Choosing Batteries and Inverters for Portable Power – Some Considerations

Do you have a gig where you won’t be near an electrical outlet? Don’t want to use a generator because of fumes or noise?

12VDC Power:
For portable, battery-powered audio, the simplest option may be using a mixer and speakers that will run off 12V power.

If you need to run 120VAC equipment off a 12VDC battery, you will need an inverter.

Pure Sine Waves vs. Modified Sine Wave: With some equipment, inverters with MSW power causes them to run warmer, which, if done regularly, could shorten their life. Over the years I’ve had some equipment on MSWs that hummed/buzzed and still worked, while other equipment was quiet.
Some of my battery backup UPS units won’t run off a MSW inverter. But battery-supplied power can be pretty stable, so you may be fine without the UPS.
I’ve gone to all Pure Sine Wave inverters.

Choosing a high efficiency inverter means less heat created and more useful power output. Efficiency can be as low as around 80% up to over 95%.
Beware of noisy inverter fans at quiet events, like a wedding.
An over-sized inverter that can put out enough power without the fan coming on may be a better choice than a small inverter with a fan kicking on and off.
Bigger, better quality inverters handle difficult loads more gracefully and will last longer.

12 inverters only go so big. At some point you will be better served by a 24V or 48V inverter.
And higher voltage can allow for longer cable runs and/or smaller gauge cable between batteries and inverter.

How long any battery lasts is a question of how efficient a particular amp/speaker system is and how loud you need it to go. Additionally, running the high pass filter up a bit and not spend a lot of energy on low frequencies will extend the run time.

A battery like this:
Will provide 12VDC x 300 watts continuous for about 2hrs 20 minutes;
can deliver 1200W for ten seconds. 17.6#
It looks expensive, but if it performs as specified and would regularly be useful,
it could end up being cheaper than a Lead battery.

With a power/time rating similar to the Dakota noted above, the Odyysey 34/78-1500 Lead AGM battery is another choice to consider:
It can deliver over 5000W for two minutes, so for high-power, highly dynamic loads
it would be better choice than a battery like the Dakota. 49.5#

A BIG Battery:
Our all electric 2014 Mitsubishi I-MiEV car will deliver about 300 watts through an inverter for more than two days.
It is actually capable of delivering 960 watts, but for some technical reasons, with this particular car, about 300 watts is as much as it will do for long periods.
Some other electric cars can deliver many more watts, for a much longer period of time.

Battery Connections need to be solid. Clamps on terminals are fine for smaller inverters. Beyond that, cables to SAE posts or bolt-on terminals are the way to go.

120VAC All-In-One: $3200

Keep extension and speaker cords short and of adequate gauge to minimize power loss.

With enough solar panels and good sunlight you can run a system off straight solar.
I would want a properly sized battery(s) in the system for passing clouds, or a bigger battery(s) for really cloudy days.
Adding solar panels to a battery powered system can extend the
number of hours of use, and lengthen the life of the battery(s).
Solar panels can add a ‘wow’ factor that may help you get a gig.
They take up quite a bit of space, and need exposure to direct sun.
Transporting and setting up panels, or a solar trailer, is an additional consideration.
Solar panels that can provide power to a home or shop can do double duty.

What can you do with 300 watts? Run a small mixer and two self-powered speakers at modest level for an outdoor event.
Obviously, for larger events, a bigger inverter and more/bigger batteries are needed.

What works for you?!

Thanks and good health, Weogo

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