I just tested my battery over the weekend. The reading is at +12.30V, but the status indicator on the battery is still showing green. My battery is about 7 years old now. Is it time for a new battery?

 

My 5 year old battery is of the same status. I will replace it when it displays the first signs of impending doom..

 

Your battery may be living on borrowed time. The newer batteries don't seem to give as much early warning (such as gradually slower cranking) as batteries did a few decades ago, and they never seem to go belly up at a very convenient time. Do you feel lucky?

 

The battery in my 2003S (delivered in Oct. '02) is still working fine, so I'm going to let it hang on until it croaks. Of course, now that I've written this it'll probably be dead when I go out after work!

 

Knock on wood BRGPA

 

The newer batteries don't seem to give as much early warning (such as gradually slower cranking) as batteries did a few decades ago,

I agree 110%. Not sure if is that the battery dies faster or that new cars want full 12 volts and plenty of amps or they just don't go ... modern electronics are not happy with anything short of what they expect. We've seen posts here of folks with wierd electrical things happening in their MINI with a battery that was old but "tested good." And usually once they bite the bullet and spring for a new battery - problems solved. In any case I replace my batteries at 5 years now after having a couple die b4 year 6 . . . and not just in my MINI.

 

That green eye only shows the condition of one cell. It is possible to have a battery with a happy green & a dieing battery. I've always chosen to change batterys before they strand me.

 

BRGPA: Nice going! Hope it goes for another 8.5 years.

 

advice taken. I just picked up a Napa Legend 75 month (BAT 7547) battery. This battery turns out to be a vented battery as well, but the vent hole on the battery is on the front (between the postive and negative terminal). Hopefully, the stock vent tube will be able to reach.

 

A good battery should not drop below about 9.5 volts while cranking for up to 15 seconds (at 60-70F, about 9.0 at 32F),
and should bounce back to about 12.4 volts (car off) or more after that challenge.
If it's much below those figures, it's gonna go sooner than later.
This may be a good time to replace that 7 year old battery.

 

If any other MBUSA alum are on this list, they might remember the late Frank King, Technical Editor for MBUSA and STAR magazine. I recall a wonderful quote from him in an article on diesels, "A lifetime warranty on your 6 year old plus battery won't start your car on a cold winter morning." I try to keep this I mind when considering when batteries are ready to go.

HTH

 

So this morning as I'm about to take my old battery back to get the core refund from Napa, i thought i'll just test the voltage again after it's been sitting in the garage for 3 days. It read +12.7V now, vs. +12.3V when it was connected to the MINI. Weird. I didn't know there would be a voltage difference on the battery when it is disconnected.