How many CCA for my 98 E300 battery to make it through a New England winter?
 

Just bought a Solar BA9 battery tester. Great little tool to have around.

The battery on my 98 E300 is six years old and is reading 750 CCA. Fine but probably not as strong as it was when new. I do notice, however, that some new batteries spec'd for my car are rated at 750 CCA.

When I head into the winter months, how many CCA do you think I would need reliably to start the car assuming a low of 0F? FYI I use a 5W40 synthetic, which makes starting easier when cold.

You'd be safer removing the battery at night, throwing it on a charger, and then install it the next morning.

Not practical in my case. My only question is how many CCA needed reliably to start the car.

Hook it up to a battery tender over night and you never have to worry about it.

If your engine is in good health and starts quickly, and the glow plugs are all working, CCA's aren't really much of a concern. Remember that at 0˚F your battery will have roughly half of the capacity it has at summer temps. Better to make sure the engine is healthy and starts easily than fretting over how strong the battery is.

Normal conditions 850 CCA Severe Conditions 950CC I would assume cold would be considered severe.

You wont hit zero very often in Rhode Island. I have a twelve year old battery 750 cca that starts my tractor well below zero. Its all about the glow

I don't know the answer, but....
 

I don't know the answer to your question, I'm sure any battery seller could tell you what size and CCA you need. You might even find the info at your local Walmart or of course a Google search could probably tell you.

That all said, I own a Ctek battery charger that has a 'recondition' cycle on it. They recommend to run it once a year or so. It hits the battery with jolts of electricity that help to shake the scale off the plates and extend battery life. Check it out on Kent Bergsma's videos.

After 10 years my Mercedes battery still has the stock 750CCA. The CCA doesn't matter if your glow plugs and starter work. It does, but not as much as you think.

Does your battery just meet 750cca, now? What temp is the battery at? My ~800 CCA battery did well over 1200 amps at ~70F, so if your battery is only testing at 750 amps at 70 deg or whatever the temp was, at zero it's going to have wayyyyyyyyyyyy less than specified. Obviously that doesn't answer whether it'll start your car, just food for thought.

Clamp on ammeters are inexpensive, maybe get one and see what it takes to start your car now? Factor in less output from battery at lower temps and double or whatever the current requirement to start your engine at cooler temps, might give you a somewhat educated guess, with some kind of data to look at.

If I remember come winter, I'll take a measurement on mine and see what it takes to start. Won't help you at all for multiple reasons, but now I'm curious.

Edit: Does the E300 have a particularly odd/expensive battery? Here in the PNW, I replace batteries every five years or so regardless of what condition they're in. On a six year old battery, I'd spend the $100 and replace it by the end of winter.

It cost a $120 at walmart for a battery. They aren't anything special.

I noticed that the one that's in there is rated at 760A. That's probably CA and not CCA. So if I'm seeing 750 CCA then battery is in better shape than I thought.

Last two batteries I've bought for our vehicles have been reconditioned batteries from Interstate. $45 or and both have been in service for several years now. Easily the best bang for your buck battery wise.

The only thing "special" about the E300 battery is that it sits under the rear seat. So Mercedes specifies that it must have certain characteristics not to leak at all. Not all FLA batteries will meet that spec. If money weren't a consideration I would throw an AGM in there and forget about it.

It has a vent tube.

Your battery is fine. Unless you've previously let it go dead a few times (which damages it), you have several years of life left. Batteries last exceptionally long in the W210 due to its location. Getting 10 years out of a w210 battery is not rare or unusual at all. Under the rear seat, it's insulated from the engine heat cycling and vibration that shorten the life of batteries installed under the hood. W210 batteries have a cool, comfortable, smooth ride there under the back seat. Nothing unusual about the battery, it's a standard Group 49 or H8 size.

I just replaced the battery in my '98 E300 this year 2017. The old one I took out had a date of April 2006 on it.