Safety standard governing battery reverse current

[geekEE]

Does anyone know if there are any particular safety standards that would have something to say about the best way to avoid having a non-rechargeable battery being charged? For example, if I have a circuit that can be powered by a 9V battery or by a plug-in power supply, I want to avoid having the 9V battery being charged. A few ways come to mind, like a series diode (simple, but you lose one diode drop in voltage), a MOSFET power switching scheme, a power jack that has a switch in it, or a simple label that says something like "hey, you better pull out the battery before you plug this in or it might explode!" (ok, that's probably a bad idea).

Is there any standard that would allow or disallow certain schemes? UL? Something else?

 

[logbook]

The power jack with the switch in it is pretty standard.

Any safety standard would require the battery not to explode under the single fault of the user plugging in a charger. It is difficult to prove that the battery will not explode, even if you test 30 and none of them explode.

If you can't tolerate the series diodes as an analog OR gate, then the switched-jack is probably your only cheap option.

 

[itsmoked]

I would always reach for the jack-switch solution. It is so standard it's practically free and beats heck out of knocking perhaps hours of battery life off the battery operation.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[geekEE]

Thanks all, I was leaning toward the jack with the switch in it and it's good to see that it's common to do it that way. However, my main question was whether there was any particular safety standard that would allow or disallow particular schemes. Oh, and I forgot to mention that this is in the consumer device arena.

 

[itsmoked]

None that I have ever heard of.

Scumbag attorneys and feeling, emotional, juries should be more than enough impetuous to avoid one from treading in unknown waters for no real improvement in cost or reliability in a product.

I did work on a charger for an mp3 player (Creative Labs) and it was for Alkaline or NiCad or NiMH batteries that all could be inserted into the same compartment. This was quite a headache!! Strange pulses issued and voltage profiles and .. arghh! It was nasty. Not recommended.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com