looking for a new battery for 355?

You can use the search function to see what others have done. Interstate doesn't list a battery for the 355 and I have a MT-34R in my 348 (battery tray was modified to retain battery via the short conic recess). This last weekend I removed a dead 24F out of a 355 but it isn't the correct battery. The 355 tray has a tab on the leading edge that requires a tang across the full length of the battery and a tang on the trailing edge for the bolted bracket. I found the small white Mercedes battery works great, weighs 43# with 660 CCA. It also fits perfectly in the Testarossa. Sears has a new series call "International" wtih the correct mounting tangs but they only have 4-5 sizes and I didn't have time to check fitment. Remember to disconnect the negative terminal first, then the positive terminal. Notice the poor job some "mechanic" did on the terminals! Good luck!

Jeff Pintler
89 348tb, 86tr
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LINK: http://www.ferrarichat.com/forum/showthread.php?t=209813

 

I put an Optima Red Top in my car a year ago. The first one failed but was replaced free. Cost a bit more but we shall see if it is worth it. I keep the car on a battery tender when not driving. No problems!

 

I am at 100% failure rate on Optima, so are most people. I will try to find what I used in my f355, but 850 cca would be my minimum. Plus I redid (welded in mounts using bigger bolts) the factory mounts because they are very very weak.

 

The correct battery is a Group 34R, BUT I have found a standard Group 34 will fit as the cables have enough room (length) to reach. The absolute best rated Group 34 battery is the Sears Platinum absorbed glass mat battery. It is rated at 880 cold cranking amps (way more than necessary), and was #1 rated by Consumer Reports in their past two tests of car batteries for power and life. Being of AGM construction, no risk of battery acid leaks, as it has no fluid, instead an acid paste. Not cheap at around $189, but available at any Sears. Four year free replacement warranty, the longest of any battery.

http://www.sears.com/shc/s/p_10153_12605_02850034000P

 

850 cca is really overkill. The my car ran perfectly fine with an Interstate Group 34R rated at around 770 cca. Obviously more doesn't hurt (other than the weight penalty of more lead plates) but I believe the factory battery was only rated around 650 or 700 cca.

 

I have always used the Interstate MT34R

 

+1 on the Optima Red Top 34R. Put it in last fall. Mine also came with a few adapters for mounting in different tray types. It had a new clip that I used to replace the "tanged" original one and fit perfectly. I went Optima because I got a great deal on it from one of my jobbers. If I were paying full pop I would go with the SEARS Platinum AGM, my truck battery is on the way out and that is what is going in there.

 

After reading the posts about the MT-34R, I wonder why not use the European style battery (like the Mercedes) that has the correct mounting tangs on all sides of the battery? This jpeg shows the forward edge of the tray that engages the full width tab on the battery. The Interstate does not have the tang on the side towards the bumper and would only be friction fit. My experence with Optima has been a disapointment (orange top and red top failed prematurely) and there have been lots of posts about Optima's quality problems. The Mercedes battery fits great in the retaining tangs/battery tray on the Testarossa. Other european cars probably have the same small battery (Mercedes are made in the USA) so you could invite a friend over to your shop and try his battery in your car. Street price is about $100.

Jeff Pintler
89 348tb, 86tr
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