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What is your 12 volt battery voltage?


ArizonaEnergi
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What Is Your 12 Volt Battery Reading?  

15 members have voted

  1. 1. Select your car's voltage

    • Greater than 12.6
      1
    • 12.6
      1
    • 12.5
      0
    • 12.4
      5
    • 12.3
      1
    • 12.2
      2
    • 12.1
      1
    • Less than 12.1
      3
    • Unknown - I have no way to measure it
      1


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I think it would be useful to know what everyone's 12 volt battery voltage is after the car has not been run for awhile, such as first thing in the morning or several hours after using it.  I am seeing 12.4, which is below the optimum of 12.6, but perhaps it's somewhat normal for the C-Max?  Let's find out!

 

General instructions (open to refining)

1.  Measure before driving the car, or several hours after driving it to eliminate the charging impact.

2.  Measure from one of the 12-volt outlets, or the jumping connections under the hood.

3.  If measuring inside the car, allow the various circuits and light that are activated by opening the door to go off before recording the voltage.

4.  If measuring under the hood, leave it unlatched the night before to get access without triggering the interior circuits.

Edited by ArizonaEnergi
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I think it would be useful to know what everyone's 12 volt battery voltage is after the car has not been run for awhile, such as first thing in the morning or several hours after using it.  I am seeing 12.4, which is below the optimum of 12.6, but perhaps it's somewhat normal for the C-Max?  Let's find out!

 

General instructions (open to refining)

1.  Measure before driving the car, or several hours after driving it to eliminate the charging impact.

2.  Measure from one of the 12-volt outlets, or the jumping connections under the hood.

3.  If measuring inside, allow the various circuits and light that are activated bt opening the door to go off before recording the voltage.

 

3. " If measuring inside" leave the hood up at night to take the measurment at the "jumping connections under the hood."

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I've seen 12.8 after a trip, and typically lose .1 volts per day...my VOM range skips from 2v to 200v so I cannot get a more refined number.  Also, owner's manual (page 312 of first printing) suggests the following if storing the vehicle for more than 30 days, which would indicate there is a voltage drain greater than a typical vehicle:

Engine
• The engine oil and filter should be changed prior to storage, as used
engine oil contain contaminates that may cause engine damage.
• Start the engine every 15 days. Run at fast idle until it reaches normal
operating temperature.
• With your foot on the brake, shift through all the gears while the
engine is running.

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  • 2 weeks later...

I have been logging the battery voltage for 9 days with a Lascar EL-USB-3 Voltage USB Data Logger

 

I measured the voltage by wiring a 12 volt plug to the logger and plugging it into the rear luggage compartment power outlet socket.

The rear power outlet is always hot making it easy to monitor and log the 12 volt battery voltage.

The voltage was logged every 60 seconds for the 9 day period. 

 

The first graph is the voltage log with the cursor showing the voltage on 3/31.  (12.75 volts)

 

C Max Voltage 13 03 31

 

The second graph is the same voltage log with the cursor showing the voltage on 4/8/13. (12.55 volts)

 

C Max Voltage 13 04 08

 

The voltage peaks are when the car is being driven and the voltage is above 14.5 V charging the battery.

The chart shows charging a total of 50-60 minutes a day but does not appear to be enough to maintain a fully charged battery.

 

The "at-rest" voltage shows a definite decline over the 9 day period.

There does not seem to be a significant drain on the battery 30-40 minutes after the car is shut down.

 

So in my case, it appears that the battery is not getting charged enough during normal driving.

 

If there are any Ford engineers lurking, send me a PM and I can send the log file in Excel.

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An interesting thing to see is what happens when I turn on my blinkers.  There is not so much a swing in voltages as there was before. I think the converter is able to compensate and let more charge out.

 

I should add that I believe the new software is doing much more than fixing the issue decribed in TSB 12-11-8, but the mere mention of that should be enough to get the dealer to update your software.

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The full Hybrid model does not have the smaller orange-covered cables (between the red arrows in above photo), but the positive and negative posts appear to be the same.

When you say "full hybrid" I assume you are referring to the regular C-Max as opposed to the Energi. In that case the C-Max does not have the orange cables?

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I am too lazy to keep a log of voltages, but after a week of doing nothing but commuting my charge levels are much better than I remember. I am no longer in the frightening 12.0 range by the end of the week and recorded a 12.45 after getting to work this morning.

