Sterling Inverter Question

[KenK]

I have a Sterling 3KW inverter on the boat, it is a little over three years old. It works ok but it does seem to spend a lot of time spinning it's internal cooling fans, even when there is no output load. It is in a well ventilated cupboard, top filter is clean and the air comming out of the inverter when the fans are running is cool. Anyone know if this is normal for these units?

 

Ken

[Guest]

I have a Sterling 3KW inverter on the boat, it is a little over three years old. It works ok but it does seem to spend a lot of time spinning it's internal cooling fans, even when there is no output load. It is in a well ventilated cupboard, top filter is clean and the air comming out of the inverter when the fans are running is cool. Anyone know if this is normal for these units?

 

Ken

My 3 Kw Sterling is a bit older but does exactly as you say, whether on load or idle. I assume it is normal (I find the fans rather noisy). As an aside, my 3Kw Sterling had NO neutral earth link, which meant that the RCD could not operate.

[KenK]

My 3 Kw Sterling is a bit older but does exactly as you say, whether on load or idle. I assume it is normal (I find the fans rather noisy). As an aside, my 3Kw Sterling had NO neutral earth link, which meant that the RCD could not operate.

 

Thanks for that, I'll check mine. In addition I made one of those crimp tools to your design, brilliant idea well done.

 

 

Ken

[Guest]

Thanks for that, I'll check mine. In addition I made one of those crimp tools to your design, brilliant idea well done.

 

 

Ken

I'll bill you for the plans in due course TBH it was somebody elses idea, I just developed it a bit. Glad it worked though.

[Arnot]

I have a Sterling 3KW inverter on the boat, it is a little over three years old. It works ok but it does seem to spend a lot of time spinning it's internal cooling fans, even when there is no output load. It is in a well ventilated cupboard, top filter is clean and the air comming out of the inverter when the fans are running is cool. Anyone know if this is normal for these units?

 

Ken

I have not had chance to look at these things closely but...

 

I was working on a boat today and installing a battery management system that (amongst other things) showed the current draw on the domestic battery bank. To demonstrate how it worked, I asked the owner to fill his electric kettle and boil it so he could see the current voltage relationship. The kettle was one of the low power 1kW versions, the current draw on the inverter was 186A at roughly 12V.

 

However you look at it, the inverter was consuming more than 2kW from the battereis to provide 1kW of mains! That would bring the fan on wouldn't it.

 

If I get chance I will have another look and meter it properly.

 

Regards

 

Arnot

[MoominPapa]

However you look at it, the inverter was consuming more than 2kW from the battereis to provide 1kW of mains! That would bring the fan on wouldn't it.

If the inverter is really less than 50% efficient I think you should post the make here, so that we can all avoid buying them. If it's dissipating more than a kilowatt, that should be pretty obvious, think 1kW fan heater. or moderately powerfull hairdryer.

 

I'm in charge of wardrobe-sized computer systems which can burn 30kW flat out, and if you stand behind them, where the air exits, it's very obvious how hard (or not) they are working,

 

MP.

[Gibbo]

I have not had chance to look at these things closely but...

 

I was working on a boat today and installing a battery management system that (amongst other things) showed the current draw on the domestic battery bank. To demonstrate how it worked, I asked the owner to fill his electric kettle and boil it so he could see the current voltage relationship. The kettle was one of the low power 1kW versions, the current draw on the inverter was 186A at roughly 12V.

 

However you look at it, the inverter was consuming more than 2kW from the battereis to provide 1kW of mains! That would bring the fan on wouldn't it.

 

If I get chance I will have another look and meter it properly.

 

Regards

 

Arnot

 

I think it's more likely that the ammeter is faulty or the cables to the inverter are too small resulting in a large volt drop hence the inverter has to pull more current to produce the output.

 

A typical sized 2 or 3kw inverter would destroy itself in seconds if 2kW went in and only 1kW came out.

 

Gibbo

[tosher]

I have a Sterling 3KW inverter on the boat, it is a little over three years old. It works ok but it does seem to spend a lot of time spinning it's internal cooling fans, even when there is no output load. It is in a well ventilated cupboard, top filter is clean and the air comming out of the inverter when the fans are running is cool. Anyone know if this is normal for these units?

 

Ken

 

 

I have Sterling 3KW inverter (combi unit) about a year old, the fans do run quite often, for short periods, but only when the inverter/battery charger is working quite hard. When just floating the batteries on shore power the fans never run. This inverter was a replacement for my original one that kept tripping out, the fans on that one never ran at all so maybe that caused the fault. It was replaced by Sterling after 2 years free of charge. tosher.

[Arnot]

I think it's more likely that the ammeter is faulty or the cables to the inverter are too small resulting in a large volt drop hence the inverter has to pull more current to produce the output.

 

A typical sized 2 or 3kw inverter would destroy itself in seconds if 2kW went in and only 1kW came out.

