Battery Charging Voltage

[freddyboy47]

Not sure if this is the correct topic area. I have a 23 BS OBX. I purchased a plug-in battery voltage display that plugs into the cigarette lighter socket. The displayed voltage at idle for the most part is around 15.15VDC. I have seen information regarding the maximum charging voltage should no more than 14.5 VDC. Has anyone measured their battery voltage? I am wondering if the alternator on our BS's are putting out too high a voltage, can this be a cause for early battery failures?

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[Dude]

I have that same display, the product claims “high accuracy (+-0.2V)” and there will be some voltage drop measuring at the cigarette lighter vs. directly at the battery.

Mark S stated “The alternator should output 14.5-15.0v” on his post #5
https://www.broncosportforum.com/forum/threads/battery-voltage-reading.5441/

Measuring 15.14 with +-0.2V is within the range Mark S stated.

you can have your charging system tested to know for sure if there are any issues

 

[freddyboy47]

I will bring this up to the service writer when I bring it in for the first oil change. The information that I read stated that the charge voltage should never exceed 14.5VDC.

 

[Meanderthal]

What voltage does your cigarette lighter plug-in gauge read when the engine isn’t running? Just wondering how accurate it actually is. Would be best to read it after a long drive when you can be sure the battery is fully charged.

 

[jofer]

You're likely seeing the smart charging system at work. If you run the car for long enough that the battery is topped off, it should drop back down to around 13.6v while the car is running. It should be a bit over 12v when the engine is off.

In cars with active battery management, a high voltage means the system wants the battery to be actively charging, but the control module should drop things down once it's topped off. Newer vehicles often have a built in desulfator cycle for the battery which requires high voltage when it's going though a cycle of that. Those are often over 15v.

I'm guessing that's what you're seeing, but I could be wrong and I am not a mechanic.

Either way, 15v is not that high and would only be a problem if it was always at 15v. You should see it drop back down eventually as the car runs for awhile. If you never do, then that might indicate a problem.

 

[freddyboy47]

Eric, with the engine off it is around 12.9VDC.
Jofer, unfortunately I do not use the BS for longer drives, so it may be the case that the battery is always requiring a higher charge.

 

[Mark S.]

Eric, with the engine off it is around 12.9VDC.
Jofer, unfortunately I do not use the BS for longer drives, so it may be the case that the battery is always requiring a higher charge.

12.9 VDC is high. A fully charged 12V automotive battery should indicate around 12.6VDC. I would suspect inaccuracy in the gauge. If you have a multimeter it's pretty easy to check the battery voltage manually.

 

[Texas Matt]

I had my battery tested at a battery dealer/ stereo shop because my auto stop/start isn't working due to "vehicle charging. My battery tested at about the same as yours, 15.something volts and 880 CCA.

 

[metalbender]

Had a battery problem with my 18 f150. Had an led type battery monitor that showed low voltage even after the battery was replaced. Freaked out, chose voltage as a parameter on my Scan Gauge. Had the dealer order a new alternator. In the meantime, did some searching google. Turns out, these new vehicles have the voltage controlled by the ECM and the voltage varies greatly. All in the name of fuel mileage of course. If the battery is charged, the alternator quits charging to save engine power. My voltage went from 12.4 to 15.9. The BS probably has the same system.

 

[Meanderthal]

I had my battery tested at a battery dealer/ stereo shop because my auto stop/start isn't working due to "vehicle charging. My battery tested at about the same as yours, 15.something volts and 880 CCA.

If they told you the battery was at 15+ volts, then they don’t know what they are doing. The battery will never have that much voltage, but the charging system can. They must have read the voltage with the vehicle running, which is not how you measure battery voltage.

 

[NMhunter]

If your making lots of short trips, especially in the winter and with lights on, your battery may never fully charge.

The first indicator for me is that the auto stop/start feature is disabled. It might be a good idea to put a battery charger on it overnight.

I found with my old f-250, that the battery would run down after a couple of weeks of short commutes to work in the dark of winter. My current f-250 has two batteries, and I scarcely drive it. Diesel is expensive and my Sport gets such good mileage (29 mpg on this tank). I put a 20 watt solar panel on the dash with a charge controller to keep from overcharging them.

Keeping your battery near full charge will keep it alive longer.

AGM batteries hold a little higher voltage than flooded lead acid (FLA) batteries. This chart is for FLA

Be aware that you want to test the voltage after the car has been sitting for at least a couple of hours. it will show higher voltage right after being charged.

 

[RSH]

I don't know if the Bronco Sport has a "smart charging system" where the ECM/PCM control's the charging system, I would assume it does.

Charging System

The PCM controlled Smart Charge charging system determines the optimal voltage setpoint for the charging system and communicates this information to the voltage regulator. The Smart Charge charging system is designed to set a DTC when a charging system fault is present. All of the Diagnostic Trouble Codes (DTCs) can set continuous faults, but not all Diagnostic Trouble Codes (DTCs) set as on-demand faults.

The smart regenerative charge system primary strategy is stored in the BCM . The BCM receives information relating to the battery condition from the battery monitoring sensor via a LIN . The BCM calculates and sends the set value needed for the generator charging voltage via the HS-CAN to the PCM . The PCM then adjusts the value received (if necessary) and sends it to the generator via a different LIN . The charging voltage is adjusted depending on various parameters, such as the current level of engine efficiency. The smallest possible set value for the generator voltage is 12.2 volts, while the maximum charging voltage can be anywhere between 14.5 and 14.9 volts. However, when the battery is in a refresh phase, the voltage may occasionally reach up to 15.2 volts. These refresh phases are required when the battery charge status is 80% over long periods of time, which increases the risk of sulfation in the battery cells.

 

[Dude]

…from the battery monitoring sensor via a LIN

…sends it to the generator via a different LIN

What is the LIN ?

maybe something like this?
“LIN bus is a supplement to CAN bus.
Often used in vehicles for windows, wipers, air condition etc.. LIN clusters consist of 1 master and up to 16 slave nodes.”

 

[kshaw]

Here are some battery tests on my BS Outer Banks and charging system. The battery test was done about 6 days from last use and I used the 700 cold cranking amps on the battery. The battery test showed that battery at slightly below 12.0v and CCA tested significantly higher than 700 CCA (976 CCA). The charging rate on my battery was rated as high and showed 14.82v-15.00v.

 

[Dude]

Here are some battery tests on my BS Outer Banks and charging system.

You have an AGM Battery .. is that correct?

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