Frunk won't open with external 12V supply connected

[gordonf238]

I tried today to follow the directions from the user manual, in the event that the LV battery should have an issue, and I was forced to access it. As many of you may (or may not know), the low-voltage (12V) battery is accessible through the frunk - which can only be released with the 12V power present.

Ergo, as you may (or may not) deduct, this presents a paradox. How does one access the 12V battery, should it die, when its power is needed to open the frunk?

Well, Ford's ingenious engineers have devised a complex solution to an already complex problem. Supply an external 12V power to open the frunk!

In any case, without getting carried away with this, seemingly dumbfounded approach, I had attempted today to connect an external 12V power supply to the 2 positive/negative terminals hidden beneath the cover on the front bumper.

Unfortunately, the frunk did not release. Nothing happened in fact. I've verified that my NOCO Boost Plus GB40 outputs 12V with a voltmeter. Sure enough, it does.

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[Frankie]

It only works when your battery is actually dead, otherwise people could break into your frunk whenever they wanted.

Was your battery actually dead?

 

[macchiaz-o]

Did you disconnect the vehicle's LVB before performing your test?

If not, you've only verified that the front leads didn't cause the frunk to open while the vehicle's body control module (which interacts with door locks and similar) was functioning.

 

[Motomax]

Congrats, you’ve proven that it does in fact work as intended lol. Can you imagine just walking around with a battery pack just stealing everyone’s stuff lol.
Btw, they could have said just call a lockout service to pop the door open like every other vehicle out there. Instead they gave you a convenient way to do it yourself so not sure why you seem to not like the frunk release feature.

 

[louibluey]

Here are the gory details. The best simulation is to pull fuse F72, which @CHeil402 and I settled on early in the project. You have to pull the frunk tub, then unfold to disassemble and open the main fuse box on the driver's side on the inside of the wheel well.

Pulling the ground terminal on the LVB did not work for me, but maybe I missed something. I think Ben reported that he did get the emergency circuit relay to activate by pulling a LVB terminal. I need to try it again someday.

 

[Carsinmyblood]

Along with all of that, the 12V supply will need not only 12 volts, but also enough amperage to run a solenoid under load.

Anybody know what this might be?

Teckno-jargon line during Apollo 16 while on the moon, from Young at 120:44:17: "68 volts; no amps."

 

[Neil4Real]

Congrats, you’ve proven that it does in fact work as intended lol. Can you imagine just walking around with a battery pack just stealing everyone’s stuff lol.
Btw, they could have said just call a lockout service to pop the door open like every other vehicle out there. Instead they gave you a convenient way to do it yourself so not sure why you seem to not like the frunk release feature.

I think it is more so the fact, in my opinion, that you have to pop the frunk then pop panels off to access the battery to charge it and then you can open the door. It would be nice if the frunk had easy access to the battery points or the bumper cutout not only allowed you to pop the frunk but also charge/jump the battery.

 

[Motomax]

Along with all of that, the 12V supply will need not only 12 volts, but also enough amperage to run a solenoid under load.

Anybody know what this might be?

Teckno-jargon line during Apollo 16 while on the moon, from Young at 120:44:17: "68 volts; no amps."

Someone was able to release it with AA batteries in series, so less than 2amp for sure.

 

[gordonf238]

Someone was able to release it with AA batteries in series, so less than 2amp for sure.

I didn't realize the system was smart enough to recognize when the LVB is actually dead. Good to know!

I've ordered 8x lithium AA batteries and a holder (8x 1.5 = 12v). It's small enough to fit inside the front bumper with some zip ties, should the need ever arise.

 

[Motomax]

I think it is more so the fact, in my opinion, that you have to pop the frunk then pop panels off to access the battery to charge it and then you can open the door. It would be nice if the frunk had easy access to the battery points or the bumper cutout not only allowed you to pop the frunk but also charge/jump the battery.

In theory, you should never have a dead battery so pulling a panel off is not a big deal for me. especially since it’s only clips.
you would need to run decent size wiring to be able to jump it from the bumper (I believe someone said it can use around 30A to wake everything up). It would also need to be fused, blow the fuse and you can’t get in.
I’ve thought about running some pigtail wiring to the bumper for a charger but there’s another problem with this. The onboard charger may not play well with an external battery charger connected. The recommended method to charge the battery manually is to disconnect it.
In theory, you should never have to do this either. Just plug into the EVSE.

 

[louibluey]

... The onboard charger may not play well with an external battery charger connected. The recommended method to charge the battery manually is to disconnect it.
...

That is really interesting, I have shared the same concern for years over past EVs. Most recently, maybe around 2018, many of us on the Bolt forum even initially discouraged 12V trickle chargers for fear of some interference with Bolt's LVB maintenance system, we said leave it alone, let Bolt care for the LVB.

Then MME came along with SSMs and TSBs about how to update the modules, and step one is always find the biggest beefiest 12V charger you can, and clamp onto the 12V jump posts before you do anything else! (Many of us since use a 12V flash programming power supplies designed specifically for vehicle module programming). The 12V charger or power supply stays connected, accessory mode, power ON, all of the time you are programming.

