battery backup for vehicle tracking system

[bikashh]

Dear friends,
I want to integrate battery backup with my vehicle tracking system. Does anybody have ever worked in this project.please share your experience...Also is Li-Ion is better than Ni-Cd battery in such systems as a backup supply.
the battery backup should be of atleast 2hrs.

thanks in advance.

 

[andre_luis]

bikashh

I already worked with alarm system.
However, the other battery was not used like backup, but stand alone, receiving a soft charge became from the main battery, just by 2 power diodes.

You did not specified power consumption , but just autonomy required.
I used a motorcycle battery ( 7,2Ah - 12V ) that is easy to buy in every place.

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[bikashh]

But if i use any other type of battery other than Li-Ion, voltage won't be stable which is quite important for a GSM/GPS module.

I've designed a Li-Ion battery charger circuit around MAX1811.Can i use this charger to charge 3 Li-Ion battery?

thanks for the reply

 

[andre_luis]

bikashh


I never worked w/ that IC.

Note that a motivation I decided to use the automotive battery was the possibility to use the same vehicle charger circuitry.
In fact, the main battery loads the alamr battery, across 2 series diodes.

The voltage curve of lead-acid battery is well known, and it is easy to determine charge status.

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