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Manual battery cooldown mod - a cure for the Roadsters insomnia

Discussion in 'Roadster 2008-2012' started by ML Auto, Nov 5, 2017.

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  1. ML Auto

    ML Auto Member

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    After years of dealing with the coolant pump running almost 24/7 here in hot sunny Florida, I finally decided to do something about it. Since the Roadster just taps into the existing air conditioning system for ESS cooling, I just connected 12V to the ESS cooling solenoid. Now I can activate battery cooling anytime I want. No more having to plug in or shut down the APS to get the car to go to sleep. I had put this off for a long time, dreading having to disassemble the dash. But after it ended up being fairly simple, I wish I had done it years ago.

    You will just need an on/off switch and some 2 conductor wire (speaker wire works good).
    For tools you need a phillips screwdriver, a 8mm socket or nut driver, and a soldering iron.

    Step1) Shut down the APS. If you don't know how to do this, maybe you shouldn't attempt this mod.

    Step 2) The A/C control module is located in the front of the center console, behind the 12V power outlet and the USB download port. You need to remove the cover on the right side. There are four retainers holding the cover with the power outlet (two on each side) and two more in the side cover. The plastic retainers have a phillips head screw that you need to back out about 1/4 of an inch, and then pull on the screw to pop out the retainer. If you completely remove the screw, you will have to pry out the remaining expanding shell, so its easier to just back out the screw. SAM_4124.JPG
    Left side showing the two retainers in the front cover
    SAM_4121.JPG Right side showing the four retainers SAM_4110.JPG Right side cover removed. You can see what the retainers look like. The front cover gets wedged against the bottom of the dash, so you need to work the cover (pry gently) out towards the front of the car

    Step 3) Remove the A/C control module. It is attached with three 8mm nuts - one on the top left and two on the right. The two on right (forward) you do not have to remove all the way, as the mounting ears on the module are slotted SAM_4104.JPG A/C module removed SAM_4109.JPG Closeup of the three studs securing the A/C module. Again, the two on the right you do not have to remove fully, as they are a pain to get the nuts back on, since you have to do it by feel.

    Step 4) Locate the wires to connect the switch. The rear connector (closest to you) has the wires you need to connect to. The connector is clearly labeled - A through K, rows 1,2 and 3. The black wire with the red stripe is the output for the ESS cooling solenoid - terminal H3. The main power input from the APS is the larger tan wire on terminal J1 (or J2 - both tan wires are power). You just need to connect a switch between the two.
    SAM_4102.JPG
    Rear connector showing tan (power), and black/red (solenoid) wires.

    Step 5) Strip back a little insulation from each of the tan and black/red wires and solder your supplied wire to each. Insulate with tape - liquid electrical tape makes it easy, as it's cramped down there.
    SAM_4107.JPG
    I installed an in-line fuse on the power lead just to be safe

    Step 6) Route the wires to wherever you want your switch and connect the wires. Secure the wires with zip ties to keep them from rubbing on anything. SAM_4118.JPG
    I mounted mine in the iPod holder.

    Step 7) Test it by turning the APS back on and listen for the click of the solenoid when you flip the switch.

    Step 8) Reassemble in the reverse order.

    Now anytime you want to cool down the battery, just turn on the A/C and flip the switch. Anything below 30'C and the car will go to sleep after you power down. I find it nice to be able to keep the ESS temp under the point where the car demands an ESS cooldown and robs you of the cabin A/C. I just flip the switch for a minute to keep the battery temp in check, and turn it off when I notice the cabin air start to get warmer.

    While I obtained power from the APS feed to the A/C module (which is always on when the car is awake), you could get power from the key on circuit to avoid solenoid activation when the key is off. The key on feed to the A/C module is terminal F2, which is a small green wire. I didn't want to put a load on that circuit, so I used the APS feed which is already designed to power everything. You could get key on power from the radio or somewhere else, but that would involve more disassembly, and I wanted to keep it simple. You might consider using a lighted switch so you can see when the cooling is on, but with the decrease in the cabin A/C output, its pretty obvious. I suppose if you left it on long enough you might eventually get condensation inside the ESS - and that would be bad. So use this info at your own risk.
     
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  2. markwj

    markwj Moderator, Asia Pacific

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    Presumably you are only diverting HVAC to ESS here, not turning on/off the HVAC? Does it work when charging, or just driving?
     
