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  1. Jeremy Harris

    Wire for wiring halls to Xlyte Hub?

    Sorry for the delayed reply, been busy with new house-related stuff over the holidays. As Neil says, we spoke on the 'phone a couple of days ago about this. I bought some of this thin PTFE wire for Halls a couple of years ago and have found it to be really good. It's a pain to strip, unless...
  2. Jeremy Harris

    looking for a battery power switch

    No need for the zener at all, if the right resistor values are used. Just an extra component that adds nothing useful. The FETs need more than about 6 or 7 V on the gate to turn hard on, and less than 20 V to be safe, so there is a massive safety margin if the right resistor values are used...
  3. Jeremy Harris

    looking for a battery power switch

    Yes, no problem if you are going to mount them on an alloy bar as a heat sink. My rule of thumb for TO220 FETs with no heat sink, mounted inside a sealed case (which is how mine are mounted), is no more than about 1W, but if you can bolt them to the case then that makes a big difference.
  4. Jeremy Harris

    looking for a battery power switch

    A good general rule of thumb for these controllers is that the FET dissipation is roughly double the resistive loss (because of switching losses). A 12 FET controller running at 40A will be dissipating around 3.6W per FET, around 1.8W as resistive loss, and 1.8W as switching loss.
  5. Jeremy Harris

    Dear America,

    I see you've quoted a comment by etriker (personally I find very little of interest in his posts so have him permanently on ignore). For the record, etriker made several posts, one after the other, on this thread that were just repetitive statements, unconnected with either the topic or the...
  6. Jeremy Harris

    looking for a battery power switch

    It's best to use the data sheet maximum figures, rather than the typical, just to be safe, so 3077s are really 3.3mohms, 4110s are really 4.5mohms and 4310s are 7mohms. If you had 4 paralleled 4310s, then the total on resistance would be around 1.75mohms max. At 40A the power loss in the FETs...
  7. Jeremy Harris

    looking for a battery power switch

    If using the much higher on resistance IRFB4310, then I would strongly advise using more of them in parallel, to reduce the total on resistance. I've found that I can just about get away with two paralleled IRFB3077 FETs (3.3 mohm on resistance each) for a 20A switch, and four IRFB4110 FETs in...
  8. Jeremy Harris

    Automatic anti spark circuit

    I described my way of doing this here: http://endless-sphere.com/forums/viewtopic.php?f=3&t=40142#p586436 I found that even for low current use there was a big benefit in using several FETs in paralell, just to keep the temperature down in the FETs. My first version used a single IRFB4110 on a...
  9. Jeremy Harris

    Nickel batteries parallel charging

    Yes, but in my case it only took one cell to fail to cause the fire, so in essence the cause is similar. My guess is that your charger may have been designed back when NiCd cells were far more prevalent than NiMH, and it's the latter than are more sensitive, it seems, to being over-charged. My...
  10. Jeremy Harris

    looking for a battery power switch

    The circuit in the thread below does this, and manages the capacitor inrush current when switched on. The isolation when the switch is off is very good, I couldn't measure any current at all flowing when switched off and two of my bikes have this type of switch as the only power switch, and I...
  11. Jeremy Harris

    Nickel batteries parallel charging

    I had a massive fire and explosion from accidentally charging some NiMH cells in parallel, at a charge rate that was only about 0.1 or 0.2C, IIRC. I'd thought (wrongly) that at a low charge rate this would be safe, but it nearly burned my house down. Are you sure that the charger in question...
  12. Jeremy Harris

    Another Lebowski controller

    The plan is to build a controller to run a paralleled pair of Colossus 80-100 motors (on a common shaft). The reason for choosing this arrangement is really because I can then fit this double motor in the space where the air box used to be on my RD50, leaving most of the old engine/gearbox...
  13. Jeremy Harris

    Merry Christmas and a Happy New Year to EVERYONE at E.S. !!!!!

    Merry Christmas to all, and the very best wishes for the coming New Year. The shear size and multicultural membership of ES, with everyone around the globe that's here sharing a common interest in pollution free, low impact, transport, is heartening in this age where so few seem to care much...
  14. Jeremy Harris

    motor dosent run

    It may be that the voltage drops with the flat battery as soon as there is any load, causing either the controller low voltage cut out to activate os perhaps the battery BMS low voltage cut out to operate. Was the meter connected all the time, or only when you were testing the battery voltage...
  15. Jeremy Harris

    European Dealers

    As already said, forget this idea, it will give no end of trouble and isn't practical for the sort of current that an ebike battery has to handle. Either get the cells welded together with nickel tabs (there's a long thread here on a cheap way to do this) or do what many have done and learn to...
  16. Jeremy Harris

    European Dealers

    There are BMS boards advertised on some of those links above. Not sure what you mean by "battery holder". If it's a battery box to slot on to the bike, then the chances are that you may struggle to get one that will accept the dimensions of a DIY pack. Most of us end up making housings for...
  17. Jeremy Harris

    What are you doing for amageddon?

    I had a friend (sadly passed away now) who was seriously into fermenting strong wines. I used to sneak samples into work and get it tested for him for ethanol content. Best he got was around 18%, which is way higher than the books say is normal. His technique was to start with a modest sugar...
  18. Jeremy Harris

    Another Lebowski controller

    Sorry, missed that question, Rick. From a quick read of the data sheet it looks like the drive capability of the 2186 is pretty much up to driving some pretty big FETs directly, probably even the massive VMM 650 HiperFETs I have for the big controller I'm planning. Here's what the populated...
  19. Jeremy Harris

    Turnigy Wattmeter clock does not work with less than 1 amp

    Defect implies that the product is faulty. The reality is that it's a product design limitation. I agree that documentation would be good, but I've yet to see decent and accurate documentation (or often any documentation) with most of this cheap Far Eastern made stuff.
  20. Jeremy Harris

    Does More Power Sometimes Decrease Rider Satisfaction?

    This is key to the success of a lightweight assist system, rather than an out and out electric moped or motorcycle, I think. The best system I've ridden is the Panasonic bottom bracket drive. It's low powered, almost silent and rewards rider effort by using crank torque sensing (i.e. to get...
  21. Jeremy Harris

    European Dealers

    There aren't a lot of EU parts suppliers, and those that I've found have been expensive when compared to buying direct from China. In France there is http://goldenmotor.fr/ In the UK there are: http://www.8funbike.com/store.asp/d=5/c=45 and http://www.alienbikes.co.uk/page5.htm and...
  22. Jeremy Harris

    Turnigy Wattmeter clock does not work with less than 1 amp

    It's designed in. I had to do the same with my home brew one, albeit with a lower current threshold. The reason has to do with the maximum resolution available on the analogue to digital converters in the µcontroller used. The majority of small µcontrollers have a 10 bit resolution, with the...
  23. Jeremy Harris

    Possible to build an electric foldable bike?

    If you go for one of the cheap programmable controllers then you can build the bike, test it, and then reprogramme the controller to get the speed to the legal limit (max speed, as a percentage, is programmable, as well as the current limit). This means you can be sure that your ebike won't...
  24. Jeremy Harris

    Possible to build an electric foldable bike?

    You can reduce the power fairly easily if you use a programmable controller, rather than the one in the kit. For example. the Xiechang range of controllers (sold by many vendors, but as you're in the Far East I'd suggest contacting Keywin in China) can be connected to a PC and programmed to...
  25. Jeremy Harris

    Bottom balancing?

    We've done this EVTV rubbish to death here, several times. The bloke that heads up that show is technically naive (that's being polite about it) and clearly has no real understanding of how the cells he is using work and why SoC can only be determined accurately when all cells are charged to a...
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