It all used to be so simple. “Hey fella, you need a jump?” they’d say. “Boy, howdy, do I!” you’d reply. They’d pull up nose to nose with your car, chuck on some jumper leads, and get you on your way. “Forget that!” said automakers. “Let’s make everything different.”
They put the batteries somewhere else. Where? We’re not supposed to know! We’re dirty little consumers who are too stupid to be trusted with three volts, let alone twelve angry ones! Why, if we dared to jumpstart a car or change a battery ourselves, we might burn the whole car down. Best to hide the battery away from curious little hobbits.
It honestly ticks me off so much. My 2007 BMW E90 buries the battery deep in one side of the trunk. My old MX-5 did the same, and you had to ensure that vent hoses were hooked up so gases didn’t leak out and rust the inside of the car to pieces. My Mercedes puts the big box of acid right under the rear passenger seat along with a bunch of fuses for easy ridiculous accessibility.
I know, I know. I’m being overly harsh. Automakers have granted us some conveniences to ease the pain. They often put nice big 12-volt and ground terminals under the hood for hooking up jump leads. Batteries are often maintenance-free, now, too, so we’re not sloshing about water and acid every six to twelve months. Hiding the battery somewhere inside makes it less likely the terminals will get all gross and corroded. And yes, putting the battery somewhere deeper inside the car reduces the chances it’ll burst open, leak, or catch fire in a crash.
But still, I hate it! I hate it so much. I hate it at breakfast, I hate it at lunch. I hate it on Mazdas, and Jaguars, and Nissans. I hate it on Mercs, and I’m filled with derision. What rude designer approved this decision?
Honestly, I hate it because I drive hoopties. I drive beat up old cars and weird German ones, and I know one day, I’m going to have to change a battery. When that day comes, I won’t just be able to pop the hood and get it done in five minutes. Instead, I’ll be pulling off seats or interior trims, then I’ll be unbolting some whackadoodle battery topper panel and trying to wiggle the thing free. The whole time I’ll be trying not to short out the battery to the chassis while unbolting the terminals. That’s much harder to avoid when you’re wrestling around behind the rear wheel well!
If someone else is servicing your car, or you’re only looking at the battery now and then, it’s probably fine. You don’t even think about it. But for me? Every time I’m troubleshooting something and I’m told to “check the battery” I wince just a little bit. Have pity, and for all of our sakes, make them put the battery back where it’s supposed to go.
Lewin out.
Shots fired! This is wrong wrong wrong wrong! I will grant that the under-seat battery in the Mercedes is bad. This is the worst place to put a battery and I also don’t like it. But having a battery in the engine bay? Also bad. There’s too much heat cycling, it’s annoying to try and jump a car on the side of the road, and the area isn’t protected.
Just put it in the trunk! My E39 has a battery in approximately the same place as your E90 battery and it rules. I can park my car nose in and my car can be jumped easily without having to move the car. If my car does on the side of the road, someone can just pull up right behind me and give me a jump without 900-foot jumper cables or trying to point the nose in the other direction.
Also, let’s not forget the big reason why this is being done in certain cars: weight balance. The battery in my E39 weighs approximately 45 pounds. It’s a big boy. The engine in the E39 weighs way more than 45 pounds, meaning that’s a lot of weight over the front nose which, dynamically, isn’t great. Thanks to putting the battery in the back (and a few other things) my E39 BMW has a nearly 50:50 weight distribution and it feels ideal to drive. So, my argument is not to put all batteries in the front, but to put all batteries in the trunk! -Matt Hardigree
Image credits: Lewin Day, Varta
As others have mentioned, putting the battery in the trunk does help weight distribution. I remember specially built drag cars back in the early 60’s that had their batteries not only moved to the trunk, but replaced by larger, heavier bus batteries to put more weight on the rear wheels thus helping traction.
Plus, putting the battery under the hood doesn’t necessarily make servicing it easier. I own a 10-year-old Hyundai Santa Fe. The battery is under the hood, but the space around it is so tight you need a special battery puller to get it out and put a new one in.
To remove the battery from my friends Peugeot 5008, would have required the removal of the bloody air box. Along with an ECU. I’d take the boot of the car any day. I suspect it would be the same for our Ford Kuga, it’s mounted so far back, I’d hate to think what I’d need to disassemble to get it out.
Lewin, please listen to Matt. He’s absolutely right. When i worked on the DEW98 platform at Ford which spawned the Lincoln LS and the Jaguar S-Type, we put the battery in the trunk. It was by far the biggest part of achieving the desired weight distribution. Shifting the battery from under hood to the trunk added 2% to the rear weight. There is nothing else you can do to a car that shifts that much weight without changing the architecture of the car. It just means you need to provide a convenient post on the engine bay to facilitate jump starts. A small price to pay.