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Touching HV contacts while Orange Plug In?

Discussion in 'Gen 2 Prius Main Forum' started by fragglestickcar, Aug 25, 2024.

  1. fragglestickcar

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    Can someone explain how the narrator is so comfortable touching various parts of the battery while the orange plug is still engaged? I guess he merely hovered his hand over the relay points, but he seems so assured. Context: I'm getting a P0AFA (low voltage hybrid system) four months after installing new OEM battery, and am needing to measure voltages.


     
  2. highmilesgarage

    highmilesgarage Active Member

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    it's kind of crazy that most you tube videos show you how dangerous it is to deal with the HV batteries, you need special gloves.. this and that.. but in reality the design was really safe unless you're stupid enough to deliberately touch the high voltage points that are live. Anyway those are for liability concerns (you won't get sued for the instructions) Most people (including me) don't even wear special gloves to handle it (I'm not saying you should do too) because we know what we're doing. Anyway he's just touching the body and not holding the 2 HV terminals, even then the 2 outermost terminals are not live (relay activated by the car) Removing that plug only disconnects the HV battery to 110v each halves, so there's still voltage in there that could kick you.
     
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  3. mr_guy_mann

    mr_guy_mann Senior Member

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    Before I touch anything at the hybrid battery, I would want to look at block voltages in scandata for the high voltage battery ecu.

    What stands out? If all HV connections were torqued (to 48 inch pounds) then I would suspect a corroded pin at the orange ecu connection.

    As far as safety, yes you can really hurt yourself with a hybrid battery, but you have to try. (Some people do seem to have a natural talent for that).

    The safety recommendations are there to minimize the negative consequences of poor decisions.

    Posted via the PriusChat mobile app.
     
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  4. pasadena_commut

    pasadena_commut Senior Member

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    For "small" DC voltages (up to several hundred volts) putting one hand near a big battery is somewhat safe. This assumes that you are wearing rubber soled shoes, standing on concrete, the other hand is nowhere near the device, there is no metal on that hand (ring, watch, or tool), and the hand is not dripping with sweat. If you managed to short the battery through a dry hand the current will not go anywhere else and it will be limited by the relatively high resistance of skin. Worst case would be a really bad burn or some nerve damage. Now if you were to use both hands it could kill you, because then the current could go through your chest. Shorting a battery in this voltage range through metal is really bad. You could easily lose vision in one or both eyes from the arc, and there might be a severe burn because of the large current. The ring, watch, or tool might weld itself to whatever it touched. (Even a car's 12V battery can do the same things.) Also the battery itself could be damaged, but that is a secondary concern.

    All of that said, use the safety switch. You can always trip, or make some other stupid mistake, and end up in a circuit with the battery. Only one hand at a time should touch the battery, whenever possible. If you need to make electrical measurements on a live battery place each lead one at a time using one hand, using some sort of clamping test lead.

    For much higher voltages all this goes out the window, and even a pin hole in a rubber glove can kill you. There are plenty of videos on youtube covering safety procedures for linemen who work on very high voltages. Scary stuff.
     
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