Battery for Frunk Release to store in bumper

[louibluey]

The 12V LVB battery problems seem largely solved by software and/or warmer temps (probably mostly the software fix).

Eventually, there will be dead 12V batteries, and I have been thinking about what to store in the bumper to pop the frunk.

There was a lot of talk of a 9V battery. Looking at the relatively heavy frunk release solenoid (?) wires, I'm thinking a standard 9V battery probably will not do the job (has anyone tried it yet?).

Do we have any small battery experts? I'm thinking something like this relatively small 12V AGM battery 1.3AH might work well. It would need be charged every 4-6 months.

(LiFePO4 would be better, but they are pricey, and I do not know if they come in this size.)

It would need the terminals well protected, and then possibly in a plastic bag and wrapped in some cushion, but I think it will fit okay:

It would be good to get some electrical measurements of the frunk release circuit, but for the first time ever with this EV, I am hesitant to cold boot it if not needed (remove the 12V battery ground terminal) for fear that something might need to be re-programmed afterwards.

There are two 15A fuses marked frunk release, possibly pulling one of them would simulate the dead LVB (close the contacts on the lockout relay) for the front wire frunk release circuit for some tests?

 

[Kamuelaflyer]

2 9volt batteries connected to each other (they're built that way so that they can easily do that). Enclose them in a waterproof bag, warp it up, and put them in the panel. You don't need much power to get the frunk to actually open.

All this preparation presumes though that this happens when you're out in the middle of nowhere and don't have access to any services.

 

[Shayne]

2 9volt batteries connected to each other (they're built that way so that they can easily do that). Enclose them in a waterproof bag, warp it up, and put them in the panel. You don't need much power to get the frunk to actually open.

All this preparation presumes though that this happens when you're out in the middle of nowhere and don't have access to any services.

Can you not just use jumpers from any vehicle to do it? Would not be the first time I walk around asking "you got jumpers?". No spare either I guess I am just living on the wild side .

 

[louibluey]

yes, jumpers from another car would do it, but I like to be self sufficient as much as I can. My Li jump pack is just a little too big to fit in there (GB40), so I could leave it in the frunk. I'm thinking if I can get to the jump posts with the jump pack (for a flat LVB), there is a chance I might not need to call for help.

 

[mburtsvt]

yes, jumpers from another car would do it, but I like to be self sufficient as much as I can. My Li jump pack is just a little too big to fit in there (GB40), so I could leave it in the frunk. I'm thinking if I can get to the jump posts with the jump pack (for a flat LVB), there is a chance I might not need to call for help.

Someone correct me if I'm wrong - Is the Frunk a pull, (non electric) release? I remember having to pull it twice to open the frunk.

 

[louibluey]

Someone correct me if I'm wrong - Is the Frunk a pull, (non electric) release? I remember having to pull it twice to open the frunk.

The short answer is that there are two wires (red/black) with round electrical terminals (like wires grounded to the chassis with a screw) behind a little door that opens in the bumper. If you cannot get into the cabin to access the manual release (the double pull, driver's side mechanical release that you describe), powering the wires pops the frunk lock release. Apparently there is some logic (probably a relay) so that if the LVB is okay, the emergency release circuit does not work.

The long story is some kind of legal mess where there was an electrical / electronic release (button and/or screen soft button?) that got nixed short term for some reason, in other threads (others know a lot more about that part).

 

[louibluey]

2 9volt batteries connected to each other (they're built that way so that they can easily do that). Enclose them in a waterproof bag, warp it up, and put them in the panel. You don't need much power to get the frunk to actually open.

All this preparation presumes though that this happens when you're out in the middle of nowhere and don't have access to any services.

That is what I am struggling with, a solenoid probably needs at least a couple of amps. Some 9V batteries can do an Amp for a moment, others no more than a few hundred mA. OTOH, if it is just an electromagnetic solenoid, why do they tell us we need to observe the correct polarity?

Unless it was mostly weather protection, those wires are definitely sized for Amps, not an electronic release signal (mA).

It would be great if someone who has access could pull the wiring diagram for these parts.

 

[engnrng]

The 12V LVB battery problems seem largely solved by software and/or warmer temps (probably mostly the software fix).

Eventually, there will be dead 12V batteries, and I have been thinking about what to store in the bumper to pop the frunk.

There was a lot of talk of a 9V battery. Looking at the relatively heavy frunk release solenoid (?) wires, I'm thinking a standard 9V battery probably will not do the job (has anyone tried it yet?).

