Inverter problems

[Dave 2]

Hi my boat has a sterling 1800W inverter its around 10 years old but works well, powers microwave kettle power tools but it won't power my 1200W Silverline sander polisher but it will power 2000W heat gun on the low setting, as this is a new boat to me and never having an inverter before I'm a bit stumped, any ideas will help.

[nicknorman]

Hi my boat has a sterling 1800W inverter its around 10 years old but works well, powers microwave kettle power tools but it won't power my 1200W Silverline sander polisher but it will power 2000W heat gun on the low setting, as this is a new boat to me and never having an inverter before I'm a bit stumped, any ideas will help.

The heat gun is a resistive load so it's startup demand is similar to its running load.

 

Your sander polisher is a motor, a predominantly inductive load at startup, probably with electronic speed control and as such will have a very high startup power demand that exceeds the inverter's peak output.

 

Probably no solution other than a more powerful inverter, presuming (if it has it) that you have tried starting it on its lowest speed setting.

Edited July 18, 2016 by nicknorman

[RichM]

Hi my boat has a sterling 1800W inverter its around 10 years old but works well, powers microwave kettle power tools but it won't power my 1200W Silverline sander polisher but it will power 2000W heat gun on the low setting, as this is a new boat to me and never having an inverter before I'm a bit stumped, any ideas will help.

 

Welcome to the forum! Is it a modified sine wave inverter? If so, I have the same or similar inverter. Like yours, it runs most things and for me, it will even run a hoover. Try turning off other appliances first if you haven't tried already. Though, unfortunately some electronics don't work when using a modified sine wave inverters and require pure sine wave to function. Reputable PSW inverters don't come cheap so in my case I just replace/return anything that doesn't run on MSW but it's not often though admittedly I've stopped short of running a washing machine.

[Dave 2]

Thanks for the comments I've tried it on the lowest speed with all other appliances of still no joy, I will probably will buy a generator in the short term anyway thanks again.

[OldGoat]

Strange -

I have the same setup - aged Sterling MSW 1800W inverter (but mine's a 24V).

Runs a 1600 W vacuum cleaner OK and a Silverline polisher (doesn't get much use 'cos is B.. heavy). However the polisher does need to be started in 'free air' and sometimes the switch need to be jiggled. It doesn't like the MSW waveform. Once started it runs OK. I have a smaller electric drill (600w) and that behaves in a similar fashion.

 

Does that fit your experience??

[Dave 2]

Yes seems to fit, I can run vacuum cleaner other power tools no problem tried to run the polisher on the lowest setting but no luck, checked on a generator site seems you need the power of three times the wattage to start this type of motor

 

From the generator site.

 

Do the items have a starting wattage? Any piece of equipment with an induction motor will have a starting wattage, and therefore a higher wattage requirement. This includes chop saws, air compressors, vacuum cleaners, pressure washers, and freezers - anything with a motor in it. Simply multiple the items wattage by three to find it’s starting wattage.

[cuthound]

Yes seems to fit, I can run vacuum cleaner other power tools no problem tried to run the polisher on the lowest setting but no luck, checked on a generator site seems you need the power of three times the wattage to start this type of motor

From the generator site.

Do the items have a starting wattage? Any piece of equipment with an induction motor will have a starting wattage, and therefore a higher wattage requirement. This includes chop saws, air compressors, vacuum cleaners, pressure washers, and freezers - anything with a motor in it. Simply multiple the items wattage by three to find its starting wattage.

 

Three times seems a little low for the inrush current of a motor. Eight times is more typical, peaking at up to 20 times for the first half cycle.

 

However many inverters can cope with a short time overload of 2-3 times their rated output, so perhaps that's where the 3 times came from?

 

Edited to make sense.

Edited July 26, 2016 by cuthound