Adding a circuit or two

Hello,

I have 2 circuits that I want to add to the car.

1. for the dash cam. It is currently in the cigarette lighter which is always powered, so it needs a new point of connection.
2. for a pair of aftermarket USB ports. Total maybe 20 watts at a time.

Both circuits should only power on when the car is on.

I prefer easy, but even more so, I prefer to do the job just once, the right way.

I understand that running 2 new circuits means putting a fuse in line. If I do it this way, do I go direct from the battery?

All tips and pointers appreciated. I'm an apprentice electrician, so I understand a bit and looking for an intermediate explanation if there is one.

I would tap into the wiper circuit to power the dash cam using a “tap a circuit “ fused connector.
If the other circuit is going to be a continuous feed I would just use a soldered connector from the battery and feed it into the cabin through the access point under the a pillar window. There’s a body plug visible when you open the door. I ran a good sized cable through it and back to the cargo area to run a 2000 watt sinewave inverter and also a 12 volt power point to run an onboard air compressor. The power points that are in the center console are not rated for anything but a phone charger. I did add a switch and inline fuse back there to prevent issues. I can add some pics if you want them.
Welcome to the Fiesta forum!

Thanks for your ideas. I am nervous about using a circuit with more than a little current on it, even though my guess is my 2 circuits don’t even add up to 1 amp. That said, I tried to do this similar to one of your suggestions scotman. I took both circuits into a fuse tap. I chose F9 which is labeled as “keyless vehicle module” because it’s the only spot that the fuse tap fits in. I obviously could have chosen a better tap that could fit into other than just a corner slot.

My USB ports work all the time. My dashcam does not work, but I think the red and black wires are reversed on it.

To solve for power on all the time, I’ll get a rocker switch, or try a better suggestion if there’s one offered to me.

for those pesky mA calculations...

1A = 1,000mA while 0.1A = 100mA (10X less - just move the decimal)

Say your Battery charger uses 20W from your source - being 12V - so Volts X Amps gets you "watts"

So your car uses regulated 12V system - so that's a gimme, so you then use the 12V - then figure 1 Amp (1,000mA) - simple math...

W = 12 X 1 = 12W (Watts)

But if you think 2 Amps (2,000mA) - then the calculation seems to go over...

W = 12 X 2 = 24W (Watts)

So it will be less (consume less) than 2 amps draw for 20W - and remember the "watts" figure is for your 12V input to your charger - being it needs 20W (rating) to push that power somewhere after its in there.

So if it's 5V out - then the 20W for that 5V - is nearly 4 amps! 5V X 4A = 20W. The higher the voltage going in, the less wattage is needed - but as you draw down to the charging voltage needed - the wattage rating takes a turn upwards - as well as it's heating factor.

• There are "smart chargers" that can see the battery and adjust input power to reduce the length of time it needs to charge by increasing voltage but lowering the charging amperage to a safer rate to recharge the battery due to how some lithium battery concepts work. (Different than older ways of thinking). The premise is to raise the voltage to overcome the drawdown that happens with voltages as chargers of old trying to push power across the cells of the batteries in series - may not be enough - so they raise the voltage using "sense" circuitry as a means to follow the charging rate using voltage instead of current

I'd be more worried about the wire AWG# rating to handle that kind of power from the Charger cord...but hope this helps.