High charge voltage

[turbo2ltr]

I could tell over the past several months the OEM battery in my 2016 (FPIU) was dying because every morning the resting voltage was lower and lower as the days and months went on.. But it started fine. It has always maintained right around 14V when running.

This morning it was a VERY slow crank (much different than yesterday). But the alternator took over and brought the voltage up to 14v after it started. I proceeded to drive 20 miles with the headlights on without issue. But when I tried to leave for lunch it was dead. I gave in and bought a new battery (Napa Group 65 AGM) and immediately noticed that the charge voltage is 15.0V. A second meter (built into my ham radio) says 15.2v. This seems very high. I confirmed at the battery it was 15.0V with a DMM.

I had read about the BCM reset. I loaded Forscan for the first time and did the battery reset procedure. Still charging at 15v. When I turn the car off, it drops back down to the high 12s.

Any ideas? 15v is starting to get uncomfortably high for all the electronics I have. And charging an AGM to 15V will kill it in short order.

I have not driven the car yet so it's only been running a few minutes since I changed the battery and reset the BCM,

 

[turbo2ltr]

So charge voltage is back down to normal.

A word of warning:
I don't know the specifics, but I'm going to make the hypothesis that the Interceptor's charging system is designed to rapidly recharge flooded cell batteries in the event the battery is low. More rapidly than a car normally would. This is very bad for AGM style batteries. Flooded cells can take high charge voltages. AGMs are much more sensitive to this kind of stuff. Not to mention that a float of 14.4v when running is still pretty high for an AGM. They like the mid 13s.

Apparently UPS got burned by this as well. They made the move to AGMs using the stock alternators and they weren't lasting, and they ended up going back to flooded.

I do not recommend AGM batteries in an Interceptor. Not sure how the retail Explorer fairs.

 

[turbo2ltr]

Mods, could you move this to the interceptor forum please? I thought it would be a general question, now I'm not so sure.

 

[peterk9]

Mods, could you move this to the interceptor forum please? I thought it would be a general question, now I'm not so sure.

Done.

Peter

 

[KayGee]

Can't remember the specifics and not going to spend time digging into it, but did you check forscan to see about resetting the battery size/type? I believe it is an option in 2016+ models and the bcm controls charge strategy. Hopefully if you select an agm battery type it will charge at more appropriate voltage.

 

[turbo2ltr]

Very interesting! I did find it on the forscan explorer spreadsheet. I will try this later. Thanks!!

 

[Mlarv5]

You need to reset your Battery Monitoring System. Tell it is a new battery so the charge circuit knows how to act. I am pretty sure the procedure is in the book. If not it can also be done with Forscan.

 

[turbo2ltr]

You need to reset your Battery Monitoring System. Tell it is a new battery so the charge circuit knows how to act. I am pretty sure the procedure is in the book. If not it can also be done with Forscan.

I did this already (it's in the first post)

 

[turbo2ltr]

Good news, thanks to the tip from @KayGee I changed the battery type to AGM and now the charge voltage is right where it should be for AGMs 13.5v.

 

[VCFP153]

Good news, thanks to the tip from @KayGee I changed the battery type to AGM and now the charge voltage is right where it should be for AGMs 13.5v.

And there was much rejoicing!