# Circuit with 2 batteries when one has a reversed polarity

1. Jun 6, 2012

### johann1301

What happens if you take lets say a 12 volt battery and connect it to a lightbulb(not LED). Well... the lightbulb lights up obviously! But then connect a 6 voltage battery also(in series), but with reversed polarity (against the current that is). What happens then?

Will there be a shortage of some sort, or will the lightbulb give half the effect/shine half as bright? (or something else maybe??)

If the battery is connected with the same polarity, the total voltage would be 18V(12V+6V)(so I've learned). Will it in this case be 12V-6V=6V???

Thanks;) (excuse my english)

2. Jun 6, 2012

### Naty1

In practice the 12 volt battery will force current thru the smaller battery and likely ruin it in short order. Depending on the internal resistances of the batteries, heat will be generated
and damage results. NEVER do this in practice because I'm pretty sure with powerful enough batteries, like those in a typical car, fire or at least melting will occur.

http://en.wikipedia.org/wiki/Ideal_voltage_source#Ideal_voltage_sources

3. Jun 6, 2012

Thanks;)