The T400s I was given a few years ago successfully upgraded to
Windows 10 and seemed to work reasonably well for its age.
However, after not-very-prolonged storage it's absolutely dead,
not responding to the power button until it's plugged into an
AC adapter. This is despite being put away with a full charge
and being shut down, not set to sleep or hibernate
Once it comes back up it charges the battery in an hour or two
and claims to have about 90 minutes of runtime with the battery
at 90-ish percent of full. That seems rather brief, but it's an
old machine. I don't mind plugging it in, but stone-dead from
the start is sort of a nuisance.
What's reasonable to expect? The hardware manual seems mute on
the subject. I've looked into replacing the battery, which is
marked 42t4690, 11.1 volts 3.9AH 44WH. It appears to be available
on Amazon, with admittedly vague descriptions. Still, it would be
nice to know how to test the battery before replacing it. There are
far too many contacts to start probing blindly.
Thanks for reading, and any suggestions!
Turns out I searched the manual for "battery testing" and variations,
but the test points were revealed under "charging". My bad....
With the battery status at 99% the removed battery measures 12.2 volts,
which seems pretty good. The run-time still seems short however.
It further turns out that the power button was set to sleep, not shutdown.
One pleasant surprise is that the machine seems to work fine with the
battery physically removed.
bp@www.zefox.net wrote:
Turns out I searched the manual for "battery testing" and variations,
but the test points were revealed under "charging". My bad....
With the battery status at 99% the removed battery measures 12.2 volts,
which seems pretty good. The run-time still seems short however.
The "battery status" charge percentage is a measure of the battery
voltage by the computer, so not surprising that it looks good at
99% charged. The symptoms sound like a typical worn out battery.
It further turns out that the power button was set to sleep, not shutdown.
Well that explains the fast self-discharge. Some laptops do seem to
wear down the battery more when stored for a long time than if
the battery is removed. I'm not sure if the T400s is one of those,
but it shouldn't discharge as quickly as you describe if it was
fully turned off.
One pleasant surprise is that the machine seems to work fine with the
battery physically removed.
I think every laptop I've encountered worked fine without a
battery.
A new battery is still worth considering, any suggestions are welcome.
Is it feasible to repair (by replacing cells) the original pack?
Computer Nerd Kev <not@telling.you.invalid> wrote:
After putting the battery back in and booting the t400s the capacity indicated 99% but the advertised run time was slightly under two hours.
That seems rather short, I think the claimed runtime is closer to five. Still, if it's true, the laptop is usable to some extent. The most obvious use is to run an Owon vds1022i usb oscilloscope, which will mostly be done within reach of power.
A new battery is still worth considering, any suggestions are welcome.
Is it feasible to repair (by replacing cells) the original pack?
On 15/01/2025 17:25, bp@www.zefox.net wrote:
A new battery is still worth considering, any suggestions are welcome.
Is it feasible to repair (by replacing cells) the original pack?
A compatible T400s battery here (UK) is about £24
https://www.amazon.co.uk/Onlyguo-3800MAH-42T4690-Replacement-ThinkPad/dp/B07YDLHXCY
Cheap. I'd get one before they get scarce, and sellers stop trading them.
bp@www.zefox.net wrote:
Computer Nerd Kev <not@telling.you.invalid> wrote:
After putting the battery back in and booting the t400s the capacity
indicated 99% but the advertised run time was slightly under two hours.
That seems rather short, I think the claimed runtime is closer to five.
Still, if it's true, the laptop is usable to some extent. The most obvious >> use is to run an Owon vds1022i usb oscilloscope, which will mostly be done >> within reach of power.
A new battery is still worth considering, any suggestions are welcome.
My fear is always of dodgy Chinese Li-Ion batteries burning my
house down, but few seem to care about that in spite of the
ever-rising Li-Ion fire statistics.
Is it feasible to repair (by replacing cells) the original pack?
