nicknorman
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Posts posted by nicknorman
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2 hours ago, NB Saturn said:
It’s entirely possible that the is no 240v on board (or wasn’t when those were fitted as 12v sockets) - not really a problem in that scenario.
A 12v appliance with a 230v plug on it could easily be removed from a boat lacking mains voltage and plugged in to mains in a house etc. Probably not by the boat owner, but his relatives after he dies/has to leave the boat, or the next owner. I can only think that people who think this is OK have never been involved in accident analysis. Just because a bodge is adequate in a very specific situation, doesn't mean that when circumstances change in an entirely predictable way, it does not become a serious safety issue.
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35 minutes ago, Kingdom Isambard Brunel said:
and will not pass too much current as the core magnetic field saturates.
Agree with the principle but not the reason. Core saturation has nothing to do with passing continuous dc current. But as other have said, having a 13A plug on a 12v dc appliance is very foolish and dangerous.
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1 hour ago, Leigh marshall said:
I don’t understand what do you mean about being rude
I think it was that Tony thought the quote for the new loom was very expensive and probably unnecessary, and if he were in your shoes he would have responded to the engineer with a rude word. Well he probably wouldn’t actually, it was just a figure of speech to indicate he thought it was a rip-off.
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2 hours ago, Tonka said:
A dip stick consumes 0 amps so why make anything else
Because you have to store it somewhere
Because it smells of diesel
Because you have to undo the cap and redo it afterwards - risk of dropping in the cut
Because it’s easy to introduce contaminants into the tank, including bug
Because you can’t really do it when it’s raining or at night
Because it is not “in your face” and one day you might forget and run out.
Because in our case there is not a straight path into the tank from the filler.
But apart from that, as you say there is no reason.
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2 hours ago, IanD said:
Which is why it's widely supported, apart from being reliable and pretty much immune to voltage drops or poor contacts in the wiring... 😉
If you're worried about a sensor "wasting" between 0.05W and 0.25W, might I suggest there are likely to be *many* other worse power vampires on the boat you need to look at first? 🙂
I know, but if you can make something that consumes microamps, why make something that consumes milliamps. Although of course with something like a tank sender, it could sleep for 99% of the time and only be powered for 1% to take a sample since the rate of level change is slow.
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12 minutes ago, IanD said:
That's true -- but also 4-20mA sensors have a standard analogue interface without the problems you describe. At least, so long as you get ones with the correct range, 0.1bar suits most tanks (full-scale is around 3' liquid depth).
I rather resent the unnecessary overhead of up to 20mA doing nothing useful. Yes of course 4-20mA is an industry standard interface, but it’s also a very old industry standard! As in 70 years or so old! -
8 hours ago, Onewheeler said:
I experimented a while ago with a pressure sensor interfaced to an Arduino, but had a lot of problems getting it to give a stable and repeatable reading. Rather than waste more effort I continued with the time honoured transparent sight tube. It's not as transparent as it was, but it's easy to shine a torch behind it. The volume passed counter also works well if the battery is replaced every few years.
I think there are pressure sensors and … pressure sensors.If you go for one that is just a bridge circuit with no amplification or signal processing, and only using a small proportion of its range, you get a very small and temperature-dependant voltage. Analogue electronics = too much hassle! Whereas if you get a sensor with integral signal processing and eg an I2C or SPI digital interface, then it’s a piece of piss once you have sorted out the interface drivers (for which there is probably an arduino library).
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15 minutes ago, Wafi said:
Thanks - more options that I thought!
Fairly happy dabbling with microcontrollers and I2C devices; I already have various devices around the house talking to each other by LoRa radio. If I can get to the pipe running through the bilge from the tank outlet I might try a pressure-based sender near the tank and a receiver in the engine room driving an electronic potentiometer for the Cerbo, which would avoid having to run a new cable. If I can't get to that pipe, a flow sensor near the accumulator (which is in the middle of the boat) may be the least worst option.
I did try plimsoll lines on the side of the boat, but there seem to be too many confounding variables (one of which seems to be that, apart from marinas and lock landings, I haven't found anywhere to moor recently that doesn't end up with the back of the boat on the bottom of the canal).
