Best Way to Tap 240v Traction Battery?

Discussion in 'Gen 2 Prius Accessories & Modifications' started by Handygeek, Jun 16, 2013.

  1. Handygeek

    Handygeek Member

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    Is this the best step-by-step to tap the 240v Traction Battery, please?

    Installation Instructions | High Voltage Tie-in

    Or is there a better set of instructions and pictures so that I may bring 240v out to the driver's side rear to be accessed via 75A quick-connect Powerpoles?

    I've acquired the APC inverter recommended by Doug Gaede and will have the generator power transfer kit installed in the house this week.

    Thanks!

    David
     
  2. pjc

    pjc Member

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    First of all, those photos look like they are for a GenIII.

    I'm not familiar with what you are actually doing (are you using your Prius as a generator?) but I would NOT recommend to connect up that way. PIS connects directly to the HV battery (before contactors), so the Prius ECUs do not know what they are doing to the OEM battery. PIS knows how to handle this and they have intervening electronics to tell the ECU what it needs to know.

    If you do not have special circuitry to keep track of the battery SOC and so forth, then you should probably connect after the Hall sensor and contactors, like Enginer does. Take a look at their installation manual here. It will also be easier to physically access than the PIS method....
     
  3. jdcollins5

    jdcollins5 Senior Member

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    I agree. I would not want to connect an inverter directly to the HV battery.

    I connected mine on the downstream side of the HV battery main contactor. This way the inverter is disconnected from the HV battery when the car is powered down.

    It is much easier and safer to gain access to the HV battery contactor compartment than the HV battery compartment. With the car powered down and the HV battery safety disconnect plug removed, there is no voltage on the contactor output terminals and no chance of creating a short circuit while connecting the inverter DC cables.
     
  4. Handygeek

    Handygeek Member

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    Is there a DIY/How-To with pics I may follow to connect to the "downstream side of the HV main contactor", please?
     
  5. jdcollins5

    jdcollins5 Senior Member

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  6. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    I am not sure of your level of electronic knowledge, but judging from your questions I would recommend you buy a pair of high voltage insulating gloves. You are messing with high voltage DC. It is lethal. Seriously, it will kill you. To top it off, you do not get the wiggles that you get from AC electrocution. With DC your muscles will contract and stay contracted until the battery is drained. No opportunity to loosen your grip and back away.

    Also as stated above, you should only make contact AFTER the safety interlock. Do not mess with the HV pack itself before the relay contactors. The car physically disconnects the battery for a reason. You do not want any parasitic drain other than self discharge and you do not want any physical path from the battery to the frame when off. If you are being rescued from an accident it is very important that there is no high voltage path present.

    Always engineer for the worst case scenarios.
     
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  7. vertex

    vertex Active Member

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    I am working on the same project. I did not get around to modifying the car yet, but I purchased the same type of connectors used on the batteries in the APC. I purchased 879-SBS50WHT housings, you need 2 for each connection, I bought 4 and 879-1339G5-BK contacts, 2 per a housing, I bought 8 all from Mouser electronics. They don't mate with the connectors on the back of the unit, but the pins are interchangeable, so I removed the housing on one, and replaced it with one of these. Now I have the housing to mate with the one on the rear of the APC that was not changed, and the one I changed. Put 1 in the car on the side of the 2 relay contactors that goes outside the battery pack. You don't need gloves, just follow the old electrician rule, work only with one hand, keep the other in your pocket. You do need the car off and to pull the orange safety disconnect plug. With a voltmeter you can confirm that there is no HV present between the contacts and the car chassis before you touch the terminals. I have done this a few times, and never found any. I will put a fuse in series with the line to prevent damage from over current. My APC is 2 KW 3 KW peak, so 30 amps is plenty.
    I ran into a problem with my installation. I did not get the APC transformer, but got a cheap Chinese 3 KW unit. It worked fine on the bench, but when I installed it, I did a much better job connecting to the transformer, with a lower connection impedance, and now the APC doesn't like it and shuts down. I am also using a spare Prius HV battery a have to allow the APC to act as a UPS all the time for automatic transfer. I have some issues to work out with that as well as to how to connect to the car with the 2 batteries in parallel. I need a way to balance the batteries. I need to get back on this project, it has been a few months, but other things have taken up my spare time.
     
