I found the stock battery woefully undersized even though I haven't put a huge stereo in. Since the stockie was on its way out it was a good opportunity to upgrade.
Looking at the 3.0 they have a much larger battery, so I checked the parts and there are only a few things you need to buy to do the conversion:
- Subaru part #82122AG001 ($10.00) "Battery Pan"
- Generic 175mm Battery tiedowns (Kmart, I think the brand is Projecta or similar). $2.99
- If you wish to upgrade your ground cables to either 4GA or 2GA thickness, you will need about 70cm for each of the two ground cables, so 1.5 metres in total. Also get gold crimp terminals for them.
- Due to the stock battery having JIN-type posts (freaking tiny) you will need to upgrade to DIN battery terminals to suit the bigger battery's posts. I bought high quality solid brass ones from Ebay which are HEAPS cheaper than overpriced car audio brands: http://cgi.ebay.com.au/DUAL-BATTERY-SYSTEM-TERMINALS-HEAVY-DUTY-FORGED-BRASS_W0QQcmdZViewItemQQ_trksidZp4634Q2ec0Q2em14Q2el1262QQhashZitem483705d377QQitemZ310160774007QQptZAUQ5fCarQ5fPartsQ5fAccessoriesQQsalenotsupported
- Any battery that is listed as fitting into the 3.0. I chose the Exide Extra X55D23C which was $170.00 I have used this type of battery in my old car before and was really happy with its value for money. 3 years warranty compared to the 1year one on lesser models. CCA and RC ratings are about 50% higher than the stock battery.
1. Turn off any battery backup alarm sirens etc you may have.
2. Disconnect the battery, negative first, positive second. Unbolt the tiedowns and remove the battery from the car.
3. The old battery tray just comes straight out; fit the new one in its place making sure the arrow points towards the front of the car.
4. You must reuse the stock rear tiedown rod + nut due to its short length and hooking height. Use the new tiedown rod + wingnut at the front, and the new tiedown on top. Secure the battery. Don't worry about the front rod being too long; it does NOT hit the bonnet when you close it.
5. You will see that the factory positive terminal has two cables which can be separated from the battery post clamp by undoing one nut. Undo that nut so the two cables can be separated. Now cut off or bend off the little tabs which protrude from the right angle terminals on each of the two cables. (see photos in end result to see why you need to do this).
6. When you fit the positive terminal, you can now bolt down each of the two factory leads to each of the side bolts. (Remember you had to break off some of the tabs so they can sit flat on the terminal?).
7. I upgraded both the ground cables which run to the battery. One goes to the transmission, and the other to the pass. side strut tower just behind the fuse box. You need to undo some of the factory black taping to reveal part of the run. The former is about 6GA, and the latter looks like a tiny 10G or similar. I replaced the transmission ground cable with a 4GA cable, and the other one with a 2GA cable.
8. The new ground cables attach to the transmission and strut tower as per stock; when you connect the other ends to the new battery terminal one cable can go in the screwdown clamp and the other will have to go one of the side bolts using a ring terminal. Sand the area around the bolt hole on the strut tower to reveal bare metal; this will allow better connection to the cable terminal.
9. Dispose the old battery properly (take it to the local mechanics).
To come: I need to fabricate some type of a perspex cover or similar for the positive terminal as it is not good to have it exposed like that. The factory cover will not fit due to the width of the new terminal and cables.
Now enjoy much reduced cranking time on cold mornings and increased running time of any accessories with the engine off =). I have also installed a voltage meter in my spare DIN slot to keep an eye on the battery.