Powering GSM phone without battery

[traxonja]

use phone without battery

How to power the GSM phone (Siemens S25 in my case) in car without using it's battery?

I have this stupit problem I'll try to explain. When using RS232 serial communication with this phone while it's connected to it's battery charger it turns OFF when fully charged and after any AT command is sent to it! So, I need a phone that would be in my car allways ON and it will be communicating with PIC microcontroller when allarm triggers for example.

Anybody has some ideas? There is a solution though, to disconnect the charger and re-connect it before sending any AT commands (also disconnecting serial connection)... That's not possible as the hardware device is allready finalized and everything connected. The only solution is maybe to use external, stabilised power at, let's say, 3,9V able to give 1 Amp?

Please help...

Best regards,
Trax

 

[gidimiz]

c35 autoignition

Hi,

I have an exstansive experiance with mobile phone, but for the embbeded world. Can you use another phone? or you want to use the S25?

If you want to use the S25, then here is a link with good information on the phone and maybe you will find your answers there:
https://www.exit99.cz/s25/english/support_en.html

Also, do a search in google for: Siemens S25 "at command" and see the links that you get.
Good luck.

 

[traxonja]

poweing a phone without battery

Thanks for the reply.

It doesn't need to be S25, it could be C35 for example...

All I need from the phone is that it supports standard serial rs232 communication at 19200 bauds (like siemens does), (could also be 9600...) and support for AT command modem inside. In this case I will use only ATDT+blabla; command, and some initialization AT commands. I've developed a small "GSM Call Alarm" and have put it in my car. The problem is that some phones goto shutdown after: the battery has been fully charged and then you try to send it some data over serial cable and it CRASHes :-(

I've connected it to the car mobile phone charger all the time (not very good for the battery - I know) but it shuts down once in a while...

You can see it here: https://www.elektronika.ba/projekti/?akc=daj_projekt&idprojekt=5


Best regards,
Trax

www.elektronika.ba

 

[jojokatada]

powering the phone without battery

the link is nice but not in english language

 

[misley]

c35 siemens autoignition

Site is in bosnian/serbian/croatian...(check what you want, all three languages are the same!!). If you need some explanations about translating few sentences, just PM-me!

 

[gidimiz]

gsm phone commands *#06#

Hi,

Today you can find everything on the web and on google!
Here is some info that can help:

Hi everybody!
I have a few C35 and A50 that shuts down when they get fully charged and the charger stays connected.
I found out that the level on the middle connector on the battery was weird even though the battery was new.

I tried to upgrade with newer firmware but no success...

Solution: Put a small piece of tape over the middle connector on the battery so this is isolated.
It works perfekt!!!

From what i read on the net, no one has the problem of the AT COMMAND that you are having. What they do say that you need to use 19200 baud only.
If you are still having problems ( after you did a search in google ), post the schamatic that you are using, and i will have a look at it.
Good luck.

 

[Zedman]

how to use a phone without the battery

I don't know if it's useful or not,
but some cables using this (called
auto ignition) to turn on the C35.

(pin 3 is charging voltage input)

Zed

 

[mitesh]

turn on gsm without battery

U can use bulkboost Low drop regulators for it. Such as MIC2941 for 3.7 to 4 volts with atleast 1.5 Amps.

 

[bobcat1]

buck/boost gsm

Hi all

I have designed supply circuit for powering GSM modem from in car battery

1) You will need to add a circuit who will block iginition spinks to the electronics
2) The supply should be of switching type 13.8V +/-10%{input} 3.3V 250 mA{output} with capability of driveing current pulses up to 2A {GSM trnsmitting using pulse methode}

All the best

Bobi

 

[kuldeep]

powering the phone without battery

LM2576 and LM2576 are the buck-boost regulators typically used for such requirements.

You can find related datasheets on net and design the supply using few external components.

Added after 17 minutes:

LM2576 datasheet

 

[AVR_Luciano]

phone without battery

See these links.
**broken link removed**
**broken link removed**

Luciano