Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Open Source Thinkpad T420 Battery Design

github.com

Post reply on HN
Print view View original

31–40 of 105 posts

Re: Open Source Thinkpad T420 Battery Design

#31

Post by 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.

Re: Open Source Thinkpad T420 Battery Design

#32

Post by etaioinshrdlu »

iam4722202468 wrote: post #16
userbinator wrote: post #12

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.

I've read a few things about using charging circuits and battery fuel gauges but it's a bit beyond what I know how to do right now. I might look in to it more in the future, or maybe someone else who knows more than me can add a fuel gauge to the schematic :)

I've used this which was very easy to get to work and there is C code out there to use with it. https://www.sparkfun.com/products/10617

Re: Open Source Thinkpad T420 Battery Design

#33

Post by cmxch »

dividedbyzero wrote: post #2

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?

The x10-x30 series are a well known design and perform surprisingly well for 8-10 year old laptops. They're also more maintenance friendly (most T/W series) than their more current models.

Re: Open Source Thinkpad T420 Battery Design

#34

Post by ghostly_s »

bluejellybean wrote: post #31

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…

What do you put in the upgrade bay that helps with web development? I upgraded from an x220 to x230 (modded to take the x220's classic keyboard) because the lack of hardware h.264 decoding in the '20-series CPUs was causing noticeable performance problems with web content.

Re: Open Source Thinkpad T420 Battery Design

#36

Post by cmxch »

userbinator wrote: post #25
dividedbyzero wrote: post #2

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?

I'm still using an X60 which is several years before that. It turns out that if you avoid the bloated "modern" software (which unfortunately includes much of the web stuff these days), it's perfectly usable. I use it for native development, browsing lightweight sites like HN, and the usual "office" stuff like email, IM (IRC), taking notes, etc. Likewise, my desktop is a first-gen i7 from roughly 10 years ago, only sl…

How do you get around the issue of parts rarity? The Penryn/Merom generation is quite hard for parts replacement, especially so if you have anything Flexview (in my case, a T61 in a T60 4:3 chassis).

Re: Open Source Thinkpad T420 Battery Design

#37

Post by konjin »

bluejellybean wrote: post #31

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…

I have a i7 4 core, 16gb, 512 ssd, 1080p, gpu accelerated, coreboot system.

I'm waiting on the open hardware platforms to come around to something like it before I upgrade. And I don't really feel the need to, apart from not having a 4 or 8k screen.

Re: Open Source Thinkpad T420 Battery Design

#38

Post by avhon1 »

tsomctl wrote: post #6
dividedbyzero wrote: post #2

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?

I'm running a T530 as my everyday rig, with Windows 10. I maxxed out the ram and got a ssd. It's fast, I can have numerous Chrome tabs, Sublime, and pdfs open, and quickly switch between them. Youtube videos play seamlessly. I can have multiple Kicad projects open. I genuinely don't feel the need for a faster computer.

For reference, the T530 (and the 14-inch T430) is 1 year newer than the T420.

Re: Open Source Thinkpad T420 Battery Design

#39

Post by iam4722202468 »

etaioinshrdlu wrote: post #32
iam4722202468 wrote: post #16

Earlier quoted context omitted.

I've read a few things about using charging circuits and battery fuel gauges but it's a bit beyond what I know how to do right now. I might look in to it more in the future, or maybe someone else who knows more than me can add a fuel gauge to the schematic :)

I've used this which was very easy to get to work and there is C code out there to use with it. https://www.sparkfun.com/products/10617

Hmm, it seems like all the fuel gauges I can find are designed to be incorporated in to a bms, instead of being added to the input/output of an already existing bms. Do you know if there's a fuel gauge that can work with 12v so I can just add it to the circuit I'm using?

Re: Open Source Thinkpad T420 Battery Design

#40

Post by cl3misch »

userbinator wrote: post #12

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.

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?
Post reply on HN