Installing Optima Battery in the WRX
Wednesday, March 29th, 2006The other day when my battery died I decided it was a prime opportunity to replace my battery. I am planning to eventually move my battery to trunk, so I spent the scratch to buy an Optima Red Top. Since my car was sittting worthless in my garage, I didn’t want to wait and special order the reversed pole (35-910) which is a direct drop in. Instead I just went out and bought the 75/35 red top, knowing that I would have to replace my starter cable when I installed it.
Most of the guides that I have read suggest simply leaving the old cable in place, unused, and zip tying the new 30″ cable to the old cable. Doing this, the install would have taken about 15 minutes. However, I don’t think that is the right way to do it. So, I decided to remove the old cable and correctly route and strain relieve the new cable. In the end this led to the install taking about 1.5 hours. But I feel that it was done right.
You will need an optima 75/35 Optima Red Top Battery and a 30-32″ starter to battery cable. The battery was about $120, the cable about $5. Plus a 12mm wrench, 10mm wrench, a very stubby flat head screw driver, electrical tape and some zip ties.
Remember — working with car batteries is dangerous. Don’t do this if you are stupid.
- Disconnect the negative battery cable.
- Disconnect the positive battery cable.
- Remove the battery hold down, and battery.
- Install the new battery (do not make the electrical connections)
- Disconnect the 2 wires from the positive battery terminal (one to the fuse box, one to starter)
- Remove the two bolts holding the windshield washer resevoir and lift it up some. You will see there is an electrical connection on the underside of it. Disconnect this connection, but leave the actual tube that the fluid is pumped through. Move the resevoir up and out of the way.
- Now, looking to the driver backside of the engine, under the intercooler, you can see the starter. It is identifiable by the large black 90 degree boot on the positive battery cable running to it.
- Reach back, pull the boot off the positive starter connection, and remove the nut holding that cable on (12mm I think). Be careful because there is a washer on there.
- Follow that cable back up towards the battery. You will see that the ground for the starter is taped to this cable, and it is connected to a hanger off the strut tower.
- You have two choices here. You can leave everything as is, and just tape the new battery to starter cable to the old one. That is fast and easy. I think wrong, but fast and easy.
- If you choose to do this the right way, you now need to seperate the positive and ground starter cables, disconnect the positive from the hanger (there is a tab that you can press in from underneath with a very stubby screwdriver), and remove the entire positive cable from the car.
- Now, starting at the starter side, move all of the strain relief and the hanger from the old cable to the new cable. Tape it all up well, and you should have a nice replacement cable. Test fit it and make sure that when it is connected to the hanger there is enough cable for when the engines moves around.
- Now, reconnect the new cable to the starter and to the battery terminal (still off battery). Reconnect it to the hanger, and zip tie the ground wire back to the new starter wire.
- Connect the wire to the fuse box to the positive battery terminal, and then connect the terminal to the, errr, positive terminal on the battery. (Hope that makes some sense…)
- Double check all of your wiring.
- Reconnect the ground terminal on the battery.
- Start your car and you are done.