Inverter discourse - warning, very boring....

Advance warning - for most normal people this will be very very boring. It was pretty boring typing it too. However, as there are a couple of people out there who like to know in detail what maintenance and repairs are needed, here goes. It might help another Nordhavn 47 owner in future too.

Background:

The boat has a pair of Victron inverters fitted. They act as battery chargers for our 24v system and can generate 240v mains style power from the batteries when we are not on shorepower and have the genset switched off. They are capable of producing around 6Kw of mains power form the batteries but we never do that - far too hard on the rather expensive Lifeline battteries as it involves a high discharge rate. We do use the inverter capability when underway with 24v power coming from the large engine alternator, for things like a kettle, keeping the fridge / freezer going, engine room fans, TV etc. The lovely SubZero refrigeration kit is quite a convoluted thing when "off grid". The inverters turn 24v DC battery power into European style 240 v, 50 Hz AC power. Then a converter device changes that into 110V, 60 Hz AC power USA style to run the USA spec SubZero devices. Not terribly efficient with losses at each stage but as the SubZero kit is so good, we forgive it.

The misbehaving inverters have been documented in prior posts so no plan to reproduce all their misdemeanours that except to say that on our last run across to Holy Loch, they refused to fire up at all (i.e. no 240v power for that trip unless we had the genest running).

Swap out:

This isn't simple at all. As an example, the remote control panel has to be changed for the newer digital type. This is the original (on a day when it decided to work) :

and this is the new smarter version - note no exposed screws hence some fitting fun:

Confusingly the lights have swapped sides so to begin with it is worrying when you just glance at it  to check all is working properly. More frustrating is that the fixings are totally different despite the panel being the same size.. Also the position of the cable that links it to the inverter pair has moved meaning you need more cable free which had to be cut free from a bundle of cables. Great start.

That is small beer compared to the inverters themselves. The big heavy battery connections are different as the old units have a 300 amp fuse inside the case. The new ones want an external fuse. Oh, and the terminations for the various sensors are different and the ground strap positions too.  Then the mounting to fix them to the wall has changed too. Get the idea?

For those of you who like electronic porn, here are a pair of topless inverters - old ones though so don't get too excited and the left hand side unit is sickly:

We got a new pair from a Victron dealer in East Kilbride at a way better price than the folks from Energy Solutions. Everything we try to buy from ES (they are the Northern Lights / Lugger dealer) seems wildly priced and never in stock either.

They sat and looked quite innocuous - if a bit heavy -  in the saloon after collection:

As we could not modify the heavy heavy 24v DC cable runs ourselves, we enlisted the help of Peter, the excellent engineer man who runs Swordfish marine in Holy Loch. We are very pleased that we did... We also got some very speedy advice from the USA Nordhavn folks thanks to a referral from Nordhavn Europe. We needed to know about a couple of configuration options (eg ground relays) as we could not "interrogate" the old inverters to see how they were setup because they refused to fire up. Catch 22 time!

The power distribution panel looked strangely dead as we removed the 24v supply:

However, by using the bypass function we could still have mains power for the fridge / freezer and to make tea and coffee! You can see that the inverter panel is "on" in the pictures above, just the gauges are dead without 24v power to light them up. The only challenge was that the kettle had to be filled from a hose as no 24v power means no water pump.

Removing the old inverters was amusing. They were through bolted to a sheet of chunky plywood. Only you cannot get your arm around behind it to reach the bolts of the furthest inverter. Wonderful. You cannot remove the back panel itself as the inverters are fitted on top of some of the securing screws. It just gets better and better. So, the end of the enclosure was removed and luckily it was sealed with silicone and not 5200 or some other infernal gunge. That allowed a long arm to reach the fixings by feel and for their removal. The back panel came out too :

A strange and sad little void was the result. Then more fun. The new units have a bracket that they are designed to hang from. Only you have to lift them up and onto it. The void is not big enough to do that! Maybe it was designed with some USA 110v inverters in mind, not the Victron units which are a very tight fit. So, two holes needed to be drilled in the top of each inverter and we moved them closer to the source of all the cabling to allow us to use the unmodified heavy battery cables. Party! Well, sort of. For a while the saloon floor was an inverter farm (if that is the collective noun? We prefer "a pain") :

Once they were in, the different position of the earth cables was the next challenge - we had to take the fan cover off to fit the strap properly. Why oh why did that need to be moved to the back of the case? Luckily the existing straps were long enough with some judicious "jiggling".

After finally coupled up the Victron software on our laptop refused to set them up as a "master and slave" arrangement. Victron must have been visited by the politically correct police as they are now called "leader and slave" by the way.  The good news was that a simpler version of the software worked and we happily saw power, inverting and battery charging again:

When using the version that allows all the parameters to be changed, the preset values in the system for Lifeline AGMs disagree with the Lifeline manual recommendations:

We reckoned that Lifeline knew better and modified things to their manual. The good news is that the config changes are pretty simple to do.

All in all, another one of those jobs that looked straightforward because the inverter casing appeared the same which disguised the many changes made to the fixings for no obvious reason. No matter, we were very happy to have functioning inverters again.