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08-16-2013, 04:25 PM
| #1 |
| I wanna be Dave Join Date: Sep 2006 Location: Anchorage, Alaska
Posts: 3,099
|  LiPo cut-off question
I know my e syst. has the LiPo cut off so the mtr. can't discharge the batt. below set voltage. But my concern is for post LED draw before batt. disconnection... Now maybe my 4 LED lights are not much to worry about as the battery gets unplugged promptly after discharge... But what if there were more LED's and the draw were higher ? Could it be possible for the LiPo to discharge below it's safe voltage if the LED's remained plugged in for too long ? I'm thinking of adding an easy access switch to turn off the LED's. But maybe it's not an issue. !? what say you ? |
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08-16-2013, 05:00 PM
| #2 |
| Yashua   Join Date: Sep 2010 Location: Learn the parable of the fig tree
Posts: 3,661
|  Re: LiPo cut-off question
You could use an external Lipo cutoff like this one from Novak; Novak 5476 Smart-Stop Auto-Detect 2S-4S Lipo Cut-Off Module:Amazon:Toys & Games That way it would shut off power to everything that is in the RX circuit. |
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08-16-2013, 05:25 PM
| #3 |
| Rock Crawler Join Date: Oct 2012 Location: Trail B.C.
Posts: 827
| Re: LiPo cut-off question
Unless you completely forget to unplug it for a couple hours I cant see 4 led lights drawing enough to drop it to below charge levels. A battery shouldn't be left plugged in anyway when not in use. |
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08-16-2013, 06:07 PM
| #4 |
| I wanna be Dave Join Date: May 2007 Location: Fairfield ME
Posts: 3,886
| Re: LiPo cut-off question
When you hit the lipo cutoff your battery is generally experiencing some voltage sag. You can see this by checking the voltage of the pack after you unplug it. A battery that hit a 3.0v lipo cutoff when under load might be at 3.3v after the load is removed. So unless you wait for the lipo cutoff to reset and keep driving and hitting it, it would be pretty hard to get the pack down from the non load voltage to under 3v by simply leaving the LEDs on for a minute. Edit: fwiw the servo sitting idle and the esc fan both probably draw more than a few LEDs. |
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08-16-2013, 06:59 PM
| #5 | |
| I wanna be Dave Join Date: Sep 2006 Location: Anchorage, Alaska
Posts: 3,099
| Re: LiPo cut-off question Quote:
Was just wondering if I should adjust the LiPo cut off slightly higher ? Currently is is set on auto detect I believe. meh... seems the majority of opinions offer little concern regarding the draw before unplugging the battery. Guess I'm just paranoid... 'cuz yesterday I had a nearly new 3s LiPo pack burst and catch fire... and for no apparent reason. Luckily I was able to remove the batt. from the RC before the burst. Good thing... 'cuz by the size of that fire... probably wouldn't have been much useable rc remaining  I do plan to add many more LED's (HP lightbar) and a higher torque servo... so those are some of my concerns. Last edited by TacoCrawler; 08-16-2013 at 07:09 PM. | |
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08-16-2013, 07:23 PM
| #6 | |
| I wanna be Dave Join Date: May 2007 Location: Fairfield ME
Posts: 3,886
| Re: LiPo cut-off question Quote:
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08-16-2013, 07:41 PM
| #7 |
| Rock Crawler Join Date: Oct 2012 Location: Trail B.C.
Posts: 827
| Re: LiPo cut-off question
Simple solution. Throw on a low voltage alarm it will piss you off enough to make sure you unplug the dam battery, |
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08-16-2013, 08:00 PM
| #8 | |
| I wanna be Dave Join Date: Sep 2006 Location: Anchorage, Alaska
Posts: 3,099
| Re: LiPo cut-off question Quote:
Venom flight paks... must've just got a bad one. Have 3 others... no issue... yet. Thanks... didn't know the esc could confuse a 3s for a 2s. I generally only start with a fully charged battery Recharging partially consumed batt. before their use. I had just recharged this recent bust pak and had started charging another... when I heard the swell (creaking) straining against the Ziptie's holding that to the slider. soon as I realized... ran outside with the chassis... cut the zip ties and let the LiPo hit the cement patio. in just a few seconds it vented... then burst similar to the intensity of a road flare. It left a hella scorch mark there on muh patio. Lol --------------------- OT... but hey... may as well ask here. Should I leave the LiPo's discharged down at cut off... when stowing/storing them ? after witnessing this batt. burst... I'm paranoid these suckers are gonna burn muh house down !? | |
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08-16-2013, 08:04 PM
| #9 | |
| I wanna be Dave Join Date: May 2007 Location: Fairfield ME
Posts: 3,886
| Re: LiPo cut-off question Quote:
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08-16-2013, 10:20 PM
| #10 | |
| I wanna be Dave Join Date: Sep 2006 Location: Anchorage, Alaska
Posts: 3,099
| Re: LiPo cut-off question Quote:
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08-17-2013, 12:02 AM
| #11 | |
| I wanna be Dave Join Date: Nov 2010 Location: 07456 N. NJ USofA
Posts: 8,314
| Re: LiPO cut-off question Quote:
The LVC cutoff in the ESC only kills motor power, the RX (and anything connected to it besides the ESC) stays working. Thus you are correct, the LED's can overdraw the battery even if the ESC no longer drives the rig. I can't imagine the LED's drawing a lot of power, but it is a consideration. | |
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