Check the date of this posting. It's old... practically ancient history in Internet time. Anyway, today's (early 2008 ) Optima is apparently not of the same quality as four years ago, although the packaging is the same. Accordingly, all of the below is caveat emptor.
I just put in an Optima "blue top" (marine spec) deep-cycle battery, in Group Size 31:
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This battery is slightly wider, slightly taller, and about 3 inches longer than stock. It's rated 900 CCA (cold cranking amps), vs. 410 for stock, and 80 Amp-Hours, vs 45. It was not necessary to use the "blue top", but I wanted the extra terminals for other projects. The "yellow top" Optima D31A is the same battery.
Notes:
1) The stock battery cover and tray/heat shield are removed.
2) You'll probably notice that the big plastic box to the right is missing in my photo (that's the intake resonator). The new battery is a tight fit with the resonator, but it will fit if you unclip the cable clamp from the bottom left of the battery tray.
3) The "blue top" negative (-) terminal was too far back. I had to re-route ground cabling and move some clamps to get it to work with the stock ground harness. This particular wiring is very simple (it's just 4 AWG) and could be duplicated.
3a) This is not a problem with the "yellow top" D31 - terminals are in the right places.
4) There is no holddown clamp in the photo. The stock clamps are about 1/8" too short and the bar is too narrow. A trip to AutoZone is in order for generic replacements. Do not drive your E without the battery clamped-down!
5) A "regular" Group Size 31 battery may not fit. Optimas are usually physically smaller than their spec.
6) At 60 pounds, this battery is double the weight of the OEM battery.
I bought the battery through http://www.remybattery.com for $139 plus $16 shipping. This was by nearly $40 the best price I could find anywhere for this size, which is the largest single-unit battery Optima makes.
I just put in an Optima "blue top" (marine spec) deep-cycle battery, in Group Size 31:
This battery is slightly wider, slightly taller, and about 3 inches longer than stock. It's rated 900 CCA (cold cranking amps), vs. 410 for stock, and 80 Amp-Hours, vs 45. It was not necessary to use the "blue top", but I wanted the extra terminals for other projects. The "yellow top" Optima D31A is the same battery.
Notes:
1) The stock battery cover and tray/heat shield are removed.
2) You'll probably notice that the big plastic box to the right is missing in my photo (that's the intake resonator). The new battery is a tight fit with the resonator, but it will fit if you unclip the cable clamp from the bottom left of the battery tray.
3) The "blue top" negative (-) terminal was too far back. I had to re-route ground cabling and move some clamps to get it to work with the stock ground harness. This particular wiring is very simple (it's just 4 AWG) and could be duplicated.
3a) This is not a problem with the "yellow top" D31 - terminals are in the right places.
4) There is no holddown clamp in the photo. The stock clamps are about 1/8" too short and the bar is too narrow. A trip to AutoZone is in order for generic replacements. Do not drive your E without the battery clamped-down!
5) A "regular" Group Size 31 battery may not fit. Optimas are usually physically smaller than their spec.
6) At 60 pounds, this battery is double the weight of the OEM battery.
I bought the battery through http://www.remybattery.com for $139 plus $16 shipping. This was by nearly $40 the best price I could find anywhere for this size, which is the largest single-unit battery Optima makes.
