Many of us will soon be looking for a replacement vehicle battery, and John M. has been doing a lot of research to find the ideal replacement. The Mopar battery (BB0H5500AB) identified in both my Specs section and my battery articles written a few years ago, has apparently been discontinued, and superseded by one or two others, and like most Fiat parts, seems to be overpriced. As Stefan reminds us in the first comment, Fiat has simply selected an existing Jeep battery that is a little smaller, so that it fits in the battery tray.
So what ended up being John’s best solution? The exact Q85* replacement battery obtained from a Mazda dealership. He writes:
I found an actual original factory battery source for our Spiders. Once again, it’s as simple as Mazda dealers. The Q85 battery in our Fiats is the same factory battery as used in recent year Mazda 3’s equipped with something called “i-ELOOP” (start-stop).
And apparently there is no substitute that will work for those cars, so Mazda dealers stock them – but in very small numbers. My closest Mazda store stocks just one and doesn’t order another until it sells (which they do regularly). Local price here is $425. Also online for about $320 not including what must be very expensive shipping.
The Mazda part number for the battery is PE1T-18-520-9U. It is a Group 35 size battery. The batteries that Mopar lists are in larger size groups and I don’t see how they could fit into the Spider battery tray.
Panasonic developed a Q85 battery exclusively for Mazda’s i-ELOOP vehicles, to be used with a non-standard alternator and a capacitor, as explained in this article that John found.
The i-ELOOP system uses a unique variable voltage alternator that can produce up to 25 volts during deceleration. The electricity that is generated during deceleration is not sent directly to the vehicle’s battery, because the battery cannot store more than 12 volts. Instead, the capacitor stores the electricity, up to the 25 volts produced by the alternator.
The Q85 battery that Mazda has installed in our cars is more generic, is only designated as Stop-Start, and is a flooded cell lead-acid battery apparently produced by a few companies, one example of which is shown in the top photo. If the price is right (and you can find one), that battery, made by Bosch @ 620 CCA would fit perfectly!
Replacement Battery: As an alternative to the spec battery, FIAT has recommended that U.S. dealers install their stocked H5 battery (currently MOPAR # BB0H5500AB), which fits OK, although slightly smaller in height and capacity (500 CCA).
See my battery article for other BETTER alternatives, which include good-value and readily available Group 35 (and Group 51R) batteries, unlike the Q85, at least here in the U.S.