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Accessing battery terminals for inverter attachment

Discussion in 'Roadster: Technical' started by will36, Mar 23, 2014.

  1. will36

    will36 New Member

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    I have recently acquired a high voltage off grid inverter that I intend to attach to my roadsters battery pack. I fully understand all the risks involved in doing so however I am a very experience Electronic Engineer and the warranty is very near expiration. Before I go removing covers, probing for voltages and cutting wires, does anyone have any ideas for the best attachment of the inverter? or has anyone seen any blog entries/forum post of other people wanting to do the same/similar?

    Ideally I would like to place it on the power module side of the ESS contactors (Which I am assuming exist???)

    Also I assume the 3 cables from the power module are the main cables from the battery however does anyone know why there are 3 and what their polarity is?
    2014-03-24 14.22.55.jpg

    Any help/ideas are much appreciated.

    Will
     
  2. marco2228

    marco2228 Roadster Signature #34

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    #2 marco2228, Mar 24, 2014
    Last edited: Mar 24, 2014
    Oops. I've been wrong with my answer.

    The cables are the cables to the ESS. Don't know the polarity. Should be visible under the small lid in the PEM.
     
  3. hcsharp

    hcsharp Active Member

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    If you open up the access cover on top of the PEM you will easily see what's going on and where to attach your inverter. One of those orange cables has the wires coming from the charge port. You will have to have your car on in order to close the contactor from the ESS. Keep in mind the electronics are very sensitive. If your inverter draws too many amps it will create a lot of noise on the ESS wires into the PEM. That might cause problems.

    It would be interesting to see your Wh/mi reading after running the inverter for a while without driving the car! Zero miles per kWh.:eek:
     
  4. efxjim

    efxjim Member

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    There is a microswitch under the cover that throws an error code. When the switch is depressed the error goes away but Tesla has a log entry of the access. The switch could be held down with a thin plastic shim slid under the slightly loosened cover. What kind of inverter are you using? I would like to do the same thing.
     
  5. will36

    will36 New Member

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    Thanks

    Thanks for all your help. I have had a look under the PEM cover and that will be a very suitable attachment point!
    The inverter is not for sale at the moment, I acquired it through R&D project. As soon as I get it working and get some more information I will let you know.
     
  6. wiztecy

    wiztecy Active Member

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    #6 wiztecy, Mar 26, 2014
    Last edited: Mar 26, 2014
    Wouldn't you need a 400 Volt (DC) to 12 Volt (DC) converter first, and where are you going to find that?? It appears you have one (an inverter of some voltage type), but how are you doing your conversion? And is this inverter also a converter? Basically reducing and converting the 400V (DC) source down to a 12V (DC) source then running your 12v (DC) source to 110V (AC) inverter in the US and most likely 230V (AC) in Australia. If not I'd suspect there's going to be allot of smoke, damage electronics (mostly on your inverter side), and open up a shocking hazard.

    I was going to run an inverter off my 48Volt battery pack on my Zero motorcycle while I had fixed and enhanced the contactor, however in order to do that, I first had to find a 48Volt to 12Volt converter. Then from the 12 Volts feed the 12Volt Inverter. Was tough finding a 48v to 12v converter, so I buttoned up the pack and just riding the bike. I wanted to use the pack as an emergency backup power-source for my home and also when I go out camping.
     
  7. jeremyz

    jeremyz Member

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    Why can't you just use a solar inverter? They can accept 600V DC and output household current (assuming you want to power your house with it).
    SUNNY BOY.SMA America, LLC
    I guess that the solar inverter might find it confusing when it was trying to do maximum power point tracking (MPPT).
     
  8. wiztecy

    wiztecy Active Member

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    Thanks J!

    That looks like the way to do it. I also found one that is 48V that'll work with the electric motorcycle:
    Magnum MS-4448PAE 48 VDC 4400-watt 48VDC to 120/240VAC sinewave Inverter

    Quite a hefty price, $2+k for the 48v input one on my link. This must be the path Will's wanting to go down. Not a bad idea having access to that power. Also a big advantage having the 2.0 PEM setup to easily access the +/- of the ESS.
     
  9. spaceballs

    spaceballs Member

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    #9 spaceballs, Mar 26, 2014
    Last edited: Mar 26, 2014
    *Warning do at your own risk.

    If you want to do it for the cheap, use the the onboard ESS to 12v converter (it's ~2,000 watts), this I believe http://www.martekpower.com/products/en/ps2450.html, then connect cheap 12v to 120v pure sinewave inverter to I think these points.

    12v.jpg



     
  10. efxjim

    efxjim Member

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    Grid tied inverters need a stiff AC signal applied to the output terminals before they turn on. If this could be bypassed they would make a perfect backup/job site AC power source. I have yet to find someone who has successfully bypassed the safeties.
     
  11. jeremyz

    jeremyz Member

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    I was assuming that will36 wanted to use the inverter to buy cheap energy at night and use it during the day. If he wanted to use it off-grid, he might be able to buy an off-grid solar inverter. In Japan, you can buy an option for the Leaf to power your house when the power goes out at your house. There's also Via Motors' truck that can be used as a job site power supply.
     
  12. Babylonfive

    Babylonfive Power12

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    No, actually there are inverters that work as an inverting 'island', providing their own timing for the AC frequency, and do not require a existing grid connection. These are NOT grid-tied.
     
  13. tom66

    tom66 Member

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    The three wires out of the PEM are the motor phase outputs, not the battery input.
     
  14. efxjim

    efxjim Member

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    I just don't know of any 380v inverters on the market except grid connect.
     
  15. marco2228

    marco2228 Roadster Signature #34

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    What's exactly what I was thinking. But they are not. Two cables are the ESS poles and one goes deeper into the PEM, probably a charging cable but I don't know.
     
  16. wiztecy

    wiztecy Active Member

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    #16 wiztecy, Mar 27, 2014
    Last edited: Mar 27, 2014
    That sounds plausible. On the 1.5 the ESS run comes in on the passenger side and the charge port run comes in from the drivers side. I don't recall seeing anything clearly visible running from the PEM to the charge port on the 2.x's, But why one solid wire unless the 3 whires from the charge port are within it (single orange cable) which I doubt. But if that's just one (single) orange wire running to the charge port it appears to be way to big. Have to see pics showing the bottom of the PEM and the charge port wires coming out of the drivers side of the Roadster.

    [update]

    Here's a pic from the top of the 2.x PEM that should help clarify things:

    2010-PEM-Connector.jpg
     

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