Over the next few weeks, I'll be running some equipment in the car that
will use more amperage than available from the cigarette lighter/ power
sockets in the car. The equipment will use a 500 w inverter and, up
until this point, I was popping the hood and hooking up the inverter to
battery via alligator clips. However, soon I will be commuting and need
the equipment to operate while in transit so no hood up. I tried to
find a spot to run a positive wire from the battery through the firewall
today, but I had difficulty finding a suitable place, so I decided to
ask here for any possible suggestions.
Thanks in advance,
Buy a step dril and a suitable grommet, and a bit od silicone caulk.
Find a spot on the firewall that does not interfere with anything
either inside or out, and drill a hole. Install the grommet with a dab
of caulk in the groove, pull the wire through the grommet, and seal
around the wire with a dab of silicone. Connect the wire to the
battery / positive power distribution point using a 50 amp maxi-fuse
in an inline fuse holder. If you want it to shut off with the key,
also install an accssory relay rated at 50 amps continuous or better,
and connect the coil to a switched power connection under the hood.
If you want to be able to switch it manually from inside, connect the
one side of the coil to the power(battery) side and run a light wire
along with the heavy wire up to the dash and install a switch with the
second terminal connected to ground, and connect the underhood end to
the other side of the relay coil. A headlamp relay might work, but I'd
use one of the continuous rated solenoid or accessory relay like a
Napa/Echlin part#AR158 (gm 15555675 or d-1793) Looks like a starter
solenoid, but designed for continuous use. A starter relay has too low
resistance on the coil and will overheat and possibly burn out in
It should be an easy task to run what is essentially a set of battery
temrminals inside the car.
First, you will need the appropriate fuse mounted as near to the positive
battery terminal as is possible. Not convient, possible. You might have to
change out the positive terminal on the existing cable, or get an adaptor
that allows the existing cable to connect, along with the new cable you want
to install. On my F150, the cable from the battery goes to a power
diustribution block that has capacity for additional connections, your
Taurus/Sable might have an equivalent power block.
Search the firewall for a grommet, this is a good location to push your
power cables through. You can remove the gormmet and make a hole in it for
the wire, then put the grommet back into the hole after you run the cable.
Once your cable is inside the cabin, then you can connect your inverter. You
should not make the battery connections until you get the wire routed as you
want it, and determine where the inverter will be located. After you have
all of this figured out, then you can make your battery connections -- do
the positive first, then the negative last.
You can pick up the negative from a suitable sized screw or bolt on the
engine, or on the body of the car. It is not necessary to get ground from
the battery, but this may be the most convenient. You might find that there
is electrical noise, this can mean that the ground point has resistance --
paint is a source of resistance.
If any of this makes you uncomfortable, then any alarm installation shop
should be well equiped to handls this for you. It is easy. You have to
calculate the wire size and fuse based on the load. It is okay to have too
much wire, but you will want the fuse to be rated properly for the inverter.
Many inverters have the wire for making the battery connections, so you
might not have to calculate anything, you only need to find a route for the
wire to take through the firewall.
On Mon, 17 Nov 2014 12:20:10 -0800, "Jeff Strickland"
Being a 500 watt inverter, a 50 amp circuit will be more than
adequate. 50X12 is 600 watts. When you are running the engine it's
coser to 14 volts, so 50X14p0 watts.
Upsize one wire size for your length to be safe. #6AWG is just on the
light edge -if you are running that inverter at full load. It's good
for 55 amps in a bundle - more in free air.
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