Runtime with extended batteries?

Question

Lenovo

Hello. Interested in the experience of the habrazhiteley how much x230 works with 9-cell batteries. Mode of operation: surfing, writing code, writing text.

Answer 1

According to your device, I won’t say, but there is a rule:
The operating time with a high-capacity battery is proportional to the difference in battery capacities. The proportion is almost linear. That is, a 10000mAH battery gives 2 times more autonomy than a 6000mAH one.

Answer 2

6-6.5 hours max. Slice will add another 3-3.5 hours.
By the way, it stopped charging the day before yesterday.
PS I'm saving money for a Macbook.