"Electrical System Drain. Service Required." DIY Fixes?

[K6CCC]

Well, this is interesting. Shortly after I posted the message above, I went out to the truck, got in, and brought up CarScanner. Note that the truck is in Silent Mode so no lights were on. I did not turn on the truck. It was showing a 12 amp load on the 12V battery which changed to a 6 amp load a minute or two later. Voltage was just over 12 volts. Turned on the truck and immediately saw the voltage climb to over 14 volts and charging current to 60 amps. The current tapered off fairly quickly. Used CarScanner to read DTC codes and saved them. It's a long report so I'm not going to post it here, but it can be read in it's entirety at: http://k6ccc.org/DTC_2025-11-29.txt
Below are screen captures of the CarScanner LVB page through this. You can see the time from my phone at the top of each image

. . .

. . .

Sponsored

 

[lister coggs]

It can be expensive to have the dealer update every module outside of warranty. The process would take at least a day in the shop - likely 2. Some of us bit the bullet and bought the connector (and a big power supply) and get a temporary FDRS subscription periodically to update our own trucks from time to time. As with anything in the computerized world, there is some risk associated with doing this but the cost is way cheaper than paying the dealer to do it.

I installed one of these: https://www.amazon.ca/ANCEL-BM200-Bluetooth-Automotive-Lead-Acid/dp/B0BZ8D71NY/ref=sr_1_5?crid=8B8INSGJOJK9&dib=eyJ2IjoiMSJ9.kdXgPqlQ-syUk-UeC0Qd1lIIQkwKP1PEfDgC2c-uFN4aZPsN_V9blfyBCJ8xsLkOuDOOXlT2LdTGwW7kD9eLQ3IlF_XDcuQLsCSFyJ0oUzbB1YJ1ft5TDrOt18a6oBs_m7KsRNa7sk0J7iVGuqUmHriRHifzzU56SwHbgF8RIk_dyCMqzKWGvJ_HypdtYDqy7VgkMhGAJYmnG1qwOf3a6d6P1wWcwkMII7SNlPNODdZo8gmF9fdLvZL6CtT9KeoplIjtIBrv45warAyISj1W2SMM3bkcDNkjxs5FUEi-N1c.7qXSGv_e4gSxms4AlQS0S2NFygMF-jCcPQ6Yr4t_rVY&dib_tag=se&keywords=battery+monitor&qid=1764356609&sprefix=battery+monitor,aps,108&sr=8-5&th=1

It was invaluable in tracking my 12v problems. I have it installed in all 3 of my vehicles now.

I see you are in Barrie. I'm Richmond Hill.

Got Bluetooth monitor installed, nice recommendation. After parking the vehicle the battery immediately begins discharging over about 3 hours, then once it hits 15%, the HV battery recharges it to 100%. This was with the vehicle not plugged in.

I'm assuming these constant cycling can't be good for the battery. I wonder if it's possible with forscan to adjust these numbers so it's not fully discharging or charging.

 

[Adventureboy]

@lister coggs you have a serious parasitic drain problem. The pattern indicates you are pulling around 6 amps continuously if your battery is healthy. It seems your truck is not shutting down properly due to some condition like a door ajar or something similar. It takes about an hour to charge a healthy battery and your charge cycle looks about right.

 

[lister coggs]

@lister coggs you have a serious parasitic drain problem. The pattern indicates you are pulling around 6 amps continuously if your battery is healthy. It seems your truck is not shutting down properly due to some condition like a door ajar or something similar. It takes about an hour to charge a healthy battery and your charge cycle looks about right.

It doesn't look good. Lol.

There's no physical evidence of door ajar, lights on, etc. Nothing like that.

I have another appointment with dealer booked for Thursday. In the meantime, I'm going to get a FORscan adapter. Looks like you can monitor module sleep states with that.

 

[lister coggs]

You're confusing SOC with battery voltage.

I understand they're interconnected measurements but technically different. In my diagnostics of the parasitic drain how is this difference relevant? Am I overlooking something?

Here is the same chart with voltage over time which shows a similar trend.

 

[Adventureboy]

The monitor only estimates SOC based on the voltage trends so it can be off a bit since it doesn't directly track the current in/out of the battery like a BMS, but it is close enough to show the trends pretty clearly.

The voltage chart doesn't show the SOC trends as well, but it tells the same story. Something isn't shutting down properly in the truck. I'm curious how many cycles it will charge/discharge before going into sleep mode. On my 2023, it would only do it once initially. Ford updated that charge profile sometime in 2024, I think.

Another thing to watch. When the truck goes into sleep mode, does the drain still happen?

Any chance you have or know someone with an infrared camera? If you point it at the fuse box and snap an infrared photo about an hour after shutting down, without a keyfob or PAAK around it may tell you which fuse is carrying the current. The problem is you need to sit in the truck and wait for 45 minutes to get the picture since opening a door will light up the modules.

 

[K6CCC]

I got that message once and it was directly caused by the obd dongle I left plugged in. Unplugged it, message went away never to return.

