Best Place to take 12V, and switched 12V on the W123
 

Guys,

I am installing a Frybrid 2 WVO tank kit this weekend in the '85. For the electrical portion I need switched battery power, and direct battery power.

I want to do it right, wheres the best place to take it from? Is there an 'easy' way to tap into the fuse block? I know there are free fuse spaces in the block.

Any help greatly appreciated...
dd

dan,

for the lead off the battery, there are battery terminals with all kinds of post options (side, top, etc.). here's a page for you:

http://www.dealtime.com/xDN-car_audio_and_video_accessories--battery_terminals

for the switched, i always take it off the ignition harness.

go to www.the12volt.com and use the wire location search engine. it should tell you exactly what color the wire color is. that is one of my favorite sites for wiring questions.

but even more importantly, im excited that you are installing a frybrid kit! take a lot of pics and notes, i'm definitely interested in learning from your experience.

if you get power off the ignition harness, wouldn't you want to just use that for a relay signal and get power directly from the battery?

Depends on the power requirements for each circuit! If you've got a Pollack valve or two and maybe ane electric heater you'll likely want fused power directly from the battery, probably through relays. The cool thing is you should be able to mount MB relays that will do the trick under the plastic cover on the driver's fenderwell bracket, I think there is room for four relays or maybe even six! You can grab a couple relay sockets at the boneyard and then it can have an almost factory install look.

If you need power for some low power controller in the cabin area, one of the easiest and best places to get that if you don't want to go deep under the dash to the rear of the fuse box(which can be done but it isn't easy especially if your no longer young and limber) is to connect with a ring terminal to the lighting switch. There is both constant +12V and switched +12V at the switches terminals, they are aready fused, and its a very secure screw terminal. Pretty easy to get at also, drop the underdash panel, pull the knob off the switch, the nut is 24 mm remove it and pull the switch out from behind. You can run the new wire into the rubber boot and connect it up. Good Luck!

I did that job once on the W-123 when I was young and limber to install the bypass fuse shunt for the blower motor. Never again.

I do understand, after the fact, that the entire fusebox can be lifted out of the cowl on the W-123 so that access to the terminals is done in a gentlemanly manner.

Can you confirm this?

I took my switch power from the 16amp sunroof fuse on the lower left corner. Just went under the dash with a philips and connect the lead to it. It's pretty cramped in there though.

Thank you for all of the ideas.

The power requirements are small for the switched power (to run the microcontroller and lights) , bigger for the direct 12V (3 solenoid valves for controlled loop). Ill have to look up the specs and make sure I use big enough wire.

Thanks bob for the links to the modified battery terminals - Ill use those.

Since Im young, limber and ambitious Ill try the fuse block rear for the switched power. Ill report back on that.

I was thinking, isn't the cigarette lighter power switched?

Im doing the install of the heated lines and tank over the weekend, electrical is next week.

dd

I tried and tried when I rewired the fogs and installed the remote entry module on mine. There's not enough slack in the main harness to get the fuse block out. However you can remove the mount screw and swivel it around and down for better access inside the car.

0.02
 

I designed my own WVO heating system and I take a different approach and it has worked well for me, 60K miles and going.

1) I always fused direct power from the battery, anything over 8A.
2) For a switched 12V, I open up the fuse cover, solder a 'small' wire to the fuse bracket and connect it to a 30A relay. Just pick any window fuse. There are other fuses to choose from. Run a suitably rated wire to the battery and you have a switch 30A circuit.
3) No need to remove any panel or clamp it with any existing wire harness, will not overload any circuit as the relay only takes mA.
4) If for any reasons that everything need to be removed, just unsolder/cut the small wire and no one will know you have been there.
5) You do not need to be nimble, young or a contortionist to install it. You need a soldering iron though.

Good luck.