Hidden 12 Volt Batteries on the 2021 Up F150 

I knew about the two batteries but did not know they were tied together, so thank you for making this video. Great info to know. Great Video!

For those wondering... if your powerboost starts acting up its normally that system. Multiple people have found their Aux battery isolator bad and replacing it fixed everything... I think there was a learning curve with these trucks and the techs are finally learning all the little things to fix them quickly.

GREAT info, thank you, lots of confusion about this on the forums, especially since the Powerboost and non-Powerboost models are different.

Excellent video; please do more of these videos with battery & pro power details. It's hard to find good videos like this out there with accurate data.

Excellent video. Very interesting

Thank you so much for this info!

Very good info... Sir

This is great for the dash cam parking mode.

Great video! I have a brand new 24 BP with the "charging system failure, service now" message and battery light on. It comes and goes while driver or parked. I have checked voltage at the primary battery with only 12.8 volts and AC on high with ign on and or engine running. With key off, 12.4 volts. I know the hybrid system charges the 12 volt battery, but shouldn't it be close to14 volts like a regular vehicle? Or with new AGM batteries, do they want the voltage low as to not over charge the battery being it's sealed. I'm dreading taking it back to the dealer and would rather fix it myself.

Great video. Quick question: if a trickle charger is used on the main battery (due to infrequent driving), will this in turn keep the 12v battery charged, or does the 12v need to be disconnected and charged independently? Thank you.

Had no idea what the compartment under the rear seat was for. Thanks.

Thank you for your information, I am concerned that is that ok for me to upgrade to Li-On battery? I don’t know is this a Start and Stop use battery.

My 2021 Lariat Powerboost gave me a "12V Battery State of Charge Low" warning today on my instrument cluster, and the radio and main screen would not function properly. I haven't taken it to Ford yet, but do you think this warning is related to this secondary battery or the main one under the hood?

Thanks for this information. I own a 21 F-150 King Ranch. I can't get sync updates because this battery is not holding a charge.

On a regular cab is the battery on passenger side? Just ordered the truck so will want to check this out once I have it.

My PowerBoost had been sitting for a long time and it doesn’t start, I changed both batteries and still nothing :/. I was wondering if there was a way to get the hybrid battery out of deep sleep? A way to bypass it to start it with the engine so it could charge the hybrid? I’ve got no luck!

So if you wanted to ad an in cab 12volt accessory would it be safe to wire directly to this under seat battery? If so I would assume an in line fuse would be needed.

My all 3 MB cars had a 2nd battery and they were mainly for internal computer n memory backup.

Any idea where the hidden battery might be on a 2023? I have the xlt 302a and it seems like there is still a second battery based on my battery tester but I can’t find it. My inverter is under the back seat but no batteries.

Would it be to ford's advantage to just have a larger hybride battery and ditch any hidden 12 v ones? Less wires running all over the place. Great narrative in your video.

Hey mate, can you put a bigger AGM battery in there so we can run a fridge centre console off?it

Would this make it so your settings stay while you're changing the main battery?

After replacing the main cranking battery due to a saving accessory power message on the screen, I still get the message. I'll do the Ford battery test on the small battery and see what it shows. PB is 40 months old with 28,000 miles.

this is great info ford really needs to make a youtube video w animations explaining all this so no one inadvertently electrocutes them selves mine has the low voltage warning. so my truck is the powerboost 7.2kw (at least i didnt get the lightning) and i doubt it makes to 100k miles i really like it and it gets 20 mpg when my old 5.0 got 14 so i think its good tech maybe w time ford will iron the bugs out but i doubt it if the tundra had the generator i would have gotten it but thr ford is soo much nicer plus ford dealers are easier to deal with and i would have had to order the tundra and pay too much for it i basically got the f150 for 6k off sticker and the tundra was going to be over sticker so we will see if it was wise to go w ford. still hard to find tundra hybrids but they will be more reliable i bet mine only has 13k miles lol so the powerboost has 3 starters and 3 batteries ? what could go wrong

I have a 2021 f150 limited and I started getting a message on my gauge that says "Charging System Service Soon" I'm at 40k miles?

I wonder would it be a good Idea to run an amp off that battery? or even small cab lights? Way easier then punching another hole through firewall!

So my question is, what is it for?

My inverter is where that battery is under the passenger side rear seat

interesting. i didn't know there was an f150 hybrid

great video and good narrative. ford should contract you to run the ",you know how", or "do you know what is this for" . which would be great for ford tech, , since they are the last to know, sad but true and for DYS like me.😂😂😂😂

If the hybrid goes into deep sleep the hvb will not charge the 12 volt battery while it's sitting off.

The G is for glass, not gel