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nicknorman

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Everything posted by nicknorman

  1. Most likely to be a fuel issue. Could it be brought on by water in the fuel tank /pipes/ filters freezing?
  2. Not done it but I have been tinkering with a BLE (Bluetooth Low Energy) module recently. Less than £3 from Aliexpress IIRC. It will certainly connect to a Bluetooth module in a Li battery BMS. However it is just serial data ie a bunch of numbers, and as far as I know there is no industry standard protocol. I suppose the BMS manufacturer might make the protocol available, but failing that one would have to reverse engineer it and that would be time consuming. It’s what I did with Masterbus but it took a while, and then I only reverse engineered just enough to meet my needs. Edit: ah well there you go, the power of Google. Looks like someone has done it! https://endless-sphere.com/sphere/threads/generic-chinese-bluetooth-bms-communication-protocol.91672/
  3. This shows that the alternator is slightly charging a nearly full battery, but not necessarily that it can charge a low battery to its fullest extent. Anyway it is just something to keep an eye on - if you have means to check the charge current, check it is giving plenty of amps when the batteries have been used without shore power. If not, just bear in mind that if it seems to take a long time to charge the batteries, it is possible that the alternator is only working at reduced output. I am not saying this is the case, just that it is a possibility.
  4. We weren't really talking about the waveform from D+ but that will be 3 phase full wave rectified (ie a sinusiodal ripple for each phase) but I suspect that will be smoothed into a more level voltage by capacitance within the voltage regulator. In the case of my alternator with nothing connected to the field diodes, the D+ will be a straightforward rectified 3 phase. I can only zoom the internet image, there is a hint of a sinusoid at the peaks but also a lot of noise. Predominantly it is a square wave. The W terminal is connected to a phase and a couple of diodes. It is connected to Bat+ through the diode when the voltage exceeds Bat+ by the diode drop. The load from the diodes is massive when compared to that from a tacho (when significant charging is happening) so it is the diodes, the battery load and the phase winding that are the predominant creators of the waveform, I doubt the tacho load on the W terminal makes a significant difference. Notice that the waveform goes slightly negative compared to battery negative, because the negative diodes only conduct when the phase voltage is less than 0v by a diode's drop worth. Your "concede" sentence is not born out by the waveform diagram.
  5. I think last time the issue under discussion was slightly diffrerent. The diagram shows that the W terminal is connected directly to one of the phase windings. The diodes only conduct when the phase voltage is either lower than the battery negative voltage (minus a diode drop's worth) or above the battery postive (by a diode drops worth). So the diodes effectively clamp the phase voltage at close to 0v or Vbatt. At voltages in between these two, the diodes don't conduct and no current flows through the phase winding. It is effecively open circuit. This by the way is discounting the field diodes. Since copper in a rotating magnetic field has current induced in it, not voltage, when current tries to flow through the winding, the voltage has to jump up to Vbatt or down to 0v before any can flow, so this happens almost instantly, hence the squareish waveform. Once the diodes conduct then the waveform becomes more sinusoidal, but the voltage magnitude is limited by the battery soaking up the current. So a large sinusoidal current flows, but a small sinusoidal voltage waveform superimposed on a large squareish wave. The square wave element is the much larger in magnitude and so it predominates in terms of the overall look of the waveform. The diodes introduce serious non-linearity into the proceedings, which is why the waveform is not sinusoidal execept perhaps at very low field currents when the diodes aren't actually conducting any significant current I might actually take my 'scope down to the boat next time we go, to see if I can capture the W waveform, it would be interesting. Only thing is that although the alternator is a 9 diode machine, the field diodes are no longer used and so it behaves like a 6 diode machine. Edit: Why do it yourself when someone on the internet has already done it! This is a W terminal waveform, looks fairly square to me although there are quite a few transients presumably caused by the diodes in the other phases conducting/not conducting. And no mention of how alternator load might affect the waverform. I plucked this from here: https://electronics.stackexchange.com/questions/395125/is-this-alternator-w-rpm-input-circuit-ok-and-how-can-i-improve-it Definitely deja vue!
  6. Although this might be slighly annoying I don't think it is a big deal. With no load on the fully charged battery and possibly some slight input from the solar, the regulator has shut right down to the point that there is no field current and hence no (or not much) voltage on the D+ terminal - just the same situation as you have when you turn the ignition on before starting the engine. Hence the light comes on as it supplies a small current to the field windings. If it annoys you, leave a light on inside! I suppose the only question is whether the alternator is otherwise charging correctly up to its full output when required. If so, I would consider this light annoyance a "feature of the model". If it is not, perhaps there is a blown field diode.
