Info on running tools on a power inverter

[Frankcw]

I'm looking at buying a power inverter for my vehicle that will convert 12v to 110v. I've seen several with various price ranges & power ratings. The tools I want to run are a drill, jigsaw, electric chainsaw & maybe a circular saw. The amp rating on the drill & jigsaw are low, the chainsaw says 8 amps & circular saw says 10 amp. In theory a 1200 watt inverter (peak watts 2400) should be big enough (120v X 10amp = 1200watts) Does anyone have any experience with this? Any recommendations are welcome.

TIA! Frank

[Andy Dingley]

Don't even think about it.

1. Inverters are expensive. A decent quality of inverter > 300W is serious money.

1. Inverters don't like inductive loads. This either puts the inverter price up, or kills the output stage.

2. Some devices don't like the output of cheap inverters. Inductive motors may overheat if fed with harmonic-rich square-waves.

If you're in the >500W region, look at generating 240V / 110V directly. Small petrol generators are cheap, especially larger S/H generators of 1.5kW - 2.5kW.

Other technologies are engine-driven generators - many off-roaders are using rebuilt car alternators to produce 110V, and the details are out on the web.

You might even find a suitable rotary inverter (motor generator set), probably mil-surplus. 400Hz kit can still be useful here, depending on your motor.

[Nova]

I have a 5000 watt unit on my company truck. The inverter is expensive (over $2000). Also with units this large the vehicle's alternator can't keep up the the unit's output when running high amperage drawing equipment. To overcome this the truck also has five marine type 12 volt batteries (wired in parallel without isolators) connected to the inverters input.

In my company's case the inverter was chosen due to space requirements. In my opinion, if space is not an issue, a generator would be a better choice.

-- Jack Novak Buffalo, NY - USA (Remove "SPAM" from email address to reply)

[Thomas Kendrick]

For serious electric tools you will need MORE than the nameplate rating. An electric motor draws maximum amps at stall, which is more like starting amps than running amps.

A generator under the hood driven by the engine will work if you have space for it. I have a 2kw gasoline generator which runs most loads and only weighs 100#. It does not start motors like a 10" chop saw as quickly as house power. When there is serious construction to perform, the 8kw 16hp generator goes in the truck bed. With 4 circuits at 15 amps each, there is enough power, but it weighs 500# and drinks 1 gallon per hour of gasoline. As posted previously, all of these are inductive loads.

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