Are there more details on the function of the battery and power management?

[Kellen Lundry]

What all does the power management handle?  Can it manage safely charging a lipo battery and supplying power to the board? Can it be used for projects that may have power intermittently? Like say a solar powered clock with a battery connected that charges the battery when there is sun and continues running from battery when there isn't?

[evilwulfie]

we use a BBB in a product and only use the battery to hold up the system for a safe shutdown. I can imagine
if you had a large enough battery you can get days out of it. the charger can seem to charge quite fast.

On 11/3/2017 8:32 PM, Kellen Lundry wrote:

What all does the power management handle?  Can it manage safely charging a lipo battery and supplying power to the board? Can it be used for projects that may have power intermittently? Like say a solar powered clock with a battery connected that charges the battery when there is sun and continues running from battery when there isn't?

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[William Hermans]

On Fri, Nov 3, 2017 at 8:32 PM, Kellen Lundry <klu...@gmail.com> wrote:

What all does the power management handle?  Can it manage safely charging a lipo battery and supplying power to the board? Can it be used for projects that may have power intermittently? Like say a solar powered clock with a battery connected that charges the battery when there is sun and continues running from battery when there isn't?

In short. Yes, and no.

Yes, the battery can hold the beaglebone up for a limited amount of time, while there is an "ac power" outage.

No, the beaglebone will not be fully functional if you require USB functionality at all. As USB requires 5v, and a typical lithium battery is 3.7-4.1v. So you lose USB on a power outage, and it will not come back until after a reboot. Assuming "ac power" is back when the board comes back up.

Without the debian package acpid installed, the battery functionality varies. With some versions the board will stay up, other versions the board will unceremoniously  immediately shutoff( non clean power off ). Just as if there were no battery.

Additionally, there is a PMIC register that can be toggled to keep the board from shutting down while there is a battery connected correctly through the board test points. I've tested this, and it works as expected.

As far as I can tell from my limited experimentation. You can not change the charge aspects of the PMIC, it all seems to be hard coded in the firmware. However, with that said, we've done extensive testing as far as physically checking the battery voltage, and it seems that the voltage rarely if ever goes above 4.0xx voltage. So it's pretty close to an 80% charge, where many lithium people like to keep their batteries for the most longevity.

Passed that, I probably can not talk much more about our design. However, I can say that sometimes, the board will get put into a state, where it hangs at reset. In these cases, one must disconnect the power, reconnect the power, then toggle the reset pin on the board. Otherwise the board will hang indefinitely. So, when I say disconnect power, I mean all power. DC in, and battery alike. The only way to do this automatically, is design a proper circuit, and use some form of micro-controller. That is, for locations where physical interaction could be difficult.

All the technical information you need, is in the PMIC datasheet. The rest will be learned through experimentation, and experience with using it. Including knowing how I2C in Linux is used.