Watch me build a new battery / inverter box!

I thought it would be fun to have you tag along as I put together my fourth battery / inverter system.

My current battery rigs work incredibly well … But are too heavy to get in and out of my truck with two people.

I’m hoping that a smaller, modular approach will work. The idea of having a box of batteries that could be used by itself for smaller events … But could also be plugged into a larger system for larger events is very intriguing.

I had an old amp rack sitting around that I decided to try out as a battery system. It was a well made case that I had the good luck of not being able to sell on e-bay … And with this year’s Dance for World Community adding another stage to power I decided to give it a try.

The case turned out to be an almost perfect fit for four group 31 AGM batteries … A total of about 5 kWh of power if I’m doing the math correctly … I only plan on using about half of that in an attempt to keep the batteries working in top shape for as long as possible.

The case was made of 1/2″ luan plywood with some sort of plastic laminate covering, all held together with very heavy duty aluminum extrusion … It was built like a tank!

My biggest question … Would the case be able to handle all that weight?

The case did make it a lot easier to wire up the batteries and inverter. The removeable front and rear covers were now going to be the top and bottom, with the main body of the rack becoming the walls of the battery pack.

Four Group 31 AGM batteries installed on back cover of amp rack

Four Group 31 AGM batteries installed on back cover of amp rack

The former rear cover had a nice set of casters mounted on a Baltic birch caster plate … And with the addition of a 3/4″ birch “sub floor”, a layer of KYDEX and another 3/4″ “collar” around the batteries it looked like a good place to start.

The next step was to figure out how best to wire the batteries to the inverter.

A circuit breaker and fuse are added to keep things safe and a metering system is added to keep an eye on how the batteries are doing.

Wiring layout for the new battery / inverter box

Wiring layout for the new battery / inverter box

Here I have the two panels I will be using with the buss bars, fuse holder, shunt and circuit breaker mounted on them. Adhesive backed shrink tubing will be added over the crimped on lugs for safety … and to help protect the wire from corrosion.

I am using 00 marine grade wire for the interconnecting all the parts and I will be using #2 marine grade wire to connect the 12 volt batteries to the bus bars.

It is very important to use the right size wire when working with low voltage DC. The general rule of thumb is to use the largest, shortest wire you can … Otherwise the resistance in the wire will rob you of too much power.

I am already thinking of swapping out the #2 cable for #1 … We’ll see!

Eventually I will be adding a 350 amp ANDERSON SB connector to the pack (to connect multiple packs together) and have included an “extra” set of buss bars to make it easier to do when the time comes.

The AGM batteries I am using are supposed to be safe to mount in any position … And I suspect someday someone will tip this case on end to get it off of it’s wheels. I’m curious to see how the spacers hold up under that!

I've added spacers between the batteries to hopefully keep everything in place should someone ever tries to test the

I’ve added spacers between the batteries to hopefully keep everything in place should someone ever tries to test the “mount in any position” feature of the AGM batteries!

A top “deck” will be mounted on the two power panels for the inverter, battery meter and the ANDERSON SB connectors.

A little paint and it’s time for the “final” assembly.

Wiring of the

Wiring of the “positive” side off the battery bank

I like the modular approach of this system a lot … Making changes as I learn will be a lot easier … In theory!

Having this kind of access to all of the connectors was wonderful … You should have seen (heard?) me trying to wire my previous rigs!

Almost done ... Just need to add the cover and a fan!

Almost done … Just need to add the cover and a fan!

Shrink tubing added … Circuit breaker and fuses installed … Notice the “trap door” for getting at them … as well as the 175 amp ANDERSON SB connector for plugging into my chargers.

With the cover closed up and the fan on the system has been working wonderfully.  The next step will be to add the 350 amp  connector and assemble a larger inverter / power distribution system.

A great project for this winter … Will keep you posted!

Ready to go to work! Trimetric 2035 battery meter on the top left ...

Ready to go to work! Trimetric 2035 battery meter on the top left, “Kill-A-Watt meter to it’s right and 1,100 watt sine wave inverter and the connector for plugging into my  60 amp solar charge controller below.

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