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  1. #1
    RC Enthusiast
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    May have killed my Lipos but questions on my new replacements :)

    Well somehow my batteries drained too low and won't take a charge. My charger says check battery voltage no matter what setting i do, balance, charge, discharge, storage etc... so they're likely toast.

    I ordered a hobbywing program box to set up my Max6 esc to make sure the voltage is set properly moving fwd.
    I also ordered up some SMC 4s 9200mah 90c batteries so i want to make sure i don't kill them also.

    A couple questions though:

    What should i set the ESC at for shut off so i don't kill those?
    And will my max6 esc hold it back in performance compared to a max5? Pro's cons?

    Also equipped with the Castle 2028 XL motor.

    Thank you

  2. #2
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    A good option would be to get a pair of lipo's alarms so you can set them for 3.8 so you will be well above or a new ESC that you can manually set the cutoff to what you want the max 6 only has low/med/high and i think the max 5 is the same way. my Max 6 set to high seems to cut off around 3.6v i like to have my cutoff a higher then the ESC Cutoff so i have alarms .

  3. #3
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    Thanks for the reply. Since I ordered the program box I can at least set it to shut off before the lipos drain too far correct?
    What’s too low for lipos?

    I do also have the telemetry expansion so I could use the app to monitor as well right?

  4. #4
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    And why was the previous post deleted?

  5. #5
    Marshal Double G's Avatar
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    Quote Originally Posted by Pbsandman7 View Post
    And why was the previous post deleted?
    Dangerous recommendation. Point 12
    The Super Derecho

  6. #6
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    Oh where he said to charge it in a different mode to bring the voltage up? Lol ya that sounded sketchy..

  7. #7
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    yeah it is extremely dangerous to do and they could explode, Lipos can be very volatile.

    yeah with the program box you can set the cutoff the low/med/high and they should all cutoff before the lipo drains too low. the max 6 on high i was reaching around 3.6 and it would cut off, i like the stop a bit higher so i have a lipo alarm. I have extra packs so not a big deal. i think its recommended to not let it drain below 3.3v

  8. #8
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    Quote Originally Posted by Pbsandman7 View Post
    Oh where he said to charge it in a different mode to bring the voltage up? Lol ya that sounded sketchy..
    I believe I remember reading about do this, but at a very low amperage like 1Amp and just charge it enough to allow it to be seen in lipo mode. Absolutely would not want to do it to a full charge.

  9. #9
    RC Turnbuckle Jr.
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    Fair enough. Iíve done it twice and it worked great. I did put a disclaimer on my post. Why I wonder physically, would it be dangerous to charge a battery thatís made to be charged, assuming it hasnít expanded, which is the main symptom of an over worked/over discharged battery.

  10. #10
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    Awesome thanks guys. I’ll set the esc to high to keep it safe above range until I get some alarms.
    Who makes a good alarm?

    I also have the traxxas telemetry app and can set a voltage alarm. If I set it at 7.4v is that total for each or divided by two so each lipo would be at 3.7v and still in a safe zone. ? It doesn’t really explain anywhere that I could find.

    Thanks guys!!

  11. #11
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    Also, what should a temp alarm be set at for the castle xl 2028?

    Anyone?

    Thanks for the help

  12. #12
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    I couldn't find a spec on that Motor for temp. I think its good to keep below 200F. if i get close to 180 ill let it rest for a few min then go back to bashing around

  13. #13
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    Quote Originally Posted by Pbsandman7 View Post
    Also, what should a temp alarm be set at for the castle xl 2028?

    Anyone?

    Thanks for the help
    Documentation I read this morning stated to not exceed 180.

  14. #14
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    One more question about voltage cut off.
    I got my new Batteries, SMC 4s 9200mah.
    Instructions state to not discharge these below 3.2v so I assume that is per cell so x 4 to account for each cell right? So that’s 12.8 & then x2 to account for both batteries to set the proper cutoff. Am I understanding that correctly?
    So my voltage cutoff would then be 25.6V on my telemetry expander. ?
    Just want to make sure I get it set right.
    Thanks!

  15. #15
    Marshal Double G's Avatar
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    Yes. However that may be a little low. A lot of respected and knowledgeable people recommend 3.5v/cell which is what I set mine at.
    The Super Derecho

  16. #16
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    Awesome I thought it might be referencing “per cell” and not total voltage per battery. SMC states for larger motors that they can be run down a little lower at 3.2v due to the draw they have but I planned on going higher for better battery lifespan. So likely 3.5-3.6 per cell.
    Thanks for clearing that up

  17. #17
    RC Champion olds97_lss's Avatar
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    I run my SMC's down to 3.4-3.5. I think the traxxas vxl-3s goes to 3.2, I think, but the ones I can set, I set to 3.5.

    I did have one SMC die on me after a year. One of the cells wouldn't hold a charge. Up to that point, it had been taking longer and longer to balance from storage or 3.5V. I tried the sketchy "force charge" for that one cell using my NiMH charger on the balance tap so my charger would then see it in lipo mode. Then balanced the pack to storage charge once the one low cell was as high as the others. I unplugged it and put it on the shelf. By the next morning, the 1 cell dropped to 1.5V. I drained the pack using a brake light, then cut and soldered the main leads together so it stays dead and doesn't recover.
    Expert rigging at it's best!

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