PT Cruiser battery upgrade
From Mopedia
It is possible to install a dual terminal D34/78 Optima battery in a 2004 PT GT. (an Optima with side terminals only may also be made to work with a change to eye type cable ends) A conventional size 34 (or other 10 inch square cornered) will not fit due to the square corner on the drivers side front conflicting with the sheet metal radiator/fender support. The rounded corners on the optima make the fit possible.
The ABS battery tray will need the left and right edge lips ground off to allow the 10 inch long battery to sit in the tray. The tray should be retained so that the battery temperature sensor will continue to function.Image:Battery tray.jpg The factory hold down can be made to work with a bit of reshaping on an anvil or a vice. The cheesy battery cable clamps can also be made to work with some judicious straightening with vice grips and channel locks.
If you install with the + terminal toward the engine and the side terminals to the front of the car, the cables will have just enough slack to reach. This puts the + terminal very close to the hold down rod where it crosses over from one end of the battery to the other. If you have replaced the factory air box with an FIPK use of the side terminals facing the rear may be a better solution.
I needed to bend the right hand (engine side) hold down bracket about a half inch toward the engine side to allow the hold down rod to hook without rubbing on the battery base. A potentially better solution might be to bolt a 9 inch long heavy steel strap to the metal base under the battery tray with a hole in each end to accept a more conventional "J" type hold down that would cross over the battery cross ways rather than end to end as the factory hold down does. This would greatly reduce any concerns about how close the battery cable clamp is to the hold down rod. Note that the battery terminals are not supposed to be used for jump start connections. Ther is a long bolt on the hood latch area for the - connection and a bolt with a removable red cover behind the air box and fuse panel for the + connection.
The thermal insulation blanket will not fit the larger battery so I did not use it. You could cut it and strap it on if you feel it is needed.
