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Hey all,

Searched a bit and didn't find anything conclusive, so asking braintrust here.

My battery is showing 55% charge state via OBDRS app, and auto start/stop is no longer working. I don't think I've ever seen the battery higher than 70% since I bought that app about 6 months ago. Car is 11 months old now, was parked for a while at dealership (I bought it used/traded in).

I have an OBDLink MX plugged in full time, which is supposed to have a power-save auto off mode that appears to work (LEDs reflect sleep state). Other than that, nothing parasitic attached like chargers, cameras, etc. Have flashed the Sync 3 FW. I do see the alternator putting out 60+A when driving, and I do see the battery charge state increase very slowly when driving. However, it's been trending down for a long time now.

Are these cars known for parasitic drain? Is replacing a battery after a year common? I've seen a few obvious battery failures in other threads, I've seen backup cameras draining the (rather massive) stock battery, but no clear indication that it's a common issue.

I'll likely take it for a warranty replacement shortly, but don't want to replace a battery every year on this car. Advice and anecdotes welcome :)
 

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Anecdotally, auto power off doesn't work, or let me re phrase, it works in the sense it turns off the device before the battery won't crank over but the slow trickle need of those devices (Cam, OBDLink) will kill the life of the battery, till what you experience.

Hence any good cam set up has a Li battery inline to prevent this....
 

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Anecdotally, auto power off doesn't work, or let me re phrase, it works in the sense it turns off the device before the battery won't crank over but the slow trickle need of those devices (Cam, OBDLink) will kill the life of the battery, till what you experience.

Hence any good cam set up has a Li battery inline to prevent this....
The OBDLink is supposed to go into a "Sleep" mode that reduces current draw significantly. As it turns out I used to help design OBD telematics devices and anything under 10mA was safe on virtually every OBD vehicle, as long as the device actually detects that it is time to go to sleep. I haven't inlined an ammeter on that device yet but I'd be surprised if it was pulling more than that. Cams that keep filming when vehicle off are gonna pull 50-100+ mA and need the battery. Remote starters and security systems similar.

Anyways I'll keep an eye on the OBDLink in more detail, but I'd be very surprised if it was drawing enough to kill battery.

What about AccessPort users? I can't imagine most users disconnect them nightly.

And yes the auto start disables itself when the battery is insufficiently charged to reliably to restart vehicle. Not sure charge level where that occurs but guessing 60-65%.
 

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I haven't had SS working in almost a year. No devices connected that are powered with the car off either. Last time SS worked was after a 4 hour drive, then stopped again after sitting for 2 days.
 

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The OBDLink is supposed to go into a "Sleep" mode that reduces current draw significantly. As it turns out I used to help design OBD telematics devices and anything under 10mA was safe on virtually every OBD vehicle, as long as the device actually detects that it is time to go to sleep. I haven't inlined an ammeter on that device yet but I'd be surprised if it was pulling more than that. Cams that keep filming when vehicle off are gonna pull 50-100+ mA and need the battery. Remote starters and security systems similar.

Anyways I'll keep an eye on the OBDLink in more detail, but I'd be very surprised if it was drawing enough to kill battery.

What about AccessPort users? I can't imagine most users disconnect them nightly.

And yes the auto start disables itself when the battery is insufficiently charged to reliably to restart vehicle. Not sure charge level where that occurs but guessing 60-65%.


Sounds like you have a background to understand the context, just the experience I seem to see is any low amp trickle draw however small that occurs on this older traditional battery technology when the alternator isn't feeding the system, doesn't do well with constant low amp draw chronically, seems to shorten the longevity of the battery significantly.
 

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Discussion Starter #6
I wonder if it's specific to the factory battery, which I don't think is an AGM. I may just spring for an out of pocket AGM replacement so I don't need to think about it, and most come with full replacement warranties for at least 3-5 years.

Don't want to go small or Li-Ion as that is basically the opposite of the solution I'm looking for :)
 

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I wonder if it's specific to the factory battery, which I don't think is an AGM. I may just spring for an out of pocket AGM replacement so I don't need to think about it, and most come with full replacement warranties for at least 3-5 years.

Don't want to go small or Li-Ion as that is basically the opposite of the solution I'm looking for :)
I have my shorai waiting to install. I've lived without SS for this long, might as well drop 40lbs from the engine bay of the little blue piggy.
 

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I think there is a slow drain issue on this car. I have a 2018 I bought last December. I've had my tender hooked up 3 different times, and it takes all day to bring it back to maintenance charge. I first noticed it when going to install my drift stick this summer, and the Ford software showed the battery was low. My auto start stop will stop working as well. I've seen a charging fault come up once before on the ford pass app as well. Granted I really only drive the car on the weekends. I wonder if this has to do with the keyless start, if it's constantly trying to ping the key? My keyless start Ducati has this same problem.
 

