
Open Source Thinkpad T420 Battery Design - iam4722202468
https://github.com/iam4722202468/ThinkpadBattery
======
captainmuon
This is a cool project, and I love it when somebody "takes back" their
hardware a little bit or keeps them useful through hacking instead of throwing
it away.

But it shows how irrationally our society is set up in some aspects. In an
ideal world, you could just send the Lenovo engineer a mail and ask for the
firmware source. But the incentives are such that they keep it secret,
probably because they make a lot of money with batteries. So hackers spend a
lot of time reverse engineering stuff. It seems really inefficient.

~~~
holri
This is why my next laptop will be a MNT Reform, you can change the individual
cells yourself:

[https://www.crowdsupply.com/mnt/reform](https://www.crowdsupply.com/mnt/reform)

~~~
danbolt
I just received my developer beta MNT Reform, and I've been really enjoying
it. They keyboard takes a bit of getting used to, but everything's very cute.

~~~
silly-silly
Any chance you could host a 'sosreport' so I could get a look at the hardware
config ?

------
bluejellybean
The T420 has been my main daily driver for nearly 6 years (using it right now
to type this!) and I super excited to check this post out in more depth as
battery duration is one of my biggest personal complaints about the system.

To those wondering about the T420, they are fantastically rugged and I still
think they are the best laptop on the market assuming you can handle either a
slightly crap monitor or the hassle to upgrade it. I've dropped them onto
concrete, dremeled them, even lit them on fire, most of the time they'll take
the abuse but even when they don't, they are dirt cheap so who cares! Ebay has
them listed at $150 a replacement, you can literally buy nearly 10 of them
before scratching the entry point for a Macbook. All of this while being able
to a modern web-dev development setup thanks to it's incredibly simple upgrade
bays.

~~~
unicornporn
I can unfortunately not live with the crap display (I do image editing).
What's the hassle like?

~~~
iam4722202468
Pretty easy, but a bit expensive considering the laptop itself only costs
around $150. A 1080p display + adaptor board for it costs about $100 and the
1440p display + adaptor is around $150. If you look up "T420 ips mod" you'll
find lots of pictures and tutorials.

~~~
afroboy
I just use another monitor, while the laptop display act like a second
display.

~~~
unicornporn
Need it on the road.

------
knaik94
I had a big brother model of the t420, which uses the same battery and can
also coreboot, the w520. It's the workstation model with i7 quad and a
dedicated quadro graphics card. I understand the audience targeted here uses
it mainly for development work.

So hardware video acceleration for newer formats isn't seen as a priority.
That is an issue I came across, even with a quad core i7 and quardo, it
struggle with h265 4k playback smoothly, and 4k vp9 pushed it a little hard
too. 1080p youtube is fine as is x264, no problems there but x265 always gave
it a little trouble.

There are many great things about it, but I thought I would mention the one
drawback of an older thinkpad with older intel chips, is poor hardware
accelerated video playback of newer codecs. If you stream online, it's a non
issue mostly.

I had mine for 9 years before it finally died. I think the gpu overheated and
burnt out, it gets to the login screen and then freezes. I was pushing it hard
in terms of video encoding so part of it was my own fault. I still miss
machine and that keyboard and nub.

------
userbinator
_Currently remaining battery % 's aren't exact because I'm assuming there is a
linear coorelation between voltage and capacity (Which is wrong). I don't plan
on fixing this, as the exact % is unimportant to me._

There are dedicated ICs which will give the remaining charge accurately, which
may possibly be even cheaper than this ad-hoc solution.

~~~
cl3misch
Could you measure a calibration discharge curve with a (digital) bench power
supply draining constant current (or constant power) and use it as a LUT?

~~~
megous
Not as simple. Voltage also changes with load and temperature for multiple
reasons. You'd also need to account for that.

------
zelly
It really speaks to how badly innovation has slowed in chip design that a 10+
year old budget laptop is still comptitive hardware

~~~
userbinator
I wouldn't consider the ThinkPad line "budget" in any way --- that would be
the IdeaPads.

~~~
Waterfall
You can find them on eBay for cheap. That makes them budget. Nobody cares if
they were $9000 last year or a million when they were released. They are
commonly found as cheap old business equipment or found in the trash. You can
get a thinkpad today for under $600 new and and old ones for under $200.
Ideapads have sometimes been more expensive than thinkpad so it's not a good
metric.

------
ckdarby
The T420 has been one of the best Linux laptops I've ever owned.

Pretty much recommend this over System76 any day.

------
linker3000
Check out this battery recall notice, which includes the T420. Lenovo sent me
a brand new replacement 9-cell unit for my T420 about 6 months ago.

[https://support.lenovo.com/us/en/solutions/hf004122](https://support.lenovo.com/us/en/solutions/hf004122)

Typed on my T420 running Linux Mint 20.

------
generalizations
I wonder if this project could be applied to the X230 laptops.

~~~
iam4722202468
Yeah it should, but the laptop's firmware would need to be modified to not
check for an authentic battery

~~~
generalizations
Nice to know. I've done that firmware mod on the T430, so it's not too hard.

------
mschuster91
Cool project, I wish battery stuff in general was more open-source friendly
and not hidden in a wade of obscure datasheets.

What I'd really like to see one day is a web site/an app where one can input a
pack voltage and sustained/peak amperage targets and the cell type that is to
be used, and it will automa(t/g)ically create a controller schematic / parts
list, with full safety features (balancing of _all_ individual batteries,
overcurrent/short circuit protection on load side, overtemperature protection
on charging side) included.

So, no matter if you're building an e-cig, a drone or a way to power a mobile
disco setup without lugging six car starter batteries around, it will always
give you a solution that works.

------
dividedbyzero
Apparently those Thinkpads are from 2011-2012, that's old. What do people do
with such old devices that makes building a battery from scratch worthwhile?

