Hi all. We created a small device that is powered by 4 AA (alkaline) batteries (rechargeable will work, but not relevant here). We are applying for CE certification in Europe and we were told by the CE regulatory agency that we need to have some kind of reverse-polarity protection, since it’s possible to insert one or more of the batteries backwards. But we can’t find any hardware that will do the trick. Ideally we’re looking for a battery holder (or add-on clips) that physically prevents a battery from getting installed the wrong way. Anyone have any suggestions or leads?
Thanks,
LauraS
Well here is our holders https://www.digikey.com/en/products/filter/battery-holders-clips-contacts/86?s=N4IgjCBcoMwExVAYygMwIYBsDOBTANCAPZQDaIMADAGwAc8IhVArAOzMAsIAuoQA4AXKCADKAgE4BLAHYBzEAF8m1RCBSQMOAsTIg4lGGGqse-IZFESZ8peACctO6vWa8hEpHKVTIQcLFScoqEALQI0GpQEgCu2h7kzDwKtuHkAEIAggAqWQCiAEoAmgAEABIA8gAyACIFxRkZSUA
but I would suggest using a diode to address the issue for protection as I have seen people ( kids ) that manage to cram in batteries incorrectly.
AA batteries don’t lend themselves very well to mechanical reverse-polarity protection; I’m not sure I’ve seen any implementation that worked.
Diodes for reverse polarity protection are an option, but the voltage drop that comes with it is significant particularly in low-voltage battery applications. An alternative approach involves use of a FET instead; connecting a P-channel FET in series with the positive supply lead with gate to negative supply causes the FET to turn on when the supply has the proper polarity, and turn off when it’s reversed. A few (dozen?) mOhm of resistance will yield lower conduction losses than a diode drop in most low-power applications.