nicknorman

However, the solar voltages (assuming as per the pdf) are set to 13.6v absorb and 13.5v float, so prolonged exposure to those voltages shouldn't be an issue. That is a very comprehensive system, must have cost a fortune to install! I can't see anything signficantly wrong with the settings, assuming they are actually as per the pdf. A couple of observations - the battery state of charge monitoring seems to be based on the Mastershunt. This is a straightforward coulomb-counting device that suffers (like all of its ilk) from a gradual drift away from accuracy over a few weeks. The cure is to occasionally fully charge the batteries (eg 14.4v until current falls to 5% of capacity) at which point the Mastershunt will reset to 100%. I can't immediately see an easy way for you to do this as the solar voltage is set low and it looks like the Mastershunt tells the alternator to go to float at (what it think is) 90% SoC. Possibly the Alter Float button on the Easyview 5 will do this, it's not quite clear to me - but only when charging from the alternator. Anyway the point is that it is advisable to fully charge the batteries eg once a month to get correct SoC readings from the Mastershunt. Also I notice that in the Alpha Pro, the "small engine" rpm settings seem very high. I am pretty sure that if the pole pairs number, and pulley ratio, are set correctly (as they seem to be) then the rpm numbers reflect the engine rpm, not the alternator rpm. I don't know what engine you have but it seems unlikely that it will rev to 4500 especially on the canals! I wonder what charge current you actually get at canal cruising speed (or a fast idle speed, say 1200rpm if it's a modern japanese type engine) because it looks to me as though its unlikely to go over 20% field current at normal speeds, giving you only about 20% output. Anyway, none of this explains why the batteries are knackered so I think you should go ahead with the new ones and just keep an eye on how the system behaves in practice, in terms of charge voltage etc. Could it be that the batteries were second hand when installed, having previously been abused? Who knows!

You had a proper battery test done then! This must be a first! Usually people report the "battery health" from one of those halfords type car battery testers, which of course are totally useless for leisure batteries. Well I think everything I said perviously, stands. The Winston cells are top quality and should have a long life. The BMS looks a pukka one. So really I think something in the setup is wrong, if the cells have died after 5 or 6 years. I see there is an App for the BMS, do you have it and if so you could read the settings and let us check them. In order to kill the cells in that fairly short time I would think they have been over-discharged (BMS failed to isolate the cells), over charged (ditto), charged at very low temperature a few times (ditto), or some such. Also have a look at the two external relays for charge and discharge disconnect, are they working correctly and not bypassed?

Even if that were the case, the solution of “professional install” would not prevent a recurrence of the problem.

This seems an entirely illogical comment. The boat in question had a “professional” installation, it blew up. So the solution to preventing a recurrence is to insist on a professional installation?

A zener diode is pretty much the same as a diode, but with different chemical doping to make the reverse breakdown more stable and predictable. So it conducts in the forward direction like a normal diode. It blocks reverse voltage like a normal diode ... up until its breakdown voltage (which depends on the detail of the chemicals and physical geometry) at which point it starts to conduct in the reverse direction. It will then maintain the rated reverse breakdown voltage across the diode (within its heat dissipation capabilities). So by using a zener as a rectifier, you get the normal behaviour when things are going normally and the voltage is as expected (say 14.4v) but if there is a "load dump" event and the voltage in the stator rises too high, the zener diode will start to conduct when the reverse voltage gets to its breakdown voltage (say 35v) and thus shorting the excess energy through itself and converting it to heat. The maximum voltage is then capped at around its rated breakdown voltage (well, a bit higher due to its internal resistance etc). It's analagous to a pressure relief valve in plumbing! I think (guessing!) that historically it was difficult to make a zener diode that performed well as a high current rectifier diode AND was a zener, but things have moved on. I added my own load dump transient absorber not to protect the alternator, but to protect the 12v services that might not like 35v. My diodes should hopefully limit the voltage to about 18v, but I have never tested in anger!

Should be OK re. earthing, I would connect the 2 earths from the shore sockets together, then pass them through the GI to join the inverter and hull earth, whilst the L and N after the selector go through the RCBO. I don't think a long internal cable from the shore socket is a problem for the BSS, but it is contra-indicated in the ISO which requires a circuit breaker within 3 metres of the shore socket if the cable is sheathed or trunked (it's 0.5m if it isn't, but eg arctic flex sheathing is adequate to satify). So it depends on how squeaky clean you want to be!

