I bought my 2022 Lariat in February 2024 with 15k miles on it. The carfax showed the battery had already been replaced due to some electrical issues.

This truck will frequently sit for a week at a time. I have not had any issues at all with the truck but have noticed it will go into sleep mode after a few days. If I walk into the garage with the keys in my pocket the perimeter lighting will not come on.

Last night I decided to put a charger on it to see what happens. It took a 15 amp charger almost 3 hours to go into float mode. This has me thinking about using the charger more often when I am not driving it. There are many examples here about how to do that. Noco's are one.

My questions are is this normal? And will battery life be extended by maintaining a full charge when not driven for extended periods? Will it hurt anything to keep at full charge?

I do have the neg side of the charger connected to the chassis ground

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Yes unfortunately that is normal, it shouldn't hurt anything as long as you use a charger that automatically goes into maintain mode and doesn't overcharge the battery

 

The last time I drove the truck was a short trip with heated seats and steering wheel on. It was chilly the other night.

Still hard to believe it takes almost 9 amps initially and 3 hours for a full charge.

I have no doubt my truck would start the next time I used it but I always thought battery life is shortened when it is not at full charge.

 

A couple good threads about the BMS and battery.

https://www.f150forum.com/f129/repla...attery-578073/

https://www.f150forum.com/f118/batte...tainer-568829/

Watch the video in the threads is a good explanation as well.

 

Answers to your questions are yes, yes & no. My trucks are not garage kept. I installed a Noco 5amp under the hood of my F150 & E350 and ran the AC cord to a position near the bumper. Using the adapter that bolts directly to the + battery and to a - ground on the frame, it's easy to plug in to an extension cord and I don't have to lift the hood and manually reconnect my maintainer for each use. You could do the same; it's easy.

 

Charger set on 15 amp level and taking 3 hours is good and normal.
It depends on what the SOC was at beginning of charge interval.
The Battery is a 74 amp-hour rated.
At the One tenth C rule for charging, 7.4 Amp charge rate would be the best compromise between speed, Cell Temo. and Battery life effects from charging.,
Lower the C charge rate, the longer it takes etc. A smaller charger just takes longer, up to the 6-8 hour time depending on what SOC was at the start.
A Battery that has been flattened, can't be recovered with a less than a 35 Amp or larger charger to start. Doing this with a larger charger until the Battery comes up in the 6 to 8 volt range, then a smaller charger can take over but expect a long charge time at lower charge currents. The Cell temp doing this has to be observed because cell over heating becomes a danger to the blowing the Cell seals open.
You're reversing chemical action in the Battery that takes time and a Temp limit.
It also takes drive time to accomplish from the truck system, otherwise because the truck system does not charge at high current rates with a 14.8 v limit due to being an AGM type Battery.
BMS will take some time to come back into control of the Battery Charge from being overridden by the external charging it had no control over.
Good luck.