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240volts @ 10amps charge possible?

Discussion in 'Model 3: Battery & Charging' started by moonfresh, Aug 3, 2018.

  1. moonfresh

    moonfresh Member

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    Hey there,

    Noob here. Just ordered a M3 (white/LR) today. I just found out that the rate of charge can be adjustable from the screen--super cool! However, can I dial down the rate of charge to 10amps via 240volts (Nema 14/50)? I have solar, so I need my inverter to also run the house. I know the maximum current is 32amps when using the stock M3 charger when plugged to 240volts. But is there a minimum? Thanks.
     
  2. P85_DA

    P85_DA Supporting Member

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    Yes u can adjust down that low
     
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  3. eprosenx

    eprosenx Member

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    I think the minimum may be 5a? But don't quote me on that. I am not in my car right now to check.
     
  4. P85_DA

    P85_DA Supporting Member

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    Correct 5a is the lowest ...could be 0a if u use one of those Home Depot RV adaptors though ;)
     
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  5. moonfresh

    moonfresh Member

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    Thanks...just watched a youtube video on this. 5a is the minimum when using 120volts. Maximum is 12a. Nothing official on YouTube that I could find for 240volts minimum amperage setting. But I trust you guys.
     
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  6. gilscales

    gilscales Member

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    Just went down to my garage to confirm for you, you can go down to 5a charge rate on 240v, i tested out 10a and it is about 9.5 miles range added per hour with a 237v input
     
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  7. David L

    David L Member

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    Charging efficiency decreases for lower charging power, so you may not want to lower the amperage too low if the total energy consumed matters to you. I've seen efficiency vs. amperage data on one of the Tesla forums, but I can't find it right now.
     
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  8. gilscales

    gilscales Member

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    I read that as well and it did mention that anything below 32a and it starts having quite a noticeable difference in efficiency, 32a and above its not so much
     
  9. moonfresh

    moonfresh Member

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    Thank you soooooooooooo much. I was looking to order an aftermarket, adjustable charger. You just help me save $300-500.
     
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  10. gilscales

    gilscales Member

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    glad i could help!
     
  11. bomquito

    bomquito Member

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    I am not sure what you meant by having solar and need to turn the amperage down to 10. I have solar also and I just charge it at night. Can you explain?
     
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  12. moonfresh

    moonfresh Member

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    I have a complete solar system with battery storage (32kw). I basically live off the grid. My inverter can invert 4500 watts continuously. I calculate 2400 watts for the M3 (240v @ 10 amps) and the rest is for my home.
     
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  13. eprosenx

    eprosenx Member

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    Wow! Impressive!

    So does that mean the grid is available, but you just don't normally use it? This is an interesting scenario. I would say this is an expensive way to charge the car! Panels + battery and inverter and all!

    So in an optimal world you would take solar and just put it straight into the car (avoiding losses putting the power into what I presume are lead acid batteries and then pulling them back out). But the car is not really set up to handle this.

    One interesting option would be if someone made a unit that could vary the pilot signal to the car to vary the amps of charge to only charge during solar production hours. (though you may not have the car at home at the right time of day for that)

    But that is not the question you asked:

    I wonder if getting a NEMA 6-15 adapter for the UMC Gen 2 would make sense so that even if you accidentally forgot to crank down the charge amps it would only pull 12 amps. That, or install a wall connector and crank it all the way down to the lowest setting of 12 amps.
     
  14. moonfresh

    moonfresh Member

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    Yes, the grid is available if I need it. I know it sounds super expensive, but it was not that bad. I did all the work myself. The 32kw lithium batteries come from a Chevy Volt. I sourced them through ebay/junkyards. Got lucky but a lot of work. Guess how much? About 6k for the battery. That's like the cost of 1 Powerball...lol. The solar panels were relatively cheap. I was lucky and was able to source some used commercial panels for 1/3 of the price. I have about 15 panels that are rated at 310 watts each. I am getting about 20kw plus a day of power. These panels averaged $150. All in all, I spent about 15k on my "Boondock Solar Storage." If it all works out as planned, my return on investment is less than 5 years. I drive quite a bit. I will post a separate thread on my solar storage later when I get my M3. Also, there is an inverter that can take solar and directly charge an EV without having a battery bank. They're on ebay if you are interested.
     

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  15. Jedi2155

    Jedi2155 Please Insert a Model 3 into Avatar

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    I'm impressed you even have a fire suppression system. Nice!
     
  16. bomquito

    bomquito Member

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    That is impressive! Kudos to you with that work. Would you do this on a side for of xtra cash?
     
  17. moonfresh

    moonfresh Member

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    Yeah...it's automatic. Peace of mind for $85.
     
  18. moonfresh

    moonfresh Member

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    You know, a lot of people ask me that...and to open up shop to work on Beemers. Lol. But yeah, I am open up to that idea on helping people build a solar storage. However, keep in mind my system seems to be a bargain because I did everything myself and I had a WHOLE lot of luck at the junkyard with those batteries--dismantling 600lbs batteries in sunny CA sucks. That to me is the key, though. I am in SoCal. And I can help you if you're interested. But be aware that I am very busy. My suggestion is to first source some reliable batteries. Message me and we can really talk. Peace.
     
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  19. eprosenx

    eprosenx Member

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    Wow! That is amazing!

    So how do you charge control the Lithium batteries? I would assume off the shelf stuff would not be setup for that? Most charge controllers are built for lead acid...

    Also, what battery string voltage are you running?
     
  20. alpinebum1

    alpinebum1 Member

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    That is very impressive! Very professional setup.
     

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