New Savage XS Battery Problem help

[Lightningfastrcman]

Ok, so I bought a Savage XS right after Christmas.
So the day I get it, I plug a 2s LiPo into the ESC and run it. The LiPo isn't fully charged, so it doesn't last for too long, but long enough to get a feel for the truck. It runs great.
But then the next morning, I try to run it, and the thing goes down to 50% power, then shuts off. I know that this is a safety feature built into the esc (it does this when the voltage drops below the set threshold for more than 2 seconds), but the battery is full charged. At first I am thinking that my battery is just going bad, after all I have had it for a long time. But putting it in my Traxxas Slash and taking that for a drive revealed that the battery was fine. The slash worked almost flawlessly for a good 20 minute drive. The slash also has roughly the same motor/esc combo in it, castle 540 size motor, sidewinder 3 (Correct me if I'm wrong on that, but that should be right around what the XS has in it.

So what is going on? Is the battery going bad? What could be causing the voltage to drop downward so quickly?

Also, when I plug the battery back into the charger after this happens, the voltage appears to be high above 3.2 volts per cell. So what is happening?

 

[X]

What are the cells reading? 3.2V per cell is low. Usually ESCs cutoff around 3.6-3.7V per cell unless otherwise programmed. When fully charged you should see 4.2V per cell.

 

[Lightningfastrcman]

Fully Charged is 4.2, so that's fine. When I am done running the Slash it goes all the way down to a little over 3.2 per cell. When the Savage does the thing where it goes to 50% power, when the battery is plugged back into the charger it reads just over 4.0. The only settings for cutoff on the XS are 3.0, 3.2, and 3.4, and it has this problem even on 3.4.

 

[X]

Is it reading a lower voltage while plugged into the Savage? If so, the ESC is dragging it down. If it is only under load (while driving) that the voltage drops, then it could be either the ESC output or motor. Do you have another similar motor or ESC that you could swap into the setup, just to isolate it one way or the other?

 

[Lightningfastrcman]

When it does the thing in the Savage it is usually down to about 4.0 per cell. I have no clue what it end up dropping down to in the Savage that would cause the thing to go down to 50% power and shut off. I'm pretty sure the ESC is dragging it down, because I have a similar motor (in fact I believe it's the same motor, just different color can) in my Slash and it works fine, just a little underpowered but the voltage appears to stay up pretty well. Then again the Savage XS is heavier by a couple pounds I think.

 

[Lightningfastrcman]

Just got a new LiPo, a 3s 5000mah 50c this time. It still cuts off but a little later in the battery pack. The manual says when this happens it means the voltage is dropping lower than the cutoff voltage (3 volts per cell), but when i plug it into the charger after it does this it says the voltage is around 3.8 volts per cell. What could be going wrong?

 

[griff7373]

By no means am I a battery expert but it could be when the pack gets low on juice the motor draw is pulling the cells to the cut off limit. Once the motor stops pulling the cells go back up in voltage, kind of like when your AC starts up in the house the lights dim for a second and then come back to normal once it's running.

 

[Lightningfastrcman]

I would assume that this would be the problem, but if it is then how do I fix it?