  7. I'm not entirely sure what we are disagreeing on, but never mind! The W terminal is supplied directly from one coil, not through any diodes, although of course being a star configuration the other 2 coils are in there somewhere! OK so let us put some numbers on it. Diode drop 0.6v, battery voltage 14.4v, SoC close to 100%, minimal field current, minimal charge current. So when the voltage on the phase that is connected to the W terminal starts to rise, no current flows until its voltage reaches 15v. Because of the minimal field current, this doesn't happen until the induced current is close to its peak. As the diode starts to conduct, this clamps the voltage at slightly over 15v because there isn't enough energy to push it up much further. Very little current flows through the diode. So close inspection of the battery voltage with a 'scope would show the voltage at 14.4v with a little bump up to say 14.5v as the induced energy passes through its peak. This very small waveform, if you eliminated the static 14.4v, would resemble the very top of a sine wave. Meanwhile the W terminal waveform would be much closer to a sine wave, just with the peaks lopped off slightly as a consequence of the diodes conducting. Of course when the W terminal voltage gets down to -0.6v the other diode will conduct hence why the bottom of the sine wave is slightly lopped off as well as the top. Or Diode drop 0.7v, battery voltage 13.5v, SoC 50%, maximum field current, maximum charge current. So when the voltage on the phase that is connected to the W terminal starts to rise it does so very rapidly because of the high field current. It reaches 14.2v quickly and the diode conducts. There is a lot of energy due to the high field current so the voltage is pushed up a fair bit above 13.5v and a lot of current flows through the diode during most of the half cycle. So close inspection of the battery voltage with a 'scope would show the voltage at 13.5v with a significant near-half sine wave up to say 13.7v as the induced energy passes through its peak. Just a little bit of the start of the sine wave is lost before the diode conducts. Meanwhile the W terminal waveform would be much closer to a square wave - it would rapidly rise to 14.2v where the diode then conducts, and then take on a small sinusoidal peak for the remainder of the cycle before plunging back to -0.7v. Because the change from -0.7v to +14.2v occurs almost instantly and is a largish voltage, to the casual observer this makes the waveform look more or less square. Yes there is the sinusoidal peak to it but that is a much smaller magnitude - only 0.2v or so and barely noticable compared to the 14.9v peak-to-peak value of the squarish component. All that said, with Li batteries (very low internal resistance) and a large combi inverter with huge input capacitors, I don't see any ripple on my BMS that measures to 3 decimal places of a volt - albeit with its own smoothing input filtering. Bottom line for me is that at low loads the W terminal resembles a sine wave and at high loads it resembles a square wave. Not exactly, but those are the predominant characteristics.
  8. Ah yes that I can agree with. But that is not the same as the waveform on the W terminal.
  9. It would be interesting to see it. My thinking was that no current flows through the winding until the voltage is either higher than the battery positive voltage (by a diode drop’s worth) or lower than battery negative (ditto). And since the winding is a current source rather than a voltage source, the voltage would rapidly flip up and down until it was clamped by the diodes. However thinking more about it, the above applies when the alternator is producing plenty of current (lots of field current). When the alternator is producing very little current (low field current) it will be more or less a sine wave. So in summary, square wave when under heavy load, sine wave when under light load. How does that sound? As an aside, alternator controllers avoid fully shutting down the field current when there is no output current demand, because if they did the W output would stop working. So they either have an adjustable minimum field current (Alpha Pro) or in the case of the chip I use, an algorithm to monitor the magnitude of the phase input and keep just enough field current to have it make a minimum voltage so the device can keep track of rpm.
  10. I am getting a sense of deja vue here and last time I was wrong and you were correct! Yes I think you are right it is roughly a square wave going from roughly zero to roughly Vbatt. It will have a slight negative component due to rectifier diode voltage drop, but not much. Anyway, the main point is that the AP2 can be fed from the W terminal if there is one.
  11. Ah well that is good re. firmware. For the pulse thing one would normally use the W terminal on the alternator which is normally for driving a tachometer. It is as you say just an ac take-off from one of the phases so if you have no W terminal, a bit of surgery will be required.
  12. I think it is unlikely that the firmware is user-upgradable. OK so I had a look at the AP2 manual. You can individually set the charge voltages for bulk, absorb and float, therefore no need to have a "user" battery type. You can also set the charge voltage temperature compensation to zero (which is what you want for Li) but also you can specify that the temperature sensor is measuring alternator temperature, not battery temperature which will implicitly give you no charge temperature compensation. You mentioned earlier about the small engine mode etc, bear in mind you need to set up the pulley ratio and number of pole pairs correctly, since this is how the AP calculates engine rpm. The AP only knows the frequency of a phase, and how that relates to engine rpm depends on those things I just mentioned. "RPM event" allows you to send an event to other MV devices to "do something" based on rpm, for example turn on a heavy electrical load when the engine is running fast, turn it off when running at idle. Not useful for you! The AP can also receive events from other MV devices, eg "switch to float phase" could be triggered by an event from a Mastershunt "SoC reached 100%" (or some other % such as 80%). So that is how you would do it properly, having set a float voltage of say 13.4v such that no more current flows into the battery but the alternator can still provide any heavy loads rather than it coming all out of the battery. However, I heard what you said about not being able to get more kit, and without that I'm afraid the only solution is a switch on the "reg on" input. Reading the manual it is pretty clear that the AP2 was not designed with Li in mind, but it is reasonably flexible when coupled with something else like a Mastershunt.
