First post and first problem (12V Battery Short)

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lsquaredb

New member
Joined
Jun 27, 2018
Messages
2
Hi Everyone,

I bought a 2012 iMiev new, and have enjoyed looking at the forum from time to time. I finally got around to joining because I now have the first problem ever with the car. I was smelling rotten eggs on the way home tonight. I checked the 12V battery when I got home, and it was hot, smelly, and gurgling. I checked after dinner and it had cooled down and wasn't gurgling but the sides were bulging out. There are no warnings on the dash, and the car boots and drives with no difficulties. So is it just the battery is toast? In the morning, I going to check the voltages to make sure it's not a charger issue, and then try to find a replacement.

Leonard
 
Hi Leonard, and welcome to the forum.

Two things come to mind with your 12v battery problem -

1. A shorted cell within the battery, the result being the dc-dc converter pumping loads of current into the other cells trying to bring them up. Result is heat generated by the good cells as well as the shorted cell, boiling off the battery fluid.

2. The output regulator of the dc-dc converter fails to do its job and a higher voltage is being fed directly to the battery, cooking all the cells. I haven't looked at the circuit so that's speculation.

I suspect the first.

Do NOT turn on the car. That battery is toast and I would simply take it out. Measure that battery voltage with everything disconnected: if the voltage is around 11.4v then the battery has a shorted cell (unless the other cells have now been damaged). Now, attach any usable 12v lead-acid battery to those car terminals (you can use jumper cables to a battery sitting on the ground, being VERY careful to insulate all exposed wiring so as not to short anything), put a voltmeter across those terminals and turn on the car. Hopefully it goes into READY, and that battery voltage should be somewhere around 14.4v when energized. If the voltage is way higher (like well over 15vdc), that would indicate a problem with the dc-dc converter.

Hopefully, all you need to do is simply replace the 12v battery and all will be well.

Good luck.
 
Unless you noticed the lights on the car (dome, headlights) being exceptionally brighter than normal, I second a shorted cell in the 12 volt battery. Won't hurt (hopefully ;) ) to rule out proper charging voltage of around 14.4 volts while READY.

By the way, welcome.
 
Thanks everybody. The old battery was showing 8.9V. I put in a new battery, and I'm getting 14.4V at the terminals with the car switched on. The car is fine now.
 
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