  8. jdcollins5

    jdcollins5 Senior Member

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    I agree with not needing gloves. As you say, with the car off the Main HV DC relays are de-energized and the HV DC battery voltage disconnected from the relay load side contacts. Pulling the orange safety disconnect interrupts the battery series connection disabling any current flow.

    You can now safely work inside the HV DC electronics enclosure without the need for gloves. Testing with a voltmeter between DC+ to DC-, DC+ to chassis ground and DC- to chassis ground will show no presence of voltage. Now you can safely work on the de-energized DC cables going to the inverter/converter module.

    The HV DC battery connections to the line side of the Main HV DC relays are also well guarded.

    I understand 2k1 Toaster's concerns for a safety but it was a little over the top. He probably scared the crap out of anyone considering connecting an inverter to the HV battery. :)
     
  9. Handygeek

    Handygeek Member

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    It's better to be safe than sorry - anyone not afraid of electricity is too careless to be working with it.

    One of my hobbies is Amateur Radios and we can be found messing with 7,000+ v at nearly an amp of current (some even higher) where getting within inches could cause an arc to jump out of a protective cage and through you should you create a more attractive path. Electrical burns are the worst!

    Anyhow, I sure appreciate your guidance, I have printed this thread as it's too late to read with both good comprehension and retention!

    After I read this carefully I'll post any questions, or lacking that, will get about the acquisition of parts and get down to business.

    Thanks again, David
     
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  10. Handygeek

    Handygeek Member

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    If you hear of someone in the GA, N-FL, E.-TN, W-SC area who wants to do this I have some of the pieces of the 240v project to sell.

    They are a nightmare to ship - they need to be picked up - or a meet-up.

    David 40m w-nw of Savannah, GA
     
  11. ChapmanF

    ChapmanF Senior Member

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  12. landspeed

    landspeed Active Member

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    I'm just going to add : anyone reading this thread : the high voltage will easily kill you if you touch it. 48 volts is the 'kind of safe' maximum; anything more is moving into defibrillator territory! Regarding the battery - pulling the orange contactor safety plug reduced the voltage (to perhaps 150 volts and 50 volts); still dangerous. Also : the power lines from the battery are not live, unless the car is on ...... or unless some relay(s) have failed, jammed on, etc. Always check, and be aware that DC voltage overrides your nerves - human hands 'clamp' with much more force than the muscles that 'open' them. DC voltage will make you 'grab' onto whatever, and you can't undo it. If you grab a live piece of battery casing or something...
     
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  13. ChapmanF

    ChapmanF Senior Member

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    All good things to be aware of. One minor point: for producing the worst can't-let-go effects, the biggest offender is AC with a frequency in the range of 40 Hz to 110 Hz (which pretty much sucks, because we pretty much all use 60 Hz or 50 Hz for commercial power distribution). Higher frequency AC doesn't tend to clamp you on as severely, and neither does lower frequency AC or DC. It's that 40 to 110 Hz range that's the worst.

    The reason it works out that way is that muscles are made up of lots of individual fibers. No one fiber can hold its contracted state for very long. In order to make a sustained pull with a muscle, you have to keep stimulating fibers, and new ones keep joining in the pull while spent ones relax and recover and then join in again. That rate of 40 to 110 stimuli per second turns out to be just the thing to produce a tetanic effect, the muscle just ceaselessly clamping for all it's worth.

    DC, if you're lucky, will give you one strong jerk when you touch it, and another when the circuit is broken. If you're really lucky, that first strong jerk will hurl you away from it.

    Just don't make being lucky the basis of your safety plans.

    Electrical Injuries - StatPearls - NCBI Bookshelf
     
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