Elitebook and battery charging, can it be disabled?

Hello everybody

I recently bought 8440p and it seems to be great machine, but I'm missing one thing from Thinkpad -laptops. In those you can set the battery to stay, for example, 40 % charge all the time with it's power manager software when laptop is on AC power. This prolongs the life of a lithium battery considerably, as you can see here:

http://batteryuniversity.com/_img/content/parttwo-34.gif

Has anyone heard that this could be enabled in Elitebooks?

 

Hi Zimmerit,

Sorry I don't have any help for you, but if you don't mind me asking, it sounds like you don't rely on battery power since you want to maintain the 40% level, so how come you don't remove and store the battery?

Is it so that the battery can save your data in case of power failures? As I am thinking about it, that sounds like a great idea and I would use it too.

Cheers.

 

there used to be an application back in the days of windows nt/2k/xp that did this for hp machines, but it sort of mutated into the 'battery manager' which then mutated into the hp support assistant.

i am not sure anything 'official' is available to set charge values into the battery - even though it does support it.

 

kgamadia: I've been keeping the battery off the laptop, but it is annoying to attach and detach it every time when I need some battery power. And sometimes that power failure point of yours is relevant too

Siorah: it is funny that instead of offering that software HP is selling this "long life" battery with lower capacity (73 Wh vs. 68 Wh)

HP AV08XL Long Life Notebook Battery (BS554AA) specifications - HP Small & Medium Business products

I bet that they have just decreased maximal voltage of the battery, and then we have an ultraextra durable battery to sell with high price tag

 

Interesting site, particularly
How to prolong lithium-based batteries
The "Simple Guidelines" (for Li-ion batteries) summary at the end includes (simplified):
- Avoid full discharge, recharge frequently.
- Do full discharge once every 30 charges to recalibrate battery guage.
- Avoid heat (including from hot computer on AC!).
- For prolonged storage, keep at 40% charge, in refrigerator.

Hmm:
- So, IF the battery-saver power profile keeps temperatures cooler, THEN it may help preserve the battery even when the computer is on AC power.

Lower charge and discharge rate improves the number of charge cycles, according to the graph that compares charge/discharge rates to number of charges.
- So, the battery-saver power profile may not only improve power available on one charge, but may also extend the life of the battery by reducing discharge rate.
- So, is that (reducing the charge rate to prolong the life of the battery) an excuse to run a "high power load" while charging the battery ?
(assuming it is not so high that the higher heat cancels any benefit from lower charge rate)

I see how battery charger controls could be useful.

(The graph is based on a 2002 paper, so I wonder if it is a fundamental chemistry limit or if battery technology may improve.)

Not sure what you mean.

The specs of the normal battery do not list an input nor output voltage.
I assume a decreased input voltage would mean slower charge times for a given battery resistence.

The specs of this normal battery claim 100% charge in 1.5hrs with system off.
(Strangely, while the title says 73Wh, the specs say 69Wh.)
HP: PB992UT - HP (7400/8200/8400/9400 series) 8-Cell Li-Ion Primary Battery - Laptop batteries
(see "Related products" tab for compatible notebooks).

The specs of this normal battery claims 90% charge in 90minutes, 100% in 2.5hrs (both with system off).
HP: KU533AA - HP 8500/8700 Series 8-cell Primary Battery - Laptop batteries
(see "Related products" tab for compatible notebooks).

The specs of the long-life battery list a 10.8v output voltage, and 100% charge in 2.5hrs (with system off)
HP: AU213AA#ABA - HP Long Life Battery - Desktop batteries

The Mfr of the long-life battery claims 40% charge in 10 minutes, 80% charge in 30min, when charging at 2C.
Boston-Power Long Cycle Life Battery Technology | Boston-Power
Boston-Power Fast Charge Battery Technology | Boston-Power
(1C is a charge rate equal to the electric-Current capacity of the battery in Ampere-hours. [I guess some energy is lost as heat during charging, so at 1C a full charge from empty takes more than 1hr.] I don't know the charge rate profiles of the chargers in HP laptops.)
Battery charger - Wikipedia, the free encyclopedia

The Mfr claims 120 patents or patents pending including chemistry as well as electrical design, so it is likely that there are more differences than simply lower "max voltage".
Boston-Power Lithium-ion Battery Technology Overview | Boston-Power

 

This has nothing to do with charging speed, it is adjusted with current.

Battery chemistries have certain discharging and charging voltage limits, that you can't pass if you don't want to kill your battery. Voltage of a laptop battery cell must remain within 3.3-4.2 volts to keep it alive, but the farther battery operates from those barriers the longer is the lifetime of the battery. Of course, you dont have that much capacity if you keep the batt between 3.6-3.9 voltage.

Here is a discharge curve, I hope it explains



3.3-4.2V would give ~98 % of full capacity, but a range of 3.6-3.9V gives only 60 %.

 

Hi zimmerit, You got my interest and since your post I've done some research. I still have no help, but some interesting things I discovered are:

- My 8540W, charges once the battery life drops below 95%, till full. Another NBR poster noted elsewhere that his/her (consumer model) HP would kick in at 90%. I can't tell from info out there whether controls are in the battery or laptop. Either way, thresholds are set so someone has the software to do it.

- The device manager shows the ACPI-Compliant battery driver with a lot of technical details on the battery - not that I know what it is. Some posts indicate that uninstalling the drivers stopped the charge cycle. Other posts state that the drivers are for reporting details from the battery. I checked a few battery applications and they focus on slowing battery drain when unplugged, but not extending battery life / age. I would think that the driver must do nothing then, as if it was a common Windows7 driver controlling charging, that some apps would provide the feature, right? And the Thinkpad software is specific to certain laptop models, not generic.

- Thinkpads aren't the only ones with this feature. As Siorah mentioned, HP had it in the day, and Sony and Dell both have it now. So for HP to re-introduce it as an advanced setting would be appropriate considering what the competition is doing.

Cheers.