MoominPapa
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Posts posted by MoominPapa
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In County Wicklow, Franklin definitely beat Eunice. Our power went out at about 3.30 and was not back when we left the house to drive to the ferry this morning. I really felt for the guys fixing it, every few hours they'd close the breakers and the power would come back for a few seconds, only to be trip with some new fault. Three Atlantic storms in a week has been a rough welcome to Ireland, and an extended power cut in a house where everything needs electricity, including the water supply, was a bit of a shock. We have a backup plan with camping stoves, generator, etc but none of that stuff has arrived yet. Thankfully by this afternoon the Irish sea had calmed down a lot, and the crossing was not too lumpy. All the trucks on the car deck were chained down.
MP.
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44 minutes ago, matty40s said:
Today's Storm Franklin could be much worse up North, with the European Estofex warning system giving an unheard of level3 for N. Ireland and Scotland. There will be a nasty squall line this afternoon and the rainfall levels will exacerbate already high streams and rivers.
Our ferry back from Dublin this afternoon is cancelled. Rebooked tomorrow, expecting a rough crossing.
MP.
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2 hours ago, Dr Bob said:
All good to hear MP.
As above, I have just forgotten about balancing. My graph of rested voltage vs Ahrs out is exactly the same now as in summer 2019 although I do need to reset the Ahrs out frequently as there are a few drains not wired into the shunt. To be honest, I just watch the voltage and dont bother with the Ahrs, and never the SOC.
I trust the BMS's idea of SOC implicitly now. When we're not using the engine I can know with confidence how many days are left before we need to move or run the genny.
MP.
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42 minutes ago, Dr Bob said:
My experience is similar, once top balancing is achieved, it stays that way.
For my first 6 months I did worry about balancing and after 9 months finally got them somewhere near balanced - a spread of 50mv over the cells, ie the bottom at 3.45V and the top at 3.5V typically at the end of the charge. It has not changed from that 2 1/2 years on. I dont think about balancing now. It's a non issue.
I am not sure if that would be the case of frequently taking the charge to 100%. A lot of the 'information' on the internet suggested high charging could lead to balance instability hence the general accepted norm of charging to 80-90%.
Given a number of us have now had Li's on board for 3-4 years and more, has everyone else given up looking at balancing as a non issue?.......but then we were all only charging to 80-90% so it wouldnt be an issue then anyway! (Tom, Simon? .....ignoring Peter as his Valences self balance and cook the dinner as well).
I've left the balancing to BMS for the past year, at least and they're all quite happy. Sometime before Christmas 2020 I added a feature to the BMS to keep a running total of charge and discharge. The two values are now around 25,000Ah and pretty similar, as you'd hope. Given that someone mentioned manufacturers hopes for this metric in the MAh range upthread, I'm hoping my cells have plenty of life left. They certainly haven'y lost any noticable capacity after three years.
MP.
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44 minutes ago, MarkH2159 said:
You speak from experience..?
There is no discernable extra heat produced as the increased resistance is actually minimal.
It is basically just enough to cause the regulator to drop the output of the alternator.
I repeat, no heat, no insulation melting, no sign of any such issues.
It is in a single coil, held by small zip ties, in an enclosed engine compartment.
Nothing is going to happen because 10mm2 cable can easily handle the total output of the alternator which is 70 amps.
I believe you, but in that case a suitable ballast resistor would stay cool too. If has the same effect it has the same resistance and dissipates the same amount of power. BTW have you actually calculated what the power dissipation is?
I can't help thinking that all this effect with B2Bs and bits of wire are avoiding the real solution, which is properly implemented alternator regulator.
MP.
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30 minutes ago, MarkH2159 said:
By using the 'long wire' and 10mm2 cable I am still connecting the alternator with a wire of sufficient size to handle its total rated output of 70 amps but the resistance induced automatically cuts the amperage.
This means that there is no need for any kind of ballast resistance or other add in that could complicate things and produce heat, thereby wasting energy.
The long wire is a ballast resistance and will produce heat. I suggest not bundling it up or installing is in enclosed compartments or touching flamable material.
MP.
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This is going to be our baptism in the new pad halfway up a hill in County Wicklow. Current predictions are 100kmh gusts. I guess we'll see if the roof stays on and the power stays on. If the power goes off we do have a load of logs stacked up outside to keep warm. They're being kept dry by a tarp though, so may end up soaked if that sets off down the field. No power means no water (well) and no cooking, as we don't have the backup camping stove yet. At least the previous snow warning is looking less likely, though we may still be kept here by fallen trees until the farmers get around to clearing them. The wind turbines on the hill above us were shut down during the worst gusts today. I imagine that will happen again for Eunice.
