Battery charger in uC system

[togarha]

Hi!

I want to add a battery charger to a battery managed system. It has 4 Ni-MH (or Ni-Cd) batteries in series (to provide 4.8V) and downloaded to 3.3V with a LDO linear regulator.

I want to add a battery charger to charge the 4 batteries if I connect the system to an external 12Vdc power.

The problem is that I can use Ni-Mh or Ni-Cd or Alkaline batteries, then if I add the charger I can have inside the system Alkaline batteries connected to the charger. There is any charger controller that avoid the problem to have Alkaline batteries connected to it?

Thanks in advance,

Regards,

 

[ldanielrosa]

First off, in a battery powered application I try to aviod using voltage regulators or anything that requires them- though sometimes it's unavoidable.

If you can run at least one microcontroller unregulated, then you can use one analog input to measure an LED. The higher the reading the lower the voltage- whether you use an arithmetic subroutine or a lookup table is not critical.

Tracking the battery voltage during discharge will give some indication of the chemistry- e.g. anything over 5V76 is a primary. Beyond that all nickel batteries will look similar, only the duration of the charge will tell you whether it had cadmium or hydrogen. You could also implement a test discharge to determine the internal impedance, but that would not guarantee accurate results.

Yes I'm sure I've seen a charger controller that could recognize an alkaline primary, but I don't think I've seen one that can manage NiMH and NaCd as well

 

[nandhu015]

Hai

Here I found a battery charger material

http://www.atmel.com/dyn/resources/prod_documents/doc1659.pdf

Hope this helps you

Nandhu

 

[imanjl]

Pay attention that Ni-mh batteries have 1.2V when they are discharge so if u charge a regular ni-mh battery its voltage reaches to 1.4 v and when u have 4 number of them total voltage of the unit become 5.6V .
Standard voltage for alkaline batteries is 1.5v .So total volatge of the four part of them become 6V .

With a simple voltage compratore u can detect whether the battries are Alkalin or Ni-mh cause 5.6V and 6V can easily be detected .