Two 6 volt batteries or two 12 volt batteries ??

SoundGuy wrote:

otrfun wrote:
Before this thread, I never gave alarm and shutdown voltage a lot of thought. Guess we lucked out with an inverter that supposedly shutsdown at 10.0 volts. Our previous inverter shutdown at 10.5 volts. Didn't realize some inverters shutdown at 11.0 volts or higher. Depending on system capability (batteries, cable length/size, etc.), a 1 volt difference like this could potentially be a huge deal in some dry camping situations. Going forward, we're definitely going to be looking much closer at alarm/shutdown voltage specs.

We don't dry camp often so I wasn't willing to invest a lot of $$$ in an inverter but decided to add one to our trailer a few years ago when found I could buy a "good enough" 1000 watt PSW for $200 Cdn at Canadian Tire. It's the only PSW inverter they sell and in reality is a Chinese manufactured NPower inverter, hardly high quality but does do what I want. It's low voltage alarm threshold is spec'd at 11.0 volts, +/- 0.3 volts, meaning it could alarm at even 11.3 volts - in reality I've found it starts to be unhappy around 11.5 volts. Both of the heavy loads I want it to run - toaster and coffee maker - are resistive loads, so excessive surge from an inductive load isn't an issue for me. If it were that would be a reason for a much better quality inverter capable of a much lower alarm threshold. Further to this though, if this inverter does shut down due to low incoming source voltage it's spec'd to not restart unless that incoming voltage rises to 11.6 volts, +/- 0.3 volts, meaning it might have to be as high as 11.9 volts before it would be willing to restart ... yet another reason a higher quality inverter that would restart at a lower voltage might for some be a better choice. No question about it, voltage drop and inverter low voltage threshold are just as important as which battery (or batteries) to use to power that inverter.

You would think higher cost inverters would have the lowest alarm/shutdown voltage specs. For our last project we simply purchased the cheapest 1000 watt PSW inverter we could find on Amazon, with very little regard for any of the specs, and lucked out with this unit that had a claimed 10.0 volt shutdown voltage. Price just went up. It was $139 just last month. Aims sells the same exact unit (in blue with an Aims sticker) for $30-$40 more. We've had it down to 10.5 volts with no alarm or shutdown---output voltage was still stable at 117 vac with a 700 watt load. Can't verify waveform distortion---but it does power a lot of sensitive stuff that won't operate with a MSW inverter. Good enough for this particular project. BTW, parasitic current is .5 - .7 amps. Not great, but for the money and wattage not bad.