[nickop]

Bit of a noob question but are the "spare" fuses in the i30 fuse relay usually active and reliable? Our dashcam was setup by a guy I paid who wired it to a 20A Spare as the constant power source (ACC was wired to Power Outlet). Tried searching but all I found is that they are spare fuses to use if another one blows, nothing about the power supplied. Asking because it works but we have some intermittent issues that may be related to power consistency on the dashcam (Viofo rear cam disconnecting).

[The Gonz]

Not sure I follow your choice of words but if the selected fuse is supplying power, then it is a spare active fuse, not just an inert fuse holder. What needs checking is whether it provides BATTERY feed or ACCESSORY feed. BATT will supply all the time, ACC only when the key is turned.

Once this is determined, there's no grey zone: power is there or it isn't. The only exception is if you accidently tapped into the time delayed dimming of cabin lights.

I had a quick look at mine, in previous cars the 'spare' fuse slot was usually devoid of any metal contacts and indeed just a spare slot to keep a spare fuse.
In my GD the one spare slot I tried has metal contacts for the fuse so I assume it's wired to something and live, whether that be with ignition on or not I don't know, a multimeter test would prove it.

[nickop]

Thanks both, yeah my older Getz just had some spares sitting around so I'm not familiar with the concept of a connected active Spare fuse. I have an IT background and "undocumented features" are pretty common there so I was wondering if this is something people use but the manufacturer doesn't officially endorse.

The background is I have a Viofo A129 Plus Duo, I think the wiring is correct and it seems to switch between park and drive (supposedly triggered by the ACC wiring). However it periodically loses the rear camera connection which is a fairly common issue reported online. I actually moved cameras between cars and it seems to break more in the i30 than the other car., and running it from a battery pack or wall charger doesn't seem to cause issues (needs more testing). So that is weird since it seems to be pointing to the i30 as the issue because I got problems there with both hardwire and cigarette lighter supplying power. Maybe the super long USB cable to the rear camera is asking for a voltage to overcome resistance which doesn't always quite get there. But this is just speculation at the moment.

[The Gonz]

Maybe the super long USB cable to the rear camera is asking for a voltage to overcome resistance which doesn't always quite get there. But this is just speculation at the moment.

I was thinking this ahead of reading the words. Indeed USB 5V does suffer loss over length and devices are not as tolerant as you might think. To illustrate, I bought a 1m aftermarket charging USB cable for my old Samsung 10.1 tablet, for the convenience of the extra length. However, it charges  MUCH more slowly than the original short cable.

You can solve your problem by providing a regulated 5~6V supply switched in via a relay close to the camera. This means you can still use the USB 5V as a switching signal in parallel with the data being sent back, but supply an independent voltage close to the device (the more current you need, the more important to limit lengths*), while not loading the original 5V line.

How many amps does the camera draw? Based on this you can select a suitable regulator. Cheap yet solid solution. The two items below look like overkill but, for the price, are probably the cheapest way, combined, to provide the solution. I can sketch how you can wire the circuit up.

relay 5-12 v | eBay

DC-DC Buck sent down Converter 6-24V 12V/24V to 5V 3A CAR USB Charger Module | eBay

* Power is delivered over long distances at very high voltages because this results in lower currents for the same power transfer (P=IV). If you try to deliver the same power over a lower voltage, more current flows, which results in greater loss as heat.

[nickop]

I'd love to see a diagram for curiosity's sake but I'm not sure I'd be up to the task of wiring it up. I have zero electronics tools (no multimeter even). I could maybe give it a go though it does look cheap to try.

I tried to find power stats online but couldn't for the Plus Duo, just regular Duo, Pro, etc. What is the power cosumption data of A129 Pro Duo, A129 Duo, A119V3, A119V2, WR1? : VIOFO Support Center

It seems well under 1A at 12V input if the pattern holds.