nbBox12

It's more just to test it, really. I would just seem like a very cheap and easy way to test if it's really a problem with the wires and voltage drop, or there's something else amiss. It might give me an idea of what to expect cost-wise before I get the engineer in.

OK, thanks. So while I'm trying to get it fixed is there any way I can get it back up and running temporarily? As its only 12 volts, could I not run it directly off a car/leisure battery or something similar - and maybe test it with some more suitable wiring to test if that's really the problem?

So is there any way to conclusively rule out the fridge itself as being the culprit rather than the wiring? Given that it's 8 years old and has worked perfectly fine up until last week, could it not be something wrong with the fridge itself? I don't want to go to all the trouble of taking out the bulkhead at the back of the kitchen, the bathroom and bedroom to replace a couple of wires, only to find out that it still hasn't solved the problem.

That was without the engine running, battery charger off, and plug disconnected from the shoreline.

I managed to read the voltage off the running fridge this morning, and it gave a reading of 12.2v. At the time, the voltage reading directly off the batteries was 12.8v. I'm guessing this is just outside the generally accepted voltage drop of 3-4%?

Yes, thanks for the clarification. I'm a compete noob at this so please forgive my misunderstandings of some of the suggestions and terminologies being used and so on. That's why I originally asked for an electrician!

OK, thanks for the info. I'll give it another go then, and see what it says under load if I can.

No, I couldn't do that. The plastic sheaths completely cover the connectors, so I had to unplug the wires to check the voltage that was coming through them.

So I managed to test the fridge with the multimeter this morning. With the mains disconnected, inverter off, and the lights and fridge running just on batteries, the voltage reading from the back of the fridge said 12.6v. I've included a picture of the fridge wires below. As you can see, they're pretty thin - about 1.5mm I reckon, but the compressor still feels warm, and the fridge is still buzzing like it normally would. But even with it turned up to maximum it's barely even cold inside, whereas it would normally be totally iced up along the back wall. I also noted that the main Voltage Reading off the batteries at the time was 12.6v (whereas the BMV said 1.96v). So I'm guessing I maybe do have 2 separate issues, with both BMV and fridge playing up at the same time. Still not totally convinced though.

OK, thanks very much for the suggestion, this is very handy. Holt Heath is only a 20 minute drive from me, so if I can't get anything resolved by the weekend, I'll see if I can get him to take a look. Cheers

Yes, you're right, the wires on the fridge are very thin, but it came installed like that from the factory and has worked fine for the last 8 years until now. I'll get the multimeter on it tonight to see what it says. The connectors on the wire going from the shunt to the BMV have what looks like an RJ11 connector at both ends, and I've unplugged both several times, but it might be worth another look to see if there's any corrosion or debris preventing it from working normally. Resetting everything back to the factory settings on the BMV might also help, but I've always avoided messing around with it, so I'm not sure why they would have changed anyway. It's also worth noting that if I have a low charge when using the inverter, it would normally flash a red light with the 'low battery' warning - but I haven't seen this happen for a very long time. The inverter seems to behave as if everything's normal, it's the BMV readings which are confusing.

OK, well my eyes were not deceiving me. All the figures I reported yesterday were correct. The photos attached show the Victron battery monitor (which I'll just call the BMV from now on) with a value of 1.99v, the SoC giving '---' and a current of 0.18 amps. And yet, you can also see the Voltage Reading off the batteries on the top display is giving 13.5v. The charger/inverter was currently on 'float' at the time. As far as I can tell, there's no issues with segments missing off the BMV display, as I can flick through all the other settings and menus and everything else displays as expected. Could it be the shunt itself is not giving the correct reading? I've included some photos of the condition of the batteries and shunt I took at the weekend. Like I said, I unplugged the shunt briefly just in case this was causing the issue. I did another test this morning by unplugging from the shoreline/mains again. The inverter kicked in like it should, and everything stayed up and running. I put everything on at once - lights, tv, microwave, taps and shower. It all worked fine off the batteries, no sign of any power shortage. I left the bathroom tap running for several minutes and there were no signs of the pump struggling. The Voltage Reading directly from the domestic batteries dropped to 12.1v, and the BMV showed a value of 1.98v - but I find it hard to believe anything would still be working if it was truly running off of 1.98v! It might be worth doing a hard reset on the BMV to see if this corrects things. I've written down all the settings, so I can always set them again. You can manually synchronise the monitor to the batteries too, so this might also be worth a shot. Of course, none of this explains why my fridge has stopped working - which does not run properly regardless of whether I'm on mains, inverter or running the engine. Could this be a separate issue which just happens to have occurred at the same time?

The figures in red are volts, read from the Victron battery monitor - which is the BMV 600s model. I admit, it does look like I've just knocked a '10' off all those values, but those are the readings I got yesterday. When I get home tonight, I'll double check everything and take some pictures of the values I have on my displays so you can see for yourselves. The other reading I sometimes refer to on the Victron monitor is the state of charge (SoC), which at the moment is just reading '----'. As I said earlier, this monitor has been known to glitch from time to time - but I've pulled the plug from the back and put it back in again, and also done the same thing on the shunt outside, just in case there was a fault with either one of them.

OK, I have managed to do a bit more investigating at the weekend. A visual inspection showed the batteries look in generally good condition, they're not getting hot, and there's only a small amount of deposits showing around one of the terminals - which I managed to brush off using a wire brush. I also switched the isolator switch off/on in the engine bay to eliminate any issues it might be causing. I have 3 x Victron 12v 220Ah AGM domestic batteries, and a Numax 100Ah starter battery. I conducted the test of switching everything off and back on again, and the voltage reading shot up from 12.6v to 14.6v, and the battery monitor shot up from 3.5v to 3.9v. I also noticed the charger box switched to 'bulk', then it went to 'absorption' after only a minute or so, and then finally went to 'float' after about 20 minutes. The monitor was only showing just over 4.0v at the time, so it's like the batteries are struggling to accept the charge. I then tried running the engine to charge the batteries. A similar thing happened, but the monitor this time went up to around 4.5v, where it seemed to stop and couldn't go any further. After 3 hours of running the engine, the monitor started to drop again, back down to 3.9v. I eventually switched it off completely as it obviously wasn't helping, and now I'm plugged back in to the shoreline, it's sitting around 2.5v.

OK, thanks for your replies. I will have a good look at the batteries over the weekend to see what's what. I'm due to take the boat out tomorrow to get the tank emptied, so that will give me a good chance to test the electrics etc. while unhooked from the mains, and see if I get any different results while running the engine. Cheers