Stock battery is 650cca, I would like to replace it with a 850cca battery. Will my stock alternator be able to handle the load? Will the new battery affect any other electrical systems? Should I just stick with the pen battery?

 

The CCA rating of a battery really has no effect on the loading of the alternator. It will effect how long it takes the alternator to charge the battery if it is completely drained. These days, by far, all the other loads on the alternator from all the electrical systems present far more of a load than charging the battery.

Now, if changing the size or type of the battery, generally it is recommended to change the battery setting in the BMS (Battery Management System) which is an integral part of the BCM (Body Control Module) and reset the BMS so that the new battery will be recognized correctly.

There are many threads here about batteries and the BMS. You might want to do some research to get a better understanding of the BMS and hoe it functions. Most modern vehicles have a BMS.

 

I want to replace my 650cca battery with a 850cca battery, the 850 fits in my battery box. What do I need to do to make sure the alternator and battery are compatible?

A you tube video said if I switch batteries and park the truck in the driveway undistrubed for 8 hrs the BMS will relearn everything. Can anyone verify this?

 

All you need to do is use Forscan to adjust the battery capacity in the BMS. The alternator doesn't know or care what the capacity of the battery is.

 

This is not correct. The truck will learn the stable current of charge for the battery in that 8 hour period. It will not relearn or reset the actual battery perimeters, such as days in service or type.

 

1. What battery does your truck have now? For users that had an H7 from the factory, the H8 from the diesel F-150 is a drop in replacement. Check your battery tray and see if an H8 AGM will fit.
2. You should to reset the BMS with Forscan.
3. You should to change the capacity with Forscan so the truck can best charge/discharge and utilize the capacity of the larger battery.
4. Your alternator will be fine with any size battery.

 

OP said
Will my stock alternator be able to handle the load? Will the new battery affect any other electrical systems?
Answers
The ecu controls the alternator and the size and performance of the battery does not matter and the existing alternator will perform just like it did with the old battery.
Other electrical systems will not be altered.
And yes the BMS must be reset for the new battery