Thinkpads Forum

while scouting i noticed for a T400 a 4 cell battery.
My Laptop is mostly connected to mains . currently it has leovos original 9 cell heavy battery.
Can I replace it with a 4 cell battery?. it has different voltage.??? so how does it work?
p9500 250 SSD, 1440X 900(tubelight) , 8GB ,

The 4 cell sits fits flush with the rear of the laptop. Should work just fine with your machine and let you open lid to full 180 degrees.

I was a bit puzzled about the voltage how much should it be...! Why ia it so much higher than the 6 cell/9cell battery?. Are these some new generation Li cells.?.
I have a battery repair mechanic who replaces individuals cells in the black containers .!....

Each cell is 3.6V, I think?

In 3/6/9-cell batteries they are arranged in chains of 3, so the total battery voltage is 3.6*3=10.8V.

In 4/8-cell batteries they are arranged in chains of 4, so the total battery voltage is 3.6*4=14.4V.

where does the power conversion from the battery pac to laptop takes place,Inside the battery?.
Where can I find details on what are the required power requirements from a battery pack?....i.e.
As the laptop is always connected to the on charger while I cox it to work I am dreaming of by passing the battery pack
entirely .

Ignorant wrote: ↑

Thu Feb 11, 2021 12:11 pm

where does the power conversion from the battery pac to laptop takes place,Inside the battery?.

I think it must be happening on the motherboard of your Thinkpad.

Ignorant wrote: ↑

Thu Feb 11, 2021 12:11 pm

Where can I find details on what are the required power requirements from a battery pack?....i.e.

I'm not sure what exactly you need..

Ignorant wrote: ↑

Thu Feb 11, 2021 12:11 pm

As the laptop is always connected to the on charger while I cox it to work I am dreaming of by passing the battery pack
entirely .

Have you tried unplugging the battery? I think your Thinkpad may just work. That said they say it's best to keep battery charged to a medium level. If you set charge starting threshold to around 50% or maybe 60% then you can

- unplug the AC
- wait for battery to discharge to slightly above that start level
- plug AC back in

The result will be that the battery will sit there connected, charged to the optimum for storage medium level and if you do need on a rainy day to grab the thinkpad and go about the house/outside you will still have a decent amount of charge in there.

There is also the battery stop charging threshold and I was setting it to around 80% but once my KingSener battery started misbehaving on my X220 (it started tanking from 30% down rapidly) I thought stop charging threshold was to blame and moved it back to 100%. So now the routine my Thinkpads follow is this: until the charge drops bellow 60% (start threshold) no charging. But if it does drop bellow 60% they charge the battery fully to 100%.

thank you....I am right now cleaning the thoughtpad for dust