MP.
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37 minutes ago, AndrewIC said:
As demonstrated by this chap (caution: extensive screwdriver abuse!) : https://youtu.be/lXskIlxbt-w
Also the world's most gnarly soldering iron.
MP.
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39 minutes ago, nicknorman said:
I wonder if they are Schottky diodes these days (lower forward voltage drop)? Of course one could design an “active rectifier” using MOSFETS which don’t have an intrinsic voltage drop. Hmm, a project for the back burner I think!In an A127 of indeterminate age, I doubt it. Modern designs, very likely.
MP.
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19 minutes ago, Tacet said:
Having the regulator inside the alternator case does seem a mistake; using the brushes within the regulator pack (on some alternators) to feed an external regulator would not be too difficult.
Is there any chance that the regulator is an informal alternator temperature monitor? And thus protects the more expensive windings?
Don't confuse the regulator and the diode pack; they are physically and electrically distinct. The regulator (and the dedicated diodes that power it) dissipate relatively little power, and the ambient temperature inside the altenator case is not crazy high for silicon transistors and modern resistors. The problem is the diodes that are carrying the full alternator output. As Jen points out the junctions of those are dissipating a lot of power and are likely the highest point temperatures anywhere in the alt by some margin.
MP.
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1 minute ago, nicknorman said:
Good work! I suppose one curative would be to have remote diodes away from the heat of the engine and windings. Take the 3 phase away to a remote set of diodes dangling in the canal. Then they definitely wouldn't overheat!
Of course I would point out that having an alternator regulator that monitors alternator temperature might be a better solution but everyone will just go "blah blah blah!"
A smart regulator is a good idea, as long as it doesn't have to throttle things too much. Remote diodes are also a good idea, which I've considered (not dangling them in the canal!). Implementation is a bit of a pain, not least providing three high current terminals on the back of the alternator, and, in my installation, a fairly long run of three phase to get to a position suitable for diodes, heatsink and a fan.
MP.
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7 minutes ago, Tony1 said:
I wonder if a non-invasive approach might be more advisable- perhaps one of those 'air duster' spray cans, with a straw to direct the air jet inside the casing of the alternator?
Might such a practice be of any benefit in terms of preventing future failures?
For an A127, certainly. The diodes and heatsinks are at the back, just behind the cooling slots, so an air duster would work quite well. Just don't shove anything conductive in there.
MP.
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22 minutes ago, Jen-in-Wellies said:
Not thought about this before. Each diode will be conducting for roughly half the time and blocking half the time. When conducting, they will drop 0.6V or so. With three phases, each diode will be trying to dissipate 0.6V x 70A / 6 = 7W. Which is a lot for a little bit of silicon. That heat has to be drawn away through the packaging, leads and solder joints, then dissipated by good air flow. Lots of dust inside won't help and the diode overheats.
The life of the diode is likely to half for each ten degree C rise in temperature inside, if it is the silicon itself that fails.
They are mounted on reasonably substantial heatsinks made of ~5mm thick metal, probably steel which form one of the diode connections. There are two heatsinks, one bolted the case forming the common for all the negative diodes, and one isolated from the case which is the common for all the positive ones.
MP.
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Alternators on boats work hard, and alternators on boats with lithium batteries work harder.
I have a couple of failed alternators on board. One failed before we got lithium batteries and one after. They are both 70A A127s.
Since the second failure caused me to have install the brand-new Ebay sourced spare that I carried, I thought I'd look at the two failures with the aim of building one functional unit to take over the role as a spare.
In both cases the only fault was a failed diode. One was open circuit and one short circuit. I wondered if cooked stator windings might be a problem, but both stators looked fine and metered out OK. I'd already bought a new diode module on Ebay for £12 and fitting that is pretty trivial, as long as you have a BIG soldering iron. The sort your Grandad had, not a 15W tidler suitable for doing electronics.
What was noticeable about both units was that the cooling air path around the diodes was clogged with dust and fluff. I suspect if I'd stuck with my good intentions and dismantled and cleaned them once a year, they would not have failed.
So, lessons learned.
A127s survive maximum output for long periods pretty well, and when they do fail, it's normally the diodes.
