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nicknorman

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Everything posted by nicknorman

  1. I disagree. Well I suppose the question is, why do you want to limit the current? Is limiting the current actually the aim (for example because the battery can’t safely take the full current)? If so then fair enough. But in the context of Li batteries and narrowboats, this is almost certainly not the reason. The reason will be due to: 1/ avoiding overheating the alternator and/or 2/ avoiding overloading the engine, belt and or pulleys at low rpm. In neither case does the actual current matter. What matters is how hot the alternator is, and how much torque is being applied to the alternator. Both these are best controlled by directly adjusting the maximum field current, not some convoluted mechanism to measure and then adjust the output current. For 1: there is no direct relationship between temperature and current, it depends on ambient temperature and fan rpm amongst other things. Having a set limit to the field current allows less current at low rpm when the fan is going slowly, and more at higher rpm when the fan is going faster for the same temperature (roughly). Which is exactly what you want. For 2, there is a direct relationship between torque and field current at a specified low rpm. Set a maximum field current, this sets a maximum limit on the torque to the alternator, which is exactly what you want. We are not miles apart, but is clear that you have not designed alternator control software, and I have. Once you actually start writing the code, it all becomes clear and there is no need to complicate things by considering output current, when the more relevant parameter, and one that is already intrinsically measured by the control chip is field current. I was going to include a Hall effect current sensor in my design, before I realised it would be completely pointless. The only thing wrong with your post is that you have this fantasy that at some point, everyone will agree on how to do it. Never going to happen!!! As you say, it is in its infancy. However the only sceptics are those who have not tried it. Those who have tried it would never contemplate going back to LA.
  2. Well at least you used pukka fuel pipe, not just some random rubber hose from ebay! However I think the fire resistance might be an issue. The general idea is that in the event of an engine bay fire, the pipe doesn’t burn through and then pump diesel into the fire. It’s a pretty unlikely scenario of course, but the kind of thing BSS gets excited about! But as you imply, there are plenty of BSS examiners who are pragmatic. And of course some who aren’t!
  3. Controlling the field current is of course what any regulator does! It is just a matter of whether a max field current limit can be set. But this is what the various existing devices do (Alpha Pro, Wakespeed). With modern precise PID digital regulation, trying to control current by adjusting the set voltage is very difficult because very small changes in voltage make a huge difference in output current especially into Li batteries, and it varies with varying load. And if you think about it, an alternator is a current source not a voltage source, a regulator is a current supply not a voltage supply - the main regulation loop adjusts the field current to adjust the output current such that the output voltage is at the desired value. So no point in complicating it by trying to control the output current via the output voltage which is controlled via the output current which is controlled via the field current. Just set a max field current (max duty cycle on the controlling MOSFET) and that is job done.
  4. Ah sorry to be negative but this could be a bad idea. BSS doesn't allow ordinary rubber hose for fuel lines. It has to be marked as suitable for diesel and fire resistant. From the BSS: Fuel feed, return and on-engine hoses must be marked, to denote both suitability for the fuel used and fire resistance, to BS EN ISO 7840 or an equivalent standard. Applicability – hoses marked to SAE J 1527, DIN 4798 or RINA DIP/66/96 are acceptable. Applicability – the presence of armoured or other external braiding is not evidence of hose suitability or fire resistance. Such hoses must be marked as above. Applicability – fuel-hose suitability may be supported by a written declaration from the hose manufacturer or supplier or, if appropriate, from the engine manufacturer/supplier or mariniser.
  5. Interesting that it has a shunt for the alternator current. Not sure why that would be necessary as one can calculate the current from field current and rpm to the necessary accuracy. In any case, usually it is the torque load at low rpm that is the issue and this again is related to the field current, not to the output current. Same field current, same torque load, gives lower output current at low rpm and higher output at higher rpm. Or to put it another way, for the same current output, the torque decreases as rpm increases. So to adjust the torque load to match the engine output at low rpm, you just need to set up a simple max field current vs rpm function.
