Q24 Plus Li-ion Battery Charging Problem


#1

Hi all, Im using OpenAT version 6.57g00gg with a new battery that match the specifications.
The internal charger was set with this parameter for Li-ion algoritms: “at+wbcm=3,2,1,4200,3300,4608,2111,962,500,4000,90,90,10000,80,500”

The problem is, the battery never become full charged. Its start charging when battery is close to 3.300mV and it never stops charging (keep receiving +WBCI: 2,3588)
but the voltage keeps close at 3.588mV.

The battery is connected in pin vbatt, power supply in chr_in and resistor 47k to batt_temp.

I really dont know what is happening and i will appreciate any kind of help!

Thx in advance!


#2

Hiya,

Have you set the charging algorithm to Li-Ion?

When using the Q2686, I found that you also have to enable the charging each time the module is powered on.

I do the following operations each time my module starts up (just to be sure!)

On Startup, ensure battery management system is:

  • enabled (AT+WBCM=6,1),
  • management & unsolicited responses stopped (AT+WBCM=0,0)
  • configured (AT+WBCM=4,1) & (AT+WBCM=3,…)
  • test if charger is connected (AT+WBCM=5 returns +WBCM: 5,1) then start charging (AT+WBCM=1,1) [else charging is started when charger plugged in - notified via +WBCI event
  • and then register handler to receive unsolicited +WBCI events

It’s ugly to set up this way - but until Wavecom adds a battery management API to OpenAT, the only way to do it is via repeated calls to the AT commands.

Hope this helps.

ciao, Dave


#3

Indeed - see: viewtopic.php?f=23&t=3570&p=13789&hilit=Battery+management#p13789


#4

Thx for your reply david!

About your question,

Yes, I made the following operations:

  • AT+WBCM=4,1 (set to Li-ion algorith, is necessary only once - command is save on memory)
  • AT+WBCM=3,2,1,4200,3300,4608,2111,962,500,4000,90,90,10000,80,500 (set the parameters for Li-ion algorith, is necessary only once too)
  • test if the charger is connected checking unsolicited message +AT+WBCM=4 (it is diferent from Q26, code 4 is connected and 5 disconn)
  • AT+WBCM=1,2 (init charging every time my module starts up )

The problem is, the module is charging the battery, but it keep its voltage at ~3588mV when should be 4200mV (like i set up with command at+wbcm=3,…,4200,…).

And to get worse, if i put one new already charged battery (4200mV), its voltage will get lower and lower until it reachs ~3588mV! :open_mouth: … and it happens even when the modulo is charging the battery (i keep receiving +WBCI: 2,xxxx)

Plz help, im lost!


#5

Hiya,

I’ve been using the Q2686, so things may be a little different on the Q24…

When you first power on the module, can you please get the results of AT+WBCM?. This should give the current status of the battery charging subsystem.

Also (and I know that this may be a little obvious), what is your voltage on the VCHARGE pins on the module? On the Q26xx there are separate VCHARGE and VBATT pins on the module. The Q2686 doesn’t do any step-up or step down (or current limiting) of the VCHARGE voltage - so you have to supply 4.2 volts (or whatever is appropriate for your Li-Ion cell) to VCHARGE. From your +WBCI results, it looks like you may only have a 3.6V supply on the VCHARGE pins.

Please let us know how you get on.

ciao, Dave


#6

Hi,

For Q24 module the manual says(just to be sure between the diferences from Q24 and Q26xx) that AT+WBCM? returns “Current values (depend on ChargeMode parameter);” and when i entry this command i get the return “+WBCM: 1,2,1,4200,3300,4608,2111,962,500,4000,90,90,10000,80,500”

but and the manual says that AT+WBCM=2 returns “[,]” and when i entry this command i get “+WBCI: 2,3586” (status 2 means Battery currently in charge and BattLevel means “Current battery voltage during or out of the charging”).

The external power suply is connected on the CHR_IN (that should be the same pin as VCHARGE, inst it?) and its measuring 4.2 volts :frowning:

Just to make a better view, this design is like a cell phone so the battery is connected on pin VBATT to suply the entire system.

… so im still without a clue


#7

Hiya,

Thanks for the info. It looks pretty sane to me.

I’ve got same style of design in my project (system runs off VBATT, charger on VCHARGE) as you have - so there shouldn’t be an issue there either.

Only other thing that comes to mind is the temperature monitoring of the battery via the NTC thermistor. I wonder if the charger thinks that the battery temperature is too hot and is shutting down charging? You should be able to get around this by changing the temperature ADC value in the AT+WBCM=4,xxx string.

Finally, it looks like it’s time to get onto the FAE at your distributor. They will be able to sit down with you and go over both your hardware and software to chase things down.

ciao, Dave


#8

Solved!

The problem: i was supplying CHR_IN pin with 4.2V when shoud be between 4.7V and 6V. Now im supplying with 5V and the battery is charging correctly!!! :smiley:

Thx very much for your help Dave!


#9

Hiya,

Cool. Glad I could be of some assistance. Interesting that the Q24 appears to have an internal regulator to do the battery charging while the Q26 doesn’t. It would make my life easier if it did - 4.2V is such a painful voltage to try and generate!

Thanks also for putting up your solution - another one for the FAQ (if it ever gets off the ground!).

ciao, Dave