10-18-2015, 08:50 PM | #1 |
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Which Fuse Always Live?
Want to hardwire a dash cam and want the ability to record while parked (will use a discharger which will cut the power of voltage runs low). However I can't figure out which fuse (glove box or trunk) can be tapped.
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10-19-2015, 04:14 PM | #2 |
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I had more trouble finding a fuse that was NOT always on. When I checked all the ones in the trunk behind the right cubby were constantly hot.
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10-19-2015, 08:51 PM | #4 |
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Scratching my head a little bit. Let me see if I have this correct. You want to run a dash cam while the car is parked for perhaps an unlimited time or until the voltage drops to a certain amount? So you can't be constrained by the "power on" after shut off? If so, bypass the fuses altogether and wire directly to a battery connection and install your own fuse. If not, and you just want a limited on, I would agree with nonot. Just use ACC fuse. If you're not awhere of this, many owners seem to have electrical problems in the early F25's with voltage drops from the car sitting for a couple of weeks. Don't know if this applies to newer model, but thought I'd mention it since you're going to have a draw on battery.
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10-19-2015, 10:12 PM | #5 | |||
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Last edited by 3002 tii; 10-20-2015 at 12:32 AM.. |
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10-19-2015, 10:25 PM | #6 |
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Have to fix glovebox fascia yet again tomorrow. This means removing glove compartment exposing fuse box and wiring. I'll take a quick look with the volt ohm meter.
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10-20-2015, 11:22 AM | #7 |
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I'll take payment in beer! Sat in the car until ACC/Lighter no longer read a voltage. Then checked fuses for "hot". These still read a voltage after others did not. Outlined in red box
Edit-I did not test all fuses, just looked for the first few that showed voltage. Remember to verify on your own car before using! Last edited by Radioactive; 10-21-2015 at 09:09 AM.. |
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10-20-2015, 10:05 PM | #8 |
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Nice! Thanks Radioactive.
There should also always be a "hot" pin in the ODB-II connector too. I would have expected Fuse 3 (Tan, 5A, right side, 3rd from the top) to be hot, but with nothing in the ODB-II socket then it may not have been drawing power. It may be easier to tap the power lead to the ODB-II socket than the fuse box. Another alternative to the fuse box might be to use an inline fuse on your power lead and go to the jumpstart terminal in the engine compartment. |
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10-21-2015, 12:15 AM | #9 |
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Thanks for spending the time to do this. Question - aren't 30/40amps too high for a small accessory like a dash cam or radar? Wouldn't I risk shorting the device?
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10-21-2015, 02:43 AM | #10 |
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Your cam will only require/ask max something like 1A of current, meaning it will require the source to deliver 1A. If your source is fused with 30 or 40A, you can connect 30 or 40 dashcams :-) before you loose the fuse. The other way around you will only loose the fuse (40A cam on a 1A fuse).
Voltage is something different, but that is normally all 12V in a car, but there if your cam would need only 5V and you connect it to a 12V source, it will burn out (and likely cause a shortage). To be sure check current and voltage requirements of the cam. |
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10-21-2015, 02:46 AM | #11 |
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By the way, I wired to the back as this turned out to be a lot easier to work in the fuse box (and no hassle to take out the glove box). Wiring took maybe 10 mins (not even)....
What cam are you connecting? |
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10-21-2015, 07:32 AM | #12 | ||
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I plan to use a 5v hardwire kit. Quote:
Rexing V1 dash cam https://www.amazon.com/dp/B00X528FNE..._Cv4jwb5BENQHN |
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10-22-2015, 06:21 PM | #13 | ||
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What route did you take for the wire? |
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10-23-2015, 02:35 PM | #14 | ||
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I have put my dashcam underneath the mirror in the center, then pushed the wire behind the mirror covers and went up toward the roof liner, via the roof liner to the front post (passenger side), then via the rubber seals to the bottom. Then via the front door covers (you can just pull them out) to the center, and via the rear door cover (you can pull them out too) via the back seat to the trunk. There I have just put the original 12V adapter and inserted it into the 12V boot connection. I have my 12 to 5 converter to connect it to one of the fuses. I a not planning to have the cam always on, but will use a fuse that shuts down after 10 mins. Planning to use one of the following fuses (with a fuse tab), but still investigating See also: http://x3.xbimmers.com/forums/showthread.php?t=727455 I only did it via the right side of the car, I end up on the fuse box side in the trunk that way and so need less wire in the trunk. 107 10 A 143 15 A 144 20 A 171 ? 176 15 A Make sure you understand fuse tabs if you use them and put them in correctly. Last edited by Jypsie; 10-23-2015 at 02:49 PM.. |
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10-23-2015, 02:47 PM | #16 |
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See the picture, the 5A can be 1A or 2A as required.