Do we have any small battery experts? I'm thinking something like this relatively small 12V AGM battery 1.3AH might work well. It would need be charged every 4-6 months.

(LiFePO4 would be better, but they are pricey, and I do not know if they come in this size.)

It would need the terminals well protected, and then possibly in a plastic bag and wrapped in some cushion, but I think it will fit okay:

It would be good to get some electrical measurements of the frunk release circuit, but for the first time ever with this EV, I am hesitant to cold boot it if not needed (remove the 12V battery ground terminal) for fear that something might need to be re-programmed afterwards.

There are two 15A fuses marked frunk release, possibly pulling one of them would simulate the dead LVB (close the contacts on the lockout relay) for the front wire frunk release circuit for some tests?

I got a small jump starter at Lowe's. https://www.lowes.com/pd/Sportsman-Series-Portable-Jump-Start-Battery-Power-Pack/1003130534 Wonder if it would fit in there. I will try later and report back.

 

[generaltso]

One thing to keep in mind with portable jump starters is that most of them have some sort of short-circuit protection built in so that you don't cause sparks if you accidentally touch the two leads to each other. This protection won't let power flow out of the jump starter unless you hook it up correctly to a battery with at least some detectable voltage. This is a problem if you're trying to jump a battery that is completely dead, and will likely also be a problem when trying to energize the leads in the bumper to open the frunk since there won't be any voltage on them. When purchasing a jump starter, I recommend getting one that allows you to manually override this safety feature if necessary. Here's one such example:

https://www.amazon.com/NOCO-GB20-Ul...d=1&keywords=noco+boost&qid=1615755553&sr=8-8

 

[louibluey]

Excellent point, plus the GB20 might be small enough to fit into the bumper opening (the GB40 does not fit through the bumper access door). I think it was @ChasingCoral who suggested velcro in another thread. I'm thinking at least some bubble wrap or soft foam. It would be kind of nice if the one unit does both the frunk pop, plus the actual boost start. It takes very little energy to start the MME, a GB20 is more than capable for that job too.

But, it is way too big to fit through the bumper door.

More on the polarity mystery. I wonder if there some kind of diode logic in this system which causes the solenoid to not work from the bumper wires unless the 12V LVB bus voltage is very low? That could explain why they demand proper polarity for what should be just some kind of solenoid latch. Just a guess. Hopefully someone can access the wiring diagrams at some point.

 

[eltonlin]

One thing to keep in mind with portable jump starters is that most of them have some sort of short-circuit protection built in so that you don't cause sparks if you accidentally touch the two leads to each other. This protection won't let power flow out of the jump starter unless you hook it up correctly to a battery with at least some detectable voltage. This is a problem if you're trying to jump a battery that is completely dead, and will likely also be a problem when trying to energize the leads in the bumper to open the frunk since there won't be any voltage on them. When purchasing a jump starter, I recommend getting one that allows you to manually override this safety feature if necessary. Here's one such example:

https://www.amazon.com/NOCO-GB20-Ul...d=1&keywords=noco+boost&qid=1615755553&sr=8-8

How far apart are the jump points? Is it me, or do the cables look kinda short?

 

[louibluey]

How far apart are the jump points? Is it me, or do the cables look kinda short?

@dtbaker61 posted some good pics with his idea to cut access holes.
https://www.macheforum.com/site/threads/how-to-add-access-ports-for-lvb-connection-points.4107/

Cancelled my Amazon order ... it is way too big. The little 12V battery from the first post (about $12 +shipping) might be best. I think it will fit through the bumper door. (I already have a GB40, they are great)

It looks about the same as the distance across a 12V battery, the NOCO wires should be long enough. But, definitely something to check. I ordered a GB20, should be here by around Wednesday.

This pic claims 19"? They sure don't look that long:

 

[generaltso]

This pic claims 19"? They sure don't look that long:

Yeah, they're definitely not 19.5" and the little USB charging cable isn't 40". Maybe that pic is supposed to be centimeters. I believe the GB20 is physically the same size as the GB40. The jumper wires are each 6", so you could jump a battery with the terminals up to a foot apart.

 

[SnBGC]

Someone correct me if I'm wrong - Is the Frunk a pull, (non electric) release? I remember having to pull it twice to open the frunk.

It is both. Opened either with a mechanical or electrical release.

 

[crabby]

12 Volt - 0.8 Ah - UB1208 - AGM Battery
Shows a size of 1" x 2.5" x 4"
Has anyone measured the space available and any thoughts on the power of this AGM to operate?


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