gnufreex

14 Posts

6634

October 10th, 2017 14:00

e5470 battery problem

I have e5470 with 6440HQ, upgraded to 32GB of RAM, 256GB SATA SSD and it has a factory battery of 62WHR. I think battery is problematic from the start, even with 8GB of RAM I was getting random shutdowns when using battery power. On AC it works rock solid. I did some testing, I use linux so I used stress uitility and monitored battery voltage. After battery discharges to having less than 50%, voltage of battery is around 7.5 (it is around 9V normally) and then on high load it shuts down. Battery is specified at 7.4 V

I was thinking of getting the 4-cell 52Whr battery, it says 11.1V. Will this enable it to run full battery load? Or shutdown is because of something else?

Responses(14)

gnufreex

14 Posts

0

October 11th, 2017 06:00

Btw, what you linked seems removed from dell site. Only place I see I can get new battery is partsPeople.

E

ejn63

9 Legend

•

87.5K Posts

0

October 11th, 2017 06:00

If what you're looking for is more battery runtime, going from 62WHr to 52 is heading in the wrong direction. It sounds like your present battery has a dead cell in it. The battery for your system is this one:

accessories.us.dell.com/.../PfydFeaturedCategoryResults.aspx

gnufreex

14 Posts

0

October 11th, 2017 06:00

I don't think cell is dead, I have read about this problem from other e5470 owners. And my battery shows in Linux to have 83 percent state (not charge, I am talking about wear and tear level), when it was 99 the problem was also there. Taking the same battery as I have and expecting different results seems dumb to me. I am not really wanting more battery life, just reliability on battery, as in no shutdowns or quirks before battery is really empty. And 52Whr battery seems to give more voltage and has 4 cells in 4 compartments when looked from behind, while this one I have looks like it has 2 cells per compartment

DELL-Alasdair R

4 Operator

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754 Posts

0

October 11th, 2017 07:00

Hi gnufreex,

You can check the battery health in the BIOS/setup (tap the F2 key at start-up) - expand "General" then select "Battery Information"

There are also battery tests in the diagnostics (power the system on whilst holding down the Fn key to initiate)

If the battery is needing replaced it will tell you there. If it does, please PM me your service tag and contact details, I'll look into your options.

gnufreex

14 Posts

0

October 11th, 2017 10:00

I did battery test in diagnostics, it passed. Says battery is good.

gnufreex

14 Posts

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October 11th, 2017 14:00

There is one more issue. When battery is outputting less than 7.5V like on pic, whenever I close the lid and open it computer restarts. It can't wake from suspend when battery is weak. Also, shutdowns only seem to happen if I did suspend before. Now I rebooted computer and battery is running fine under stress test, probably will go till 0%.

gnufreex

14 Posts

0

October 13th, 2017 03:00

I learned that there is a battery for this laptop that is 2XNYN part number, 66Whr and 11V. I think I want this battery regardless if the problem I am having is connected to battery. This battery I have will wear and tear, already at 80% so 2XNYN is next battery I will get. Problem is I can't find it from dell.

Regarding this problem with the shutdown, I have updated bios like Alsdair told me, I have not got a shutdown since. Lets hope it is fixed. Also I found another suspect for shutdowns, this dmesg warrning

ahci 0000:00:17.0: port does not support device sleep

This is SATA port where my SanDisk is connected. I can't update sandisk firmware in Linux, i might take it to some other computer to update. But I think it is not due to firmware. I will probably get Samsung NVMe drive soon, and this SanDisk will move to desktop workstation.

gnufreex

14 Posts

0

October 15th, 2017 08:00

Bummer. I now get shutdowns even when battery is at 70%. The laptop is totally useless when not plugged in. And battery went down in wear, now it is 78% and it was 82%

I chatted with Dell support about 66Whr battery, they say they don't have it and not sure when they will get it if ever.

gnufreex

14 Posts

0

October 18th, 2017 10:00

I was thinking what changed after I thought that problem is fixed unti it got worse. It was that I left laptop with lid closed but inpluged and in suspend mode entire night. In morning it had some battery left, clock was showing wrong time, and it actually shutdown before battery was fully discharged. Then it took like 12 hours to recharge.

I think CMOS battery might be the culprit of wrong time problem... and also shutdowns might be due to CMOS battery...

gnufreex

14 Posts

0

October 18th, 2017 11:00

I got this after one of shutdowns on battery. I power it up and plug AC, works without hitch. Really puzzled.

Also noticed some coil whine when battery is charging and discharging.

gnufreex

14 Posts

0

October 20th, 2017 11:00

Voltlog

7113000

7039000

7139000

6998000

===================

Shutdown.

gnufreex

14 Posts

0

October 20th, 2017 11:00

So the the verdict is. Battery I am having, the 62Whr one, is 7.4 V, 2x2cell, and sometimes does not feed laptop with power. I need 11v battery, either 48Whr one or 66Whr one. They are both 11v.

gnufreex

14 Posts

0

October 20th, 2017 11:00

currentlog

2042000

2021000

----

shutdown

gnufreex

14 Posts

0

October 20th, 2017 11:00

Did some more debugging on this. The problem with 2 minute battery run time was due to lose cable on battery. After fastening it, that problem was fixed, and we are back to the old problem that laptop shutsdown on high load when on battery and only when battery is under 40-50%.

The heating problem was due to the fact that I tried to power it on immidiately after shutdown, and then it does not kick in the fans every time. If shutdown was when CPU is on high load, then CPU is hot when it turns on and displays that message.

So overheating is not a problem. here is what I think it is a problem. I did a volt loging and current loging script in Linux.

while true; do cat /sys/class/power_supply/BAT0/voltage_now | tee -a ~/voltlog; done

while true; do cat /sys/class/power_supply/BAT0/current_now | tee -a ~/currentlog; done

The logs are pretty long off course, but this is the gist. As battery discharges, voltage goes down, and current goes up. When voltage goes bellow 7V and CPU is on high load, laptop shutdowns.

Here are ends of logs right after shutdown I did earlier.

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e5470 battery problem