Ultrabay Slim battery

[gunston]

Are you using slim battery together with your 6cells/ 9cells battery?

what is the designed capacity for slim battery, how long it would prolong the laptop working hrs with 6/9cells battery.?

[SHoTTa35]

The 3 Cell LI-Pol battery usually only gives a max of an extra 1hr to 1hr 30mins. This is with Vista so with XP you might get a bit longer. Total running time for 9 Cell plus 3 Cell gave me about 6hrs. The 9 Cell started off at 66WHrs instead of 77. With the extra 11 i could have probably get 30mins more . This is with WIFI running the whole time and i was chatting on MSN and browsing the net. PLayed some music for a while and Outlook constantly connected to an Exchange server.

[macadamiaman]

I use one most of the time. The designed capacity was 2,200mah. Looking in IBM's power utility it also says it was about 24Wh. With light use it's about 1.5 hours (16 watts usage or so) on my T43p.

I think there was also an ultrabay slim "advanced" li-poly battery, that was 2,700mah. Couldn't find one for cheap though.

[gunston]

I use one most of the time. The designed capacity was 2,200mah. Looking in IBM's power utility it also says it was about 24Wh. With light use it's about 1.5 hours (16 watts usage or so) on my T43p.

I think there was also an ultrabay slim "advanced" li-poly battery, that was 2,700mah. Couldn't find one for cheap though.

but the discharging behavior cannot be changed.
seems like it discharge the slim battery first before discharging the main battery, therefore cannot even hot swap the main battery.

[ricerocket]

Yup. It also means the Ultrabay battery gets the majority of the wear associated with charging/discharging.

[BigMacSangwich]

Yup. It also means the Ultrabay battery gets the majority of the wear associated with charging/discharging.

Does anyone know if there is a way that makes it discharge the main battery before the ultrabay one? Like tell the program to make the ultrabay battery the second battery rather than the primary one somehow?

My main battery is 2-3 years old with 200 cycles and I want to put it to use as much as possible while i can before it dies from old age instead of putting unnecessary wear on my newer ultrabay battery while the main battery just sits there unused.

Also, I noticed the computer lets the ultrabay battery discharge completely before switching to the main battery... aren't full discharges like this bad for li-ion batteries?

[gunston]

this is the way it works,
no way to change, unless you write the BIOS yourself

[SteveS]

BigMacSagwich wrote:

Also, I noticed the computer lets the ultrabay battery discharge completely before switching to the main battery... aren't full discharges like this bad for li-ion batteries?

You are not really discharging the battery to 0% even though the gauge indicates this. The “smart battery” chip controls this, and sets the 0% point at the minimum safe value of discharge. If you run the battery to 0%, remove it and measure the voltage with a meter, you see that it is still 10.8V. Attach a load to it and it continues to discharge for some time.
It is interesting that the computer bases the operation on what the battery chip tells it. I have a 9 cell battery that is in good condition (87% of original capacity, only 36 cycles), yet something happened to the battery chip. The computer can’t read it, and the gauge always reports 0%. It runs long enough to boot, but then enters “critical battery level” stage and goes into hibernation. I can charge and discharge the battery externally using with a power supply/ electronic load on the battery terminals and it is fine. Seems a shame to waste a good battery.

Back to the ultraslim battery – I have a couple of them and am really disappointed. IMO, they are a waste of money. Yes, they have very short operating time, even new with 90% capacity remaining. Not only does the computer discharge them first, but the power switching circuit will not operate the computer on only the ultraslim battery. I have tried “hot swapping” the main battery when I am low on power during transpacific plane trips. I don’t install the ultraslim battery until the main is low. Sure enough, it is recognized, and the remaining charge meter jumps to a higher value a few seconds after it is installed. But when I remove the main battery, the computer instantly loses power, in a non-graceful windows shutdown. Even putting the PC in sleep mode first does not work – it still loses power when the main battery is removed.

Cold booting Windows, with its associated 300+ file accesses, takes a noticeable drain on the battery. I was hoping the Ultraslim battery would give a method of hot swapping main batteries, but alas it does not….

[BigMacSangwich]

Not only does the computer discharge them first, but the power switching circuit will not operate the computer on only the ultraslim battery.

When I had my really old ultrabay batteries (over 900 cycles), I took out the main battery and stuck the ultrabay battery in to charge it. When it was fully charged I was able to run the computer for about half an hour on the ultrabay battery alone (15 min, then another 15min after it reached 0%). It only ran for 15 minutes when the main battery was in there with it though because it would switch over once the ultrabay battery reached 0%. Maybe different T40 series have different circuits.

[SteveS]

The situation I described was with a T43p

[JimL]

BigMacSagwich wrote:

I don’t install the ultraslim battery until the main is low. Sure enough, it is recognized, and the remaining charge meter jumps to a higher value a few seconds after it is installed. But when I remove the main battery, the computer instantly loses power,

What happens if you start on the main, switch in the slim when the main is low and DON'T remove the main battery?

[SteveS]

The point is that I am trying to swap the main battery without shutting down. The ultraslim only powers the PC for about an hour tops, and I still have 4 hours on the flight.

[yak]

You could always hibernate. It probably drains more power than sleep mode but less than a cold reboot.

[whizkid]

Hibernate draws the same power as being off, because the machine is off. The battery drains itself though, but very slowly.