Forum Discussion

Explorer

Oct 23, 2013

Why wont invertor power range?

Over the past couple of years I had a 750 watt Vector Invertor powering a small microwave with no problems , I recently bought a little 1000 watt range that I wanted to use and I knew the 750 watt invertor would'nt power it so I bought a more powerful 1500 watt Roadpro Invertor from the truck stop . Problem: Not only would'nt the Roadpro 1500 not power the range , it also wont power the little microwave that the less powerful 750 watt invertor can , Whats the problem here?
The road pro would give a fault code Lup ,,, meaning input voltage to the invertor going low .
Batterys are fully charged , all tight good connections , 3 foot long thick guage wires powering it , I'm at a loss , even tried when the alternator output was powering it and same code.

23 Replies

ktmrfs
Explorer II
Oct 23, 2013
could be several things. However, one thing is do NOT repeat NOT look at the watts of the microwave. Look at the current draw and calculate Volt amps. (volts x amps) Long explanation but microwaves, etc. draw more current than the watts rating is. And second a 1000W microwave refers to the cooking power NOT repeat NOT the power draw from the line. A 1000 watt microwav will typically draw 1500 or more Volt Amps. I've measured several microwaves and it's very consistent.

then there is the input voltage drop to the inverter. to provide 1500VA to the microwave, the inverter will draw about 1700/12= 150 Amps, yes 150 amps. voltage drop between the battery and inverter can be significant. And with 150A , the battery voltage will drop as well.

so you need to do some measurement and calculations to determine what the cause(s) of the problem are.
time2roll
Nomad
Oct 23, 2013
How thick is thick? How many batteries?
westend
Explorer
Oct 23, 2013
The Roadpro is not living up to it's ratings, I'm guessing. Could it be rated at 1000 surge watts. I've seen that kind of rating scheme/scam used with cheaper inverters.