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nicknorman

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nicknorman last won the day on December 26 2018

nicknorman had the most liked content!

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Profile Information

  • Gender
    Male
  • Location
    Aberdeen
  • Interests
    Electronics, gliding, motorbikes

Previous Fields

  • Occupation
    helicopter pilot - retired
  • Boat Name
    Telemachus
  • Boat Location
    Fazeley Mill Marina, Tamworth

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  1. nicknorman

    400amp megafuse

    Yes wot MP says. You have to consider the feasibility of a fault causing a current in your 35mm cable that is say between 150A and 400A. Pretty unlikely! A dead short will pass a lot more than 400A and blow the fuse rapidly, and that is by far the most likely significant fault condition.
  2. nicknorman

    Fazeley Mill

    We’ll keep a look out for you. When are you expecting to arrive?
  3. nicknorman

    Another Lithium battery thread

    Yes it is the same unit as millibars but at some point about 10 years ago, ICAO (international civil aviation organisation) decided that us pilots and ATC would all have to call it hectopascals not millibars. I've no idea why! Some bureaucratic ivory tower perfection-seeker I expect - he probably decided that the pascal was the SI unit, not the bar. After 10 years I've nearly got used to it! The sensor does oversampling internally - up to 4096 times, which takes it 8 mS, and thus has an apparent 24 bit resolution. I've made sure there is no I2C bus activity whilst that is happening.
  4. nicknorman

    Another Lithium battery thread

    The bottom side has copper fill, separated into digital and analogue grounds so not much gets etched away. This circuit is virtually entirely digital with the 3 pressure sensors and the remote temperature sensor all having digital outputs (I2C and Onewire) so hopefully it will just "work" as the current lashup on breadboard does! Hopefully the groundplane and separate digital and analogue 3v3 regulators will help to reduce noise on the barometric pressure sensors which need to be super un-noisy. Output is from 200 to 1200 hPa and jitter of 0.01hPa is too much!
  5. nicknorman

    Another Lithium battery thread

    Oh and while I’m on, this is the top copper and silkscreen layers of the board I’ve sent for manufacture. Board is 76 x 50mm. Checked endlessly but no doubt something will be wrong!
  6. nicknorman

    Another Lithium battery thread

    AIUI surface tension is only an issue whilst actually reflowing, and mostly for any components on the underside (which might fall off). I don’t have any components on the underside! At a pinch I think one can glue components down, but when I reflowed this board (that’s the tiny sensor I posted a pic of earlier, and a couple of decoupling caps) I just kept the airflow rate slow and there was no tendency for them to get blown around. I guess it depends on pad area vs windage of component. Of course with a proper solder mask it will be much easier (I hope!). I’ve decided to use 1206 passives which are relatively large (but still tiny!)
  7. nicknorman

    Another Lithium battery thread

    Yes it does use a bit of juice, although when the measured current is zero it’s not massive. But the differential supply and output swing is a bit of a pain. The differential output can be dealt with by a fairly simple circuit but not sure how that would affect the critical zero point accuracy. If i we’re doing it I think I would use a shunt and digitise the value locally, send it via CANBUS etc to the main control system (all done with a PIC, obviously!). Which of course is exactly what my Mastervolt Mastershunt does (so I don’t claim any originality!) Incidentally I just sent off my PCB files to China, £29 for 10 boards 75mm x 50mm on 48 hr production and 2-3 days delivery. We’ll see what happens!
  8. nicknorman

    Another Lithium battery thread

    As far as I can tell ( because the datasheet is a bit sparse) these sensors are bidirectional. Quoted current range is +-200A and it mentions being suitable for AC. I suppose the question not directly answered in the data sheet is whether the output indicates the current flow direction. But since the nulling coil’s current must be bidirectional it seems likely that the output is too. It is of course a lot more expensive than the sensor you are using. edit:definitely bidirectional, you can see from the schematic that the output can swing both ways. Downside is that it needs a + and - power supply.
  9. nicknorman

    Another Lithium battery thread

    Are you using an open loop or closed loop (nulling) hall effect sensor? I've never used them but I would have thought a closed loop sensor whereby an opposite magnetic field is generated to create a null (which is all that the hall effect sensor then detects) might not suffer from magnetisation issues since the net magnetic field is zero. https://uk.rs-online.com/web/p/current-transducers/1883783/
  10. nicknorman

    Fazeley Mill

    The thing is that once you are “inserted” into the gap between the two rows of boats, there is only one way to go, and the other boats shelter you from any wind. So as reversing goes, it’s pretty easy. I don’t think it makes any difference whether you are 70’ or 59’ as we are, once you are in the slot. And it is generally fairly sheltered from the wind unlike the other marinas you mention.
  11. nicknorman

    Fazeley Mill

    Yes she’s still there. If you are thinking of cruising from Lady Lane to FMM in the near future, don’t forget that Broad St bridge is closed until 15th March.
  12. nicknorman

    Fazeley Mill

    Main gate is now electric. You phone the number, the gate opens. Or press the code buttons on the panel. However when leaving, the panel is on the left which makes doing it from the car rather difficult (unless you have a passenger). So phoning the gate is the answer. Pontoon gates are still a padlock but with a bit of luck that is something ABC might change.
  13. nicknorman

    Fazeley Mill

    Yes the pontoons are long and the manoeuvring gap is not that big. We are 1 boat along from the gate so we have to pass about 6 or 7 boats (each side) to “escape”. However, this has never been a problem, nobody has glared at us and why should they? We take the boat out nearly every time we visit and whilst there are a lot of boats that never seem to move, it has caused no problems in the 8 years we’ve been there. I reverse in and drive out. Although I have done the reversing in “solo” quite often, it is of course better to have someone on the bow deck to fend off when reversing. But once I am “in the slot” it’s pretty easy. It has to be said that Jeff doesn’t like to take the boat out on its own, or if he does he tends to drive fwds in on return (so the boat is wrong way round and needs the long power lead). But it’s not a big deal.
  14. nicknorman

    Another Lithium battery thread

    Did you recompile the Arduino code? I am getting a compile error " 'average_EPC_utilization' was not declared in this scope" My god the Arduino IDE is caveman-like compared to Microchip's IDE. Truly crap! Did I mention I hate Arduinos?
  15. nicknorman

    Another Lithium battery thread

    Well 2 things, firstly what is the hysteresis of your sick squid board? If it shuts off at 14v, the battery voltage will rapidly drop to say 13.6v and then if the relay closes again, you will just have a chattering relay. And secondly for people who cruise their boats a lot, once the battery was fully charged and the relay opened, for the rest of the cruising day the battery would be depleted by the boat's loads. Well unless you have a LA battery as well, but that seems a fudge to me. Nothing, for most boats. The alternator remains operating until it stops (or nearly stops) spinning
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