So, MME is pretty robust 12V system wise. Feel free to clamp just about anything 13v to 15V onto the jump posts. Even funnier, the Ford documentation actually discourages lifting the 12V LVB negative terminal with the little BMS computer on it. I think that is mostly bogus nonsense (if done with some care and not over torqued), but officially (work shop manual and Police version maintenance note) Ford effectively says do not disconnect the LVB unless you intend to replace it.

 

[Motomax]

That is really interesting, I have shared the same concern for years over past EVs. Most recently, maybe around 2018, many of us on the Bolt forum even initially discouraged 12V trickle chargers for fear of some interference with Bolt's LVB maintenance system, we said leave it alone, let Bolt care for the LVB.

Then MME came along with SSMs and TSBs about how to update the modules, and step one is always find the biggest beefiest 12V charger you can, and clamp onto the 12V jump posts before you do anything else! (Many of us since use a 12V flash programming power supplies designed specifically for vehicle module programming). The 12V charger or power supply stays connected, accessory mode, power ON, all of the time you are programming.

So, MME is pretty robust 12V system wise, feel free to clamp just about anything 13v to 15V onto the jump posts. Even funnier, the Ford documentation actually discourages lifting the 12V LVB negative terminal with the little BMS computer on it. I think that is mostly bogus nonsense (if done with some care and not over torqued), but officially (work shop manual and Police version maintenance note) Ford effectively says do not disconnect the LVB unless you intend to replace it.

Power supplies are a little different than chargers. They basically say here’s power take it or leave it. Chargers monitor voltage so if the onboard charger kicks on, the outboard charger turns off (or vise versa). So both chargers end up not working effectively. It’s not going to damage anything but you might not end up with a properly charged battery in a decent amount of time. Disconnecting the POS terminal only will accomplish the same thing of isolating the onboard equipment.

 

[louibluey]

Someone was able to release it with AA batteries in series, so less than 2amp for sure.

Geez, I should rename my name to @someone (hey it's not taken!).

I wish I had broke out the digitizer or scope to get a good shot of the current waveforms, but it was initially powering a 47k ohm load to bring up the electronic board and micro (very low power), followed by about two 1.2A events, each about a second in duration.

https://www.macheforum.com/site/thr...ery-does-not-work-12v-works.4774/#post-141023

Frunk Bumper Release 9V battery does not work, 12V works

 

[dtbaker61]

I didn't realize the system was smart enough to recognize when the LVB is actually dead. Good to know!

I've ordered 8x lithium AA batteries and a holder (8x 1.5 = 12v). It's small enough to fit inside the front bumper with some zip ties, should the need ever arise.

yes, the frunk-popper bumper leads will ONLY work if LVB is too dead to energize the door locks to open the doors. I hope you have set/memorized the 'manual' door code to get into the cabin if you lose or damage your phone/fob?

if the LVB is indeed dead you are going to need a 'jump' from a running vehicle for a good 15 minutes to get enough energy into the LVB to get it's voltage up high enough to restore functionality to 'start' the MME at which point the HV should take over the task of charging the LVB. So stashing a pack of AA batteries under the bumper is probably a waste of time since there would be a vehicle there already to give you a jump.... after you remove the beauty panel(s) to gain access to the jump points.

 

[louibluey]

Power supplies are a little different than chargers. They basically say here’s power take it or leave it. Chargers monitor voltage so if the onboard charger kicks on, the outboard charger turns off (or vise versa). So both chargers end up not working effectively. It’s not going to damage anything but you might not end up with a properly charged battery in a decent amount of time. Disconnecting the POS terminal only will accomplish the same thing of isolating the onboard equipment.

yep, A lot of us the Clore Automotive PL6100 Flash Reprogramming Power Supply 100 Amp for both programming (in power supply mode) or charging (60A charger).

I also have this little 20A unit for easy quick charging. Clore Automotive PL2320 20-Amp Fully-Automatic Smart Charger, 6V and 12V Battery Charger, Battery Maintainer, and Battery Desulfator with Temperature Compensation. Its power supply function does not have a high enough ampacity for MME programming.

There are many other types an options. There is no need to disconnect the MME LVB when charging. But, doing so is okay too.

Lifting the negative terminal is about a 10 second operation if you must (e.g. for electrical work). Lifting the positive terminal is a more involved operation. Lifting the chassis side of the negative terminal cable is an absolute PAITA, which is what the workshop manual calls for.

Update: While out working on MME last evening (more measurements), I remembered that to lift the positive clamp from the LVB, you have to remove the frunk tub, a much bigger project. I can do it pretty fast now, especially since I retapped all the threaded holes (some were binding pretty bad, others have reported broken screws from binding). But, if it is your first time, it will take some time. I would not opt to remove my frunk tub, over the 10 seconds it takes to lift the negative LVB terminal clamp, if trying to do a cold boot at a highway rest stop!

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