I've done that, replacing with cells from a battery from a broken
laptop. The tricky thing is that the battery cases are all stuck
together differently. Some are plastic welded, others
snap-together, others glued (with glue of various strengths). The
battery I dismantled for cells ended up a shredded mess of plastic
due to strong glue, but the plastic welded case for the battery I
was re-celling came apart without much damage.
If attempting that, you do want to remember that denting,
puncturing, or shorting out a Li-Ion cell can all cause it to
catch fire, sometimes after a delay or when charging.
If you do trust the Chinese reproduction batteries, note that
they're often not much more expensive than buying enough new
individual Li-Ion cells (except maybe for the most dodgy
unbranded Li-Ion cells).
Computer Nerd Kev <not@telling.you.invalid> wrote:
bp@www.zefox.net wrote:
Computer Nerd Kev <not@telling.you.invalid> wrote:I've done that, replacing with cells from a battery from a broken
laptop. The tricky thing is that the battery cases are all stuck
together differently. Some are plastic welded, others
snap-together, others glued (with glue of various strengths). The
battery I dismantled for cells ended up a shredded mess of plastic
due to strong glue, but the plastic welded case for the battery I
was re-celling came apart without much damage.
If attempting that, you do want to remember that denting,
puncturing, or shorting out a Li-Ion cell can all cause it to
catch fire, sometimes after a delay or when charging.
If you do trust the Chinese reproduction batteries, note that
they're often not much more expensive than buying enough new
individual Li-Ion cells (except maybe for the most dodgy
unbranded Li-Ion cells).
I wondered about re-celling the old battery pack, but couldn't
find any descriptions of folks actually doing it and one demo
of letting the magic smoke out, so I'm wary.
It's also unclear what kind of cells are required.
In the meantime I set the power button to shut down while on both
battery and mains. Turned the machine off, it seemed to do so.
Couple hours later I noticed the machine was warm, opened the lid,
found it was up and running. Re-checked "what the power buttons do"
and they still claimed to cause shut down. This looks like a bug.
Anybody else seen this behavior?
bp@www.zefox.net wrote:
Computer Nerd Kev <not@telling.you.invalid> wrote:
bp@www.zefox.net wrote:
Computer Nerd Kev <not@telling.you.invalid> wrote:I've done that, replacing with cells from a battery from a broken
laptop. The tricky thing is that the battery cases are all stuck
together differently. Some are plastic welded, others
snap-together, others glued (with glue of various strengths). The
battery I dismantled for cells ended up a shredded mess of plastic
due to strong glue, but the plastic welded case for the battery I
was re-celling came apart without much damage.
If attempting that, you do want to remember that denting,
puncturing, or shorting out a Li-Ion cell can all cause it to
catch fire, sometimes after a delay or when charging.
If you do trust the Chinese reproduction batteries, note that
they're often not much more expensive than buying enough new
individual Li-Ion cells (except maybe for the most dodgy
unbranded Li-Ion cells).
I wondered about re-celling the old battery pack, but couldn't
find any descriptions of folks actually doing it and one demo
of letting the magic smoke out, so I'm wary.
Seems like there are videos on YouTube, though I made it up as I
went along since it's just a case of hooking things up like they
were when you started (after fighting your way in). I've read some
battery controllers might 'die' when you disconnect the old cells
if you don't hook external power to them, so they're tricky.
It's also unclear what kind of cells are required.
The type of Li-Ion cell is almost always 18650. The capacity (mAh)
is the only thing that varies, and can be calculated by comparing
the battery circuit (add up the capacity of the batteries in
parallel) with the capacity of the battery pack if it's not printed
on the cells themselves (often it is). Note that over-stated
capacity figures are a common complaint with cheap Chinese
replacement cells. You can also choose to use different capacity
cells, but the OS's battery hours estimate might be wrong then.
You will need cells with solder tags attached so you can wire them
up. They are usually crammed together tight in the battery pack so
it can be tricky.
In the meantime I set the power button to shut down while on both
battery and mains. Turned the machine off, it seemed to do so.
