Just curious, is 12V the correct voltage for this AGM battery? Is traditional battery usually 12.3 - 12.5V?

I have seen an error message stating 12V in my car. Not sure if this indicates the correct voltage.

XC60 R Design T8
NORWAY
Mileage: http://bit.ly/2C2gQ9n

 

Was the message about 12V voltage reading is too low, or 12V battery needs attention?

Coming, Fusion Red XC60 T8

 

AGM batteries and lead acid batteries are pretty close in charge voltage. AGM is fully charged at about 12.8 V and lead acid 12.7 V. 12.0 V indicates about 25% charge. In other words at 12.0 V, you will have issues. Not sure how accurate your USB voltage display is but you could always cross check it with a volt/ohm meter at the terminals or at least the positive jumping terminal under the hood, assuming the XC90 has one.

 

I plug in to 240V and charge it overnight. And the 12V battery is supposed to be charged also. Seems I need to double check. And it was just back from software downloading at dealer. They are supposed to charge it too. I read the voltage when hybrid battery is low but it should not affect the AGM battery.

VOC app shows me battery is at 1/4 level, while charging is in progress, 2 hours to complete. Is this hybrid battery level only? I don't see AGM battery voltage reading.

Em, getting interested now. Will check if voltage info available in Sensus Car Status app. And also measure the AGM voltage when charging.

Coming, Fusion Red XC60 T8

 

Looks like the voltage reading is low from the usb charger.

After charged at night, multimeter shows 12.3V, while USB charger shows 12.1V on same trunk ignitor socket. While on the trunk battery, multimeter shows 12.38V. Once precondition starts, it gets to 13.8V read on usb charger on the socket. So looks pretty normal. Precondition starts hybrid charging, and trunk battery also gets charged.

I don't know if it could go up to 12.8V when charged after longer trip. I'll try later for sure.

Rolling, Fusion Red XC60 T8

 

Looks like the voltage reading is low from the usb charger.

After charged at night, multimeter shows 12.3V, while USB charger shows 12.1V on same trunk ignitor socket. While on the trunk battery, multimeter shows 12.38V. Once precondition starts, it gets to 13.8V read on usb charger on the socket. So looks pretty normal. Precondition starts hybrid charging, and trunk battery also gets charged.

With any instrumentation (including the voltmeter in your USB charger and multimeter), readings may have some level of inaccuracies. When I keep track of readings for a certain instrumentation (e.g. voltage, vacuum/boost pressure, oil temperature, etc.), be it one that is provided by the vehicle's original instrumentation or an add-on instrumentation, the key is to track whether the reading is unusual relative to an established baseline.

Looks like almost all voltmeter involves running a low amount of current into the meter's circuit (as one do not want to incur an excessive current draw just to take a reading), which involves having a large impedance ( think of it as large resistance ). Unit to unit, there can be variations in the actual impedance, which will affect the reading. Most lab-grade instrumentation may have a smaller error tolerance specifications, and may require periodic calibration.

For your case, perhaps getting an OBD2 scanner that sends data to a handheld for real-time monitoring would work? (for example, OBD2 to bluetooth, then an App on the phone taking in data from the bluetooth transmission), maybe like this one (note: i have no personal experience using this):
https://www.amazon.com/Foseal-Scanner-Adapter-Diagnostic-Android/dp/B00W0SDLRY

 

13.8V is standard charging rate - on our other cars I keep a battery tender and while plugged in they read 13.8v. T8 charges 12v while plugged in to EVSE or while driving. The 12v charges off the hybrid battery.

 

Right. The trunk battery gets charge along with hybrid charging. After hybrid battery is fully charged, EVSE will stop and trunk battery charging also stops. A usb charger is handy to confirm this, while I need to consider its reading difference.

Rolling, Fusion Red XC60 T8

 

I hope they add voltage reading in Car Status app. Also, when the main (trunk) battery falls to 12V, computer should force ICE engine to run and charge the main and start battery..

 

Don't all vehicles with start/stop do this already? Isn't this why some report that their start/stop doesn't work - because their 12v batteries were too low so the engine needed to stay on to charge them?

 

I would only expect to see that on a brand new or very close to brand new battery. On a battery that's a year or two old, 12.4-12.6 would probably be pretty close to average. Batteries lose their ability to hold charge over time. It's not like they can be charged to 100% year after year, and then just one day can only hold 25%.

 

Oh of course, battery in my car built in last November should be less than 6 months old I guess.

 

Fully charged healthy Volvo AGM battery measures 12,8V.
But you have to measure directly on the battery couple minutes after the car has been locked.
Or you have to disconnect the battery.
If the car is open, the voltage measures less, something like 12,4-12,6V.
I have never measured the voltage on the cigarette lighter, but most probably it should be the same as directly on the battery.