I left my rhino 1750mah 2s lipo plugged into my esc for 3 days at a half charge. When I finally found it plugged in today I put it on the charger and it charges normal. Will it be affected in any way as far as performance goes? The esc is a sidewinder 3.

If it took a charge like normal, there is a good chance that you didn't harm it. It can, if left plugged in for longer periods of time, can cause the battery to discharge below the threshold. That is when the pack will be damaged.

Good to know. Thank you

You are not the first to leave a battery plugged in. We all make mistakes. I've done it few times. Overnight and once couple days.
It was the one rule I gave my nephew. If it's found that he leaves truck plugged in. My sister will take it away for as long as she wants.