Thinkpads Forum

The battery I ordered for my T400 arrived today! It's an original Lenovo 9-cell unit. I have several questions about maximizing runtime and the battery's lifespan (OS is Windows 7 Ultimate x64/ elementary OS Freya):

1) What are the first few things I should do with the battery? I have done nothing with it, except install it into the T400 to ensure that it is functional- it arrived with 57% charge, Power Manager says that the battery is in good condition, cycle count is 1, and the manufacturer is Panasonic.

2) Are there any settings I need to enable/disable in Power Manager? Charge thresholds, or something of the sort?

The conventional wisdom, which is also supplied as instructions with some new batteries, is to do a full charge/discharge/charge on a new battery. I don't do that. It seems wasteful of the cycle count. If a battery shows signs of a sudden drop-off, then it definitely needs recalibration, which is accomplished by the above procedure.

Lithium batteries have two curious characteristics:
1. The lower the charge state of the battery, the longer it will last.
2. It you cut it too close to the bone, and the battery discharges below "0%", the keep-alive circuit in the battery will fail. The battery is then dead, because it takes specialized skills and equipment to initialize the keep-alive circuit.

Lenovo PM has a tab, "Battery maintenance", that allows optimizing the charge thresholds for individual use. If I'm taking a trip, I charge it all the way, or close. If I'm hanging around home, I might keep it 60% charged. But I find that an occasional charge to 100% is still required. Otherwise, metering errors seem to gradually develop.

I would not do a full discharge on the battery. I have tried this on a few near dead batteries, and the full discharge just ended up decreasing the remaining charge capacity, or bricking the battery all together. Panasonic batteries seem to be more resistant to complete discharges than sanyo ones before the charging circuit stops working.

Batteries stored at 40% tend to be best for preserving longetivity. A more realistic charging cap is 80%, which still allows you to use most of your battery, but without degrading the battery as fast.

brchan wrote:I would not do a full discharge on the battery. I have tried this on a few near dead batteries, and the full discharge just ended up decreasing the remaining charge capacity, or bricking the battery all together. Panasonic batteries seem to be more resistant to complete discharges than sanyo ones before the charging circuit stops working.

I've noticed that too, which is why I disregard the manufacturer's instructions to cycle a new battery.

brchan wrote: Batteries stored at 40% tend to be best for preserving longetivity. A more realistic charging cap is 80%, which still allows you to use most of your battery, but without degrading the battery as fast.

That is not strictly true. The chemistry of the cells themselves makes them last longer at 30 than 40, and the lower it goes, the longer they last. Longest cell life is at 0% charge. Unfortunately, this is not practical because of the keep-alive circuit.

On systems that I wake up monthly, I set the charge level to 15%-25%, depending upon past behavior of the battery discharge in the previous monthly period. For longer term freezer storage, I set the charge to 40%, in order to preserve the keep-alive circuit.

Thanks! So far, I have enabled charge thresholds to stop at 80%- where should I set them to start?

NadavCE wrote:Thanks! So far, I have enabled charge thresholds to stop at 80%- where should I set them to start?

I choose a point >= 10% different from the stop threshold. So, around 70%

Bear in mind there is no mathematical solution to battery life optimization. Everything stated is an opinion or a hunch, except for the relationships between shelf life, temperature, and charge level. An extensive collection of articles and graphs resides at http://batteryuniversity.com/learn/arti ... _batteries

Battery University is the authoritative web resource on batteries. I have no relationship with the company that maintains it, CADEX.

precip9 wrote:

NadavCE wrote:Thanks! So far, I have enabled charge thresholds to stop at 80%- where should I set them to start?

I choose a point >= 10% different from the stop threshold. So, around 70%

Bear in mind there is no mathematical solution to battery life optimization. Everything stated is an opinion or a hunch, except for the relationships between shelf life, temperature, and charge level. An extensive collection of articles and graphs resides at http://batteryuniversity.com/learn/arti ... _batteries

Battery University is the authoritative web resource on batteries. I have no relationship with the company that maintains it, CADEX.

Alright, thanks. I'll definitely have a look at that.

Is there any way to disable the CD-ROM drive or Smart Card Reader? The Smart Card Reader alone uses ~3W according to Powertop, and the CD drive uses ~0.7 W.

On the task bar, an "up arrow" pops a small panel. One of the icons represents a USB plug. Click. The CD ROM should be there as an ejectable device.

To reinstall the CD ROM, you'll have to either reboot, or physically eject the CDROM ~ 1/2" and reinsert.

precip9 wrote:On the task bar, an "up arrow" pops a small panel. One of the icons represents a USB plug. Click. The CD ROM should be there as an ejectable device.

To reinstall the CD ROM, you'll have to either reboot, or physically eject the CDROM ~ 1/2" and reinsert.

Thanks. Is there any way to do this under Linux (Ubuntu 14.04 to be exact)? And the Smart Card Reader has gone up to 7W- how can I disable it?

Linux, not familiar.

7W for a Smartcard reader sounds erroneous. It would be on fire.

precip9 wrote:Linux, not familiar.

7W for a Smartcard reader sounds erroneous. It would be on fire.

Thanks. I'm sticking to Windows, so I disabled the devices I don't need in the device manager. Are there any other steps I need to take?

7w watts implies a hardware defect, or a bug in reading the power.
I'd use one of these: http://www.homedepot.com/p/Unbranded-Ki ... /202196386

to assess how real the reading is.

precip9 wrote:7w watts implies a hardware defect, or a bug in reading the power.
I'd use one of these: http://www.homedepot.com/p/Unbranded-Ki ... /202196386

to assess how real the reading is.

I don't live in the U.S, and it's probably a bug anyway. Thanks, though.

LiPo cells have a marginal voltage of 3.7 V. When you charge on the voltage of a new cell will reach 4.1-4.2V at 100% charge. A rough guide is voltage decreases 0.1V per 10% of remaining charge.

Often chargers, or the cells themselves, will have a circuit which will refuse to charge a cell with a voltage less than 3.0 V. The cell may still be fine, but if it's under 3.0V you have a riddle to solve. How to charge a cell which the charger refuses to charge?

The answer is to simply get some energy into the cell any way you can. You can use another cell to jump start it, or use a charger which doesn't measure voltage.