipment
Blanket Warmer IV Warmer Monitor
250W + 250W + 400W = 900W