07-30-2020, 06:48 AM
(This post was last modified: 04-12-2021, 02:45 AM by dsimic.
Edit Reason: Wording cleanup
)
Hello,
I've been poking around PineBook Pro for some time, and one of the issues is the battery charging current, which is way too low at slightly under 3 A at 5 V. It even gets ridiculous, e.g. the battery pretty much never charges back to 100% once you try to recharge it from an empty state while still using the PBP. Not to mention that the battery discharges when running higher CPU loads, which is both ridiculous and very bad for the battery life.
So, I took some time to investigate the PBP's wiring diagrams, trying to isolate the culprit. In a few words, the good news is that everything points into that increasing the max. battery charge current should be a relatively easy mod. It could even be incorporated into the next revision of the main PCB. The bad news is that a mod like that must be discussed first.
The PBP's battery can easily take up around 5A during the constant-current part of the charge cycle, which is according to its data sheet. The PBP's battery charger IC is configured to think that the system current is always zero, which means that only the max. charge current needs to be tweaked; again, this is according to its data sheet, page 17 in particular. The PBP wiring diagram, page 11 in particular, shows the way the BQ24171 IC is configured, as already described.
In a few words, increasing the battery charging current to 4A would be pretty simple; all that's required is to replace the R44, R45, R47 and R48 SMD resistors, so their values configure the BQ24171 IC to take 4A from the charger (IACSET) and output 4A (ISET) as the battery fast-charge current. Of course, any chargers providing less than 3A could not be used any more, which would render the factory-provided barrel-type charger useless; however, I don't think anyone would complain.
I cannot see anything that would prevent this mod from being successful. The PCB traces designed for 3A can easily handle 4A, which isn't a huge increase of the current. Maybe the F1 fuse would also need to be replaced, but I don't know that for sure because its max. current isn't available from the wiring diagram.
Thoughts?
I've been poking around PineBook Pro for some time, and one of the issues is the battery charging current, which is way too low at slightly under 3 A at 5 V. It even gets ridiculous, e.g. the battery pretty much never charges back to 100% once you try to recharge it from an empty state while still using the PBP. Not to mention that the battery discharges when running higher CPU loads, which is both ridiculous and very bad for the battery life.
So, I took some time to investigate the PBP's wiring diagrams, trying to isolate the culprit. In a few words, the good news is that everything points into that increasing the max. battery charge current should be a relatively easy mod. It could even be incorporated into the next revision of the main PCB. The bad news is that a mod like that must be discussed first.
The PBP's battery can easily take up around 5A during the constant-current part of the charge cycle, which is according to its data sheet. The PBP's battery charger IC is configured to think that the system current is always zero, which means that only the max. charge current needs to be tweaked; again, this is according to its data sheet, page 17 in particular. The PBP wiring diagram, page 11 in particular, shows the way the BQ24171 IC is configured, as already described.
In a few words, increasing the battery charging current to 4A would be pretty simple; all that's required is to replace the R44, R45, R47 and R48 SMD resistors, so their values configure the BQ24171 IC to take 4A from the charger (IACSET) and output 4A (ISET) as the battery fast-charge current. Of course, any chargers providing less than 3A could not be used any more, which would render the factory-provided barrel-type charger useless; however, I don't think anyone would complain.
I cannot see anything that would prevent this mod from being successful. The PCB traces designed for 3A can easily handle 4A, which isn't a huge increase of the current. Maybe the F1 fuse would also need to be replaced, but I don't know that for sure because its max. current isn't available from the wiring diagram.
Thoughts?