I think setting the charge voltage to 13.8v makes this pretty unlikely. The 175A alternator doesn't have "ordinary" diodes, they are zener diodes. From the spec sheet: "Sandwich construction of the rectifier with press fit Zener diodes provides for low temperatures of the rectifier diodes, high resistance to vibrations and protection of loads on the vehicle against alternator overvoltages." Depending on how hard the alternator was working at the time I think there would still be quite a large transient into the 20s or 30s of volts, and possibly other 12v appliances connected might suffer so I would prefer not to test it! I think the automotive standard is something like ability to withstand 35v (12v system). On the other hand a high voltage disconnect is most likely to occur towards the top of the charge when the current has decreased significantly, hence less energy stored in the field windings hence lower transient energy. And of course the system has been in operation for a good while without blowing anything up.

Yes you should be able to configure everything via the Easyview. Charging Lithiums at a lower than recommended voltage is not a bad thing at all and certainly doesn't explain a short life - unlike lead acid batteries lithium doesn't particularly like to be fully charged. I would leave the settings the same when you put the new battery in, perhaps with the exception of increasing the solar absorption a bit to maybe 13.8v, just to make best use of the capacity. It's been hinted that perhaps the 50% capacity figure is wrong - as they said it is a long and tedious process to test the capacity of a lithium battery and without knowing exactly how they did it, we are suspicious! But then again you say it seems to deplete quickly - but of course that depends on how you use it! It doesn't sound as though you have any battery state of charge or current monitoring, I would suggest getting something like a BMV712 so that you can have a better idea of what is going on - without adequate monitoring, electricity is invisible and a complete mystery!

Yes it should be a straightforward swap, provided you can physically lift the heavy battery and it fits the available space. However I would be concerned about the present state of the existing batteries. Li batteries are generally considered knackered when they reach 80% of badged capacity, and yours are way worse than that. The question in my mind is "why"? Unlike lead acid batteries, Li has a very long life of perhaps 5000 cycles which should be 15 years or so even on liveaboard useage. It seems unlikely that your present batteries are 15 years old? Are they showing any physical signs of distress (ie swelling)? I would therefore question whether the present charging setup is working properly - or rather, is set up properly. I would review all the settings on the Alpha Pro to check it is set up correctly. There are a lot of options! Do you have the ability to connect the Alpha Pro to a laptop etc running MasterAdjust? ie the Masterbus USB interface? If not I would suggest that, before shelling out lost of money on a 460Ah battery, you get that to ensure that the new batteries will be charged correctly. Regarding charging from the generator, you don't mention the charger output (amps). Perhaps it is too big for the generator in terms of initial current?

Agreed but there is a lot of geographical separation between Falkirk Wheel and Cheshire. I think the problem with Foxton is that it is not a new link, it is just a bypass for the locks, and it is rather remote and hidden round the back of the more interesting locks. After all, the plane was abandoned in the first place because the locks were better!

Although it can work. The Falkirk Wheel has been and remains pretty successful despite the very limited amount of boating happening on the Scottish lowland canals. I think it would be more about a tourist attraction than a facility for boat owners to reach the Weaver. But as said, there is probably no money for it.

No. The charger will give what it is designed to give (10A or whatever) and if the load is higher the rest will be supplied by the battery. If you have an always-on charger, there is no point in having a big one. The only requirement is that over the 24hr period the charger is capable of supplying more charge than you take out over a 24 hour period. The point of having a larger charger would be if you are eg charging from a generator and don't want the noisy thing running for hours on end.

It only takes a very small current to be tingly. If the RCD was set to a low enough current that it would trip before something felt tingly, it would always be tripping. Rather, it is designed to trip before the current is fatal. Which is a lot worse than "tingly"!

You don't need to have an RCBO specifically for the shore line, if there is another RCBO somewhere before the appliance sockets etc. To clarify, you could have an inverter feed and a shore line feed, selectable via a switch or plug & sockets, then after the selection and before the appliance sockets etc, there should be an RCBO or RCD + MCB. It is true that the shore bollard should protect you, but the BSS sees it differently as there is no guarantee that you will always be plugged into shore power via a protected bollard, or that the bollard protection works.

Hopefully I didn't say that because I certainly didn't mean to. I said or meant to say that Combis have automatic NE bonding, inverters generally don't. EDIT just read what I said, yes open to misinterpretation. I meant that an inverter always has an NE bond as there is no need for that to be disconnected, but what I didn't say was that it was up to the installer to create that NE bond, assuming the inverter has a floating output. It might possiblty have a centre-tapped output. One has to check the detail before adding an NE bond! However if the inverter can't be NE bonded that is because there is already a bond between N and the system (dc) negative or positive. There is thus no need to add an NE bond and an RCD will still work. Although it's not a great configuration!