~~~
iam4722202468
The T420 is old, but still has some advantages over laptops currently on the
market. Up until 2018 many laptops still had dual core cpus like the i7-7500u
which are worse than the i7-3840qm that can be put in a T420, and the few
currently available laptops that have 1440p displays and quad core cpus are
still pretty expensive. Some other reasons people still use the laptop are
being able to use coreboot with it and the upgradability of it. It's really
cheap to upgrade the laptop to work with bluetooth 5 and wifi 6 and multiple
ssd's can be added using the two 2.5" slots and the one msata slot. Using
this, someone could make a large 150wh or even 200wh battery that would let
this laptop last longer than most new laptops.

~~~
andromeduck
The display quality is so far behind more modern laptops like the macbook pro
though.

~~~
iam4722202468
One of the mods that can be done is adding 1440p 14" ips display, like the
LP140QH1-SPB1 from the carbon x1 gen 2. It's not as good as a new macbook pro
display, but it's very nice to use.

------
iamgopal
As a concept, lots of industrial innovation are restricted due to lack of
collaboration. Lots of University level innovation are restricted due to lack
of lots of real world testing, open source can solve these two, but lacks lots
of funding. Can all of specific industrial knowledge and technological
knowledge be open source to the tune of making a viable product ?

------
javchz
I use a t430 with a t420 keyboard, and let me tell you haven't found no other
laptop so comfy in layout terms. Yeah I would like a mechanical switch, but
I'm happy to see the t420 still alive in the community.

------
castratikron
Is this still needed if coreboot is installed?

Will this work to make a slice (bottom) battery too?

~~~
iam4722202468
Yeah, this is still needed even with coreboot. The attiny isn't doing anything
too complicated, it's just there to tell the laptop the status of the battery.
In the testing I did, if you supply 12v without any of the SMBus stuff the
laptop will shut off after a few minutes of use.

I'm actually looking in to making a slice battery, it should be possible but
sourcing the docking connector seems to be much harder than getting the
battery connector.

~~~
castratikron
Would it be possible to write directly to /dev/i2c in Linux and spoof the
messages? Not sure what the use case of this would be, but might be useful for
something.

~~~
iam4722202468
Yep definitely, I had this exact thought last night and found an example
kernel module to spoof a battery, and one to read i2c messages. There's
probably all kinds of cool things you can do with a kernel module to
communicate between the laptop's i2c port and a microcontroller. The docking
connector conveniently has an i2c port on it, maybe I'll look in to this in
the future

------
Waterfall
As an owner of a T420 and x230 thank you but these laptops are too old. The
CPUs use like 25w, the screens are 99% really bad TN screens and a few
touchscreen IPS on the x220t and x230t. The screens are the deal breaker.
Lugging around a heavy laptop or a small laptop with a crappy screen sucks.
The new generation starting wirh 40s are modern battery can have internal and
external batteries and the screens aren't overpriced crap, you can easily find
a cheap IPS in FHD for under $60 on eBay. These need adapters or expensive
crappy screens that aren't produced anymore.

I wish they had better screens to make them worth using. Using an IPS and
going back to these is hell, and the 720p on the T420 is also really
saddening. It's the worst part of these computers.

~~~
regularfry
The rest of the package makes up for it, for me. The keyboard is fantastic,
the CPU is more than fast enough, enough ports, they're rugged as hell, and I
can get at the parts to swap them out when they fail. It's always been a
desktop replacement for me, so lugging it about was rare. I can forgive the
screen. Mine spends most of its time plugged into a monitor anyway these days.
I think the graphics chip might be on the way out, though, I'm starting to see
rendering glitches...

~~~
Waterfall
The new keyboards are good too. Where are you getting the screen from? They're
way overpriced when I find them (12.5in screens, 14in and 15in aren't much
better either).

Wait until you get a T440P. About the same, but way more powerful and the
screen and battery life are way better. Only like $120 usually and even less
pretty often. The batteries are cheap and genuine too. I'm looking forward to
more devices like the surface so Keyboards aren't attached to laptops anymore.
The new Lenovo keyboard is pretty good but it's expensive!

------
0x_rs
I would imagine with works well with W520s too. Nice project! Unfortunately
aftermarket batteries are always a lottery and more often than not have really
poor quality, if not even dangerous.

------
iso1210
I've had two t410s, both have died after the screen hinge breaks in some
fashion (nut wears through plastic, hinge breaks, then the plastic cover on
the screen separates.

Are t420s better?

------
taf2
I love in the final video he has the distance finder on a breadboard. I have a
similar one and just found that awesome to see

------
gnom69
I'm on the lookout for a FHD IPS screen for the T420 that is compatible for
max 150$.

Where do I source those?

~~~
iam4722202468
I got a few displays from aliexpress, all of them were good quality. If the
seller has a good rating, they'll most likely send legitimate displays. You'll
also need a FHD adaptor. Together the adaptor and the screen will easily be
under $150.

------
diminish
I have a dream:

A large company buys Thinkpad as a brand and launches a few shiny Linux
Laptops

~~~
tomcooks
Instead of making bad Mac Air clones a company should make 1:1 replicas of
sturdy, old school, ThinkPads (t420, x230, x220, etc)

There's a market for cheap, reliable, battle tested equipment

~~~
generalizations
I wonder how much of the design of those oldschool ThinkPads is patented or
otherwise protected. What's to stop some enterprising hacker from making those
replicas without authorization?

