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Power Inverter Determine Battery Rating

How much battery will my power inverter need? Power Inverter: Determine Battery Rating

Determine Battery Amp Hour Rating to Calculate Power Inverter Run Time

Batteries are rated with voltage and Ah reserve capacity. This capacity in AGM and deepcycle may be built on a drain rate. In lithium batteries, how fast you drain the battery is less important to its capacity.

Overall the larger your load on your power inverter, the faster your battery bank will be drained.

A simple rule of thumb for AGM and Deep Cycle marine batteries is that for every 100 watts you run on an inverter, you will drain about 15 amp hours from your battery. Although because of the drain rate being higher, you could actually have a higher amount from the capacity of the battery for super high drain rates. This is where lithium batteries shine.

This is a small video in the Series on how to calculate power inverter run time. This video covers how batteries are rated and what information we need to calculate how long a battery can supply power. This video lays out why we look for Amp Hour (Ah) Rating instead of Cold Cranking Amps (CCA) when looking for battery capacity. This information is important to both inverter run time and solar battery charging times. 

Many people have found thess videos useful when determining overall battery bank capacity as well.

Lithium batteries have come down a lot in price over the last 10 years. When we first started selling these batteries, they were hard to come by and a 100 Ah battery would cost over $5000. Today they are much lower cost and the power denisty is getting greater.