Couple hours later I noticed the machine was warm, opened the lid,
found it was up and running. Re-checked "what the power buttons do"
and they still claimed to cause shut down. This looks like a bug.
Anybody else seen this behavior?
Sometimes I've had thinkpads intermittently fail to fully turn off
at shut-down, just sit running with a black screen and maybe the
CPU fan running. Holding the power button down for a while forces
them off. It doesn't boot back up though, just hangs, so it must be
a bug.
You could check that Wake on LAN is disabled in the BIOS settings.
Computer Nerd Kev <not@telling.you.invalid> wrote:
bp@www.zefox.net wrote:
Computer Nerd Kev <not@telling.you.invalid> wrote:
bp@www.zefox.net wrote:
I wondered about re-celling the old battery pack, but couldn't
find any descriptions of folks actually doing it and one demo
of letting the magic smoke out, so I'm wary.
Seems like there are videos on YouTube, though I made it up as I
went along since it's just a case of hooking things up like they
were when you started (after fighting your way in). I've read some
battery controllers might 'die' when you disconnect the old cells
if you don't hook external power to them, so they're tricky.
It's also unclear what kind of cells are required.
The type of Li-Ion cell is almost always 18650. The capacity (mAh)
is the only thing that varies, and can be calculated by comparing
the battery circuit (add up the capacity of the batteries in
parallel) with the capacity of the battery pack if it's not printed
on the cells themselves (often it is). Note that over-stated
capacity figures are a common complaint with cheap Chinese
replacement cells. You can also choose to use different capacity
cells, but the OS's battery hours estimate might be wrong then.
I can't see how the cells could be 18650, the pack is only about
half an inch thick. Even AA cells are too thick to fit.
Maybe that's why replacement packs seem scarce.
In the meantime I set the power button to shut down while on both
battery and mains. Turned the machine off, it seemed to do so.
Couple hours later I noticed the machine was warm, opened the lid,
found it was up and running. Re-checked "what the power buttons do"
and they still claimed to cause shut down. This looks like a bug.
Anybody else seen this behavior?
Sometimes I've had thinkpads intermittently fail to fully turn off
at shut-down, just sit running with a black screen and maybe the
CPU fan running. Holding the power button down for a while forces
them off. It doesn't boot back up though, just hangs, so it must be
a bug.
You could check that Wake on LAN is disabled in the BIOS settings.
I looked for wake on LAN, but couldn't find it in the BIOS. Might it
be set in Windows 10?
Haven't seen it there, but I'm mostly unfamiliar
with Win10 and could easily miss it. I'm certain I didn't hit the power button, but did unplug and plug the power jack and also open/close the
lid. Could either trigger a startup?
The machine stayed off all night, when I checked the battery this morning
it read 12.26 volts, same as last night. No parasite drain. Knowing now
where to test voltage direct on the battery I'm tempted to apply a small light bulb load, say 2 amps, to do a capacity check independent of the computer.
Any hint what the several intermediate contact on the battery do?
bp@www.zefox.net wrote:
I can't see how the cells could be 18650, the pack is only about
half an inch thick. Even AA cells are too thick to fit.
OK, might be the flat cells like they use in phones.
Maybe that's why replacement packs seem scarce.
Seems like Lenovo might still be making them actually. Quite a few
sellers claiming to have genuine "Thinkpad battery 59+" in stock,
if that's the right one.
I looked for wake on LAN, but couldn't find it in the BIOS. Might it
be set in Windows 10?
I doubt it, usually it's set in the BIOS. I've seen the option on
earlier Thinkpads, believe it or not the T400s is still a bit too
new for me.
Haven't seen it there, but I'm mostly unfamiliar
with Win10 and could easily miss it. I'm certain I didn't hit the power
button, but did unplug and plug the power jack and also open/close the
lid. Could either trigger a startup?
I wouldn't have thought so, unless the OS didn't really shut down
fully after all.
