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.

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.

How thick is thick? How many batteries?

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.

smkettner wrote:How thick is thick? How many batteries?4 guage cables that come with it ,, 2 -----6volt golf cart batterys

6 volt golf batteries are designed to handle about 30-40 amps. You are trying to get 150 amps through both of them. It's likely they will burn out inside or explode soon.That's the biggest problem with 6 volt batteries, they are in series, so the current draw to handle a big load is passed through both batteries. With 12 volt batteries, each battery provides half the current draw because the batteries are in parallel instead of in series.

Why wont invertor power range? | Good Sam Community

23 Replies

mobileempire
Explorer
Oct 27, 2013
Yes , indeed "Good Stuff"
mena661
Explorer
Oct 24, 2013
wa8yxm wrote:
You answered your own question when you said the road pro gave a LOW BATTERY VOLTAGE error light.

The cables connecting it to the batteries (you do have batteries right, not just a small Grop 24) are too small.. AND/OR the batteries are too small.

You need (for batteries) at least 200 amp hours, Two Group 29 31 or GC-2 minimum, if you plan on using that single burner to cook double that.

And at least double the gauge of the wire, Tape the black and red wires side by side together for as much of the run as you can.

Also you may need to upgrade any jumper wires in your battery bank.

1,000 watts is right close to 100 amps off the batteries, Use 100 amps to calculate battery size and such

TEST> Hook a digital volt meter to the INVERTER's power terminals and watch it as you power on.
X2 Good stuff!
Chris_Bryant
Explorer II
Oct 24, 2013
wa8yxm wrote:
You answered your own question when you said the road pro gave a LOW BATTERY VOLTAGE error light.

The cables connecting it to the batteries (you do have batteries right, not just a small Grop 24) are too small.. AND/OR the batteries are too small.

You need (for batteries) at least 200 amp hours, Two Group 29 31 or GC-2 minimum, if you plan on using that single burner to cook double that.

And at least double the gauge of the wire, Tape the black and red wires side by side together for as much of the run as you can.

Also you may need to upgrade any jumper wires in your battery bank.

1,000 watts is right close to 100 amps off the batteries, Use 100 amps to calculate battery size and such

TEST> Hook a digital volt meter to the INVERTER's power terminals and watch it as you power on.

This ^^^^^
The problem is basic troubleshooting. The inverter gives low voltage alarm, so test the voltage at the inverter terminals under load. Is it low? If no, the inverter is alarming in error. If yes, test the voltage at the battery. Is it low? If yes, you need more battery. If no, the cables and/or connections are bad/undersized.
No need to guess or speculate.
BurbMan
Explorer II
Oct 24, 2013
Why RVs have propane on board....much more efficient at delivering heat than trying to use electric:
wa8yxm
Explorer III
Oct 24, 2013
You answered your own question when you said the road pro gave a LOW BATTERY VOLTAGE error light.

The cables connecting it to the batteries (you do have batteries right, not just a small Grop 24) are too small.. AND/OR the batteries are too small.

You need (for batteries) at least 200 amp hours, Two Group 29 31 or GC-2 minimum, if you plan on using that single burner to cook double that.

And at least double the gauge of the wire, Tape the black and red wires side by side together for as much of the run as you can.

Also you may need to upgrade any jumper wires in your battery bank.

1,000 watts is right close to 100 amps off the batteries, Use 100 amps to calculate battery size and such

TEST> Hook a digital volt meter to the INVERTER's power terminals and watch it as you power on.
ktmrfs
Explorer II
Oct 24, 2013
robatthelake wrote:
The bottom line here is this! " Do Not use any Inverter to power a Heat source"

They just don't work the way most people think!

They are great for Small appliances like Computers, Televisions ,Phones Etc.

They are OK for small Motors like Blenders and Drills .

They suck when it comes to Heaters and such!

Huhh....?????? PSW on a heat source is no different than the line power or generator. Now does it make sense to do so when a generator or propane is available is another discusion.

and MSW work just fine on a resistive load such as a heater.
mena661
Explorer
Oct 24, 2013
ktmrfs wrote:

Well, the new inverter could have a higher cutoff voltage for the low voltage alarm.

His batteries could have been much further discharged than previous attempts with the 750W unit.

the cables with the new inverter could be inadequate for either case.
This here.
robatthelake
Explorer
Oct 24, 2013
The bottom line here is this! " Do Not use any Inverter to power a Heat source"

They just don't work the way most people think!

They are great for Small appliances like Computers, Televisions ,Phones Etc.

They are OK for small Motors like Blenders and Drills .

They suck when it comes to Heaters and such!
hershey
Explorer
Oct 23, 2013
Alternative????
Go to an induction cook top. It is much less energy hungry and works much better than the hot plate type cook tops. You do need cookware that is attracted by a magnet for it to work.
mpierce
Explorer
Oct 23, 2013
A lot of the newer microwaves require a true sine wave. I had a modified, put in new microwave. Would not work. Needed true sine wave for the unit.