Matteo Posted March 10, 2016 Share Posted March 10, 2016 Is it normal that I can measure 53 Volts with a Multimeter between the bolt heads on the rotor/rim and one of the three contact pins inside the charging socket? I don't have the equipment for testing wether the current is limited between these two points. High Voltage down't have to be hazardous if the current drops immediately. Just wondering if it is safe. Anyone know? Please don't test it by touching with your hands after reading my post Link to comment Share on other sites More sharing options...
Keith Posted March 10, 2016 Share Posted March 10, 2016 Yes of course it is, if the pin you are reading from is the power pin, then you would expect the wheel to be at ground potential. Link to comment Share on other sites More sharing options...
Matteo Posted March 10, 2016 Author Share Posted March 10, 2016 with the pins being accessible with fingers I would expect the wheel being electricall insulated. A safer charging socket would be better. Link to comment Share on other sites More sharing options...
Keith Posted March 10, 2016 Share Posted March 10, 2016 49 minutes ago, Matteo said: with the pins being accessible with fingers I would expect the wheel being electricall insulated. A safer charging socket would be better. 50-60V is not a hazardous voltage, a simple home telephone operates at 50V d.c. and telephone ringing is sent at 80V a.c. You would expect the wheel to be electrically Insulated from what exactly? the charging pin next to the power pin is, and has to be, an earth pin, what in hell's difference does it make if other parts are also at ground potential - which is after all normal practice, at the very least to prevent EMF issues, every part of your car is earthed as well. What is hazardous is poking around with meter leads in the charge socket. 50+ Amps is most definitely a hazardous current and is the very least you might experience if you short power to earth and create your very own personal arc welder. If your wheel is well designed there may well be a diode in the positive charge line to prevent damage if you do create such a short - but not all have it. Is there a good reason you are poking about with a meter? They fact that you even considered attempting to measure current between power and earth would suggest you don't have a safe grasp of what you are testing. Link to comment Share on other sites More sharing options...
esaj Posted March 10, 2016 Share Posted March 10, 2016 1 hour ago, Keith said: What is hazardous is poking around with meter leads in the charge socket. 50+ Amps is most definitely a hazardous current and is the very least you might experience if you short power to earth and create your very own personal arc welder. This is what shorting the battery for a fraction of a second (so short time that even the meter fuse didn't blow, the BMS must have cut the power or the connection was lost pretty much immediately as the probe end melted/exploded and the shrapnel welded itself inside the connector) did to my multimeter probes: Stupid mistake, but after that I'm pretty sure to check whether I have the probes in the right holes before poking them anywhere with the battery... I was supposed to measure the pack voltage, but the probes were set up for current measuring There was someone else who had done the same mistake, and in his/her case, the entire uncovered metallic part of the probe tip had melted completely off. Link to comment Share on other sites More sharing options...
DS Posted March 10, 2016 Share Posted March 10, 2016 1 hour ago, Keith said: What is hazardous is poking around with meter leads in the charge socket. Exactly...just reminded me my poking: So, @Matteo, I was lucky but learnt my lesson. Link to comment Share on other sites More sharing options...
Matteo Posted March 11, 2016 Author Share Posted March 11, 2016 Measuring voltage on the charging socket isn't dangerous when you use probes with very short tip. Link to comment Share on other sites More sharing options...
dmethvin Posted March 11, 2016 Share Posted March 11, 2016 @Matteo you underestimate my abilities! I think for the case that @esaj mentioned he had the probes in the "amps" holes so he was basically shorting the current path. A short probe wouldn't help there. BTW I agree with @Keith that 60v is not hazardous in general, at least when you are touching it with your hands. Don't stick your tongue on it though. Link to comment Share on other sites More sharing options...
esaj Posted March 11, 2016 Share Posted March 11, 2016 6 minutes ago, dmethvin said: BTW I agree with @Keith that 60v is not hazardous in general, at least when you are touching it with your hands. Don't stick your tongue on it though. I don't know if these models are really accurate: https://wrwkwb.files.wordpress.com/2014/10/24fdf-effects.jpg But assuming they are in the right ballpark (you actually find slightly different numbers depending where you look, and I believe the values are slightly different depending on your sex, body type, water content etc), there'd be 1 kilo ohm (internal) between your hands, assuming a "perfect" conduction (zero resistance) between the wheel/battery conductors and your skin is wet (the "worst" possible option, add another 2k for "both ends"), 60V could (theoretically) cause a current of 60V / 3000 ohm = 0.02 A (20mA). Potentially this could already cause muscle spasms. So don't go touching it with wet hands (or your tongue ) just to be on the safe side With dry skin, the skin resistance is in the hundreds of kilo-ohms range, so likely the current will be so small that you don't feel anything. Link to comment Share on other sites More sharing options...
Keith Posted March 11, 2016 Share Posted March 11, 2016 When I was MUCH younger, and careless and nobody thought that it would be a bomb, I built an electric shock machine I.e a 9v oscillator fed into the low voltage side of a 3V transformer. The "mains " side then gave out 720V a.c. which was wired to the insulated lid and base of an old Swarfega tin. Left on a table in our local pub the tin regularly flew across the room when a curious drinker tried to open it. One day a daft friend asked a security guard to open the tin for him. The guard did so and handed the two halves back to him, at which point it flew across the room again. That guards skin was so dry he hadn't even felt 700+ volts! Link to comment Share on other sites More sharing options...
dmethvin Posted March 11, 2016 Share Posted March 11, 2016 I have regularly checked the charge on a 9-volt battery with my tongue. A good strong tingle means it's fresh. The reason you shouldn't lick the EUC charge port is that it tastes so good it might kill you. Link to comment Share on other sites More sharing options...
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