You can add the pressure sensor anywhere before the pump that is vertically near the bottom of the tank, since there is no pressure drop when the pump isn't running, it is only a matter of the height difference.
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1 hour ago, GUMPY said:
Much as I love a gadget I never saw the point in water or fuel gauges. The water always lasted 8 days so I filled it every 7 so no need for a gauge. The fuel I did have a calibrated stick for but rarely used it as I again could guess within 20 litres how much fuel was in the tank due to the rough tally of engine/heating hours I kept in my head.
For me gauges only really come into their own when you are using a large amount of fuel/water capacity in a short space of time.
That is fine if your life is formulaic. For us as “part time” boaters with a washing machine and occasional parental trips, water consumption was very varied. Before we had the gauge we would needlessly stop for water. Now we have it things are much more controlled, as someone said, would you prefer to have a car without a fuel gauge and just rely on noting the mileage? I had motorbikes like that. But in the 1970s. And they had a fuel reserve tap.-
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Since the Cerbo only accepts a resistive input (eg a tank float moving a wiper over a wire wound resistor) the easiest way would be to use the GX tank 140 interface and use an opamp etc to adjust the output span of the pressure sensor to the 0-10v the GX tank expects.
If I were doing it I’d probably use an I2C output pressure sensor with microcontroller controlling an electronic potentiometer straight into the Cerbo, but I have invested a lot of time to be able to do that easily.
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10 minutes ago, Wafi said:
I have no idea how to determine the fill state of my water tank, which is a stainless job under the well deck; it fills through a pipe that's too bendy for any dipstick, and I've yet to find a way to even see the outside of the tank, let alone get sufficient access to fit a level sensor. At the moment I wait until it's banged twice and then refill at the next opportunity, but that system was thrown into doubt at the last refill; it had only banged twice when I was using water, but there were three bangs on the refill.
I think the answer must be to fit a flow sensor on the pipe feeding the accumulator; does anyone know of one that will calculate an effective tank level and feed it to a Cerbo? Otherwise it might have to be an electronics project for the Winter.
The easiest way to sense water tank contents is by measuring the static head of pressure at the tank outlet. This is typically by means of a T piece and pressure sensor as per the MCS water tank gauge. Obviously it doesn’t read properly when the pump is running but it reads accurately at any other time.A flow meter will suffer from cumulative integration errors and issues if you don’t fully fill the tank.
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1 minute ago, Tonka said:
What is the point of all this Bluetooth stuff, WiFi on domestic appliances and gauges for your tanks?
Money is the answer. The units cost more to buy. Go wrong quicker so as you have to buy another one.
I just don't get it.
I had to Google what a Cerbo thing is.
£185
We don't have any Victron stuff aboard
Am I missing out ?
No, No, No, Yes, Yes.
I’ve been building some small items with Bluetooth. The little Bluetooth modules cost £2.20 retail in one-off quantities. So the delta on the cost of say a £100 product is insignificant and adds a lot of convenience. It is true that it can’t be used to make fire by rubbing sticks together so I can see why you are anti.
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We have the MCS fuel gauge, top entry onto the tank. It does rely on not losing any air pressure ever, but of course it does, slightly. I have to pump it up about once a year but it only takes a few minutes.
In the OP’s case I have no idea what sort of input the Cerbo needs. The sensor for the MCS device is a pressure sensor which is a bridge, so the output would be very small and some amplification would likely be needed to get it into a range suitable for the Cerbo. Or just steal the principle and find a low pressure sensor with a suitable output, the rest is just plumbing.
https://www.mcsboatproducts.co.uk/our-products/fuel
Edit: looks like they’ve changed the design. Ours had a Schroeder air valve to top the pressure up in the down-pointing pipe, and it was much narrower than the type shown. -
1 hour ago, Jen-in-Wellies said:
I have mentioned this before, but it has been a while, so time for a repeat. My dip stick is calibrated from the top of the tank to the diesel surface, rather than from the bottom of the tank filler neck to the diesel surface. That way, the stick doesn't have to be dipped to the bottom to find the volume of diesel in the tank.