  6. This reminds me of helicopters. Lots of warning lights for dire things like tail rotor gearbox chip. But then you have to have a means to be confident that the warning system would work in the once in a lifetime actual problem, because if it didn't lots of people are going to die. So you make it failsafe ie if the system fails, the light comes on. And then because you are not totally confident in that scheme, you add a test button to simulate the gearbox chip and bring the warning light on which tests the bulb and all the wiring, and hope that decreases the failure rate to "extremely remote". But then with so much complexity, you are plagued with false warning lights. And you get so fed up with that, you start to ignore them...
  7. No, 2 alternators are not a fundamental problem, but some rewiring would be required. Just get the Zeus, you know you want to!
  8. The difference is probably how the cycle life was calculated. Guesswork by 2 different people gives 2 different results. With such long cycle lives, it all becomes a bit academic and depends on how it was cycled and under what ambient conditions. And calendar life comes into play as well. No a "hybrid system" is where 2 batteries of different chemistries are directly connected together. It is unreasonable to consider a Li battery charged by a charging system that just happens to be assisted by another battery, to be a "hybrid system". A vehicle alternator, if it is from a car built in the last 10 years or so, is unlikely to have a built in regulator. The regulation of the alternator is controlled by the vehicle ECU (engine control unit) as it adjusts the voltage according to what the car is doing (eg lower voltage during acceleration, high voltage during overrun or braking to recoup some of the energy) and according to the SoC and load. So you would need an external regulator. Other than that, it would certainly allow for higher % of alternator load. There was a thread on here where someone had done that. No. For example our 175A alternator can run at about 125A continuously without getting too hot. When we had LA, the current would be below 125A after the first 5 mins or so, and then spend many hours gradually reducing with the final hours at below 20A in order to fully recharge and ward off sulphation. With Li, we can put in 125Ah an hour every hour until 15 minutes before the battery is full. This is why you need 2 stages of protection. The first stage is that the charge source is designed not to overcharge the battery. The second and independant stage is that if the first stage fails, the BMS disconnects the battery. What is to be avoided IMO is to use the second stage routinely as a means of controlling the charging.
  9. Yes however there are two undesirables - one being that modern boats generally have 2 alternators (although this issue can be overcome by rewiring) and the B2B is both very expensive and very inefficient, turning a lot of generated power into heat.
  10. It is because of the similarities, and also the differences, between the two battery chemistries. Under discharge, the Li battery voltage remains above 13v until it is nearly flat, and so discharge current comes only from the Li, not from the LA which would have to be pulled down below 12.7v to get significant discharge. On recharge, a voltage of 14.4v will fully charge both an LA battery and a Li battery - although from the previous para you can see that it is unlikely that the LA will need significant recharging. All well and good so far, but the devil being in the detail... the Li battery sits at around 13.6v or less during charge, until it is very close to full. To correctly charge a Li battery, the voltage will be above 14v only for a few minutes. Li batteries do not like being held up at 14.4v or whatever, for extended periods. Whereas if the LA has in fact been discharged (due to nearly depleting the Li such that the voltage falls below 12.7v) then it needs to be held up at 14.4v for several hours to properly recharge. It is here that there is the conflict between the needs of the LA vs the needs of the Li.
  11. My point was that the BSS has a history of applying different standards from those required by the relevant ISO. A simple example being that the ISO allows soldered lpg gas connections such as you would find in a house, whereas the BSS does not. So a boat built in full compliance with the RCD/RCR can still be a "fail" for the BSS. Similarly, things that are allowed by the BSS are contrary to the ISOs applicable to the RCD/RCR. So in answer to your final question, who knows?!
