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Topic: [Q] Help needed to choose proper power source / battery. (Read 829 times) previous topic - next topic

xlm13x

Hello everyone.

I am building GPS vehicle tracker using Arduino Uno and this SIM 908 shield.

Usually I use 9v batteries as a power supply for Arduino (I live in a very small village and getting electronics stuff here is really very difficult) but I am facing problem with this one.

I assembled the shield with board and tried to power it with regular 9v battery but it seems like the shield is not getting enough power and it did not worked well so I contacted the seller and they told me to use 2A power supply.

Now the issue is I am not having any 2A power supply with me and as I said it is not easy for me to get it. Is there any alternative way I can power the device with 2A supply. Can I use couple of regular 9v batteries connected in parallel to power it up? How many number of batteries will be needed to power the device and about how long the device will run on that supply?

Kindly help me with this one. Thanks.  :)

ieee488

You should contact the manufacturer *not* the seller to find out the maximum current draw for the shield.

More about SIMCom SIM908
Please contact:
Tel: 86-21-32523300
Fax: 86-21-32523200
Email: simcom@sim.com
Website: www.sim.com/wm

DrAzzy

9v batteries are *terrible* for current output, just awful. Wifi, GPS, and cell communications will typically involve peak current in the hundreds of mA; I wouldn't expect that to work on a 9v battery. 

If you're using it in the car, power it from a car cellphone charger - those are available in 2A size.

Otherwise, I'd use it with 6 AA batteries in series.
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xlm13x

You should contact the manufacturer *not* the seller to find out the maximum current draw for the shield.

More about SIMCom SIM908
Please contact:
Tel: 86-21-32523300
Fax: 86-21-32523200
Email: simcom@sim.com
Website: www.sim.com/wm
Sorry for mistake, actually I contacted the manufactures (and yeah, they do sell their shields) which is libelium and they informed me that regular 9v batteries cannot give 2A peaks so they suggested me to use 2A power source.


9v batteries are *terrible* for current output, just awful. Wifi, GPS, and cell communications will typically involve peak current in the hundreds of mA; I wouldn't expect that to work.

Use 6 AA batteries in series instead if you need 9v (you could use 4, except that the regulator on the Uno has fairly high dropout, and can't provide 5v off 6v input :-( ), or if you're using it in the car, power it from a car cellphone charger.
According to details provided by shield manufacturer it will need up to 2A peaks. I think you did not get my question. My question is I need to power my device with 2A power source. I do not have any alternative power source. I am having couple of 9v batteries with me. Is it possible that I connect them in parallel and can get higher current peaks with them? If it is possible how many of 9v batteries are needed to be connected in parallel?

jremington

Using 9V batteries is a complete waste of time. Even if you put enough in parallel to power the GSM module, they would be very quickly exhausted. Find another power source, or another project.

xlm13x

Using 9V batteries is a complete waste of time. Even if you put enough in parallel to power the GSM module, they would be very quickly exhausted. Find another power source, or another project.
Kindly suggest me some other power source which will be able to provide 2A peaks.

jremington

AA rechargeable, C or D rechargeable or alkaline batteries, automobile 12V with noise reducing adapter, any lead acid battery. AA alkaline batteries will provide 2 A only when fresh.

If this is to be a vehicle tracker and must be battery powered, the battery capacity should be sufficient for double the expected run time.

xlm13x

AA rechargeable, C or D rechargeable or alkaline batteries, automobile 12V with noise reducing adapter, any lead acid battery.

AA alkaline batteries will provide 2 A only when fresh.
Thanks for the information. I can arrange 12v vehicle battery. You said noise reducing adapter will be needed, can you tell me what it is and where do I get it or how to make it?

xlm13x

If this is to be a vehicle tracker and must be battery powered, the battery capacity should be sufficient for double the expected run time.
Yes sir, it will be a vehicle tracker.

jremington

If the vehicle battery is isolated, you don't need a noise reducing adapter but you may need a voltage regulator. A fully charged lead acid battery can produce over 14V which is outside the range of some Arduino compatible circuitry.

If connected to an automotive power source, then while the engine is running there can be spikes of several hundred volts from wiring faults and the ignition circuitry. These can instantly destroy unprotected electronics. Most "cigarette lighter" power adapters have such protection circuitry built in and this would be the easiest way to go. There are lots of DIY automotive noise filter circuits on line.

xlm13x

If the vehicle battery is isolated, you don't need a noise reducing adapter but you may need a voltage regulator. A fully charged lead acid battery can produce over 14V which is outside the range of some Arduino compatible circuitry.

If connected to an automotive power source, then while the engine is running there can be spikes of several hundred volts from wiring faults and the ignition circuitry. These can instantly destroy unprotected electronics. Most "cigarette lighter" power adapters have such protection circuitry built in and this would be the easiest way to go. There are lots of DIY automotive noise filter circuits on line.
Thanks for the information.

Currently I am just building this thing and right now I want to test that the device I built is running or not. Right now I am not going to install this device in a car. So I will be using isolated battery for right now and if the device is working successfully then I will work on integrating it with car.


As you said it may produce up to 14v which can damage the circuit. So can I use LM7805 to control the voltages?

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