View Full Version : Low voltage cutoff
09-07-2011, 06:21 PM
Alright I bought a mini e revo brushless off of a friend that had about three runs on it. I ran it about 4 times while waiting on some upgrade parts. When my rpm stuff came I put it in the car decided to drive it again ran fine using 2 of the stock batteries for the first run. I then waited a little bit and ran a second set of batteries and did not get alot of runtime out of it and one of the batteries was too hot to handle. I put that battery aside and put the car up for a couple of weeks. I just got it down the other day and decided to run a 2cell lipo. I set it up for lipo and started to run it and it went into low voltage cutoff within the first 2minutes of running and my lipo was warn not hot just warm. I called traxxas and asked because I was reading where some have had that problem. He said he was not aware of that issue and to take the motor off and check for anything binding. I cannot see anything that was binding to cause batteries to heat up like that. Is it safe to say my esc is going south. Thanks for any help.
09-07-2011, 06:32 PM
LIpos will get warm when you use them... thats normal. The SUPER short run time isnt normal. If there is a short in the system its likely the ESC or motor would get very hot very fast. If the ESC and motor are within normal temps and its just the battery thats warm to the touch it sounds to me like everything is fine.
Nimhs on the other hand DO get very very hot when being run hard. Especially in a brushless vehicle. So the fact that your stock nimh packs got really hot isnt a surprise.
09-07-2011, 06:50 PM
Thanks for the input, but also when using the lipo it goes into lvc and esc slowly flashes red after about two minutes of running. I understand nimh get hot but the one on the left side was not even warm and the one on the right was hot enough to warm up the battery tray and when I removed it you could not hold it for more than a few seconds, so something is going on with it, just trying to figure out where to start
09-07-2011, 07:25 PM
Double check your parallel cable. I had one come apart on me the other day while I was running, if yours has a loose wire it could cause you to only be using one of your two batteries, and could also be causing a huge current draw if its shorting out.
That's where I'd start.
09-08-2011, 06:01 AM
See when you are connecting the esc male connector to the female battery connector if there is a spark when you connect it something is wrong with the system / motor, esc, servo /. If not put only one battery. Check if the battery is ok /for every one/ .... But i think that they are okay.
So if there is a spark that means that when you stop the merv and remove the batt something is using electricity /from the load in the capacitors/ or something is shorting...... remove the servo first try everything from the start. If it is the same Remove the motor and try again. If it is the same i will be the esc. I have the same problem .... and a few weeks later my esc burn out.
And check Chris95GT post!
09-08-2011, 09:27 AM
Depending on where you live, weather affects the set up with lipo, where I'm at in Oklahoma it's been over 100 everyday that temp caused my car to go into lvc, changing your gearing will help, if thats not the issue then it could possibly be the esc, I've read a lot of over heating posts on several forums, those where the two main causes.
09-08-2011, 09:49 AM
Are you sure it is hitting LVC and not going into thermal protection? Check the manual I cant remember but one is indicated by a slow blinking red light the otehr by a fast blinking red light. Or even better would be if you have a temp guna nd could take the temp of the ESC when it shuts down.
09-08-2011, 10:26 AM
Your right dad, it's wasn't hitting lvc, it was over heating wasn't paying attention when I was typing.
09-08-2011, 04:58 PM
Yes I'm sure its hitting lvc unless the manual has a mistake in it. Slow blinking red is lvc and fast blinking red is in thermal protection. I do have a temp gun that I use on my 1/10 sct's. I will start there when I run it this weekend and see the temp of the motor and esc when it goes into lvc. I do know it only does it under a load as in running on pavement as that is all I run it on. I have tried to get it to go in lvc with the wheels off the ground and turning the steering left and right and it will not go into lvc once I set it down and run it it goes into lvc. Thanks for all the input and help
09-08-2011, 07:41 PM
If its going into LVC you need to check the actual voltage of the pack when it does
If its higher than 3.7v / cell resting then you may have an issue
Easy to rule out the LVC, simply run it in nimh mode and see if it still does it
09-08-2011, 08:35 PM
should you stop your run when your lipos hits the 1st lvc cut off? (50% throttle, slow blinking red) or can you/should you run it untill the full shutdown??
im not sure cause my car is still pretty fast and fun even with 50% power...
09-09-2011, 07:11 PM
got home took the truck down checked the lipo and voltage was good. I plugged everything up ran it and in less than a minute went into LVC. I checked motor and esc with temp gun motor was 78 degrees and esc was 80 degrees. I reset it and unplugged servo lead and ran it did not go as soon as before, but maybe a minute later went into LVC. I cannot see, or hear anything binding and everything moves freely. I really do not want to tear the truck down if it is just a esc problem as i have read online these things have had. What do you guys think? thanks mike
09-09-2011, 08:26 PM
Also ran it with lvc off for about three minutes ran fine, but as soon as I put it back into lvc it went into lvc protection. I checked the esc and it was 94 degrees the motor was same as before. I also checked the temp on the lipo and it was 104 degrees. The nimh get just as hot if not hotter. I have to lean towards the esc is going bad or has a short in it. I believe I will just pull the esc out and part it out.
09-09-2011, 08:31 PM
It definitely sounds like a premature LVC, this was a some what common issue with the VXL-3s ESC but not very common with the VXL-3m ESC, in fact I think this is the first time I have heard of this happening on a VXL-3m. You might want to give Traxxas tech support a call.
09-09-2011, 09:14 PM
Ive red around on here and on another sight and it has happened before, it's not a frequent problem but it does happen.
09-09-2011, 09:31 PM
Yeah I called traxxas support and they wanted me to send it in too them. I was fine with that but I was also told it would be around 45 dollars since it was past 30 days.I just can't see that if I had more runs on it sure but just what little it has been run can't see it. I support traxxas because they support the military and with me being in the military I respect that. I might have got a customer service rep that just didn't want to help.I did pull one of my brushless speed controls of my sct trucks and it ran fine no lvc, lipo was cool and esc stayed cool. So this esc went bad with about 10 runs on it. I think what I'm going to do now is just get a different esc and run that. Thanks for all the help and input.
09-10-2011, 04:50 AM
Buy a $5 lipo warning buzzer from ebay and run the ESC in nimh mode, problem solved
09-10-2011, 09:40 AM
Na just going to get a new system the old esc is heating the batteries up and I do not use electronics I know that are not working at 100%.
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