  12. It might be very "odd" but it is the case for a number of BSS standards.
  13. The problem arises when one uses an alternator designed for charging lead acid, to charge lithium. Not using a device for its intended purpose is always likely to be problematic! The answer is to use an alternator designed for charging lithium. Simple! And that would include having communication between the BMS and the alternator such that the latter would know if the former were about to isolate itself. Another, or possibly additional, method is to have a load dump absorber. Sterling sell one, although they are a bit scant on the detail of what size of alternator it would cope with, and just how high a transient would be produce from a full output load dump. I made one out of a bunch of high power Tranzorbs, it was not expensive although I have never actually put it to the test! Mostly for peace of mind just in case the bistable relay I use as the battery isolator/protector, ever goes open circuit on its own. Yes so for instance one could use a BMV712 battery monitor, which has a built in configurable relay, to shut down the alternator field current when some specified SoC (80, 90, 100% or whatever is configured) was reached. It would need an intermediary relay due to the current involved. Quite doable I think, but people seem a bit scared of opening up their alternators to intercept the field current. Its a shame because there are a number of alternator controller chips around - every modern car uses one - that are adjustable via some sort of computer interface. The chips can be had for a few £. All the hard work is done for you. You just need to send it the right data in terms of regulated voltage and field current limit plus optionally a few more subtleties like field current ramp rates. Not difficult for some small electronics company to take on. I guess the market is just too small to make it worthwhile.
  14. Li batteries are fantastic. However, there are a lot of pitfalls and it is not easy to put together an effective system. Why fantastic? Well they are just like a big bucket of electricity. You can pour energy in as fast as the tap will run. You can discharge it way down to nearly 0% and still the voltage stays up around 13v. No need to fully charge between uses. It is worth bearing in mind that Ah is not a unit of energy, because for that you need to mulitply by the voltage. So 100Ah of lead acid (LA), where the discharge voltage is 12 to 12.6, is worth less energy than 100Ah of Lithium (Li) where the discharge voltage is 13 - 13.3v. So more energy for the same Ah. And that is before you remember that you shouldn't really discharge your LA below 50% Soc, whereas you can discharge the Li to 10% or lower quite happily. So 100Ah of Li is worth about 200Ah of LA. That is the good news. The bad news is that, being a big bucket of electricity, a Li battery will hoover up 100% of the maximum output from an alternator until it is nearly full. Alternators fitted to boats are generally not rated for continuous operation at maximum output, and so they will fry themselves in fairly short order. There needs to be some means to limit the maximum alternator output, to protect the alternator. Other things with Li: They hate being overcharged or even held at charging voltage once they are full. The mantra is "charge to full, then STOP CHARGING". Full is defined as charge current reduced to 5% of capacity. This can be easier said than done because many charge sources don't recognise when the battery is full. They (hopefully) have a built in battery management system (BMS) that is there to protect the cells by disconnecting the battery if a cell voltage gets too high or too low or too cold. However if the BMS decides to disconnect the battery when it is being charged by an alternator, a massive voltage spike will ensue which can damage the alternator and other equipment connected to the electrical system. So IMO one should avoid triggering the "battery emergency disconnect" algorithm in the BMS. ie set a charge voltage that is somewhat lower than the BMS cutoff voltage. The BMS protection should be considered "last resort" not "day to day control". For the solar, you can set a fairly low charge voltage around 14.1v or so (which will still get the battery nearly full) and a float voltage much lower, say 13.3v so that no more current flows into the battery. The absorption time (time between reaching the charging voltage, and going to float) should be very short, maybe 10 minutes. It is a bit problematic in summer if the boat is not being used - every day the batteries are pushed up to their charged voltage, without anything being taken out. This is not very good for them. So not much of an issue if you are aboard permanently, but if you leave the boat unattended with no loads on, disconnect the solar panels. He and I both have the Fogstar in a caravan! But the Fogstar is good for a caravan because it has the built in heating element. If you try to charge the battery at too low a temperature, the charge is diverted to heating elements until the battery is warm enough. However on a boat, where the canal water is a great temperature stabiliser, low battery temperature is unlikely to be much of an issue especially as you can site the Li battery within the cabin where it is hopefully warm! Otherwise, the Fogstar seems well put together but it does have quite a conservative BMS so it would be inportant to make sure the charge voltage doesn't trigger the BMS shutoff.
  15. I suppose it could be. Do you have an LA in parallel? If not then a HVD is obviously going to remove any sort of battery connection to the Combi. I don’t have a Victron, but I know my Mastervolt is a bit funny if I remove the DC power with shore power connected, sometimes it carries on working, sometimes not. Anyway it will certainly be a good idea to have the HVD set higher than the Combi charge voltage.
