I researched battery options for my E46 M3 and decided it would be crazy to purchase anything other than a modern lithium-ion batter with modern technology. So I purchased the Antigravity ATX30-RS battery. With money. From my own wallet. And it saved a
few lot of weight.
The battery in my car was manufactured in 2017, only 4 years ago, however it will no longer hold a charge. Spring’s near, I have a track day scheduled in little over a month, and I needed a replacement.
Whenever I need to replace a part on my M3, I question if there is something better available from the aftermarket? The catch is that it needs to come without a trade-off of reliability or drivability.
In the case of car batteries, there is a great upgrade waiting!
The factory battery in my E46, and most every car sold in the United States, is a lead-acid battery originally designed in 1859 with several standards evolutions in the mid to late 20th century to improve reliability and reduce maintenance.
1859? Late 20th century?
You sure you want to replace your battery with that?
Not if I had a better option.
What I wanted was a modern lithium-ion battery because they offer a number of benefits over the old lead-acid batteries. First, they can be around 80% lighter than a equal sized lead-acid battery. Second, a lithium-ion battery can produce twice the cranking power of an equal sized lead-acid battery. Third, the lifespan of a lithium-ion battery can be nearly three time as long as a lead-acid battery. Fourth, and I’ll stop here, is that they’re safer for the environment than lead-acid batteries because there is no acid or metals like lead, cadmium or mercury that could possibly leak.
Downside? Sure. A lithium-ion battery is probably going to be more expensive.
I had heard of Antigravity a few years ago through the BMW forums. Back then, lithium-ion automotive batteries was still somewhat of a new thing, but they were expensive, and reserved for die-hard racers, weight weenies, or those with deep(er) pockets.
But now in 2021, lithium-ion battery prices have dropped considerably.
So I read through the M3 owner boards on NAM3.com and found a thread on the best battery replacements. Antigravity came recommended.
And Why Antigravity
What’s super cool is that Antigravity offers lithium-ion batteries that also include a feature they call RE-START Technology. Essentially, what it does is cut power to the battery before it runs out of juice. So for example, if you leave the lights on, or have an electrical drain, it won’t kill your battery and possibly leave you stranded. Or at best, calling for a tow or a jump-start. With RE-START, you re-enable the battery by either pushing a button on the battery itself, or with a wireless key fob.
All of this sounds perfect for my car, which sits in the garage for weeks at a time between drives.
In case of the E46 M3, the standard H7 sized battery weighs nearly 50 pounds. This AC Delco replacement weighs 51.6 pounds. Antigravity’s H7 replacement weighs just 18.5 pounds. Those with sports cars know that’s a lot of weight to save, especially if the battery is mounted at the front of the car!
It sounded like I had the product I wanted, but no, I chose to take it a step further. My primary motivator behind the decision was price. The H7 spec battery is over $800 and that was just too much for me to swallow. Luckily, Antigravity’s ATX-30 weighs in at less than 6 pounds and according to members of the BMW community, offers plenty of cranking power for the E46 M3!
|Capacity||Voltage||Cranking Amps||Dimensions||Operating Temp||Charging Temp|
|204Wh/16Ah/32 Ah PbEq||12.8||880A||166x126x173mm||-20 to 43c||0 to 40c|
Additional Required Hardware
The ATX30-RS is not a 100% drop-in replacement but it is easy enough to fit in less than an hour. The smaller dimensions of this battery mean the factory tie-down hardware simply doesn’t fit and requires a custom solution to properly secure it in place. And again, thanks to the fantastic BMW community, the installation has been done and documented before.
Additional parts I picked up were J-bolts, a plastic hold-down, and brass battery posts. All the parts I purchased are linked below. The ATX30 RS battery was $360 and the rest about another $30.
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Weight Comparison and Installation
High level installation of this smaller ATX30 battery goes like this:
- Disconnect battery cables
- Remove the old battery
- Position new battery on battery tray
- Mount battery hold-down securely over new battery
- Measure and mark holes for J-bolts
- Drill holes for J-bolts
- Install mounting hardware
- Re-attach battery cables
While I had the batteries out I figured I’d place them on the scale to get their exact weights. The old battery came in at nearly 46 pounds. The Antigravity ATX30 didn’t even register on the scale so I had to place it on top of the old battery to get the difference. 5 pounds or so. Exactly what I expected.
Really guys, this upgrade is almost like a battery delete. My wife’s purse is heavier than the ATX30. The only other modification I’ve done that comes close to this in terms of dollar-to-weight savings is the S2R Tuning carbon fiber sunroof panel.
And here’s an installation video I created for additional help.