Droid 4 Battery Pinout

[Milp]

Hi there,

I'm currently working on building a bigger (and uglier) external battery for my droid 4. One that uses laptop cells, because i only care about capacity.

At this point I'm not quite sure of the pinout. I get that the two holding screws for the battery connector are + and -, and it seems that the "pin" next to GND is also pulled to GND. However there seems to be a random voltage between 0 and 4ish volts measurable between the pin next to the positive pole screw and the positive pole. It does not resemble the batteries current voltage, it is always lower. If you measure between GND and this pin you get zero volts.

I guess i'll have to look at it on an oscilloscope once i get time.

I don't need android's internal battery stats to work with my battery, I'm already happy if the actual battery voltage gets updated, however so far i only managed to get it to update when connecting and disconnecting the charger. Is there a way to trigger/force android to read out/update the battery voltage value?


Does anyone have tips on this? I already did some googling but it's hard to find battery pinout related content inbetween all the other battery related topics.


I'm glad for any help.

 

[Septfox]

...are you sure about the screws?

The markings on the battery and the back of the ribbon cable suggest that the two center pins are +/-, leaving the two screws and thicker traces to offer a ground connection and physical rigidity.
Though if this were the case, I guess you wouldn't get any voltage off the screws at all. *shrugs*

As far as getting faster voltage readings, the Droid 4 unfortunately has a pretty "dumb" battery controller. It's quite possible that it only spits out battery stats at a fixed, non-adjustable interval. Something that might help, though: try looking up information about patching Android to give battery level in 1% increments (as the D4 originally refreshed in 10% increments). This sort of patch hasn't been relevant for years, since it's already merged into every available ROM, but the changes needed for it to work might give some insight.

Please continue publishing whatever you figure out, as you've noted, there's precious little information already available.