integral flashlight cell charger and reverse voltage protection

Flashlight Modding and DIY Parts
1

I am working on a flashlight driver design that will include a charge capability for 1-4 cells. I am considering how to implement reverse voltage protection for improper cell insertion. All battery charging ICs I am finding do not include this as a feature the best I can tell. The cell gets connected to the BAT pin or some similar name, and the maximum reverse voltage on such pins is generally less in magnitude than –1V. A simple approach is to put a schottky diode in series, and many chips have the capability of remote sensing to allow for this.

Any other ideas here? What control chip would you recommend? I am looking for something I can hand solder. I don’t have a hot air gun and am not looking to get that complicated. I realize this may cause it to be a bit bigger due to needing to have an external switch.

2

How will the charger be able to function with a diode in series with the cell dropping voltage?

What about physical (as compared to electronic) polarity protection? Sure you sacrifice flat-top cell compatibility but it’s a whole heck of a lot easier (and usually cheaper)

3

The sense for the cell voltage comes directly off the cell. It is a separate line back into the controller.

good idea, cheaper and more efficient. I would still like to see what is out there though for an electronic solution.