  13. No it won’t damage the epoxy - if it’s been applied correctly. The only time our epoxy had an issue was when we indulged in a couple of days cruising through fairly thick ice, and then the damage was confined to a small area at the bow where the ice was parted.
  14. Is there some cross purpose discussion conflating the DC connectors with the mains AC connectors?
  15. It is interesting comparing my boat system - bare cells with no FETs in the way (I use a bistable relay for emergency disconnect) - with the Fogstar that has FETs and a BMS - configured as directional switch so that charge and discharge can be turned on and off separately. Charging at a similar C rate, the Fogstar gets to a higher terminal voltage earlier and thus has a longer "flattening off" period of charge current. I am guessing this could be due to the slightly higher internal resistance of the cell and FET combination. But of course although I say "longer", it is still massively quicker than lead acid.
  16. I don’t think so. The charge rate naturally reduces as the SoC approaches 100% due to the chemistry, and most charge sources have “soft” regulation which means the supplied current gradually reduces as the regulated voltage is approached. A BMS can’t control the charge rate, the FETs are either on or off. They can’t be partially on otherwise there would be massive heat dissipation and they’d fry in moments. I suppose they could PWM but that would seriously screw up any inductive charge sources such as an alternator.
  17. The BMS is password protected. I think Fogstar will give you the password but then refuse any subsequent warranty claims, which is fair enough. Fogstar have chosen some fairly conservative settings for the BMS, which is fine by me.
  18. You had better make some more posts then! Generally LiFePO4 charge termination current is 5% of capacity. The charge voltage is less critical unless you desperately want to get the last 1/10 Ah into it, I use 14.3v. So I charge to 14.3v until the current drops to 5% of capacity, wait a couple of minutes for the BMV712 and Mastershunt to synchronise to 100%, then stop charging. I could have made it 14.6v (3.65v/cell) but I didn't feel the need to go that high and it gets very little extra Ah in. Less than 0.1%
  19. I don’t have an alpha pro but I do have some familiarity with other MV kit. As I understand it, you need a Mastershunt connected for the Alpha Pro to be good with Li batteries - it gives charge current, SoC and battery temperature to the Alpha Pro. I have Masteradjust v2.20 for windows. It’s 4.4Mb so I could email it to you if you give me your email. However as I understand it the way Masteradjust works is that MV devices broadcast the parameters that can be adjusted, MA picks that up and presents a form on which you can change those parameters. So the list of parameters that can be adjusted is not built into Masteradjust, and so if a parameter you are expecting is missing, I think it’s more likely that the device doesn’t support editing that parameter rather than anything to do with MA itself. It is tricky to get an alternator control system that covers all the requirements for Li, with a stand alone AP you at least have protection against the alternator overheating but not much else. Wakespeed excepted, but it is expensive! You could use a BMV712 or other battery monitor with a built in relay to control the “reg on” input to the AP, such that the AP is shut down when the SoC reaches the value set on the BMV. Or if absolutely no new equipment is possible, fit a switch in the “reg on” line so that you can manually turn off the alternator when the batteries are charged.
  20. Northamton arm's only appeal is as a route to the Nene. Lorra Locks and then Lorra Locks again. Shallow after the locks and moorings at the end a bit grim. Stoke Bruerne has some appeal, although it is a bit over-rated IMO. Pleasant enough provided you don't expect shops etc! But what about the Leicester Section? A much nicer detour.
  21. It is noticeable that when external power (shore or generator) is connected to the input of a Combi, the Combi continues inverting for a couple of seconds before switching to pass-through mode. As IanD says, this is to allow the inverter to match frequency and phase to the incoming power before switching over. Instantly switching to a new supply at a significantly different instantaneous phase could cause nasty things to happen! On the other hand, when the external power is removed, the inverter instantly takes over because it has been tracking the frequency and phase in the background even though it was not producing any power, so it can seamlessly match the phase and frequency.
  22. No! Both of them are very bad ideas! Connect the shore power and the generator to the inputs of the selector switch. Connect the output of the selector switch to the Victron mains input. Connect the output of the Victron to the RCD and ring main. That is all!
  23. Ah the power of social media to leave a false trail!
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