 

he short three mile commute I make is doing a much better job of re-charging the battery.  There is still a .2V decline when letting the car sit, but the improvement appear to be in the ability of the car to charge, I regain at least .15 V whereas before it was .1V which left the battery rather depleted at the end of the week.

 

My personal guess as to the total dead battery problem is that at some lower system voltage they relays don't work properly leaving one of them open to completely drain the battery.  I'm glad to be not operating close to that range anymore.

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  • 4 weeks later...

The just found this thread this morning.  ...Interesting information.  Until I had a dead battery this weekend I didn't pay much attention to this problem.  Now I'm logging the voltages and trying to see what caused the problem.  Our car never sits more than overnight, and if I measure the voltage in the evening, it hasn't dropped more than .3 volts by morning.  The car is going to the dealer this morning, and I'll make sure to tell them about the TSB.  I noticed the evening before my battery problem that the level 2 charger was still running after 5 hours, so I shut it down.  Perhaps a stuck relay?  I wish I had measured the voltage then.  A bit ironic that leaving the charger running possibly caused my battery to drain. 

 

I couldn't honestly answer the poll, since I'm reading different voltages almost every time I check.  I have seen 12.2 - 13.1 volts.  Before charging I usually see 12.2 - 12.6 though. 

 

...Car is back from the dealer.  They load tested the battery, and updated the firmware to keep some module from draining the battery when the car is parked.  When my wife drove it home (about 3 miles) and plugged it in, it wouldn't charge until she turned on the ignition. 

Edited by 67gtcougar
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Measured mine this morning, after driving around yesterday and seeing a 13.8v-14.5v charging voltage.  The voltage today went from 12.2, to 11.9, to 12.1, and finally, after about three minutes, settled at 12.5v.  A fully charged battery should have a reading of 12.6v, so this is very close.  I had the DCDC charging software update TSB 13-5-1 done a week ago and it appears to have improved my battery status, so at this point I think I can rely on the battery to start the car pending further developments (stuck relays, water in connections, worn wires, on and on).

Edited by ArizonaEnergi
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Mine is 12.67

 

I last drove it at about 11am and this is reporting at 5pm, so about 6 hours it sat.  This is under the hood using jump points.

 

I'll post again tonight when it has sat longer.

 

I have a November build date and I have not had TSB 13-5-1 applied.

 

I should also say that I haven't had any electrical problems.

Edited by zhackwyatt
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We went car camping over the weekend.  Opening and closing the hatch and doors several times really took its toll on the voltage.  It was down to 11.7 volts the first night, so I turned the car on to give it a short charge.  I kept about 5 miles range on the lithium battery, so I didn't have to start the ICE.  Too bad Ford doesn't let us disable the lights, especially with the small 12 volt battery.  Since the trip to the dealer I haven't seen voltages higher than about 12.5, and usually they are closer to 12.2 after the car has sat for awhile. 

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Over the night, it was 12.57.

 

We went car camping over the weekend.  Opening and closing the hatch and doors several times really took its toll on the voltage.  It was down to 11.7 volts the first night, so I turned the car on to give it a short charge.  I kept about 5 miles range on the lithium battery, so I didn't have to start the ICE.  Too bad Ford doesn't let us disable the lights, especially with the small 12 volt battery.  Since the trip to the dealer I haven't seen voltages higher than about 12.5, and usually they are closer to 12.2 after the car has sat for awhile. 

There is a button near the interior light (on my SEL) that you can press that prevents the lights from coming on when you open the doors.

 

 

 

Mine was back down to 12.2 this morning, after sitting all weekend. Disappointing.

Is it possible that your battery has been damaged before the TSB was there to charge it better?  Although the DCDC TSB does not affect power drain the system may have.

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  • 1 month later...

I've usually measured after leaving the car sat overnight: Get in, close the doors, measure the voltage right away, and then watch (without starting the car) as it settles back towards a higher level (30 seconds or so). It will generally start 11.8-12.1v, and settle to 12.0-12.3v.

Edited by Noah Harbinger
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  • 4 weeks later...

Over the night, it was 12.57.

 

There is a button near the interior light (on my SEL) that you can press that prevents the lights from coming on when you open the doors.

 

 

 

Is it possible that your battery has been damaged before the TSB was there to charge it better?  Although the DCDC TSB does not affect power drain the system may have.

I know how to disable the dome lights, but I haven't been able to disable the exterior lights. 

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