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Sharing 50 amp circuit with two EVSE

Discussion in 'Model S: Battery & Charging' started by ai4px, Jul 23, 2018.

  1. ai4px

    ai4px Member

    Joined:
    May 2, 2018
    Messages:
    238
    Location:
    Sumter SC USA
    Since we are a tesla and bolt house, I want to share the 50amp circuit in the garage with a siemens versicharge and a tesla HPWC. The Siemens Versicharge has a logic level input on a small terminal block that is used to stop it from charging gracefully. So I found a current sense relay that will sense current from the wife's tesla EVSE and stop the versicharge from charging. I wasn't worried about balancing the current between the two units... I'm just fine as long as only one of them can charge at a time. This little relay works perfectly with the terminal strip input on the versicharge unit and fits neatly in the subpanel in the garage.

    With this, the tesla can charge at 40amps and the bolt can charge at 32amps. If the tesla starts to pull more than 8-10amps (adjustable), the bolt will stop charging.

    [​IMG]

    https://www.amazon.com/gp/product/B00I9IFJOM/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
     
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  2. P85_DA

    P85_DA Supporting Member

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    Location:
    Chula Vista, CA
    Never seen anyone use anything like this for sharing across diff brands of EVSEs...normally have seen pairs of clipper creeks or pairs of HPWCs ...Any issues so far ?
     
  3. ai4px

    ai4px Member

    Joined:
    May 2, 2018
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    Location:
    Sumter SC USA
    So far so good. I set the current threshold at 9 amps. That way getting in and out of the Tesla and the little bit of power it draws won’t stop the Bolt from charging. If the Tesla draws more than 9 amps, the relay contacts on the current sensor close and the versicharge drops the Bolt like a hot potato. The versicharge shows two blue LEDs (one of them a little lock symbol). When I set the Tesla to draw 8 amps the versicharge starts and the little Bolt begins charging again. The bolt does send me a text message saying that it’s charge was interrupted.

    I figure 50amp circuit is 40amps continuous... the bolt draws 32 max, so 32+8 (or 9) is 40... the safe limit.

    Tomorrow I’ll run the low voltage relay wire around the perimeter of the garage ceiling.

    There are two LEDs on the current sensor... Green LED = a little current sensed, but not enough to trigger, Red LED = enough current sensed to trigger the switch. The HPWC in it’s off state doesn’t draw enough power to even light up the green led, but if the contractor on the HPWC is pulled in the current sensor’s green LED is on.
     
    • Informative x 1
  4. ai4px

    ai4px Member

    Joined:
    May 2, 2018
    Messages:
    238
    Location:
    Sumter SC USA
    OK, today I ran the low voltage control wire around the garage. I used twisted pair that’s used with those underground dog fences (it was laying around the shop). Twisted pair so that any inductive pickup would cancel out. Our garage has a room over, so I couldn’t go across inside the ceiling, I had to go around the long way in the attic, estimated 75 feet. Since I used the same path thru the attic as the 6 gauge wire for the charger, it was important to use the twisted pair.

    Here’s the sub panel in the garage
    [​IMG] https://photos.app.goo.gl/QeSDaoefbC8f8AsJA

    Here’s the inside of the versicharge unit with the terminal strip hooked up.
    [​IMG] https://photos.app.goo.gl/9apeusKpR3JABmqy6

    Here’s the versicharge interlocked... note the blue “lock” LED symbol.
    https://photos.app.goo.gl/J26tU7CeYHgoR97PA

    So when wife got home today, I changed her charge current to 5amps and the Bolt EV continuted to charge. Once the Tesla charging current was set to 10amps, the Bolt was interrupted. Tesla presently charging at 40amps. In about 2 hours when it’s finished the Bolt should resume charging.

    https://photos.app.goo.gl/RCG4aGqG4SNm4mih8
     
  5. davewill

    davewill Member

    Joined:
    Feb 5, 2014
    Messages:
    785
    Location:
    San Diego, CA, US
    Very nice! You could probably do something similar with a generic EVSE by using this to trigger a relay that either interrupts the pilot or pulls it down hard.
     

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