To use it, I slowly lower the stick in till I see it just touch the surface, then read the volume from the stick. In my case, this is the litres needed to fill up to the top. Subtract from 225l and that gives the volume in the tank. This way means only a tiny drip of diesel is on the tip of the stick. The rest remains dry. In this picture, the tank is nearly full. Perhaps 30l from the the top.
Never thought of that before, it’s a great idea. Well it would be if you have a tank like yours. Our tank is under the engine with a long flexible and slightly curving filler pipe from gunnel to the tank. Which is why we have an electronic gauge! -
9 hours ago, dmr said:
There is also a difference between ignorance/poor workmanship, and making an informed decision to deviate from the rules.
I like to solder things, but I know how to solder. I have some 240volt and 12volt cables running next to each other under the gunnel (previous owner stuff), but I know they are there and would turn the 240 off before messing with the 12. We have a sink drain very close to the waterline, so the hose is all done correctly inside the boat etc etc.
My point was not to tell you that you must comply with the letter of the law. You are a big boy (so they say) and have a good dollop of experience and common sense. My point was that when giving advice to questioners on here, it is advisable to stick with best practice. Best practice being designed to cope with a low common denominator. Someone coming on here to ask questions is doing so because they don’t have the experience / competence to know the answers and we can’t know what other factors might be present to turn some minor bodgery into disaster.
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Even though failing to meet the ISOs and then stating that the boat is RCD/RCR compliant is most likely a very common issue that has probably never been prosecuted on canal boats, IMO people on the forum should not be advocating ignoring best practice as per the ISOs. It is irresponsible. Just because one has done something that contravenes the ISO and has “got away with it” - ie not had a problem as a result YET, does not give that experience any credence in a world with thousands of people and boats. Accidents usually happen due to a combination of unfavourable circumstances, and reducing safety margins in one seemingly trivial area can have unintended consequences when combined with other unanticipated factors.
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I think you might struggle to install it low enough so that shower water reaches the manifold by gravity in order to activate the pump. Most shower waste outlets are virtually on the baseplate.
And if it fails, sink water may flood the bathroom.
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20 minutes ago, Alan de Enfield said:
Maybe I'm totally misunderstanding, but that reads to a simpleton such as myself, that a (say) 600Ah bank could increase by :
2x 600 = 1200 degrees C per minute.
I doubt that is correct so could you show a calculation, as an example, of what that formula means in real life ?
Yes I am not clear about this and it is a bit late to get my head around it but anyway I see I mis-wrote. What was actually written was degC/min-Ah. I'll edit my earlier cockup.
But that little detail aside (!) my point was about the differences between LFP and the more energy-dense chemistries, around a factor of 100.
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I've recently gained access to British Standards online, giving me access to the latest version of "small craft - lithium-ion batteries. Most of it is pretty sensible and I am compliant eg with things like
"Charging sources shall be operated/controlled to meet the charging profile recommendations
provided by the lithium-ion battery or cell manufacturer."which I would take to mean that relying on the BMS cutoff to ensure safe charging, is not acceptable.
But relevant to the discussion about battery abuse, the BS makes reference to a paper "Investigating the Role of Energy Density in Thermal Runaway of Lithium-Ion Batteries with Accelerating Rate Calorimetry" which is freely available on line.
There is a graph of thermal runaways with different chemistries. First of all it is interesting that thermal runaway only really "takes off" when the temperature gets over 200C (or 180 for LiCoO2). Which is quite hot. But once thermal runaway is in full swing, LiFePO4 suffers a rate of (adiabatic) temperature rise of around 2 or 3 degC per minute-amphour. Whereas the likes of LiCoO2 is around 400 and NMC around 170. So there is a massive difference between the rate of energy released by LiFePO4 vs these other chemistries. I know that we knew that, but it's good to see the hard data.-
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2 hours ago, Ronaldo47 said:
Our 20 year old electric bikes use SLA batteries. We used to leave the chargers plugged in when not in use, as the chargers would provide a trickle charge once fully charged. One of the chargers developed a fault, outputting more than 50V instead of the circa 42V charging voltage specified for the 3 x 12V SLAs. It must have been like this for the several days that the bike was not in use, and when it was next needed, the battery box was quite hot to the touch. Inspection showed that the cases of the batteries (Varta I think) had swelled significantly, making it difficult to remove them, but no liquid was lost, and they would not hold charge. The charger was the one originally supplied with the bike, and after buying a fresh set of batteries and a new charger, I now use a plug-in timer where you can set your own number of ON/OFF sequences, and programmed it to charge in three periods of 2 hours, well spaced apart so that the charger does not operate continuously. We normally only do short trips, and 2 hours is normally long enough to fully recharge.
