Can anyone recommend any decent 3.7V 1S LiPo batteries *WITH* a 10k or
100k ohm NTC for use with the Beaglebone?
I've searched around the Beagleboard google group and found information
on the Beaglejuice and other similar devices, but I'm more interested
in using the battery connector on the Beaglebone to provide power
for short durations in situations where mains 5V power goes away
unexpectedly.
I've been able to find a wide variety of 3.7V 1S LiPo batteries for use
in radio control models, but it's difficult to find one with the NTC
connection exposed (assuming there's even an NTC inside most of them).
I'd like to have the NTC thermistor (rather than cheating it with a
resistor) in order to monitor the temperature properly for charging. I
don't need the battery to be pinned out with a connector that mates to
the Bone battery connector, I just want one that has the proper wires or
terminals and I'll wire up my own harness.
I don't need much capacity, just enough (200mAh is probably enough) to
last a few minutes at most. My main use will be to shutdown safely in
case 5V from mains is lost and turn off the PMIC. A damaged filesystem
is a "bad thing" in my case.
If this has been asked before, I apologize for my horrible Internet
skills. If you could kindly point me in the right direction, I'd
appreciate it.
Thanks,
Andrew
Typically, these are “custom” type arrangements. Most batteries do not have the NTC or resistor built in. You have to have them made up as an assembly from a battery supplier. They basically create a battery pack with these devices either on a board installed under shrink wrap, or discretely wired in.
Now, if you can find a replacement battery used in a commercial product, get the specifications on it, and adapt it to what you need, that may work.
We also have the BeagleBone Battery cape that uses four liION AA batteries. It will power a BeagleBone and a 7" LCD panel on all the time for about four hours. It is connected via a diode to protect it if the 5VDC power is plugged in. It has not been tested for backup if 5V is removed, but I don’t see why it would not work. I can have the guys test it and see what happens.
This battery has the charging done externally, so we don’t have t worry about the NTC or the resiistor for battery charging.
Gerald
Typically, these are "custom" type arrangements. Most batteries do not have
the NTC or resistor built in. You have to have them made up as an assembly
from a battery supplier. They basically create a battery pack with these
devices either on a board installed under shrink wrap, or discretely wired
in.
Now, if you can find a replacement battery used in a commercial product,
get the specifications on it, and adapt it to what you need, that may work.
OK, I'll take a look around. Guess I'll be learning more about
batteries...
We're going to be pretty low volume, getting custom batteries built
sounds expensive if normal customers for these things are cell phones
and the like with their huge volumes.
We also have the BeagleBone Battery cape that uses four liION AA batteries.
It will power a BeagleBone and a 7" LCD panel on all the time for about
four hours. It is connected via a diode to protect it if the 5VDC power is
plugged in. It has not been tested for backup if 5V is removed, but I don't
see why it would not work. I can have the guys test it and see what happens.
The picture on Beagleboardtoys shows 4 alkaline batteries (meaning
6V?). How exactly is the diode setup to enable both the battery cape
and the 5V external input from the wall adapter? Are you feeding 5V
from the battery cape down through the P9 header 5V pins?
You say liION batteries. What kind? What voltage is each cell? How
are the cells arranged? I have all sorts of questions 
Can 1.2V NiMH cells work with the battery cape?
Depending on the answer, there might be a way to adapt the battery cape
for my needs but maybe use NiMH and use a dedicated NiMH cell charger
chip on our cape. I was thinking since the PMIC already has charging
and auto fall-over built in, it'd be nice to just use that, but if it's
more trouble than it's worth I'll look at other options.
Thanks,
Andrew
Gerald, thanks for your answers! 
The environment our boards will deploy to aren't conducive to manual
battery changes and mains power should be available most of the time,
thus the desire to use rechargeables. Time to go harass some
lithium battery companies...
Thanks,
Andrew
What I did as a quick hack:
http://www.sparkfun.com/products/10718
http://www.sparkfun.com/products/10300
Connect the output to SYS_5V (or VDD_5V, I forget) on the bone. That gave me about 50 minutes on a single charge. You should be able to connect power to the microusb to keep it charging while it powers the bone and run of battery when it fails.
No idea on the thermals, as I said, a quick hack
regards,
Koen
Thanks! Good to know about the runtime, 50 minutes out of a 400mAh pack
is better than I expected. Granted, I assume that booster gave you the
full voltage range of the LiPo versus what I'm intending to do of
running off battery through the Bone battery header till it hits about
3.5V or so and then the DC-DCs start to sag (or so it looks to me right
now). But then again, I only need a minute or two of runtime, enough to
shutdown safely and not need to fsck on next boot.
I've got an inquiry into a local LiPo battery company, so we'll see what
they say about getting the NTC integrated and harnessed out.
Thanks,
Andrew