BONE STOCK RALLY ISSUES ON 3s LIPO

[BYRDMAN313]

As the title says I'm having intermittent issues on 3s. The problem is once in a while I put a fully charged 3s lipo in the rally, I will run it for about 2 mins and it goes into stage 1 thermal protection. Its knocked down to 50% power so I shut it off unplug the lipo (cool to the touch) check the motor temp (maybe luke warm but barely) plug in the lipo turn it on and no problems. I run to low votlage cutoff and battery stil shows 3.86v per cell. Any thoughts or comments are welcome. My 4x slash didn't do this, did I get a bad esc in my rally?? Thanks in advance

[zippogeek]

I would run a smaller pinion and see if you have the same problem. Either that, or stick to 2S like I do. On 3S you're going to burn through stock parts like crazy...my $.02

[snookerd1206]

What is the c rating of your 3s battery, I suspect that under load you are hitting the LVC, (which traxxas LVC's sometimes have a high cutoff), your batteries may be the problem, at resting voltage they may say 3.86vpc, but under a load they may be dropping voltage to under the LVC cutoff point.


Sent from my iPhone 5

[zippogeek]

your batteries may be the problem, at resting voltage they may say 3.86vpc, but under a load they may be dropping voltage to under the LVC cutoff point.

Snook makes a lot of sense! ^^^

[BYRDMAN313]

I thought about it and its a 35c 4000mah 3s. I might need a 5k or larger 3s. But after it goes into limp mode and i shut down unplug it, ill throw it back in and get the 30min run out of it. Thats where im confused. All in all i figured its prolly the battery

[DiggerPede]

Here's a little info on the VXL-3S ESC:

Stage 1: 3.6v it cuts 50% power
Stage 2: 3.3v cuts off all power

So if the truck is WOT and under load and close to LVD it will hit stage 1 first, then stage 2 if it reaches that threshold. Its all good for a reason though to save your LIPOs. They are known to LVD early at times though.

The good thing with Castle Speed Controls is you can control their LVC behaviour (voltage you want it to cut 50%) to start with.

[pavmentsurfer]

You do NOT need a bigger or higher amp lipo. Its very likely your simply experiencing a slight glitch with the ESC. If things arent hot, your not thermaling the ESC. But it could be an early LVC issue like has been mentioned. That pack you have can deliver more than enough amps for the VXL3S system. (unless its a rediculously crappy lipo, which is possible).

But, I will say this, 3S in the rally with a stock VXL3S system is not a good idea. You will most certainly overheat the motor at some point. If your running for 30 minutes on a 3S, even geared down, your going to over heat it. The motor just cant take that kind of power in a 4X4 vehicle. If your not checking your temps OFTEN, you should be. If the motor goes over 200degrees, its permanently damaged. 180 is max safe temp and on a 3S, getting to that point does not take long at all. Sometimes only a few minutes if your running hard.