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What about AccessPort users? I can't imagine most users disconnect them nightly.

And yes the auto start disables itself when the battery is insufficiently charged to reliably to restart vehicle. Not sure charge level where that occurs but guessing 60-65%.
Auto Start Stop disables itself below 69% Battery SOC.

I have an OBDLink MX and Cobb AP and have no problems with battery drain disabling ASS. I have my AP set to power down when the car is turned off. There may be a slight parasitic drain when it's powered down but I've never had the battery go so low that ASS disabled itself. I'm still running my original battery, April 2016 build. Yours may have a bad cell.
 

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Auto Start Stop disables itself below 69% Battery SOC.

I have an OBDLink MX and Cobb AP and have no problems with battery drain disabling ASS. I have my AP set to power down when the car is turned off. There may be a slight parasitic drain when it's powered down but I've never had the battery go so low that ASS disabled itself. I'm still running my original battery, April 2016 build. Yours may have a bad cell.
Thanks, exactly the kind of info I'm looking for. Maybe I'll try one more OEM battery (under warranty presumably) and see how I'm doing in a year. Dropping $250CAD on an AGM battery is an annoying way to spend money, but being stranded in a Canadian winter is a lot more annoying...

Confirmed again that the OBDLink is going to sleep (slow flash on power LED) even when the vehicle wakes up from sleep on door unlock, but haven't attached an ammeter yet.
 

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Thanks, exactly the kind of info I'm looking for. Maybe I'll try one more OEM battery (under warranty presumably) and see how I'm doing in a year. Dropping $250CAD on an AGM battery is an annoying way to spend money, but being stranded in a Canadian winter is a lot more annoying...

Confirmed again that the OBDLink is going to sleep (slow flash on power LED) even when the vehicle wakes up from sleep on door unlock, but haven't attached an ammeter yet.
Perhaps throw a charger on it once a week? That's probably good for the battery anyway, especially if it's a charger under 20 or so amps.
 

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Perhaps throw a charger on it once a week? That's probably good for the battery anyway, especially if it's a charger under 20 or so amps.
Not worth the effort. It should just work. This car isn't a garage queen, it's an all purpose daily. I have a CTEK ideal for purpose but it would annoy me to have to hook it up. I drive it almost every day.
 

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"My battery is showing 55% charge state via OBDRS app, and auto start/stop is no longer working. I don't think I've ever seen the battery higher than 70% since I bought that app about 6 months ago. Car is 11 months old now, was parked for a while at dealership (I bought it used/traded in)."


It wouldn't surprise me that maybe the battery was frozen once while sitting around the dealer lot or elsewhere. It happens all the time. Hit them up for a battery under warranty .
 

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I never tested the battery itself; however, Ford did report during a regular oil change that it was low. A month later my car wouldn't start after work. After having Ford tow it to a different dealer it was determined that the cause was a poorly connected ground cable. They used a dremmel and cleared away some paint around the negative terminal and put a large washer in there to increase connectivity. Haven't had a problem since. They believed that during my head replacement that the negative terminal was never tightened down. properly but had no actual proof. *shrug*
 

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I'd put it on a real charger (10A+) connected right at the battery, and see if you can get it to show 100% and enable the start/stop function. Then go from there. If you can't get it to 100%, or at least close, then most likely the battery is bad. I can leave my car sit for 2 weeks, and it starts fine, but start/stop doesn't work right away. I have to drive it for 30 min or so, before it starts working again.
 

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I drive mine daily and during the week most of my trips are relatively short with mostly surface street driving. I disable Start/Stop as soon as I start the engine so my observation is not fully scientific but some of the time I forget and even then the system doesn't engage with the grayed out symbol.

However during weekends I have longer trips that are mostly on freeways and during and after these I've noticed that the system would mostly engage (stop the engine).
 

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I took my RS to the dealer for a few things that were broken on my car 3 weeks ago. One among them was the loss of the auto start stop feature. I know it's most likely because of the very low battery resting voltage(11.3). Being the cheap scotsman that I am, I figured I could get a new battery out of Ford for free. HA! They took 2 whole days running ODB scans, as well as taking the RS for "test drives" (spirited rips to the redline in 1st gear).

They decided that I have some kind of "aftermarket alarm" installed on the car. It's a dashcam BTW. So, no replacement under warranty. Mmmmmkay, it was worth a try.

I do leave the RS sitting for weeks at a time, and it's always started. I'll likely replace the battery before it leaves me stranded somewhere. I do keep a booster jump pack in the rear hatch just for this occasion. I haven't experienced any parasitic drain. The dash cam will only record in parking mode for about 20 minutes after turning the car off. I still think the battery's in these cars are weak.
 
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