When they fail, they are easy and cheap to repair.
Keeping them free from fluff and dust will probably stave off diode failure.
I have a good spare now, but I think I'll probably carry a spare diode pack too. There's good access with the alternator installed on the engine, and it's actually easy to remove the back half of the case and stator whilst leaving the front half, rotor and belt in place. That allows a quick change of the diodes with very little dismantling of the installation. It also saves having to undo the pulley nut to move the pulley to a new alternator, which is the most difficult part of a swap.
MP.
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12 minutes ago, Murflynn said:
thank you for using a meaningful description of the work performed by the bloke wot visits the boat and installs bits and bobs, albeit probably in a highly competent manner.
many folk use the word "engineer" to describe any bloke with an adjustable spanner or a pair of pliers in his pocket, from which so much confusion arises.
I used the same term the OP did, so any credit is due to them.
MP.
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20 hours ago, luggsy said:
Hi currently I am in Boston, I have 4 x 6 v Trojans that are at there end of life , I have a 200amp lithium & 2 x 12v 135 amp lead acid batteries , I need some one to fit them for me , been in touch with 2 marine electrical fitters one does not know enough about the hybrid set up the other one does tells me to ring him and don't get a answer getting a bit pixxed of now is there anyone on here who can set it all up for me obviously I will pay
I've installed a Hybrid Lithium system. It involved adding a high current Schotky diode and a bistable contactor into the charge wiring, changing the alternator regulator to one which could be computer controlled, a PCB full of electronics and an Arduino running 2500 lines of code I wrote. The resulting system is stable and foolproof and I'd be happy for it to be used on my boat by other people. I would not sell copies of it: that would require extensive testing with different charge sources and different batteries.
Without casting aspersions, if you can find a marine electrical fitter capable of replicating what I did, I'd be very surprised. The skill-sets are rather different.
MP
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24 minutes ago, matty40s said:
The side ponds were due to be dredged out at some point, the arial shots show how desparately this is needed for water capacity storage.
Side pond capacity isn't too critical as long as long the locks don't leak. They just need to be able to supply one lock-full without the level dropping too much, when turning the flight round from descending to ascending.
MP.
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7 minutes ago, Tony1 said:
Great thanks, I'll hang on to my rubbish for a few more days in that case- my plan is to go through the 8 locks on Saturday.
Can I change the question please? 😄
What is Chester basin mooring like, next to the student accommodation?
Are the youngsters very noisy in the evenings, for example?
Most people would tend to go through there in summer, when there would be few students about, but at the moment they'll all be in residence.
Last week the main noise nuisance in the basin was boaters running generators 11-11 directly under the students' windows. I expect that mooring will be closed eventually as a consequence: the majority suffer because of the thoughtless arseholes. It was sufficiently busy in the basin that you couldn't be confident of rocking up and getting a space.
Consider the moorings by the gardens under the city walls between Cow Lane Bridge and the corner of the walls. If there's no one moored there, as is often the case, it's easy to miss them. There's no sign and the rings are difficult to see. Very pleasant.
MP.
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3 hours ago, matty40s said:
Boats dont normally moor in that pound, Blaby about 5 locks up is where the next boat usually is.
Last time we went through we moored overnight there and were not alone. A quiet night was enjoyed.
MP.
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12 minutes ago, frangar said:
Much as I love boating through Leicester this is why I wouldn’t moor between Kilby bridge & the city centre pontoons….
https://www.leicestermercury.co.uk/news/leicester-news/boat-dangerous-position-after-vandals-6500911
We've only ever ended up on the bottom at a precarious angle due to vandalism once and that was above Wardle Lock in Middlewich. I wouldn't avoid Middlewich even so.
MP.
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Sounds like you're running very old software. Is there an option to update it? I wouldn't hold out too much hope for something made in 2009, but you never know.
MP.
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3 minutes ago, dmr said:
or leaving the back sticking out a couple of feet when in shallow water.
I resemble that remark.
Can we start dissing boats that bang around at the end of loose ropes and then pull inadequate pins out, or is that still automatically always the fault of passing "speeders"?
MP
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You'll be making quite a bit of extra smoke yourself, to replace all the heat you're dumping out of the vents.
MP.
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Ah, EU roaming charges. Another Brexit benefit. How blessed we are.
MP.
When is everyone coming out to play?
in General Boating
Posted
A convoy of three Alvechurch hireboats came past us today at Henhull........
MP.