New 12V battery drain in 3 days!

[Deauxrite]

Reading through this thread, there is a lot of mis-understood information that is leading people to the wrong conclusions. Just for "fun", I tested my battery basically twice a day for a little over a month. Here is what I learned:

1) When 100% charged, the OEM lead-acid battery has a max voltage of 12.65V. If you are seeing anything higher than that when not driving, you are seeing a "surface charge" which is not relevant. It takes about 3 hours after a battery is charged for the surface charge to fully disipate (but most seems to be gone after the first hour). If you have an AGM, the voltage will be higher (13.1V?).

2) Under normal driving conditions, the BMS will not fully charge the battery. As pointed out, it seems to only charge the battery to about 80%. This bad for the longevity of the battery since sulfation starts at about this range and rapidly increases below this amount. I have zero idea as to why Ford engineers did this (I assume it is something the lawyers made them do) but it will result in batteries dieing earlier than they should. I use my trickle battery charger to try to get my batter to 100% at least once a month.

3) Unless you physically disconnect the battery from the vehicle, getting an accurate and repeatable voltage is really, really hard. To get an accurate voltage with the battery connected you basically need to get in, lock the doors, make sure that everything is off, and then wait 5 minutes before checking the voltage under the seat. During that 5 minutes you will hear numerous clicks as the truck slowly shuts stuff down. If you have a voltmeter attached for this entire time, you will see at least 3 significant changes in voltage. You may even see the voltage go up, then down, and then up again (i.e., something turn off, then on, then off again). Generally speaking, if you just hop in the truck and check the underseat voltage, it will read somewhere between .1V and .2V lower than the battery actually is (due to current draw from who-knows-what).

4) Under-seat voltage and under-hood voltage are slightly different (by about .05V). This difference is a little more than I would expect from wire resistance so the BMS is effecting things somehow.

5) The parasitic draw of the Maverick is pretty high (much, much higher than any other vehicle I have owned). With absolutely everything off that you can turn off (no wifi, no call home, no app, nothing...) and the truck locked, you can expect to loose roughly .05V a day (but have seen up to .1V in a day). If you don't lock your truck, expect to see closer to .1V loss. If you have wifi, the Ford app, and other stuff running then .1V to .2V loss each day would not be unexpected. Based on what others have reported, the truck gives the low voltage warning at 11.8V. Thus, if you have a good battery but it is not fully charged, you can get the warning between 3 days and 14 days depending on what you have turned on and if the truck is locked or not.

Thanks for the clarity. Very helpful.

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[Caravan to Maverick]

Good morning fellow hybrid mavericks. I bit the bullet and replaced my 12V battery because my truck would occasionally be dead in the morning and I would have to jump the 12V to get the car to turn on. Anyhow changed it out last Sunday and at 3am this morning, three days later, got a notice from my ford app that it went to sleep mode. Are there any modules i need to turn off such as WIFI or anything I can do to check where the electricity drain is coming from?

My add-ons are I have two amps powering my sub and speakers, I have a blackvue dashcam that's powered at the fuse box passenger side. I don't have my dashcam running while in park due to battery drain. Getting annoyed, I may need to take it to the dealer but I feel like they always give me the run around. Just want to check and do it myself if possible.

I let my 2023 Mavrick hybrid set for a whole week with the last cold wave here in Michigan. Truck started with no issues.