If your source is 10A, if you connect your fuse tab correctly, you can split up in 5 and 10. (drawing 2). If you do it wrong, your source is at risk (and unprotected) as it might have to handle 15A and not 10 with what it was protected to start. I hope I explained it well enough..... So in the drawings, the 5A (or 1A or 2A) goes to the dashcam), the 2nd drawing is what you should do. SO make sure you put the tab in correctly. Last edited by Jypsie; 10-23-2015 at 02:56 PM.. |
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10-23-2015, 03:56 PM | #17 |
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Thanks for explaining how you routed the wire to the back of the car.
You confirmed what I was thinking, which is you still need a fuse for whatever accessory you are connecting. Yes, you should leave the original fuse in the bottom slot, so it still handles all the load. So in theory, if you use a tap at a 10A fuse, and you add a 5A accessory, if whatever was running on the original fuse draws 10A, and your accessory draws 5A, then you'd have a total of 15A drawn on that circuit, and the 10A fuse should blow. I didn't realize there is a way to screw up installing a fuse tap though? How do you use it in parallel vs. serial? Isn't it by default in serial? If you reverse the fuses, then the lower fuse, which is 5A will just blow quickly, as soon as there's that much draw on it. You won't turn it from serial to parallel? |
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10-23-2015, 07:39 PM | #18 |
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10-24-2015, 04:39 AM | #19 |
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Post 15 is the wrong way of doing it (parallel), it needs (is better) to be serial. The original fuse (10A) stays the same (so no risk to overload), the new one comes after the original one and will blow first if your cam has a problem (as it has a lower value 5 or 2A). This will leave the original circuit unchanged.
A fuse tap is like a fuse, you can put it in with the wire sticking out to the left or to the right. What is the battery side of the fuse? Remove the fuse, measure which side OF THE CONNECTION still has 12V: that is the hot side, goes to the battery. The other side should measure OV without the fuse, goes to the device. Added an updated picture, hope it helps..... the red arrows are the fuses in the fuse tap. Remark: Yes you can go the parallel way too, but then I recommend to lower the original fuse with the value you put in in parallel, that way you don't overload, but the original device will have to do with a lower fuse, which not always might be a good idea (could be ok if it is only a cigarette lighter). So replace the original 10A with 8A if you add a 2A in parallel... |
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10-24-2015, 07:22 AM | #20 |
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With no time to investigate; I'll delete some messages as not to cause any confusion.
Edit-Although as stated before I'm not an EE, my retired father is! Just happen to be going for a visit today. I'll ask him about it. But without tubes/valves...... Last edited by Radioactive; 10-24-2015 at 07:42 AM.. |
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10-24-2015, 06:46 PM | #21 |
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Update-Going to make this fast since I really don't have the time to write a lot or discuss ampere physics. Ran this discussion past my father, who retired from a major American aircraft manufacture as a electrical engineer after 40 plus years of work. Worked on some of America's greatest military aircraft and commercial aircraft / Specialized in electronic circuit troubleshooting (perhaps the difficult in electronics) Back in the day was on airline flight that was being delay because electrical problems on a plane that he worked on when being manufactured, went to the cockpit and worked with the ground crew to fix the plane. / Built and installed his own electronic ignition system in the 1960's. Another words, I trust his judgement in electronics.
Both types of circuits would probably work in real world situations. Best design practice: Parallel http://x3.xbimmers.com/forums/attach...1&d=1445730196 Took one look at this and without me saying anything, he said "This is wrong". http://x3.xbimmers.com/forums/attach...1&d=1445730294 As far as running on smaller circuit such as 5A, he chuckled. No need, 30A just fine. |
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10-24-2015, 08:17 PM | #22 | |
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