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Token Ring
Posts: 494
Registered: ‎11-04-2010
Location: Sydney
Message 1 of 7 (856 Views)

27++ battery discharge pattern

So, I have two batteries.  55++ and the 27++.  Both are 9cells each, and with a designed capacity of 93.24Wh.

 

The dischrge pattern between the batteries while they're both hocked up to the W520 is that the 27++ will first get dischange...all the way down to 0%, then and only then will the 55++ start to discharge.

 

This is potentially damaning to the 27++ in terms of faster wear, and long term battery health.

 

Is there a way to configure the system to switch over and use the 55++ battery once the 27++ drops down to a particular level, say, 25%.  ...without manually disconnecting the 27++?

Guru
Posts: 1,320
Registered: ‎04-20-2008
Location: US
Message 2 of 7 (847 Views)

Re: 27++ battery discharge pattern

[ Edited ]

The slice battery is protected from total discharge.The system will switch over to the internal battery when the microprocessor on the slice battery signals that it is at 0%. The microprocessor will protect the battery from further discharge when that power state is reached.



W520 Windows 7 SP1 Pro, i7-2820QM, BIOS 1.42, 1920x1080 FHD, 32 GB RAM, 2000M NVIDIA GPU, Samsung 850 Pro 1TB SSD, Crucial MX200 mSata 512GB, WD 2TB USB 3.0, eSata Plextor PX-LB950UE BluRay

W520 Windows 10 Pro, i7-2760QM, BIOS 1.42 1920x1080 FHD, 32 GB RAM, 1000M NVIDIA GPU, Crucial M550 512GB mSata SSD, Hitachi 500GB HDD, WD 2TB USB 3.0

P70 Windows 10 Pro, XEON 1505, BIOS 2.0, UHD 4k Display, 64GB non-ECC RAM, M3000M NVIDIA GPU, RAID 1 512GB Samsung 951 PCIe-NVMe SSD x 2, Samsung 850 Pro 1TB SSD

T460s, BIOS 1.11, Windows 10 Pro, QHD display, 20GB RAM, I7-6600U, Samsung PM961 1TB PCIe-NVMe SSD, EM7455 WWAN
Token Ring
Posts: 494
Registered: ‎11-04-2010
Location: Sydney
Message 3 of 7 (844 Views)

Re: 27++ battery discharge pattern

So even when the slice is reporting 0%, it in fact is not the cells' 0%?  Am I understanding correctly?

 

Does this logic also apply to the 55++?

 

 

Guru
Posts: 1,320
Registered: ‎04-20-2008
Location: US
Message 4 of 7 (828 Views)

Re: 27++ battery discharge pattern

[ Edited ]

Yes, the 0% is not the cell discharge level, but the 0% of power that can be safely drawn from the battery. All Li-on batteries from Lenovo have the builtin microprocessor that protects the cells.



W520 Windows 7 SP1 Pro, i7-2820QM, BIOS 1.42, 1920x1080 FHD, 32 GB RAM, 2000M NVIDIA GPU, Samsung 850 Pro 1TB SSD, Crucial MX200 mSata 512GB, WD 2TB USB 3.0, eSata Plextor PX-LB950UE BluRay

W520 Windows 10 Pro, i7-2760QM, BIOS 1.42 1920x1080 FHD, 32 GB RAM, 1000M NVIDIA GPU, Crucial M550 512GB mSata SSD, Hitachi 500GB HDD, WD 2TB USB 3.0

P70 Windows 10 Pro, XEON 1505, BIOS 2.0, UHD 4k Display, 64GB non-ECC RAM, M3000M NVIDIA GPU, RAID 1 512GB Samsung 951 PCIe-NVMe SSD x 2, Samsung 850 Pro 1TB SSD

T460s, BIOS 1.11, Windows 10 Pro, QHD display, 20GB RAM, I7-6600U, Samsung PM961 1TB PCIe-NVMe SSD, EM7455 WWAN
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Guru
Posts: 9,240
Registered: ‎12-26-2009
Location: Toronto, Canada
Message 5 of 7 (821 Views)

Re: 27++ battery discharge pattern

While the cells will still have charge at "0%", the closer to the reported 0% you drain, the faster the battery wears out. The declared 0% is simply the somewhat arbitrarily determined threshold set in the controller.
W520: 2720QM, Q2000M at 1082/1376, 32GB RAM, 500GB + 750GB HDD, FHD screen & MB168B+
X61T: L7500, 4GB RAM, 500GB HDD, XGA screen, Ultrabase
W550s: 5600U, K620M at 1164/1281, 16GB RAM, 512GB SSD, 3K touchscreen
X200s: SL9400, 6GB RAM, 160GB HDD, WXGA+ screen
TPT1: 1839-23U
Guru
Posts: 1,320
Registered: ‎04-20-2008
Location: US
Message 6 of 7 (816 Views)

Re: 27++ battery discharge pattern

The behavior is normal. There are no settings in the power manger to change the switchover %


W520 Windows 7 SP1 Pro, i7-2820QM, BIOS 1.42, 1920x1080 FHD, 32 GB RAM, 2000M NVIDIA GPU, Samsung 850 Pro 1TB SSD, Crucial MX200 mSata 512GB, WD 2TB USB 3.0, eSata Plextor PX-LB950UE BluRay

W520 Windows 10 Pro, i7-2760QM, BIOS 1.42 1920x1080 FHD, 32 GB RAM, 1000M NVIDIA GPU, Crucial M550 512GB mSata SSD, Hitachi 500GB HDD, WD 2TB USB 3.0

P70 Windows 10 Pro, XEON 1505, BIOS 2.0, UHD 4k Display, 64GB non-ECC RAM, M3000M NVIDIA GPU, RAID 1 512GB Samsung 951 PCIe-NVMe SSD x 2, Samsung 850 Pro 1TB SSD

T460s, BIOS 1.11, Windows 10 Pro, QHD display, 20GB RAM, I7-6600U, Samsung PM961 1TB PCIe-NVMe SSD, EM7455 WWAN
Token Ring
Posts: 494
Registered: ‎11-04-2010
Location: Sydney
Message 7 of 7 (777 Views)

Re: 27++ battery discharge pattern

I wonder if there's a way to submit a feature request to Lenovo...

Or maybe they just want the batteries to wear out quicker...so they can sell more.

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