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Discussion Starter #1 (Edited)
As many of you know, there may be a connection between your 12v battery going bad and your HV battery "bricking."

If you have one of our battery test units or another unit, there is a way to get a reading from your 12v battery. However, to get an accurate reading, you want the car to have not been used for several hours (overnight is good) and you want to take the reading with the contactor to the HV battery being off. In order to do this, you do not turn the key to the "ON" position. Just hook up your test unit and press the door lock or unlock button. This will light up the instrument cluster and the "P" on the shift mechanism. Then you take your reading as usual and as you can see in my example below, your HV numbers will be zero and you will get a message that the contactor is "OFF." Probably anything under 12.5v might indicate it's time for a new 12v battery.

And, yes, I will follow my own advise and replace my battery very soon. :)

SOC : 80.5 %, realSOC: 78.7 %
HV : 366.3 V, 0.00 A, 0.00 kW
LV : 12.2 V

-----------------------------------------
CV mean : 3937 mV, dV = 21 mV
CV min : 3919 mV
CV max : 3940 mV
OCVtimer: 1338 s
-----------------------------------------
Last measurement : 5 day(s)
Measurement estimation: 0.713
Actual estimation : 0.609
CAP mean: 18446 As/10, 51.2 Ah
CAP min : 17638 As/10, 49.0 Ah
CAP max : 17897 As/10, 49.7 Ah
-----------------------------------------
HV contactor state OFF, for: 45885 s
Cycles left : 294381
of max. cycles: 300000
DC isolation : 37501 kOhm, OK

Len
2014 EV Coupe 20,000 miles - results from it above
2014 EV Cabriolet 17,500 miles
 

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Super Moderator
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1,516 Posts
Discussion Starter #3
New battery - 12.6v with the test unit. 12.75v with a hand held multimeter. But interestingly enough, when I put the old battery on the bench and tested it with the multimeter, it read at 12.73v. Could I have squeezed more time out of the old original battery - probably, but after six years, I sleep better at night knowing that there's a new battery in there.

Len
2014 EV Coupe 20,000 miles - results from it above
2014 EV Cabriolet 17,500 miles
 
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