I have a 15 f150 lariat that I recently switched from the sync 2 to the sync 3 radio. Now if it sits longer than 5 minutes with auxiliary power on it will drain the battery to the point it has to be jumped off. I do have forscan on my laptop. How to I adjust the settings to where when switch is off it turns everything off or adjust BMS where it won't let battery get so low before it shuts it down.

 

To me this sounds like your battery is in the process of dying. I can leave full aux power on in my '17 for 20 minutes with no problems at all.

 

I've had the battery checked twice and it shows good. Now that's not to say it's not in the process of going bad but as long as I shut it off and get out and lock the doors that shuts everything down and it's fine. It's just when you sit with auxiliary on it drains it. By the time the battery management light comes on it's to late. I've changed some stuff with forscan such as splash screen and mirrors but nothing that would justify draining it like this. I was told that the sync 3.4 does use more power than the sync 2 but not sure.

 

At this point I would suggest a DVM with current sensing capability and see what the drain is from the battery. A couple of amps for five minutes shouldn't bother the battery at all, given that they are rated for 600 to 800 amp-hours. You could also watch the battery voltage over the several minute span to see the affect of the drain on the output voltage. Something just sounds strange in what you have happening.

 

I agree something is strange about because I didn't have a problem until I changed the radio. I may hook up the DVM and see what kind of amps it's pulling with just the radio on. If I could figure out how to set the system where auxiliary power is off when you push the start button to turn off I would be happy. Lol

 

If your battery is truly okay, then I do not think the Sync 3 is draining it in 5 minutes.
To drain that battery in 5 minutes something would need to pull about 1,200 Amps (100Ah/(5m/60m)=1,200 Amps). That's an approximation, but I promise you the radio would be on fire (or realistically blowing a fuse) if it were drawing anywhere near enough power to drain a good battery from full in 5 minutes.

I'd recommend the following:
1. Check voltage with engine running to verify alternator is good and charging battery to full. ~14v.
2. Monitor voltage with engine off, and watch it over that 5 minute span. See if the voltage crashes. It should hardly move.
3. Measure current draw from battery. If you're not familiar with this, be careful and watch a couple YouYube videos. The meter must be inserted in series between the battery and vehicle. Don't put the leads across + and - in when the meter is in the Amps configuration.
4. Pull whatever fuse powers the Sync 3, and see if the behavior changes.

I would be more inclined to think either the battery is weak, the alternator isn't charging it, a BMS issue, or misconfiguration somewhere in the Forscan changes.

If the battery checks out, I'd look into the BMS and try reverting some of those Forscan changes.

These trucks do have a BMS (battery management system) that monitors amps into and out of the battery. I don't know anything beyond that, but maybe check if there is a BMS reset procedure.

Maybe there's some misconfiguration in Forscan. Perhaps an additional setting that needs changing, or something that shouldn't have been changed. Could have some confused modules doing funny things.

Good luck!

 

For measuring current from the battery, it would be best to get a meter with a current loop that be clipped over the cables as opposed to trying to tie the meter in with a series connection. If there is an abnormal draw, the series connection with the meter could be fatal to the meter....

 

Yeah, a current clamp would be ideal. But, not many people have one and even fewer are DC compatible. If one is available, by all means use it.
On a standard meter the current range is usually fused at 10 or 15 Amps, so nothing catastrophic should happen. Unless it's an unfused China special. But I doubt there's significant current draw.

 

I checked the alternator and it's putting out 14.7 into battery. For the most part what I changed with forscan was things like global windows for remote. Changed quiet a bit to get the climate controls on the radio like it was supposed to be. Battery is about 2 years old and has been drained several times but every time I get it checked it checks good. Don't get me to lying about anything lol. I set in the truck a few minutes ago with just the radio on and no climate on and it took 6 minutes for the BMS to come up and say battery was low and it would crank. Put battery charger on it for about 10 minutes and it started.

 

I would not suggest resetting the BMS battery in-service counter. Ford makes it very clear you're only to do that when you replace the battery with a new one. Resetting the BMS battery in-service counter while using an old battery may resolve an issue in short-term but it's not a fix.

How long as the truck sat, unused and uninterrupted? The BMS needs about 8 hours of uninterrupted sleep to relearn the proper battery SOC.

How are you charging the battery? The battery must be charged so that the current goes through the battery sensor, otherwise, the BMS does not properly see the battery is being recharged.

Are you fully charging the battery with a battery charger? Or using the truck enough that the alternator has enough time to charge the battery? Keep in mind alternators are not really designed to fully charge a dead battery. They also can't do it in minutes.