GSM module, lock up due to battery?

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#1
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Hi All

 

I would like to know if someone has had similar issue to what i am experiencing.

 

I am using the Quectel BG95/96.  The module is powered with Li-poly batter 3.7-4.2V 2000mAh.

 

There has been few times, when the device has locked up where it id no longer functional,  to get it back to normal i need to remove the battery.

 

Resting the module or powering up/down the module does not work, therefore the only option is removing the battery and re inserting it.

 

 

Has anyone else experienced such issues?

 

 

I am thinking that this could be due to my battery capacity?

 

The modules do have a peak current of 2A, therefore i am thinking even thou the batteries can output more then 2A for short periods, there could be a possibility there could be a short voltage drop below the min requirement of the module, causing it to lock up.

 

Could this be possible?

 

What battery capacity would be recommended to use?

 

 

 

 

 

 

 

 

Thanks

Regards

DJ

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The bg96 has had a number of software issues. Ensure you have the latest update.
How do you know the module is locking up? How much current does it draw when in this state?
I used a 150mAHbattery. I got over 2 days of runtime on a charge.
I’m assuming you have the recommended capacitors mounted close to the unit? The capacitor spec is rather critical here.

Last Edited: Sun. Jul 12, 2020 - 01:56 PM
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Hi

 

Thank You

 

When i say module is locking up, i mean that even after pulsing the PWR KEY  or RST PIN, the device does not seems operate. 

 

My application would preforming as it should and all of sudden no AT commands would be acknowledged. Therefore my application would try re power cycle the module and preform a reset. And it would fail , as no AT commands would work still. This would happen till battery is removed and re attached.

 

I am following the hardware guide lines, in regards to CAPs, and using the follow Tant Cap

https://www.mouser.co.uk/datasheet/2/40/taj-776811.pdf

 

During the lock up, the current draw is low, 20mAm but this my XMEGA and other circuit is also functional. 

 

Yes, at times, by device have been working for over fews months. But then there is this hang up. so i am thinking it could be the battery.

 

What would happen if voltage of the battery was to drop below 3.3?

 

 

 

 

 

 

Thanks

Regards

DJ

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Speak to Quectel. Their support is surprising good.

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Yes it is, they are also looking into it.

 

I was just wondering if anyone else has had the same issue.

 

Thanks

Thanks

Regards

DJ

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Sure - i’ve had bg96’s lockup in the field - even when powered via a psu. I’ve even had them lose their application code - two of them at similar times in different parts of a building.

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Did you find the reason why?

Thanks

Regards

DJ

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Just out of curiosity the PSU must have created 5V, but 4.2V power supply for the module, what was the max current on that supply rail?

Thanks

Regards

DJ

Last Edited: Sun. Jul 12, 2020 - 03:43 PM
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djoshi wrote:
The modules do have a peak current of 2A, therefore i am thinking even thou the batteries can output more then 2A for short periods, there could be a possibility there could be a short voltage drop below the min requirement of the module, causing it to lock up.

 

Could this be possible?

Absolutely.

 

This is a very common problem in any sort of radio transmitter system!

 

Getting your power supply & routing correct - with good, solid supply & ground - is critical.

 

djoshi wrote:
What battery capacity would be recommended to use?

Raw capacity is not the issue here.

 

The issue is maintaining a solid supply through the peaks - as mentioned above.

 

The module manufacturer should have guidelines on power supply design.

 

What measures do you have in place to determine when the battery has insufficient charge remaining to power the transmitter?

 

EDIT

 

djoshi wrote:
Resting (sic?) the module or powering up/down the module does not work, therefore the only option is removing the battery and re inserting it.

* Resetting ?

 

So what is the difference between "powering up/down the module" and removing the battery ?

 

What else is in the system other than the cellular module? Could that be what's "locking-up" ... ?

 

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Last Edited: Mon. Jul 13, 2020 - 09:27 AM
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Hi

 

Thank You for the reply.

 

Yes, I am following the guidelines. 

 

At the moment, there batteries are getting constant charge . The batteries are there as some form of back up. So there setup is

 

AC/DC--> LiPoly Charger--> LiPoly Battery-->GSM Module

 

 

The power up/down is when my XMEGA is pulsing the PWRKEY of the module. I am note sure what the difference is , but removing the battery seems to get it back to normal.

 

I can confirm my XMEGA is not the issue. As if  i was to erase the flash in XMEGA, and then physical control PWRKEY(apply 3.3.v to the transistor), there is still no response.

 

Quectel support has mentioned that the module seems to be going to into it boot loader mode, i am waiting for there reply on how to get out it using AT commands.

 

 

Thanks

Regards

DJ

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Did I ever find out what caused it? Nope. I left the company. I got to the point where I'd identified that the application had been corrupted as the module defaulted to its bootloader. I was able to reload the application and the modules were operating again.

 

As for the power supply, I used a 3A linear LDO regulator. Since i was running NBIoT, the current peaks were nowhere near 2A. Nevertheless, the current consumption of these modules is very dynamic - going from a couple uA to 100's of mA's. I used a microchip pac1934 to measure and integrate the power usage as I was interested on the overall power consumption.

 

As Andy mentions, layout for these modules is critical. If you're not careful the RF gets into everything and unless you have some expensive test instruments, you're not going to see it. Grounding and guard rails are very necessary as the pcb acts as a waveguide. Go crazy on those vias!

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djoshi wrote:
The module is powered with Li-poly batter 3.7-4.2V 2000mAh.
Another topic I suppose, but I'm glad to see 4.2 volts.

 

The stupid smart phones I've checked charge to 4.35 volts and there seems to be no way to change that except rooting.  They are smart as seen by the manufacturers but they aren't smart as seen by me.

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Yes. the batteries we are are using are 4.2V.

 

Are the batteries on your phone rated to 4.3V?

 

 

Thanks

Regards

DJ

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I don't know the rated voltage.  I thought the li-on cells are all alike.  The higher the voltage, the more the charge, and the quicker they lose capacity.  I've read that some industrial chargers charge to 4.1 or lower to increase the life of the cell.  But I'm not an expert.

 

I have several chargers at home for charging the cylindrical cells, like 18650.  They all stop at 4.20.  When I saw my cell phone cells at 4.35 volts I was surprised and not happy.  Maybe the cell phone li-on cells are different and can take a higher charge without damage. 

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What cell phone is it? It could be a custom battery

Thanks

Regards

DJ

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Yes, I just got educated.  In the fine print of that battery, it says Charge voltage 4.4 so actual charge of 4.35 is okay.     Then I looked at the battery in my flip phone.  It says Rating voltage 4.2 - 3.7 and it charges to 4.12 .    So my phones are charging correctly.