Bed outlet power without key in the ignition?

That's funny! And believable. Earlier today I grabbed my 6.5 amp circular saw & 6.5 amp Ryobi angle grinder & tried to power them (one at a time) with the bed outlet @ the 100w setting. Nothing happened. I then started up my truck & tried again. Each tool ran perfectly at high speed.
400W divided by 120 VAC is 3.33 amps then why was it able to power both of those tool? Sorry but I just don't understand how that works.
The label on the Ryobi reads 120 V AC, 60Hz, 6.5 A

 

try cutting a PT 6x6

 

I'm sure that will take forever. I did cut a 4x4 pressure treated wood post. I did take my time with it. It was slow but it worked & the inverter never shut off.

 

Exactly. It thought is was a great feature even though (as an engineer) I knew the outlet was NOT of great capacity. I tried to run an older refrigerator off of it during a power outage thinking that the 'frig wouldn't drawn much - wrong!

If you're lucky, it might power a work light or a small coffee maker.

 

Simple - tools are rated on their maximum amperage draw under load. Free-running draw will be substantially less.

 

Zombie thread, but there's a high likelihood you'll damage your AC powertools running them on a dirty inverter. They aren't meant for inductive loads.

 

The answer is because AC is not a straight forward as DC is.
The formula for DC is: Power = (Amps)(Volts) -> W=(I)(V)

For AC there is an extra factor in there called the power factor that varies based on the type of load.
Specifically for single phase AC (like the inverters in our trucks): Power = (Amps)(Volts)(PF) -> W=(I)(V)(PF)
Where PF typically ranges from 0.5 - 0.99

So if we rearrange for Amps: I=(W)/(V*PF)

Then assume that power and voltage are constant I=(400W)/(120V*PF) we see that Amps can change based on the PF.

So thats why

 

whoa - how about a resurrection of this post after 5 years? =)

looking for feedback on an idea. i have one of those 12v fridges i want to run from the bed outlet. what are your guys' thoughts on using one of those solar trickle chargers to keep the battery charging and/or topped off? yes, i plan on leaving the key in the ignition turned to enable the on-board inverter and such. will this ruin the battery in any way?

 

Why not just use 12V? Run a dedicated feed with appropriate fuse. Add a switch if desired.

Using the inverter is inherently inefficient: truck DC > AC > back into DC at the fridge. Plus with the key on, the truck accessories will be drawing power (and you need to leave the keys in your truck all the time). The electrical demand will be higher using this method

 

this is the kind of straightforward answer i was hoping for! thank you. i never would have thought about other possible devices that would be sucking power when the key is turned to acc.