Standby no-load current draw 2-3amps

[andyP]

Hi. I've got a generic PSW inverter rated at 2500w/5000w peak.

It's been in full time use for a year. I noticed the fan comes on regularly when it's in standby. It didn't do that when it was new, and it's standby temperature is 40C.

It's in full time use on a boat so humid environment.

It's also drawing 2-3 amps in standby with no output load. I'm sure it didn't draw that much when it was new.

Is this normal?
Is there some internal maintenue i can do? (Wash board with alcohol?)
Or part of the circuit i can investigate for failure?

 

[Bud Martin]

What is the make and model to start with?

 

[andyP]

Non branded.

 

[RCinFLA]

Assuming it is a 12v inverter for the 2-3 amps idle , 24-36 watts of idle power consumption for a cheap 2.5kW sinewave inverter would not be too unusual.

As to fan operation, it will likely come on periodically to dissipate 20+ watts of internal heating. You may just have not noticed it or had it in a cooler location. It is possible the thermistor that controls the fan activation has drifted in value making the controller think it is hotter than actually is.

If you have something plugged in that has some interference suppression capacitors across AC, even when turned off, it may raise the inverter idle current.

 

[curiouscarbon]

without a data baseline of prior behavior, it’s hard to say for me.

qualitatively, the behavior seems to have changed

some inverters have idle consumption as high as 50-75W from reading around a bit.

As to fan operation, it will likely come on periodically to dissipate 20+ watts of internal heating. You may just have not noticed it or had it in a cooler location. It is possible the thermistor that controls the fan activation has drifted in value making the controller think it is hotter than actually is.

interesting!! analog components are known for changing in characteristics over time and heat etc. had not even considered an analog thermometer inside could have changed. good idea about operating climate as potential confounding factor.

If you have something plugged in that has some interference suppression capacitors across AC, even when turned off, it may raise the inverter idle current.

unplugging idle devices and observing if there was a change in dc current, could reveal more?

 

[andyP]

Idle current measured with no load connected. Literally nothing plugged in.

Temp. I can feel it's warm. And it's using 2amps of current to do nothing so not surprising it's warm.

My question was more... What could be failing in the inverter to make it start to consume more idle current than before?

 

[Supervstech]

Hi. I've got a generic PSW inverter rated at 2500w/5000w peak.

It's been in full time use for a year. I noticed the fan comes on regularly when it's in standby. It didn't do that when it was new, and it's standby temperature is 40C.

It's in full time use on a boat so humid environment.

It's also drawing 2-3 amps in standby with no output load. I'm sure it didn't draw that much when it was new.

Is this normal?
Is there some internal maintenue i can do? (Wash board with alcohol?)
Or part of the circuit i can investigate for failure?

Standby as in low power mode? Or standby as in not plugged into something?
Most inverters with a low power mode dont run all the time, they pulse a seek charge periodically looking to see if any loads are connected...
If yours did this before but isn't any longer, the board may have failed. Nothing I can think of would solve that.

If it just has an on and an off setting... it might be fuzzy inside and need a cleaning. Dust bunnies could be insulating the heat dissipation abilities.

 

[RCinFLA]

Just to clarify definitions,

Standby is a mode that inverter wakes up periodically, like every second or two, for short period to check if there is an AC load on inverter. If AC load is detected it remains on, otherwise it goes back to sleep with low current draw. It usually takes a 8-15 watts of AC load for inverter to stay active, out of standby operation.

A small load less than 8-15 watts, like a small light, may not deactivate standby strobing causing the light to blink on and off with inverter standby strobing.

Low cost or smaller wattage inverters usually do not have a standby mode. If it has a standby mode it is usually user selectable so it can be deactivated and stay in idle mode, preventing standby strobing. Standby strobing can be a problem when plugged in appliances have a microcontroller that could reset for every strobe cycle. This usually prevents the appliance from being turned on.

In Idle mode, the inverter stays on continuously with output AC voltage continuously present. It will take 20-80 watts of continuous battery power just to chop the high frequency switching power MOSFET transistors. The more powerful the inverter the greater the no-load idle power consumed. For sinewave inverters there is a compromise between idle power and AC output PWM filter as the reactive current of the filter will cause some extra inverter idle power consumption.

 

[solar8484]

Hi. I've got a generic PSW inverter rated at 2500w/5000w peak.

It's been in full time use for a year. I noticed the fan comes on regularly when it's in standby. It didn't do that when it was new, and it's standby temperature is 40C.

It's in full time use on a boat so humid environment.

It's also drawing 2-3 amps in standby with no output load. I'm sure it didn't draw that much when it was new.

Is this normal?
Is there some internal maintenue i can do? (Wash board with alcohol?)
Or part of the circuit i can investigate for failure?

What's the battery voltage? 20-30W idle is not unusual for cheap inverters. Can you post photo of the internals? It could be failing transformer winding insulation.

 

[time2roll]

The inverter is living in a 40C environment? Check for good ventilation and dust in the vents. Otherwise I call normal.