Interesting. Yes, I have left the OBD2 dongle plugged in for quite a few months.

 

[lister coggs]

The monitor only estimates SOC based on the voltage trends so it can be off a bit since it doesn't directly track the current in/out of the battery like a BMS, but it is close enough to show the trends pretty clearly.

The voltage chart doesn't show the SOC trends as well, but it tells the same story. Something isn't shutting down properly in the truck. I'm curious how many cycles it will charge/discharge before going into sleep mode. On my 2023, it would only do it once initially. Ford updated that charge profile sometime in 2024, I think.

Another thing to watch. When the truck goes into sleep mode, does the drain still happen?

Any chance you have or know someone with an infrared camera? If you point it at the fuse box and snap an infrared photo about an hour after shutting down, without a keyfob or PAAK around it may tell you which fuse is carrying the current. The problem is you need to sit in the truck and wait for 45 minutes to get the picture since opening a door will light up the modules.

Wow, that's genius. I have a thermal camera I use for detecting thermal leaks. I'll give that a try. It's consumer grade though, so might not be sensitive enough for those tiny fuses.

I can probably just use a screw driver to close the passenger door latch to have the vehicle think it's fully closed.

I'll keep an eye on 12V when the truck is in deep sleep mode as well.

 

[lister coggs]

When you have a parasitic draw you don't look at voltage or SOC, you monitor amperage.

Tracking amperage seems like it would be the most precise way to monitor parasitic draw.

That said, can't I calculate amperage from the voltage drop data I already have? (I.E. I can calculate rough amperage from battery capacity, SOC or V drop rate / time period.)

Also, even if amperage is the most accurate way of detecting parasitic drain, wouldn't a repeatedly draining SOC / V still be a sufficient indicator? What else would that possibly be?

 

[lister coggs]

I would have to teach you the way I was trained in how to detect these things and I'm no teacher. We were taught to look for current draw as you can have full voltage on a circuit that's just potential power, it's nothing until it starts moving (current flow).

Once you isolate the current flow circuit, then you can isolate components via voltage drop which really only helps in detecting bad connections, grounds and such. Does nothing for a circuit that's energized by a working component, in that case it would show no voltage drop provided there are no bad connections.

In short forget about voltage entirely, current flow is what you want to look for. Isolate the circuit then pinpoint from there.

Ok, I think I get it. Detecting amperage (current flow) on each circuit while the vehicle is off would be the most accurate way of determining which circuit is pulling power from the battery.

My graph was looking at the voltage of the battery itself as an indicator of parasitic drain, rather than the voltage of any individual circuit. The declining voltage of the battery is indicative of parasitic drain.

Either way, before I start tracking amperage to narrow which circuit, I'm going to try FORscan to see if it can tell me which modules aren't sleeping.

-

In a related note, while trying to use my thermal camera on the fuse panel, I've had the vehicle alarm repeatedly go off. I noticed that no matter what I do, I can't get the alarm system motion sensors to stay off. They keep turning themselves back on even after setting the menu in the system.

Going to experiment more once I get FORscan running, but perhaps this is related to the parasitic drain issue.

 

[mr.Magoo]

Well, this is interesting. Shortly after I posted the message above, I went out to the truck, got in, and brought up CarScanner. Note that the truck is in Silent Mode so no lights were on. I did not turn on the truck.

You woke up the truck by opening the door, polling the modules via OBD will keep them awake and/or wake them up even though the truck is otherwise off, hence drawing a lot of power.

This is the reason why I monitor the 12V supply to the dongle so that I don't keep making requests once the truck is off - as that would drain the 12V / LVB battery.

 

[Adventureboy]

Wow, that's genius. I have a thermal camera I use for detecting thermal leaks. I'll give that a try. It's consumer grade though, so might not be sensitive enough for those tiny fuses.

I can probably just use a screw driver to close the passenger door latch to have the vehicle think it's fully closed.

I'll keep an eye on 12V when the truck is in deep sleep mode as well.

Make sure you don’t take PAAK or key fob when you go out to take the picture.

I can't get the alarm system motion sensors to stay off.

Try turning WAL off and leaving it unlocked. This should keep the alarm from arming.

There is a second fuse box near the firewall under the passenger frunk cover. That one will be harder to get an undisturbed picture.

 

[srspring551]

Does anyone know if it makes a difference if I hook up the ANCEL BM200-US upstream or downstream of the BMS? I would think not but....

 

[Adventureboy]

Does anyone know if it makes a difference if I hook up the ANCEL BM200-US upstream or downstream of the BMS? I would think not but....

It doesn't matter on a monitor like this since it uses so little power. The absolute purist would hook it to the positive terminal and the truck side of the BMS, but the readings will tell the story either way and the BMS and battery won't know the difference. In either case, make sure you have the monitor on the top closest to the nut and not between the main cable and the battery connection.

 

[Adventureboy]

@lister coggs did you manage to get your drain issue sorted? I'm curious what was causing your problem.

Sponsored