X41 - extended battery life

Message

Tigger · #1 Post by **Tigger** » Tue Jun 10, 2008 9:28 am

My first posting, whilst I await impatiently for the arrival of my first Tablet - X41...

I am looking at options to extend the battery life of an X41.

As far as I understand the battery optons are:-

a) standard 4 cell battery is 1900mah (approx 2.2 hrs)
b) standard 8 cell seems approx 4300 -4500 mah. (approx 5 hrs)
c) alternative 8 cell battery 5400mah. (est 6.2 hours) based on pro-rata of batteries above???

Has anyone ever purchased a 5400mah battery? If so what batterry life are you achieving.

I also understand flat base batteries also available - not sure if I have the term right.

Finally, I underrstand people use a combination of sleep and/or hibernate to extend battery life (and reduce boot-up time). What are the pro's and con's of one over the other.

Thanks in advance for any advice

mange_ · #2 Post by **mange_** » Tue Jun 10, 2008 12:36 pm

I have a 5400mAh high capacity battery I bought on ebay.co.uk from China and it's working great so far (two months usage). I also have the extended life battery that fits underneath the laptop and all togheter I get something like 11h batterytime with the wifi off, and this is with a low voltage cpu and not a ultra low voltage cpu.

I still have a couple of extended life batterys left that I want €60 each for if you want one, http://forum.thinkpads.com/viewtopic.php?t=61146.

pgoelz · #3 Post by **pgoelz** » Tue Jun 10, 2008 12:37 pm

SLEEP means the RAM remains powered while most of the rest of the machine is powered down. However, some power is still drawn from the battery. The machine resumes very quickly from sleep...... 5-10 seconds.

HIBERNATE means the contants of RAM are written to the hard drive and then the machine is totally powered off. No power is drawn from the battery. The machine resumes faster from hibernate than from a full reboot, but much slower than from sleep.

My X41 discharges the battery at about 20% or more per day in sleep mode. I am not sure if that is normal or not, but it is MUCH higher than my old Thinkpad 600, which drew next to nothing in sleep mode.... I could leave it for a week or more and not notice any appreciable battery discharge.

At home I use sleep mode because the machine is always connected to AC power. Away from home, I use hibernate.

Paul

Tigger · #4 Post by **Tigger** » Tue Jun 10, 2008 8:50 pm

Thanks for the replies so far... learning more all the time - Paul - excellent explanation on hibernation and sleep.

My slight apprehension with the 5400MaH battery at this stage is that whilst it's listed on about half a dozen or so websites these appear to be closlely linked. No other stores, no news items, no reviews.
Who else of you have heard of these batteries or are using them?

Would a 5400 battery possibly need to be 20% heavier / larger than a 4500 unless it is using some superior technolgy whiich is not apparent. Is there an accurate way of measuring the mAh?
Mange_ can you help with any of the above?

pgoelz · #5 Post by **pgoelz** » Tue Jun 10, 2008 11:12 pm

There are a couple possibilities that come to mind.

1. 5400mAH is a typo.... 45 transposed to 54.

2. The 5400 mAH cells could be more "optimistically" rated than 4500mAH cells. There is a lot of that going around.

3. It could be genuine.... and weigh a bit more.

There is a lot of game playing in the lithium ion marketplace these days, with many cells rated more than their true capacity. From what I have been able to put together, the true power density is about the same from one manufacturer to the next. But that means there is some variation in cell weight for the same mAH capacity depending on the maximum safe discharge current rating. Trouble is that we never know what the actual cell manufacturer rated the cells for..... all we have to go on is how they are rated by the maker of the pack.

Paul

mange_ · #6 Post by **mange_** » Mon Jun 16, 2008 10:52 pm

As far as I can tell my battery is bigger in size then the genuine high capacity one.

It is reported as 63,36Wh but I can't see anything about mAh so I might be wrong in my previous post.

mtbiac · #7 Post by **mtbiac** » Mon Jun 16, 2008 10:58 pm

what kind of battery life are you getting with that thing? looks huge

mange_ wrote:As far as I can tell my battery is bigger in size then the genuine high capacity one.

It is reported as 63,36Wh but I can't see anything about mAh so I might be wrong in my previous post.

mange_ · #8 Post by **mange_** » Tue Jun 17, 2008 1:22 am

mtbiac wrote:what kind of battery life are you getting with that thing? looks huge

With this one and the extended life battery it is enough for me to not use NHC anymore. I never see low battery if I charge it every night.. I can tell you it's awesome not having to bring that big ac-adapter with me all the time!