 

Gibbo

Actually it was simpler than that eventually... The label on the kettle originally read 1800w but wear had obscuered the bar in the eight. Interestingly it had been sold to the user as a "low power" one - whoops! Also I suspect that the primitive current measurement on the management system was slightly flummoxed by the inverter input current waveform but I didn't have time tonight to compare it to a proper instrument. I am going to visit the boat again in the next few days and, just for the interest, do the comparison.

 

I don't know if you have any experience of these units but it sounded very "zizzy" but it might just have been the cupboard it was in bouncing the sound around.

 

Regards

 

Arnot

[Guest]

Actually it was simpler than that eventually... The label on the kettle originally read 1800w but wear had obscuered the bar in the eight. Interestingly it had been sold to the user as a "low power" one - whoops! Also I suspect that the primitive current measurement on the management system was slightly flummoxed by the inverter input current waveform but I didn't have time tonight to compare it to a proper instrument. I am going to visit the boat again in the next few days and, just for the interest, do the comparison.

 

I don't know if you have any experience of these units but it sounded very "zizzy" but it might just have been the cupboard it was in bouncing the sound around.

 

Regards

 

Arnot

MySterling is very "zizzy" too. Iknow the noise well, and it has always made the noise. It reminds me of the noise that HV overhead lines make in damp weather.

[Gibbo]

Actually it was simpler than that eventually... The label on the kettle originally read 1800w but wear had obscuered the bar in the eight. Interestingly it had been sold to the user as a "low power" one - whoops! Also I suspect that the primitive current measurement on the management system was slightly flummoxed by the inverter input current waveform but I didn't have time tonight to compare it to a proper instrument. I am going to visit the boat again in the next few days and, just for the interest, do the comparison.

 

That made me giggle.

 

I don't know if you have any experience of these units but it sounded very "zizzy" but it might just have been the cupboard it was in bouncing the sound around.

 

Yeah that sound is pretty normal for high frequency pure sinewave units. It's the inductors in the output filter whistling at the chopping frequency subharmonics. They could get rid of it by potting the inductors, but that would cost another thrippence in potting compound and a slightly bigger inductor. One of my products does it

 

Gibbo

[KenK]

That made me giggle.

 

 

 

. One of my products does it

 

Gibbo

 

Well I know it isn't the Smartgauge cos thats in and working, and very well too. Haven't fitted the Smartbank / relay yet as I wanted to see how well the single alternator coped.

 

I'm going to stick a thermocouple wherever they put the heat sensor on my Sterling and see what temp the fans cut in at, if its a silly temperature I can replce it with a more sensible one.

 

 

Ken

[Gibbo]

Well I know it isn't the Smartgauge cos thats in and working, and very well too. Haven't fitted the Smartbank / relay yet as I wanted to see how well the single alternator coped.

 

The relay does it

 

I'm going to stick a thermocouple wherever they put the heat sensor on my Sterling and see what temp the fans cut in at, if its a silly temperature I can replce it with a more sensible one.

 

You might have some trouble there. It's an analogue temp sensor that goes into a processor which decides when to switch the fan on. The software also switches it on under heavy load even if it's freezing cold.

 

Gibbo

[Guest]

The relay does it

 

 

 

You might have some trouble there. It's an analogue temp sensor that goes into a processor which decides when to switch the fan on. The software also switches it on under heavy load even if it's freezing cold.

Gibbo

That explains a lot. Ours seems to switch thefan on pretty constantly when near full load (very rare ). Can't half discharge batteries quickly at full load.

[MoominPapa]

The software also switches it on under heavy load even if it's freezing cold.

Our Statpower 1800W pure-sine inverter does something like this, and it's incredibly annoying because the start-up surge of the fridge triggers the fan every time. The inverter is perfectly capable of running the fridge without the fan on, and it goes off again after running for a minute or so.

 

MP.

[Gibbo]

Our Statpower 1800W pure-sine inverter does something like this, and it's incredibly annoying because the start-up surge of the fridge triggers the fan every time. The inverter is perfectly capable of running the fridge without the fan on, and it goes off again after running for a minute or so.

 

MP.

 

I worked for that company when that unit was being designed. I asked them "why have you got the fan coming on under heavy load?". The reply..... "Because it's going to get warm".... Hmmmm I see a flaw there somewhere.

 

But they all seem to design in this "feature". I think it's stupid.

 

Gibbo

[MoominPapa]

But they all seem to design in this "feature". I think it's stupid.

I agree. In all other respects the inverter seems to work very well.

 

MP.

[KenK]

The relay does it

 

Ok well I won't moan at you Albrite are right next door!

 

You might have some trouble there. It's an analogue temp sensor that goes into a processor which decides when to switch the fan on. The software also switches it on under heavy load even if it's freezing cold.

 

Any idea whether its a resitive input or a voltage?

Gibbo

 

Ken

[WJM]

Mine is totally silent unless it is under a big load. Only then do the fans run.