nicknorman

We are of course only hearing one side of the story and not the words or demeanour of the OP’s communication with the trip boat skipper. Personally I think that if abuse is hurled at a passing boat, it is not too unreasonable to respond in kind, it is just human nature, although of course I have no idea if this relates to the OP’s communication or not and certainly am not intending to make any accusations. It is an annoying feature of modern life that people feel empowered to rudely shout orders to passers by - but only if they can do so without fear of physical retaliation by being isolated from the other party - eg by water, vehicle etc. Once again I will make it clear that I am not accusing the OP of bad behaviour, I am just commenting on the general situation.

This won't have done the gearbox much good, but probably not too much harm either since you didn't run it for very long. Just as well he didn't forget to put oil in the engine! Personally I would never trust routine maintenance to a "professional" because as you have discovered, they often don't really care and just want the money and to get on with the next job. The old saying of "if you want a job doing properly, do it yourself" is true! Obviously this can be tricky if you are not mechanically minded but you can go on training courses to be shown how to do basic stuff like changing the oil. You will then be empowered to DIY and you will take more time and trouble over it than a "professional", and you will get to know your engine so that it is a friend rather than something to be frightened of.

The canal is quite deep there so whilst those trip boats do seem to pass fairly quickly, it has never been an issue for us. Please bear in mind that the canals are a transport system and it is up to you to moor as best you can, rather than expecting everyone else to pass extremely slowly so that a badly-tied up boat doesn't move. We often see badly tied up boats with for example, ropes at roughly 90degrees to the boat/bank. Ropes quite loose so that the moored boat can "pick up speed" prior to the ropes snatching tight. Of course we weren't there to see how your boat was tied up nor how fast the trip boats were moving, but bearing in mind we have often moored there and never had a problem - in fact I can't remember the last time we had any issues with a boat passing too fast - my suspicion is that you could tie your boat up better. Sorry if you don't like the sound of that but sometimes one has to be cruel to be kind! Please ensure your ropes are tight and not at right angles. As so often is the case, we find the rings in Birmingham at the wrong distance apart so if we just use 2 lines then the boat is not really restrained in the fore/aft direction, which is the main way the boat wants to move when another boat passes. You have to use 3 lines, with a line going both fore and aft from either the front or the back. This holds the boat stationary in the fore/aft direction. Then you just need one line at the other end to keep the boat into the side. NEVER use the centre line to tie you boat up, this just makes it heel alarmingly. Once you are moored properly you will find that passing boats are not a problem however fast they go (within reason) and your life will be much more relaxing!

Just to clear up this point there are two types of alternator, a 9 diode machine like the one in your pic. This requires current through the warning light bulb into the D+ terminal to get charging going. Then there is a 6 diode machine, this does not require a warning lamp to be connected in order for it to work. It is not uncommon for the smaller engine alternator to be the latter type.

Yes I suppose an obvious point is - are you familiar with how to rev your engine whilst keeping it in neutral? The way this is done varies according to the type of engine control but sometimes involves pulling out a knob or some such. Is it possible that this knob(if there is one) remains out from when the mechanic did the service?

If you had an issue with the selector shaft seal, this is usually due to too much travel on the cable which flexes the shaft and wears the seal. Replacing the seal only fixes the immediate symptoms, not the cause. So I would check to see if there is signs of oil leaking from the shaft again, and check the gearbox oil level. The gearbox is operated by oil pressure and so if the oil gets low, the gears won’t engage.

You can’t access the database directly, other than via eg the CRT website if you have a licence with them. Or maybe the EA website.

The info will be on the BSS database, maybe try phoning the BSS office?

Let’s hope the leaves being grabbed aren’t yew.

No I don't think so.

Limiting the max duty cycle is one way of avoiding alternator overtemp, but it doesn’t take into account the ambient temperature of the engine room - which even with your setup could probably vary by at least 20C - or the fact that the alternator can run flat out for a short while before overheating. Using a temperature sensor is of course the better way to do it.

