Is it worth disconnecting the battery leads and re-connecting to see if it resets the gauges?

Ive been driving the X5 and noticed the fuel gauge has moved abit but still not fully accurate at the moment. The temperature reading has also come down to 14 degrees which is better. I think the problem is with the battery and planning to put it on a slow charge tonight. If this fails I will purchase a new one and see how things are