Heavy Man

Obviously, the inverter is dependent on batteries for its supply.  So what kind?  Like many aspects of this project, different sources offered different suggestions.  There are two basic types of batteries, or two types for each of two types of batteries.

Battery Construction

There are "wet" cells and "gel" cells.  Wet cells, as their name implies involve water.  These are batteries like car batteries, "back in the day," that had little cap on top where you add water periodically.  These batteries, aside from required maintenance, are less expensive and higher capacity/longer life.

"Gel cells" are sealed batteries, some time referred to as AGM or anti-gassing.  These batteries are relatively expensive, lower capacity and shorter-lived than their "wet" counterparts.  Their advantage is zero maintenance and, as the AGM name implies, they do not emit fumes, which may be significant, depending on where the batteries will be located relative to breathing animals, like dogs or humans.

Load Cycles

Within each of these two battery construction types, there are two types of batteries, deep-cycle and high cranking.  High cranking batteries are designed to produce high power for short periods, like the battery in your car, used primarily for starting.  To provide power for the inverter, over a hopefully long period of time, a deep-cycle battery is preferable.

For cost and capacity, it is desirable to use a wet cell.  In our design the batteries will be in the equipment compartment, separate from the grooming compartment, so wet cells will be OK.  The next step is to select the best wet cell, deep-cycle battery.  I stopped by an industrial battery dealer, Industrial Battery Supply in St. Louis.  I asked a variety of questions and they offered as much information as possible, with caveats that they were a battery distributor, not an engineering/design firm.  From that discussion, I left intending to use a Trojan, www.Trojan-Battery.com, 12 Volt deep-cycle battery, model J185H.  This is the largest of its type with impressive power, weighing in at 122 pounds each.  Based on available space, we have room for four of these batteries in the equipment compartment.

Selection

Looking for confirmation or second opinion, I contacted Trojan Battery and ended up with a different solution.  The J185H would have been a good solution.  There is a 6 Volt battery, L16H that offers slightly higher capacity and value.  In stead of using four 12 Volt batteries in parallel, we will use four 6 Volt batteries in series-parallel to provide 12 Volts to the inverter.

Mounting

The Trojan representative also pointed me to Ardemco Marine, www.Ardemco.com, as a source for a mounting solution for the L16 battery.  Ardemco makes a heavy plastic "box" to hold two L16 batteries.  We will use two of these boxes to house the four L16 batteries.

Run Time

How long should the system run without charging?  Longer is better.  Based on the specs for the Trojan L16H battery, it will run 885 minutes putting out 25 Amps.  This value is for a 6 Volt load.  To adjust for the 12 Volt inverter, assume the batteries are used in pairs.  They will run 225 minutes putting out 75 Amps.  These are full discharge values, which is something you shouldn't do.  Typically deep-cycle batteries are recharged at 50% discharge.  If the active electrical load is 200 Watts, the inverter will draw about 26 Amps, very close to the spec we have for 25 Amps and 885 minutes.  So, using four batteries, the system should run almost 15 hours before needing a charge.

Here is a link to a simple spreadsheet used to calculate the runtime...