  3. spaceballs

    spaceballs Member

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    I'm guessing he turns flips the switch and then turns on the AC manually.
     
  4. ML Auto

    ML Auto Member

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    The A/C must be turned on and operating for this to work. This mod just opens the flow of refrigerant to the ESS cooler, which is what occurs when an ESS cooldown is requested during either charging or while driving. The only difference is that the compressor does not run at the max 6000 RPM , but at the normal 2000-3000 RPM. But it still cools down the ESS in just a few minutes.
     
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  5. Rolf68

    Rolf68 Member

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    Hello

    Great Mod !!! I always wanted to have such a feature. Is it mandatory to strip the wires or is it possible to plug the 2 cables in the same J1 H3 than the original wires in order to make this reversible?? DOes this work with every roadster ?

    Thanks, and have a nice day :)
     
  6. ML Auto

    ML Auto Member

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    The original wires need to be kept in place for the factory battery cooling to remain operational. Since you are not cutting any wires, you can easily remove the switch and return it back to stock, with just some tape over where you spliced into the harness. The terminals to connect the switch are the same for the 1.5, 2.0 and 2.5 models.
     
  7. Rolf68

    Rolf68 Member

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    Hello

    Thanks for the answer. I didn't meant to say I'd want to unplug the original wire, but try to add the 2 other in the same connector "holes" instead of cutting things ;)

    Glad to ear the switch are "universal" among the roadsters

    Have a nice day :)
     
  8. ML Auto

    ML Auto Member

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    That would work if you used a solid wire or a paperclip to push into the terminal cavity, but the electrical connection would only be made thru surface contact, and you could bend the terminals or have them arc if they were loose.
     
  9. Stefan T

    Stefan T Member

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    IMGP7508.JPG


    The coodown worked good
    I hold the temperture constant (+-1 C)under charging with Jdemo (50kw Chademo)
    The sesion was approx 20 min
     
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  10. ravng

    ravng Member

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    Thanks for this, I will defeinitly be doing this to keep jdemo charging temperature down.

    But how about doing this with a relay and let OVMS control it? I would guess that there is some spare IO to use?
    Anyone know?
     
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  11. Rolf68

    Rolf68 Member

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    Hello yall ;)

    I'd like to do this mod in a few weeks as weather become hotter here. Just to be sure, what is the rate of the in-line fuse on the power lead ???

    thanks :)
     
  12. Stefan T

    Stefan T Member

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    I have 7,5A and it havn't blown
    I think you can use a smaller one without any prolems
     
  13. Rolf68

    Rolf68 Member

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    Thanks a lot :)

    I'll try a 5A then. I assume there's no risk if it blows isn't it, just replace with a stronger 7.5A ?

    Have a nice day ;)
     
  14. Stefan T

    Stefan T Member

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    yes
     
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  15. Rolf68

    Rolf68 Member

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    Wonderful, thanks ;)
     
  16. driver_EV

    driver_EV Member

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    Let me add my thanks for finding and sharing this modification! and share photos of my efforts:

    I followed the example shown and found a ground wire to tap at the light switch for the LED.

    I am finally doing Roadster updates and fixes. This was an accomplishment and confidence builder.
    Thanks to everyone who participates at TMC. I have gained greatly from the sharing.
     

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  17. gregd

    gregd Active Member

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    Nicely done. Good place for the switch, and good to add the LED as a reminder.

    Wondering, what path did you take to get the wires over to the center console?
     
  18. Rolf68

    Rolf68 Member

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    Cool Job :) Where did you take the ground from? If you don't wire the ground the Led would not switch on / off but the system would be functionnal anyway ?

    Best regards :)
     
  19. driver_EV

    driver_EV Member

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    So in finding the path for the wire, of course I spent some time looking for a simple obvious way for that seemingly trivial part, but only too small gaps going from lower dash area to go over the top and back down. No loose free gaps to route through were found. But then I found a simple way that looks like it is perfect for this.

    There is a bottom dash structure that has a hollow rectangular section. The wire passes through that, directly where we need to go.
     

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  20. driver_EV

    driver_EV Member

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    True, without the ground connection the LED does not work.
    Fortunately The headlight switch right beside the new switch location also has a light in it, and I found a small black wire on that connector that is available to provide the ground connection.
    I just used a squeeze/tie-in to make that connection.
     

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