AGM Battery Voltage?

[blackhawkrider]

Does anyone know what the AGM battery voltage should be when the truck is off and parked? These are my stats:

- Truck running at idle (3.5 Powerboost) 12.98-13.0 volts.
- Truck Accessory on, engine off 13.0 volts. I'm guessing it's pulling the aux battery or hybrid battery for some juice?
- Truck off after driving for over an hour on the highway, 12.5ish volts.
- Truck sitting overnight off, 12.3 volts.

I've had no issues starting the truck or noticed any issues, aside from not getting any recent OTAs. I've seen that you need 12.5 volts to do anything in FDRS and wonder if it's the same for OTAs.

The dealer killed my battery once during an attempt at the trailer brake recall back in March/April. I asked for a replacement, but it just passed the 5 hour dealer battery load test. I also had a build date of March 2021 with delivery in October 2021, so I'm pretty skeptical that the battery hasn't had the best life and has been kept fully charged. My only experience has been with lead acid so maybe AGMs are more robust with sitting at lower volts?

Thanks!

Sponsored

 

[blackhawkrider]

After talking with Ford Support they said they don't know the minimum voltage for OTAs, but did say that the battery State of Charge (SOC) must be above 80%.

Any ideas what that might correlate to volts? Is SOC available to read via Forscan?

Thanks!

 

[Pedaldude]

No clue what the dealer 5 hour battery load test is or if it is a specific PB thing but for a regular starting battery, you want to check the voltage drop when cranking the engine to assess your starting battery health.

For any old car, anything below 10V when cranking and it’s time for the battery to be replaced. However, with newer vehicles and all the associated electronics, the vehicle might still start but you can experience electrical gremlins if some of the computers wake up and don’t see the voltage they need.

The Powerboost is an even more unique example, since it’s a hybrid and it also has I believe 3 different methods for cranking the engine at startup. The actual starter, the PB motor in the transmission and the thing that resembles an alternator can all turn over the engine and I have no idea what battery the current is drawn from through each of these alternatives.

You should try posting in the Powerboost specific forum:

https://www.f150gen14.com/forum/forums/3-5l-powerboost-hybrid-v6.12/

For my 5.0, I have been using a plug-in voltmeter to check to see how my battery is; when I took delivery of my truck, the battery light was on and several error messages were present. So I have been keeping track of its health, since the desert heat is pretty hard on batteries.

Sponsored