The machine stayed off all night, when I checked the battery this morning
it read 12.26 volts, same as last night. No parasite drain. Knowing now
where to test voltage direct on the battery I'm tempted to apply a small
light bulb load, say 2 amps, to do a capacity check independent of the
computer.
Not recommended. Over-discharge could kill it, or even cause it to
catch fire when you try to charge it again (although the battery
controller should prevent that).
Any hint what the several intermediate contact on the battery do?
They're so the battery controller can talk to the PC and tell it
things like why it doesn't want to charge because someone hooked
a light bulb to it and over-discharged it.
The core error I made was not realizing the power-off
button was only putting the machine to sleep. Now it's turning off
for real and does seem to remain off. Self-discharge isn't a problem,
after all is said and done.
It arrived more than a month early, which seemed odd. It seems to fit with
a little fiddling, though the plastic case is very slightly warped.
I settled on a test cycle of simply letting the machine idle without sleeping, using the "best battery life" performance setting. The new battery, after the suggested three charge/discharge cycles, yielded around 4.5 hours till self-shutdown.
When I repeated the test with the original battery, the run time seemed to
be around 4 hours. The longest run times reported on-line were maybe five hours, though it's not clear what the test settings for power were.
Does anybody have a sense whether this is reasonable? I'm told the original battery dates from the purchase time, around 2009. I think it was taken out of service around 2020 and given to me in 2024, so the oem battery is about fifteen years old. I'm very surpised the old battery works so well, if in fact the as-new runtime was five hours..
Thanks for reading, and any sanity checking 8-)
I'd say the main inconsistency here is that in your previous post
you said you tested discharging the old battery and it had a
"little over one hour of endurance". Yet now it lasts four hours?!
A difference in run time like that makes no sense to me unless
you were working it hard or had power-hungry devices plugged into
it during the first test. I guess Windows could also have been
doing an upgrade in the background before, if you didn't disable
that during the test (or, since it's Windows, if it ignored you and
did something anyway).
Computer Nerd Kev <not@telling.you.invalid> wrote:
A difference in run time like that makes no sense to me unless
you were working it hard or had power-hungry devices plugged into
it during the first test. I guess Windows could also have been
doing an upgrade in the background before, if you didn't disable
that during the test (or, since it's Windows, if it ignored you and
did something anyway).
After I got the new battery and started exercising it per the seller's directions (which did seem to improve the performance) I gradually
learned about low power settings. When the new battery clocked in at
only 4.5 hours at low power settings, I got curious and re-tested the
old battery with the new settings. Lo and behold, they were similar.
The new battery is better, but for ~100$ not by much.
I'm left wondering:
1. could a fifteen your old battery still have 80% capacity?
2. should a new 4400 mAh battery last more than 4.5 hours?
bp@www.zefox.net wrote:
Computer Nerd Kev <not@telling.you.invalid> wrote:
A difference in run time like that makes no sense to me unless
you were working it hard or had power-hungry devices plugged into
it during the first test. I guess Windows could also have been
doing an upgrade in the background before, if you didn't disable
that during the test (or, since it's Windows, if it ignored you and
did something anyway).
After I got the new battery and started exercising it per the seller's
directions (which did seem to improve the performance) I gradually
learned about low power settings. When the new battery clocked in at
only 4.5 hours at low power settings, I got curious and re-tested the
old battery with the new settings. Lo and behold, they were similar.
The new battery is better, but for ~100$ not by much.
You are actually timing how long until it automatically shuts down
due to running out of charge, not just going from the estimated
time remaining, right? Those estimations aren't reliable with old
batteries.
I'm left wondering:
1. could a fifteen your old battery still have 80% capacity?
Discharge/recharge cycles are quoted as the key factor for battery
aging, so it might fit if the battery was never used much.
2. should a new 4400 mAh battery last more than 4.5 hours?
Was the screen on/off for both the old "little over one hour" test
and the new tests? I don't know what's normal for a T400s, but
details like that and whether you were using it or just letting it
sit would be important for getting a real answer.
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