Battery packs and delayed ACC fuses

[Mapiarz]

Hi! I have a quick question. I have a 70mai battery pack that I'm looking to use in my car. The car is a 2019 BMW where the ACC fuses are delayed. They shut down roughly after 6 minutes after turning off ignition. I presume battery packs drain much more power when charging than a dashcam would in those 6 minutes. Is this going to be a problem?

Thanks!

 

[Julian23]

I would not recommend it. It could drain your vehicles battery quicker, especially if you drive many short trips.
Try to tap into a ignition only fuse. This way, it will only start charging if the ignition is on, and after turning off the engine, it immediately stops.

The battery pack will draw up to 11A

 

[Mapiarz]

Yes, it makes sense. Although I'm not sure how much of a choice I have. I know for a fact that the front fusebox doesn't have any non delayed ACC fuses. I'll research the back fuse box later. Maybe someone with a bimmer too can chip in.

 

[LeeShadow]

I don't have a BMW, but just an adviso that you might be able to find a somewhat easily accessible switched wire in the front of the vehicle. For example, my Blackvue battery's ACC line is connected to the front12v accessory socket wiring. It is relatively easy to pull out those sockets without disassemble using a specialized tool or releasing the internal tabs with a screwdriver (a bit tricky, but doable). I used a 12v socket harness splitter from Amazon so didn't even need to use a wire tap. Of course, this solution depends on that socket being immediately switched off when the vehicle is. I'm running a separate independent rear cam with its own battery and my rear 12v socket is always on, so I had to add a relay connected to a rear switched USB module to cut power to the battery when the car shuts off. That was a bit more of a complicated solution.

 

[Julian23]

Yes, it makes sense. Although I'm not sure how much of a choice I have. I know for a fact that the front fusebox doesn't have any non delayed ACC fuses. I'll research the back fuse box later. Maybe someone with a bimmer too can chip in.

I have a BMW.
Just go for the rear fuse box.
It's much easier. The cables are long enough to reach the front windshield, depending on the location of the battery.
I put my battery under the passenger seat.

 

[Julian23]

Of course, this solution depends on that socket being immediately switched off when the vehicle is.

BMW cars will turn on the 12V sockets when unlocking the vehicle. The 12V socket will turn off 3-6 minutes after locking the car.

 

[Mapiarz]

Hey thanks for the replies. I went for the rear fuse box where I found a non delayed ACC fuses which work perfectly. My initial plan was to install the battery in the glove compartment or under the seat but there was no room. Ended up having the battery in a pretty neat spot in the trunk, with the fusebox nearby. All in all, all good. Thanks!