A-Class (W177) (V177) 2018 to present

Permanent Live Fuse

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Old Jan 18, 2023 | 03:22 PM
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A35Sam's Avatar
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A35
Permanent Live Fuse

Hi All,

I have hardwired a BlackVue dashcam that has voltage monitor for parking mode. The camera monitors voltage and cuts off at a set threshold to ensure the battery is not depleted for start up.

the camera is wired in via ACC (switched fuse) and BATT (Permanent live feed). After doing some research I wired into fuse 164 for the perm feed and fuse 125 for the switched feed.

Both work very well, ignition off means camera goes into parking mode and ignition on goes into normal mode. When I leave the vehicle is when the trouble starts….

The camera stays active for around 55 minutes and then powers off - however the powering off is not the camera cutting power due to low voltage but is the car cutting the power to fuse 164 55 minutes after ignition off so it appears to be a false live (assume it is a sleep mode timer).

I tried numerous fuses and all seem to react the same way, however I tapped into fuse 129 which is the alarm system and that kept the camera active so is a constant true live, however due to the location of 129 and 125 being so close I can’t fit both fuse carriers in.

Now comes my question, does anyone know of any fuses that are true lives? I’ve spent the best part of 3 days searching forums and trial and error to no luck yet! There must be someone’s who’s wired one of these in successfully!

The only way I could check is with a meter but I don’t fancy sitting in the car for an hour locked!!

Any help would be appreciated.

Thanks
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Old Oct 29, 2023 | 06:34 PM
  #2  
PoMo's Avatar
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A250 2013
Originally Posted by A35Sam
Hi All,

I have hardwired a BlackVue dashcam that has voltage monitor for parking mode. The camera monitors voltage and cuts off at a set threshold to ensure the battery is not depleted for start up.

the camera is wired in via ACC (switched fuse) and BATT (Permanent live feed). After doing some research I wired into fuse 164 for the perm feed and fuse 125 for the switched feed.

Both work very well, ignition off means camera goes into parking mode and ignition on goes into normal mode. When I leave the vehicle is when the trouble starts….

The camera stays active for around 55 minutes and then powers off - however the powering off is not the camera cutting power due to low voltage but is the car cutting the power to fuse 164 55 minutes after ignition off so it appears to be a false live (assume it is a sleep mode timer).

I tried numerous fuses and all seem to react the same way, however I tapped into fuse 129 which is the alarm system and that kept the camera active so is a constant true live, however due to the location of 129 and 125 being so close I can’t fit both fuse carriers in.

Now comes my question, does anyone know of any fuses that are true lives? I’ve spent the best part of 3 days searching forums and trial and error to no luck yet! There must be someone’s who’s wired one of these in successfully!

The only way I could check is with a meter but I don’t fancy sitting in the car for an hour locked!!

Any help would be appreciated.

Thanks
I had some issues finding this also and I note nobody ever answered this post, so for anyone else in the future, I'll post the below.
I have a 2023 Australian delivery A250.
Fuse number 130 has permanent power and I suspect all in that block do, but I did not test. I used 123 (which is a larger size) for the switched power.
Fortunately both of these were spare on mine, but I had to cut a little out of the fusbox to accomodate the fly wire from the fuse tap - nothing serious.


Hope this helps others.

Cheers


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