Tapping in to a string af batteries?

Hi there.

I'm doing a little something for a toolcabin, involving some 12v LED strings, an Arduino nano and 11x 1.2v rechargeable batteries. (I know it's too many, but counting on voltageloss through wire and transistor) My quistion is: Can I just tap in, in the middke og my series wired batteries to get the voltage for my board??

Yes, you can, but it is not a good idea. Different cells will be discharged at different rates which creates lots of problems for charging the pack. It could also lead to "polarity reversal" (where some cells are discharged completely, while others are not) and this destroy cells very rapidly.

It is better to use a switching regulator on the entire pack to bring the voltage down to something the Arduino can use. Pololu has a nice selection of very small, efficient regulators. http://www.pololu.com/category/131/step-down-voltage-regulators

Ok, thanks for the quick and informable answer :slight_smile:

I think i’ll just solder it up myself, instead of buying it, then i can do it in the weekend.
I live in Sweden so it’s a bit of a way for such a little thing.

Thanks again :slight_smile:

Pady: Can I just tap in, in the middle of my series wired batteries to get the voltage for my board??

Yes, because the Arduino power consumption will be a lot less than the LEDs.

PS: Monitor the battery voltage and shutdown the LEDs when you're getting close to fully discharged.