Can a battery change its polarity?

[Noddy]

I have a battery that was given to me. When i tested it, it dimley lit a light so thought i would try charging it. When i put it on the charger the reverse polarity light came on. i checked the leads and they were on the correct way. i put my battery tester on and it gave no voltage untill i put the leads on the wrong way then it read 5v.

So is it possible that a battery can change its polarity???

 

[Davren]

Yes.... if the battery has gone flat and then charged with the positive and negative leads reversed, it will adopt a reverse charge.

 

[Most Easterly Pandas]

Yes.... if the battery has gone flat and then charged with the positive and negative leads reversed, it will adopt a reverse charge.

Never knew that. I assume it'd also ruin the battery. No chance of making it go flat, re-charge it, and it being useable again

 

[Davren]

If you kept it reverse charged for very long, then yes it would ruin it. But........

There's a theory that if you flatten a lead/acid battery then reverse charge it then flatten it again and charge it correctly. Some of the lead sulphate that contaminates the plates will be dissolved back into sulphuric acid and increase the performance/lifetime of the battery.

Never tried it so don't know if the theory works.

 

[Noddy]

well will have to give it a try!!!!

 

[EI4GGB]

never seen that happen, but I have seen a battery with incorrect poles and markings fitted.. it was working ok only the poles had to be swapped around (this was on a tractor with DIY replacement battery clamps)

 

[Most Easterly Pandas]

never seen that happen, but I have seen a battery with incorrect poles and markings fitted.. it was working ok only the poles had to be swapped around (this was on a tractor with DIY replacement battery clamps)

Didn't think that perhaps the polarity on the battery had changed

 

[sludgeguts]

In days gone by (and even I cannot remember this far back!), your electricity payment was determined by a chap coming into your house and removing the plates from a suspension. As charge flows from Positive to Negative so it would take metal with it (the process behind electro-plating). It was known that a given amount of electricity would move a certain amount of metal from one plate and deposit it on the other and so payment could be calculated.

Of course, the more 'canny' householder quickly caught on to this process and would swap the plates around mid term - thus getting free leccy for a while.