BQ24810: Lithium battery charger

Hello Mark,

Mark Kastner said:

I'm starting a new design that will require two separate battery charging circuits.  Both circuits will be powered from 15 watt wireless receiver circuits

Are you wanting the same batttery charge for both projects?

Are you wanting a host controlled device(I2C/SMBus) or a standalone device?

What charge current are you using?

Is there a system load in this project?

Best Regards,

Christain

Hi Christian,

Thanks for responding to my post.

Both battery chargers will go into the same system on the same machine, but will be electrically isolated from one another.  The power source for each will be a matched wireless charging system (a transmitter and a receiver) similar to those used to wirelessly charge cell phones.  The transmitters are identical; the receivers are identical except that one is jumpered to produce 12 volts out (which will be the power source to charge the mult-cell lithium battery pack) and the other will be jumpered to produced 5 volts out (which will be the power source to charge the single cell lithium battery).

These should be stand alone systems (not host controlled).  When the machine is in the home position, power will be available from the wireless charging components; the battery chargers should charge the batteries at this time.

Charge current will be limited by the 15 watts available from the wireless charging components.  It may be further limited by the charge rating of the cells.  The multi-cell battery pack will be composed of (probably 3 or 4) 18650 batteries.  The single cell battery pack will likely be a LiPo battery of around 2000 mah, so the charge current will likely need to be limited to much less than the 15 watts available would otherwise dictate. 

When charging, the load on the system will be minimal.  When not charging, the single cell will power a Raspberry Pi, including bluetooth and/or wifi.  When not charging, the multi-cell cell battery will power a Raspberry Pi (again including bluetooth and/or Wifi and a stepper motor.

I'll also need a stepper motor driver, with winding currents around 1 amp.  Any suggestions in that regard are also appreciated.

Thanks for any suggestions on suitable components!

Mark

Hi Christian,

While charging single cells is relatively straightforward, my understanding is that when charging multiple series lithium cells, it is best to have integrated cell management, whereby each cell is individually managed to ensure none are overcharged or undercharged.  I don't see that function listed under the features shown on the battery charger selection page filters.  Is that no longer considered important, or are there other ways to address charge imbalance in series cells?

Thanks,

Mark