Inverter issue

Boris7

Boris7

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My inverter has developed an issue.

When in use the power goes on and off repeatedly every few seconds.

I had a compressor fridge/freezer fitted recently and I’m wondering if that’s anything to do with the issue.

Anyone got any suggestions? I’m in Spain heading south (very slowly) so can’t pop back to the workshop any time soon.
 
That’s exactly what I thought, so I waited till this morning when everything had cooled down and it’s no different.
 
I would look at any changes made such as your fridge.
My victron inverter won’t allow my wife to use her hair dryer on the low setting, but it’s fine on the high setting, seems weird, but apparently it’s common with inverters.

I would try turning off the supply to the fridge and see how you get on.
Also if you have a victron inverter some things won’t operate on Eco mode.
if you have bluetooth it should indicate cause.
 
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Be useful to have more details e.g. make & model of inverter, size, what is connected when it goes on and off, etc.
Also, did it used to work and just developed this problem? any changes made that co-incide with the issue starting?

You said you have a compressor fridge/freezer recently fitted? is it a 12v one or 240V (12V ... should be irrelevant to inverter, 240V ... runs through inverter)
 
If start up current is high due to heat the inverter may be at peak and keep swithing on and off, maybe a bigger one would be better.
 
It’s an NDS SP-3000 fitted about 2.5 years ago and till now has been faultless. It’s 3kw and the issue arises when using a 2kw kettle or an 800w microwave.

The compressor fridge was fitted the week before last and runs of 12v (I’ve check with inverter on and the fridge still shows 12v only)
 
Boris7 said:
It’s an NDS SP-3000 fitted about 2.5 years ago and till now has been faultless. It’s 3kw and the issue arises when using a 2kw kettle or an 800w microwave.

The compressor fridge was fitted the week before last and runs of 12v (I’ve check with inverter on and the fridge still shows 12v only)
Click to expand...
sounds like it has gone faulty assuming your batteries have enough charge to drive it.

If the inverter IS ok, then the only reason why I can think you would have a issue with the kettle or the microwave on it is if the battery bank didn't have enough power, causing the input voltage to drop below the minimum allowed under the load.

Have you got something you could plug in with a much lesser load to see if that works? and look at the battery voltage when the loads are put on (bearing in mind the voltage into the inverter will be lower due to cable losses).
I am assuming decent cables have been used for the inverter installation? And sadly that means NOT using any supplied with the inverter as they are invariably undersized.
 
Boris7 said:
Batteries are at 100%.

I’ve been driving and the inverter has charged the EcoFlow with no issues.
Click to expand...

It is simple then.
Plug in the microwave into the Ecoflow. Does it work? If no, Microwave appears faulty.
If it does, plug it into the Inverter. Does it work?
If not, Inverter is faulty if the supply to the inverter is good, which you have seemed to confirm above.
If it does, repeat process with kettle to see if it is something to do with load levels.
 
Too much effort to plug the microwave into the EcoFlow (it’s built in) but the kettle works fine on the EcoFlow therefore looks like the inverters gone up it 🤬
 
The way I#m reading this..
In the good old days, you had a 3kw inverter and it ran a 2kw 230v kettle and a 800w 230v micro wave with no problem.

Put then you added a 12v compressor fridge and the inverter switches itself off when you try and run the kettle and the microwave.

Now Kepner Tregoe problem analysis says examine what has changed and that clearly highlights the fridge has a factor.

The theory that @wildebus put forward is that the fridge reduced the input voltage to the inverter causing it to cut out seems very plausible.

To test this theory just switch the fridge off before using the microwave or kettle.

If the theory is proven a couple of things need looking at.
a) the size and condition of the battery bank
b) the size (diameter & length) and condition of the 12v cable (particularly from the battery to the inverter). A 3000w inverter draws 250 w. Don't forget that any connections are part of the cabling and a bad connection could be to blame.
 
The first thing I'd check is to test the voltage at the input terminals of the inverter while the inverter is powering either the kettle or the microwave because this will tell you what's NOT at fault. If there's constant good voltage then it's almost certainly the inverter that's up the Swannie.
If the inverter terminal voltage drops drastically then it could be a poor connection somewhere on the power wiring.or if you've got paralleled batteries then it could be that you have a battery down and one battery alone can't deliver the necessary current and it's BMS is tripping out.
 
The fridge kicking in could cause a potential intermittant low voltage situation on the inverter as there would be a in-rush surge load on the battery of around 70A for a second or two, but once running, the fridge load would be just noise compared to a 2kW kettle.

Before condeming the inverter for sure, if you have a meter, I would definately put a meter on the Inverter DC Terminals (NOT the battery terminals) and see what the voltage is at no load and then when you try and run the kettle.
I don't know the spec of your specific inverter, but they usually will accept a voltage down to around 11V before complaining about low voltage (for example, the Victrons from memory are preset to 10.8V). If you are seeing a voltage in the low 11V, then I would look further into the DC supply end.
Expanding on R4Dents point b, check for any signs of overheating - melted heatshrink, discoloured terminal lugs, distorted fuse holders - these can be signs of a bad connection and bad connections cause voltage losses. And it is a vicious circle with voltage losses and inverters .... as the voltage drops, the input current will often rise to try and provide the demanded wattage, and the increased current will create a bigger voltage drop, which leads to a higher current, that .... you get the picture.

Oh, and also try the sniff test... A failed inverter will often be rather smelly ;)
 
r4dent said:
Now Kepner Tregoe problem analysis says examine what has changed and that clearly highlights the fridge has a factor.
Click to expand...
Having been involved in electronics and electronic repairs for over fifty years I can tell you that coincidence seems to laugh in the face of Messers Kepner and Trego.
Remember the recent WC post about an electrical short that appeared immediately after the OP put some screws through the wall panelling? Needless to say that wasn't the cause and I doubt the fridge is responsible in this case either.
 
merl said:
Having been involved in electronics and electronic repairs for over fifty years I can tell you that coincidence seems to laugh in the face of Messers Kepner and Trego.
Remember the recent WC post about an electrical short that appeared immediately after the OP put some screws through the wall panelling?
Click to expand...

Which would have been identified using KT problem analysis. :)

If Charles H. Kepner and Benjamin B. Tregoe methodology is good enough for NASA it is good enough for me.

It is one of many problem analysis techniques, but is usually the first I use.
 
I’m staying put today, I’ve just spent an hour picking up other people’s litter around the Aire I’m staying at then I’m going for a walk. After that I’ll try and get to the bottom of this, but I fear it’s the batteries or the inverter.

Turning the fridge off makes no difference so I find it hard to believe the fridge is at fault. Obviously I could be wrong.

In hindsight I was less than happy with the people who did the lithium and solar, but it’s been on the van a few years and I’ve not had any issues other than the fact I was lied to (they are no longer trading)
 
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