Posted: Wed Apr 10, 2019 6:06am

Hi folks, I've been having some electrical issues with my Victron inverter box which I can't resolve and would appreciate any assistance. A short while ago, I started to notice a buzzing sound coming from my inverter box, which was very unpredictable and intermittent. This would only happen when I had the boat plugged into the shoreline mains socket, not when running on batteries only. After a few weeks, I then noticed what sounded like a 'crunching' noise coming from within the inverter box at the same time it was buzzing - like there was a bunch of switches inside flicking up and down quickly, like it didn't know whether to be on or off. Then after a while I noticed a smell of burning coming from somewhere in the bedroom, and when I opened up the back doors of the boat, there was a thick layer of smoke drifting across the back deck of the boat. I then reached outside and pulled the plug from the socket to disconnect it from the mains. When I inspected the socket outside the following day, I found that what looks to be the live pin had charred and blackened (see pic) - so this is obviously not good. Do any of you folks have any idea what could have caused this? I was not using any heavy appliances at the time - just lights, 12v fridge and TV. I've replaced the mains power cable itself in case this was the cause (I couldn't actually see anything wrong with it) - but it still started making the same noises again a few weeks ago. I've reported this to the boatbuilders, and they said they've never heard of this happening before. There are no signs of any fuses blowing, or any burnt wiring in the main control panel. I've even invested in a thermal imaging camera, because these can help you to see behind the walls to detect any hot spots or anything potentially short circuiting, but no joy. Any suggestions as to what may cause this would be much appreciated. Many thanks Nick

Posted: Wed Apr 10, 2019 7:08am

First of all the forum reduces images to a size that is unusable, if anyone feels they need to send am image it is best to email me directly - Tony@tb-training.co.uk. Secondly is this a simple inverter or an inverter *replaced* battery charger, I think Victron make both. The first thing that struck me was that the image you sent seem to have no cover on it to keep rain and mist out. I am also unsure as to how it is orientated on the boat. In my view the part with the pins should always be at the top so any water getting to it can drain away. Although too small to be sure it looks to me as if the pin with black around it might be the large earth pin, not one of the small live or neutral pins. If so that suggests water caused a shorted between live and earth but if it did then I do not understand why the RCD on the power bollard did not trip (assuming you are in a marina). My next thought was about how well the batteries were charged at the time and if the Victron was acting as a battery charger. Talk of the boatbuilder makes me suspect you may be new boaters (no info given) and the combination of inverter plus new boater all far too often results in battery failure caused by consistent over discharging of the batteries. A battery with a shorted cell or cells would really load the charger part of a Combi unit (inverter-charger) so would cause it to draw a relatively large mains current through the shore line. There is a relay or relays in many inverters and inverter chargers so you may have heard one of those chattering and the buzzing might have been the inverter delivering a heavy load combined with arching in the plug/socket. Make sure the socket fixed to the boat is protected from the weather and any rain that might get in is not trapped on a ledge or some such. Make sure the individual pins and sockets are not loose. You will have to do this with the mains and inverter OFF plus boat battery master switches off, take care mains can kill. Send me the domestic and engine battery voltages taken as you get up in the morning with no electrical equipment running. Don't have the battery charger running over night. That will give a clue as to the state of the batteries. That is about all I can suggest on the present information.

Posted: Thu Apr 11, 2019 5:15am

Hi Tony, Thanks for your response. Its's both an inverter and a charger - you can switch between the two, but I normally have it switched to inverter. The socket does have a rain cover, it's just lifted up on this shot so you can't see it. I always have the cover down and protecting it as much as possible when it's plugged in. The batteries are normally fully charged, as I like to keep the batteries topped up, and very rarely let them run down below 80% or so. I'm not a new boater, my boat was brand new when I bought it 8 years ago - the reason I reported it to the boatbuilders is that I also rent my mooring spot from them, and I'm plugged into one of their own power bollards. They said they've not had any issues or complaints about their electrics, and they've just had them all upgraded, so I'm ruling that out as the potential cause. Both the socket on the boat and the bollard look to be fine, condition-wise, and I can't see anything there that would cause the fault. I've inspected the pins on the cable and socket to make sure nothing could be causing it to short out anywhere. My biggest concern is that I've had lots of other issues on the boat since it first arrived - leaks happening just about everywhere, windows, roof hatch, shower, fridge, central heating, you name it. One of my latest discoveries was that the porthole window in the bedroom had been leaking water straight down through my light switch, and this was in exactly the same spot I discovered the burning smell. So I'm concerned something like that might causing it as water doesn't mix well with mains electricity. I will do the test with the battery levels, to check what state they're in, but I'm pretty sure they'll be fine. I'm away from home at the moment, but I'll get back to you with the readings as soon as I can. Many thanks

Posted: Thu Apr 11, 2019 6:34am

I an afraid that you are not going to like what I must now advise. Long experience from me and others indicate that in the vast majority of cases boaters who talk about batteries being a percentage discharged or charged almost invariably are using an "Amp hour counter" type gauge like the Victron BVM. Unless you have studied is great detail AND have reset all its settings AND very regularly ensure the batteries fully charged and the resynchronise the unit they are first rate at ably assisting you in destroying your batteries but consistently overstating the state of charge and understating the degree of discharge. These errors get larger and larger as the months go on so batteries sulphate and lose capacity that the BVM does not know about and also causes the batteries to cycle more deeply and that also shortens the battery life. Please ignore and percentage charged, percentage discharged, or charge left readings. You can rely upon the Voltage, Current, and Amp hours OUT (not in) as being accurate. It is best to charge until the charging current falls to 1% to 2% of battery capacity at a 14.4 charging voltage and the is as close to fully charged as you will get. Use rested voltage to *replaced* the state of discharge. I can send you an indicative table if you want. Never discharge to below about 12.2 Volts while nothing is turned on or running if you want optimum battery life and always recharge as soon as you can. The above explains why I asked for voltage readings taken first thing in the morning. The reason I suspect you might have a battery problem is that you got clouds of smoke and although a short circuit between the line and earth pins in the socket would cause this (damp/water) so might a high current draw and with the loads you say you had turned on the only things that could cause a high current draw that I can think of is the battery charger working into a shorted battery cell(s) or an inverter fault but if you cured the problem by replacing the shore line I suspect the most likely explanation is damp/water in the plug.

Posted: Thu Apr 11, 2019 6:35am

PS very happy to wait for the voltage readings.

Posted: Mon Apr 15, 2019 9:12am

OK, I did the test over the weekend and the voltage readings in the morning were 13.0 and 12.8 for the domestic and engine batteries respectively. Cheers Nick

Posted: Mon Apr 15, 2019 9:44am

Thanks, as long as no solar or other charging had been done since the previous evening then the domestic bank look fully charged but in normal use I have doubts about that reading. I suspect they had wee on charge or had very recently been on charge. The reading if true implies you used no electricity since the last charge was shut down. If we take the readings as true then with your stated 240V use it seems to me that a high inverter current could not be the issue so we are back to a faulty inverter which is not likely or shorting/poor contact in the shoreline which is more likely and on an inverter that offers "assist" to add to the shore power I suspect a connection fault would cause the relays in the inverter to chatter. I think with just a poor resistive connection it may also make the inverter hum. I still feel the most likely problem was water in the plug/socket. Sorry I can't be of more help.

Posted: Tue Apr 16, 2019 9:30am

OK, thanks very much for your help.