A lithium battery subjected to the same period of severe overcharge would no doubt have have resulted in a very different outcome. The chargers supplied by the bike company are also used for their current models that use 36V lithium batteries, but having experienced the safe behaviour of SLA batteries when the charger malfunctions, I am not inclined to swap our SLA batteries for lithium ones.
What very different outcome do you envisage? For a LiFePO4 battery it would have been a much better outcome- the BMS would have isolated the battery with no damage occurring. This is the thing with Li batteries, there are two levels of protection, the charger’s regulation AND the BMS. With lead acid there is only one.But even with the double failure of charge regulation and BMS, chances are the LiFePO4 battery would have suffered a similar fate to the LA - been badly damaged. But not gone on fire nor risked spraying boiling sulphuric acid around.
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Oh dear! Can’t say I’m too surprised though.
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5 hours ago, Bargebuilder said:
So no actual data or evidence, just hearsay and someone’s opinion. -
I would strongly recommend reviewing the BSS inspection criteria before starting. https://www.boatsafetyscheme.org/media/299451/bss-complete-ecps-private-boat-public-version-2023.pdf
For example the boatyard is quite correct, the starter must go through the engine battery isolator ditto the alternator. It is not that one needs to isolate the battery from the engine, it is the other way round ie isolate the engine electrics from the battery (source of a lot of energy). If someone is working on the engine they don’t want an accidental touch of eg a spanner on the starter stud and the engine casing, to short circuit the battery, melt the spanner and spray molten metal in their eyes.If you just rewire it your way, it may fail the next BSS check and you would have to redo it.
Most boats have 2 isolator switches, one for the domestic and one for the engine batteries.
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12 minutes ago, MoominPapa said:
There's a subtle misunderstanding here. It's not that boat insurance policies don't cover third party liabilities (they have to, in law) , it's that they don't cover third party liabilities if the insurer breaks the contract of insurance. Examples may make this easier to understand.
If I get into my comprehensively insured car pissed as a fart, set off down the M1 and crash into another car, the insurance company will not pay out for the damage to my car, even though it's comprehensively insured. That's because the accident was caused by my negligence and there's a clause in the insurance policy that covers that eventuality. It will, however, still have to pay out for the damage to the car I hit, because the road traffic act says it must.
If my boat sinks because I haven't maintained it and there's a rust hole in the gas locker floor, the insurance company will similarly not pay out, because there's a clause in the policy that says the boat must be maintained and it wasn't.. The difference to the car example is that if the sunken boat leaks the contents of the diesel tank and strips the blacking off the waterlines of marina full of boats, the same clause atill renders the policy void, and the insurance company will not pay for the third party owners of those boats to get them re-blacked.
The first example is hypothetical, the second definitely happened to me (I was one of the third parties).
The clause in the British Waterways act analogous to the one in the road traffic act that says BW and it's successors can insist on third party insurance is the same as the one in the road traffic act, except that it misses out the stipulation that third party cover must be unconditional. To the best of my knowledge
all marine insurance policies take advantage of this. When I was affected it was certainly the case that the sunken boat's insurance did, and I asked my insurers and the same was true of them.
MP.
Interesting. It’s hard to think of a reason why a boat would sink that didn’t involve some negligence of the owner. Perhaps this is why boat insurance is so cheap!
How fast did flyboats go?
in History & Heritage
Posted
It’s clearly AI generated. If it were real there would be hundreds of shouts of SLOW DOWN!