Battery life of t420s

The 6 cell on t420 is 57Wh and is said to last for 6hrs on average.

The 6 cell on T420s is only 44wh , but the 3-cell ultrabay is 32Wh.

Then, if both t420 and t420s consume similar amount of power, will the 6+3 combo (77wh) on t420s have about 30% more battery life than t420's 6 cell (or at least 7+ hrs)?

 

That's the trade off for the slimmer form factor

 

Yes it will.

 

So t420s is not as bad as some described...
With a 3cell ultrabay battery, it has about 20-30% more battery life, and is 0.4-0.5lbs lighter than a t420 with a 6cell.

 

One thing to consider is that these bay batteries have a shorter life span so expect to see a faster decreased life in battery as time goes on.

 

If two batteries are installed, are there going to be two power meters for each of them? If so, maybe one can remove the bay battery once its power is below, say, 10%, and have the main battery do the job.

The bay battery is hot-swappable, right?

 

^^^ When I said the T420s was like a "high-maintenance girlfriend," this gives you an idea of what I meant.

Why think of all sorts of ways just so that you can hold a "slim and sexy" notebook? The tool should serve you!

 

Unless lenovo made changes to this, the way that it has been in the past is that there is only one power meter for the battery. The system is configured to drain the bay battery down first and then the main battery. The system will not discharge your main battery as long as there is a bay battery with power left in it.

And if I'm not mistaken, the charging order is main battery first and bay battery second. Possible issues that some might care about is that your main battery may be constantly sitting there fully charged, which might not be good, and your bay battery is going to have a high charge/discharge cycle, which is going to degrade the capacity.

Personally, this issue alone would be too much of a hassle for me to keep taking out and putting back the bay battery so that I can trick the system to discharge one over the other.

 

then maybe one can insert the bay when the main battery is about to drain?

 

I have a bay battery and to honestly it doesn't really bother me enough to pull the battery out ...

 

Just want to confirm this one. After 1 year, the main battery on my T410s went from 44Wh to 37Wh (40+cycles) but the bay battery went from 29Wh to 19Wh (120+cycles) after 1 year.
Considering the bay battery is much cheaper, I'd say this is not a bad result.

 

Especially considering the fact that you need to flip the computer over to do that. I still prefer the old ultrabay design.