I fully charged my 4s lipo and only ran it for about 5 mins can i plug it back into the charger and fully charge it back to 4.2v? Another question when do you know when to stop running the car before it hits the low voltage cutoff i have mine set at 3.4

Yes, you can recharge the pack immediately after you are done running regardless of how much/little mah you used. However, if you are done running for the day, do not recharge it and store it fully charged. Would also recommend storing packs in a lipo sack when not in the car.

LVC is itself to tell you when to stop running - yours is set very conservatively so you don't need to worry about trying to avoid it.

Well first, you only want to fully charge a battery if you intend to use it that day. Otherwise keep your battery at a storage voltage of around 3.8v per cell. Your charger should have a storage function. There is nothing wrong with running the lipo for 5 minutes, then charging it back up for another run though.

The voltage cutoff is there for a reason, it tells you when to stop driving by limiting throttle below 50%. So no need to stop driving before you hit the cutoff.

Basically what MarkA is saying is you don't have to manually stop running the car when you have low voltage cutoff in your electronics. When your battery hits 3.4volts per cell it will just stop working. You will still have steering but no throttle etc. That's when you know the battery is drained to 3.4v.

i just didint think it was safe to go that low meaning 3.4v i guess im wrong lol

3.4v is actually playing it safe. You'll see some guys turn their cutoff down to 3.2v or even 3v to squeeze as much run time as possible.

Oh ok thank you.

On my carpet 2mod buggy, using a low-profile shorty combined with the massive draw that type of racing produces, I had to turn it down to 2.8v/cell or it might "tease" the LVC on a full throttle punch before the end of a main. LVC is usually triggered first under load, not static so even if you hit it at 3.0v/cell, your pack will still probably read at least 3.6v/cell when hooked back up to a charger - easily a safe setting.