The inductance doesn’t matter for steady state, it only affects the max dI/dt. 100% duty cycle will put the battery voltage (13.whatever) across the rotor. Which is fine and will give max alternator output for the rpm. There is a reasonably close correlation between % duty cycle and % rotor current. The limit vs rpm is to reduce load at low rpm by reducing the duty cycle (very useful if you have a large alternator) whereas the max duty cycle puts an overall cap on the max output. Not sure why you would want to do that other than to establish a rough max current into a battery in the absence of a shunt, although as I said before it seems unlikely that you would want to put a blanket reduction on max output regardless of eg alternator temperature. Then again I do remember when I said our alternator (before the advent of my controller) could stuff in 180A into our 450Ah of Trojans at the beginning of charging. You said I was cruel! Trojan of course recommend a max of 20% C charge current and that was 40%. But that was crappy old lead acid batteries, who uses them these days?

Yes the rotor is a surprisingly resistive load (bearing in mind all the whirly round magnetic bits in an alternator). Of course it has inductance too but in the longer term, the current is based on ohms law. So if eg you want to limit the alternator output to about half, you could specify a max of 50% duty cycle. Certainly this would work fine for an rpm vs load map to reduce mechanical load at low rpm, or to control max temperature. In my case the chip had field current measurement built in (measuring the voltage drop across the FET probably) and I use that, having identified that the alternator max field current was about 4.5A with 13v across it. Obviously that made it “tuned” to my specific alternator, but that isn’t a problem for me. In fact having just checked, I see I can read the instantaneous duty cycle but I can’t set a duty cycle limit. Only a field current limit in amps. This seems to be the industry standard for a LIN interface alternator controller. Anyway, it works fine for me!

Well done for just continuing to read this thread. It is a geeky thread for geeky people, but spectators are of course welcome!

No. In order to set an alternator load vs rpm curve, you use the rpm and a max field current limit as the axes on the curve. Otherwise, if you were foolish enough to use the alternator current instead of the max field current, when there was a sudden load on the alternator there would be transient overswing on the alternator current and hence on the mechanical load. Which is bad design. Why go for the added complexity of requiring a shunt to measure alternator current so that you can make a bad design, when instead you can use a field current limit that doesn’t require an external shunt, and make a good design with no load overshoot?

I am not complaining that you have purchased a cheap shunt / found a dusty one in a cupboard. It is more the issue of why Arco bothered to include the ability to measure alternator current and what they proposed to do with that data. That will have cost money, and wasn't necessary. Certainly as you have already paid for it, you might as well install it.

Anyway, Ive said this before and I’ll say it again, I don’t see why an alternator controller needs an accurate measure of its output current. It does need to know SoC but that comes from measuring battery current, not alternator output current. I think the Zeus has the option to specify a max output current but why would you want to bother with that, unless you have a very large alternator and a very small battery or at least very small BMS max current rating? Not really appropriate for a narrowboat installation.

I would say that absolute accuracy (gain accuracy) is not that important provided it is proportional both ways. It doesn’t particularly matter if it thinks 101A has been taken out for an hour, and 10.1A for 10 hours put back in again, when in fact it was 100Ah both ways. What is important is that the zero is accurate and errors are symmetrical about zero, otherwise the integration errors will accumulate rapidly.

Yes this does seem to be the case. Of course number of bits is all very well, but one also needs to look at noise, linearity and offset and gain temperature co-efficient etc. But yes there are certainly devices that do fit the bill.

A ground shunt will have one input at ground. But the spec says minimum input voltage is GND + 1.5v Not going to work. But oh sorry, my mistake, of course it will work because you said it would and obviously you designed the chip.

Not going to work. From the spec sheet: Common-Mode Input Range AGND + 1.5V to AVDD – 1.5V And it would be unidirectional whereas a shunt has to work with both + and - currents. Next...

It would be helpful to know what make of battery these are.

Yes it does seem very good for a cheap product. There is a little bit of calibration drift but it is very small. 10mA in 500A is 16 bit resolution, it would be interesting to know how they did 16 bit AtoD but presumably there is some range switching in the AtoD converter input.

You will need to be more specific please, eg what exactly do you mean by "flat as pancakes" and what exactly do you mean by a "damaged cell"? If the cell had physical damage such that is was deformed, I would definintely send it back. How did you pay for it? The only thing I would say is that "batteries are different in SoC, as much as 20%" is not an issue. Li batteries are to be stored and transported at around 30-50% SoC but that is nothing like critical. If you want to connect them in parallel then just charge each battery separately until the SoCs roughly match.