nicknorman

According the BMV. Or just discharge until the voltage gets to about 11.5 or so. Or even until a low voltage disconnect. Just put it on charge straight afterwards. Just cell voltage of the lowest cell. Although it might also have an overall low voltage cut off too. Certainly nothing to do with SoC.

I suggest discharging it right down to 10% or so. Don’t forget that taking Li to 10% is in not damaging although it’s best to start charging again fairly soon. Taking it up to 100% is worse!

How many reasonably deep cycles has it done now? Mine got much better after 3 or 4 reasonably deep cycles. It is pretty good now. Its a year or so old now, so I doubt it would be a more recent firmware version than yours.

I don’t believe Peukert has any relevance to the SoC of a Li battery. But then again, neither did it for an LA battery. It was a myth, legend and mantra that I didn’t believe in. You did leave the “get a room” post which is now a bit confusing!

The Victron BMS seems a good design in many ways, particularly impressive is the ability to limit current at 100A without dissipating too much heat (presumably). It would of course work best in an all-Victron system. But for me there would be a couple of issues relating to alternators, firstly that max current is 100A whereas I can easily run our ubiquitous Iskra 175 alternator at 125A without overheating, and that could probably be 140A or more with better cooling. Secondly, these big alternators even on a fairly large engine like our Beta43, sap a lot of torque from the engine if field current is max at low revs, making it struggle to accelerate from idle and putting a lot of stress on the belt, pulleys and crank. 100A at idle is too much. Really one needs an alternator controller that reduces field current at low rpm (Wakespeed etc). And with a proper alternator controller, the need for the Victron external BMS more or less disappears.

Mid summer, quite a few boats are out cruising, including ours. The same photo taken now would look very different. You could pop over with your drone… Interestingly there’s just been a post on the FMM moorers Facebook page from the new Jules Fuels fuel boat lady. Apparently they have been given permission to sell within the marina, so I would presume FMM is going to stop providing services (fuel, coal, gas) altogether even to the moorers.

Yes people in marinas do take their boats out sometimes! But at the marina in question I’d say occupancy was getting close to 50%. I am aware of 9 boats that have left recently, all previously long-termers like us. Whereas at the new marina there was a waiting list. Here’s a pic of a different part of the marina and bossy note from kat on the bollard!

That’s good. Kat will be spitting feathers if she sees that on her CCTV screens! Yes Ben is a lovely chap, I did mention that upthread. Not sure he will last long though. Last night I emailed Ian Rothen asking if he would be interested in feedback as to why we and so many others have left. It will be interesting to see if I get a reply.

I sympathise muchly. A horrible job and the chances of your clothes escaping without holes seems slight. I’d continue with the bicarbonate of soda treatment for as long as possible, maybe do a rinse and repeat a few times. You will get it sorted eventually!

That was the other Tony. I always suspected there was a fault with the other alternator (blown diode etc).

Personally I’d call it a buffer battery. Not that it matters what you call it!

B2B current flows one way, but of course a box of tricks might well have 2 B2Bs in reverse parallel. And of course faster than light travel of information is already available, just awaiting a firmware update. I think what is relevant about that is that the B2B continues to charge the engine battery even after the van engine is stopped. So if the engine battery is running at a deficit for a few hours, this will be recouped overnight or whatever, by being charged from the domestic Li battery. It would be interesting to know if the van could tolerate very long drives without lengthy periods of the engine being stopped (overnight etc).

So as I said, it is unidirectional. No doubt it could in the future be made to be bidirectional. Along with faster than light travel, coming soon…

If it is MOSFET switch then it’s the same as a relay. A direct bidirectional connection. A B2B is not a direct connection even though the circuitry might contain MOSFETs amongst other things. Input and output voltage of a B2B are likely to be quite different, unlike a relay or VSR. And current can’t flow bidirectionally.

I would say it’s more like a VSR. Probably with MOSFET switching rather than a mechanical relay.

I think it was probably a combination of bungs left in AND voltage sense wire on the wrong terminal. Like most accidents, more than one contributory cause. Eliminating just one of the two causes would have prevented the accident.

But in my experience Li cells, once properly balanced, never go out of balance unless they are faulty. The algorithm mention by the OP implies 2hr absorption every time SoC goes below 70%, which could be every day.

Maybe it was a typo?

A proper system! I would just say that 2hrs absorption seems excessive even bearing in mind the caveats you mention. Once the voltage has hit 14.0v (which is presumably when the absorption timer starts), I would have expected the current to have fallen below 5% in 15 to 30 mins, and holding the voltage up at 14v after that doesn’t really achieve anything, and does slightly stress the batteries. Might be worth observing the behaviour / charge current during the absorption phase after you have discharged below 70%.

I think it is reasonable in theory. It’s the same idea as connecting the boat alternator to the domestics and then using a split charge relay to charge the starter - because the domestics need the most charge. 4A does seem quite low but led lights on modern vehicles don’t take much current. It seems to work for them, anyway.

Yes. Although personally I have enough reasons already!

There is a stoppage notice about it. Definitely not available to passing boats. https://canalrivertrust.org.uk/notices/30146-fazeley-mill-marina-facilities-birmingham-fazeley-canal

New signs at the entrance say something like “welcome to Fazeley mill marina” “private marina, no entry”, which is somewhat oxymoronic. I guess it would still be possible to rock up in a boat and use the elsan, but that is verboten by the “head of marinas”. And not on Thursday or Saturday when the office is manned.

It is. And FMM is not really a marina any more, it is a moorings with very intermittent services, no caretaker/supervision for 5 days out of 7. And although they have finally partially sorted it after 6 months, no security. One could walk in under the bridge and walk onto our pontoon. Not great for an urban “marina”. They cut down the protective vegetation under the bridge and declined to fix the pontoon gate lock. Now 6 months later they have just installed fencing under the bridge but still no pontoon gate lock. One thing which really tickles me is FMM’s new website. See screenshot below. Slight problem, FMM is not in Warwickshire, it is in Staffordshire. Oh and it is not on the Coventry, it is on the Birmingham and Fazeley. So they don’t seem to actually know where their new marina is! That website has been up for about 6 months, they haven’t noticed!

It’s certainly closer to Aberdeen, but since my mother lives near Stratford on Avon, we still need to drive the same distance when we go to the boat because I feel obliged to visit her as well - she is after all 102 now!