HOWTO: Booting A Kindle DX Graphite without a Battery

[TinyApps.Org]

Neil Ramsay has posted a detailed walkthru of Booting a Kindle DX Graphite without a Battery. Handy for those who might be using an old DX as a second monitor.

[TinyApps.Org]

If you can still boot to a root prompt on the Kindle, it turns out that the battery check can be bypassed in the software instead of hardware. Posting a comment I made on Neil's blog here for posterity in case anyone else is searching:

It turns out that /etc/rc2.d/S50battcheck offers all sorts of possibilities for skipping the battery check. I elected to simply change the two lines reading "_SKIP_CHECK=0" to "_SKIP_CHECK=1" - worked a treat.

Here is some partial output from /var/local/log/really_long_name.gz before the change when starting with a dead battery:

init: Entering runlevel: 2
...
system: I S50battcheck:def:running
system: I S50battcheck:def:current voltage = 3738mV
system: I S50battcheck:def:gasgauge capacity=2% volts=3794 mV current=179 mA
system: W S50battcheck:def:battery low. Not booting
...
system: I S50battcheck:def:current voltage = 3882mV
system: I S50battcheck:def:gasgauge capacity=4% volts=3864 mV current=363 mA
system: I S50battcheck:def:battery sufficient, booting to normal runlevel
init: Switching to runlevel: 5

and here is the output after editing /etc/rc2.d/S50battcheck as described above and rebooting:

init: Entering runlevel: 2
...
system: I S50battcheck:def:running
system: I S50battcheck:def:skipping battery check
init: Switching to runlevel: 5

[geekmaster]

I think I saw in some system scripts (at least on some models) that there is a flag file you can drop in the file system (perhaps at root rather than userstore) that bypasses battery check.

Editting your scripts will work, but may interfere with a firmware update (depending on firmware update integrity checks). Some updates throw an error if they detect "hacks" (modified files). But if not a concern, then your suggestion is a good (easy) way to do this.

However, if you disassemble a dead battery, you can use the little circuit board inside it between the kindle and the power supply, and the kindle should "see" an official amazon battery (though I have yet to try that myself). Not sure how confused the kindle battery charging algorithm would get with an infinite capacity battery (i.e. external power supply masquerading as a battery).

[TinyApps.Org]

Hi geekmaster,

Many thanks for your reply. Always a pleasure connecting with you.

I think I saw in some system scripts (at least on some models) that there is a flag file you can drop in the file system (perhaps at root rather than userstore) that bypasses battery check.

Apparently in Kindle 3.1, /etc/battcheck.conf contains the following line:

_NOBATTCHECK_FILE="/mnt/us/system/nobattcheck"

On my Kindle DX running 2.5.5, /etc/battcheck.conf does not contain any such reference to nobattcheck.

However, etc/rc2.d/S50battcheck offers all sorts of possibilities for bypassing the battery check... here's another:

# Check a boot arg to see if we are configured to
# skip the batt check
grep -i "nobattcheck" -q /proc/cmdline
if [ $? -eq 0 ]; then
    msg "nobattcheck in boot args" I
    _SKIP_CHECK=1
fi

[knc1]

Originally Posted by geekmaster

- - - -
However, if you disassemble a dead battery, you can use the little circuit board inside it between the kindle and the power supply, and the kindle should "see" an official amazon battery (though I have yet to try that myself). Not sure how confused the kindle battery charging algorithm would get with an infinite capacity battery (i.e. external power supply masquerading as a battery).

Thanks for the tip.
I have a 7" tablet whose battery is getting real close to having that surgery done to it.

[geekmaster]

Originally Posted by knc1

Thanks for the tip.
I have a 7" tablet whose battery is getting real close to having that surgery done to it.

The kindle battery contains a thin metal and plastic frame, which is also worth keeping (to keep the circuit board in contact with the battery terminals on the kindle). Just snip the LiPo cell tabs and connect another single-cell LiPo (perhaps stolen from a radio-control toy). Single cell LiPo batteries should all be the same voltage (just different storage capacity) and they lose capacity with age. You can buy multi-cell LiPos for just a few dollars from online R/C shops, and snip out a single cell (with only physical size being the issue). Kindle replacement batteries for under a dollar that way...

Or connect a power supply to the LiPo terminals on the salvaged battery circuit board (labelled + and -). Beware that cheap wall-wart power cubes might put out a much higher voltage than is printed on the package, under a light load.

[knc1]

I have a few, thin, small, Li-Ion batteries that I purchased (surplus) that I never had a use for -
AND
they are two terminal - so I think they are just storage cells (no management controller inside).
They might have been for some sort of RC rig.

I haven't seen the tablet's battery yet - I will see that when I see it.
but it is hard to imagine that its battery will be smaller than these.

[geekmaster]

The kindle battery circuit expects Lithium Polymer (LiPo). Not sure how other lithium battery technologies would work. But, the battery cover I peeled off lists BOTH 3.7v (standard LiPo voltage) AND 4.2v (common for other lithium batteries, such as older kindles used). I suspect anything below 5v is probably okay, and perhaps anything up to what could cause overheating of voltage regulators in the kindle (probably lower than IC max specs, because no active cooling). The battery thickness is typical of a single LiPo cell. The length and width are limited by the battery storage frame, but there are backplane support ribs that could be ground away to make room for a larger battery cell (at least in the open PW2 I just examined while typing this, and my PW3 was identical in all ways to my PW2, from a visual inspection).

[geekmaster]

FYI, I started a "kindle battery surgery" thread, which ended in two successful battery repairs (K2 and PW2/3):

https://www.mobileread.com/forums/sho...d.php?t=274761

[atonement]

Is this still applicable to the Kindle Paperwhite 3? Navigating to the etc folder in Kindle File Explorer freezes the device. In Kterm I am able to cd to etc folder but thereafter I am informed that rc2.d doesn't exist. Maybe I used an incorrect command. Plus no mnt/us/system/nobattcheck exists.
Edit: There's an rc.d folder instead.