  16. If the Combi is switching to inverter mode, it is likely to be because the Combi doesn’t like the incoming mains. Possibly when the generator is unloaded by the charge finishing, the regulation is a bit lax and the voltage gets too high, or the waveform is a bit nasty. Pretty sure there is a setting or two to make the Victron more tolerant of ugly waveforms and to widen the acceptable voltage range. “Weak AC” is the setting to try, and it looks like you can increase the maximum input voltage.
  17. Beta says max fuel flow for the 43 is 10 litres/hr. This is "not a lot" so I would imagine that any electric diesel pump would do.
  18. Sorry I am talking about the summer daily rate, I don't know anything about the winter mooring rates. But a prime city centre long-ish term mooring is never going to be cheap! Yes I had a look and see that for winter moorings there is a £7 daily electricity fee. That is about 25 kwh worth. If you have "free" electricity you would be a bit stupid not to use it. 25kwh is one 1 kw heater on all the time plus a bit extra for lights etc. Put in 2kw of heating and you are well in. You could at a pinch use about 3.5kw 24/7 and that would cost around £24. So £7 is not unreasonable.
  19. The daily charge is not just about the electricity, there is also water on each pontoon and rubbish collection and maintenance of the facilities. It is effectively a city centre marina and in that context, not expensive. And I’m sure there is an element of pricing it to avoid the likelihood over-use by a few.
  20. I phoned them about this yesterday. There is just some administrative delay -trying to decide on the daily charge for one- and it will be up on the website in the not too distant future once they’ve got their ducks in a row.
  21. It is sounding to me like a fuel blockage at the tank outlet or the pipework. I would try to eliminate this possibility before spending money on a new pump which may well be unnecessary.
  22. One thing to bear in mind is that the pump is operated by a cam on the engine. If the cam is at the peak, the plunger is fully home and operating the lever doesn't really do anything. You can usually feel if there is some pumping action or whether you are just operating against a spring. Anyway, one thing to try is to rotate the engine 1/2 turn or so, or just a momentary poke with the starter to get it off the peak of the cam. It's a possibility rather than a probability. Where is your fuel tank? Many boats have it in the counter ie above the engine, so you would think that pretty much just gravity would get the fuel to flow. Is there something you could loosen nearer the tank outlet just to see if fuel comes out under gravity? Some detail and photos about the fuel's route from the tank to the engine would help. You mentioned having turned the fuel tap off to change the filter, if you loosen the filter and turn the tap on, does fuel leak out? Presumably it should, otherwise why turn off the fuel tap to change it? Blocked fuel tank outlet is certainly a possibility.
  23. One problem for us on the forum is that "Beta 43" has been around for yonks with various different details. Ours has the filter on the engine with the black plunger knob on top. Pumping this knob circulates diesel through the injector pump and back to the tank. On our boat with a tank below the engine, you can hear it running back down into the tank which means it is also coming out of the tank! you can also "feel" whether it is actually pumping fuel, or just air. Anyway, you should be able to disconnect something in the return and pump the pump to circulate the fuel and see fuel coming out. If you don't have that pump, you should be able to manually operate the lift pump to similar effect. On our boat with the tank under the engine, we also have an electric lift pump however this is not necessary to keep the thing running PROVIDING there is no air leak that allow air to get sucked in in preference to pulling fuel up. So for you, a blockage is one possibility but an air leak is another. With air being so much less dense than diesel, a tiny leak can let a lot of air in, but virtually no diesel out. On our engine there is also a small knurled nut on the side of the injector pump that is the automatic air bleed. Beta advises to keep this open all the time, so it might be a good idea to check it is. Beta also advised that if there was a problem, it might be best to close it! So in other words, whether it is currently open or closed, try putting it the other way!
  24. Thanks. However it's not something I was planning to do - my tinkering with the BLE module was for a different project unrelated to boating, and anyway our own boat Li batteries have my homebrewed BMS without bluetooth - although of course the BMV712 bluetooth gives me overall sight of the battery state.
  25. It is certainly true that the multi pin connectors are a weak point, however I am struggling to see how that could cause the problems mentioned. Normally they just cause electrical or indication problems. A diesel engine doesn’t need electrical power to run, so the only electrical thing that could cause it to stop once it is running, is if the stop solenoid became powered due to a short circuit. And then you’d think it would just cut out.
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