you need a battery with 1000 CCA... I have one, even in FL its needed.

Some basics have been missed here:
-Don't assume that since the battery is "new" that its fine. Take it to a battery shop and have it load tested.
-Don't assume that your charging system is perfect. Verify that the charging system is fully charging the battery and that the alternator is not weak and just barely doing its job.
-Don't assume that the "new" glowplugs are functioning. If you are having hard start issues I would benchtest them all. They need to glow bright red.
-Carefully check the battery/starter cables. They can be internally corroded and you would never know. If the current cannot get to the starter then it won't do its job. I'm a big fan of "upgraded" double-sized battery cables custom built from welding cable. Maximum flow to the starter to spin the engine as fast as possible.
-Use FULL synthetic oil. The engine needs all the help it can get to spin as fast as possible.
-Its rare but the starter itself could be weak. If all else fails a starter rebuild shop could likely test it for you.
-Compression test and adjust the valves? Make sure the engine is sound.

All these things should be checked and verified before spending lots of cash and time on a second battery. RT

__________________
When all else fails, vote from the rooftops!
84' Mercedes Benz 300D Anthracite/black, 171K
03' Volkswagen Jetta TDI blue/black, 93K
93' Chevrolet C2500HD ExCab 6.5TD, Two-tone blue, 252K

Wiring batteries in parallel is perfectly fine. Semis and diesel pickups have been doing so for decandes without problems.

It is.

No, you don't need an isolator if you wire them in parallel and they are the same age and type.

These cars were designed to start in the dead cold of winter in the Alps and Scandinavia. I recall from my Army days, it was US equipment that needed extra batteries (even before the NATO 24V standardization.)

__________________
1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!

Like a lot of other posters have written, I would get the best 1000CCA battery you can get and this is a reason I have an Optima!

I've got an OEM MB battery. I like how it looks in the engine compartment.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

And often a better option than the aftermarket replacements too if you want enough power to operate the vehicle properly! How Much?

Review this and the "Ampacity" section and the "wire fusing current" - bottom 1/4th of the page.
http://www.interfacebus.com/Copper_Wire_AWG_SIze.html

Treat your high current carrying cables as if they are in a bundle, not free air.

__________________
1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!

well i am gonna throw in my solution here. has got me out of a lot of tough spots. buy those portable battery jumpers, get the biggest one u can get, don't go cheap here.

when u attempt the start the car and running low on juice, i usually hook it up and the extra supply will get me going. its the single best thing i have ever bought and i have used it this way countless times. I also got the biggest battery advance auto part sells that helped a lot too.

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198? 300D ???K - Future DD
1989 300TE 285K - traded in '12
1984 300SD 186K - Sold in 08
1978 300SD 330K - Died in 05

Well, I had mine put in by MB roadside assistance because I got stranded....it cost me $142.90.....which is what I think they normally cost anyways. They only charge the parts cost for the service, no labor or anything.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

What is the CCA rating on the replacement that MB put in?

John

__________________
Certified Registered Nurse Anesthetist (CRNA)
2002 F250 powerstroke with Plantdrive WVO conversion
1983 300SD 190K miles ,sold
2006 E320 CDI

I was having similar behavior from my SD just before Christmas, at only ~40s weather. I finally got around to replacing the starter after having checked for proper glow operation, as well as charging (which I thought to be the problem..)
It was amazing what a difference a strong starter makes! I didn't think it would make that much of one, but it definitely spins the engine over faster, and I've gotten starts in cold weather down into the 20's that start as fast as hot weather starts on a warm engine last year, when I was using the old starter.

It also behaves like I have a MUCH larger alternator now, nowhere near discharging the battery even after a day of starting and parking the car. Before I was worried about how much charge it got, even with a 15mile drive home, wondering if it would start in the morning! I'm writing this off to having a lower current demand with a healthy starter.

I know that the cost of a starter is a little steep, but I suspect that it might serve you well to consider it.

Oh, when I had my starter off, it tested "good" at a local Schucks parts house, made all the right noises, but didn't have the speed, torque, or something that this diesel engine was looking for.

__________________
-Josh
Testing the cheap Mercedes axiom, one bolt at a time...

I would do several things to assure starts in very cold weather.

As other have said, find the highest amp hour battery you can find. Talk to a battery shop not a retailer. The retailer will only sell you what they have where the battery shop has much greater access and can tell you the pros and cons of high density batteries. I go to the battery shop in our industrial area where the cities largest truck stop is, along with Mercedes, Freighliner, and Volvo maintenance shops.

Assure all of the connections between the battery and the starter are very clean and coated with electrolytic grease before re-connecting.

Covert the glow plugs to a system like the Beru ISS http://www.beru.com/english/produkte/iss.php or the Diesel Forum http://www.dieselforum.org/meet-clean-diesel/what-is-clean-diesel/new-technologies/glow-plugs/ Unfortunately this system is only for four and five cylinder cars or I would have it in my 300SDL.

Mercedes dealers uses M1 0W40 full synthetic in all MB cars. Flows better at low temp than 5W or 10W...

Have all the maintenance up to date, valve adjustment, clean banjo bolt, good compression etc. How many miles? Is the car ready for new/rebuilt injectors?

Does she know how to start the car? When it is cold does she know how to count the timer down for maximum heat? By doing this my car always starts instantly, I mean it does not even turn one revolution, hit the starter and the car is running! My owners manual says when starting to hold the key in the start position, after the car has started, until the motor runs smoothly.

Does she understand that after a deep start the car needs time to recharge? She can't drive five miles let the car sit all day, start and drive five miles back to the dorm let the car sit all night and do it again. I carry two keys all the time. If I am grabbing a cup of coffee at the connivence store I leave the car running and lock the door.

The car was designed to run anywhere in Europe. If you look at Germany on the map you will it's latitude stretches from the northern US border to Alaska. I lived in southern Germany for 15 years at 50 degrees Northern latitude.

A well maintained MB diesel will start easy at -20.

nrk

Its "Made in Spain" and its a 100A and 1100 CCA battery. It easily starts the car in the coldest of temps....even when I had to crank 8-10 seconds when it was 0F out a month ago. Cranked strong the whole time without slowing, and that was after a 25 second glow. Good battery.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

They are.

I just converted to the updated Bosch system and have bench tested the GP.

Using 5-40W semisynthetic

Valves adjusted 4000 miles ago, no banjo bolt on the 240D, not sure about compression. Put in new injectors yesterday. The old ones were really grungy, probably original.

We have been over this several times, but I have not been there when it does not start for her.

I hadn't thought about that. This is exactly how long her one way commute to highschool is. I will put the battery on trickle charge overnight for cold weather.

Thanks.
John

__________________
Certified Registered Nurse Anesthetist (CRNA)
2002 F250 powerstroke with Plantdrive WVO conversion
1983 300SD 190K miles ,sold
2006 E320 CDI