Sometimes battle timers suffer from an error, and do not perform as they are supposed to, becoming frozen or glitched. In these rare cases, the battle will not end until the server restarts, or it is ended by an individual from Tech Support. When a battle is frozen/glitched, the timer will look like either of the below shown images images:
Since the start of 2016, due to a lot of fake reports Tanki Online Tech Support decided not to accept reports of glitched timers. You can still contact the Tech Support at firstname.lastname@example.org with the link of the battle that has glitched timer, and a member of TS will come to finish the battle.
Other than that, you can join shorter battles or ones with kill limit to reduce the chance of encountering this problem. Hundreds of thousands of battles are created every month, out of which only several battles may have this issue, so the chance is pretty low. Please note that the developers are aware of the problem and are working hard on fixing the bug.
Customer support service by UserEcho