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Battery on my 1994 S320

5K views 6 replies 7 participants last post by  anziani 
#1 ·
I've only had this car for a few weeks, and sometimes it would be a little hard to start and I'd have to crank it for about 3 seconds before it fires up.

Today all of a sudden the central locking worked intermittently which I found strange. I went for a drive and parked it up for about 15 minutes, and when I got back to start it, I could hear the starter motor click once but the engine wouldn't turn over at all. The lights are all coming up on the dash like they're supposed to when the ignition is turned on, but it just wouldn't start. I measured the battery voltage and it was 12.6V.

I then jump started it off another car and the 15 minute journey home was uneventful. I took the battery out and noticed that all the cells were quite low on water, and it took at least 500mL of water all up. I've currently got it on charge.

I don't have a battery load tester, so after I've charged the battery on my batter charger, should I hook it back up to the car and hold a multimeter up to it while someone else cranks the engine over? I don't have a proper battery load tester so I thought this should be the next big thing.

Also, what size battery do I need? Does it really need at least a 850CCA battery? That seems quite large for a 3.2L engine. My 1990 1.8L 1C diesel engined Corolla only has a 450CCA and that starts very easily even on a frosty morning (a 1.8L diesel should require a similar size battery to a petrol engine double the size, right?) and today was a nice summer day. I just want to make sure that the charging system is OK before I buy a new battery and ruin that one by running it down.
 
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#2 ·
I'm fairly certain you do need an 850CCA or larger battery. It's what the electrical system was designed for; there's more going on than just cranking the engine.

One thing new owners should understand about these cars is that there are very few -- if any -- shortcuts when it comes to maintenance. A lot of people figure they can just do the 'good enough' solution, only to have it come back and bite them, which leads to frustration with the car. Doing things by the book ensures a happy ownership experience, even if it's a little more expensive up front.
 
#3 ·
Rule # one : " Never ever Jump Start a W140 " , the 1st thing that always fry's is the cluster , looks like you got lucky this time .
Disconnect the terminals & charge the battery all night unless you have the professional battery charger of course (3 hours) .
There is a specific procedure how to disconnect the terminal battery leads , same for reconnecting it , do it the wrong way around ,there goes the cluster .
Four W140 friends of mine that played with the Battery ,all needed to replace the cluster .
Change the Pressure Regulator and make sure that your fuel pump comes on when you 1st insert the key & turn it , fuel pump can be heard for about 5-10 seconds underneath the rear wheels just before cranking the engine.
Changing the Fuel Filter would also help .:thumbsup:
 
#5 ·
I Didn't Know This

Rule # one : " Never ever Jump Start a W140 " , the 1st thing that always fry's is the cluster , looks like you got lucky this time .
Disconnect the terminals & charge the battery all night unless you have the professional battery charger of course (3 hours) .
There is a specific procedure how to disconnect the terminal battery leads , same for reconnecting it , do it the wrong way around ,there goes the cluster .
Four W140 friends of mine that played with the Battery ,all needed to replace the cluster .
I don't see this need ever cropping up on my car, but it's good to know that you should not jump start the W140's.

When you say "cluster", I assume that is a set of fuses. Where is that located? Pics? :nerd

When you say there is a specific procedure to disconnect the battery terminals, what EXACTLY do you mean?
Disconnect the Negative terminal 1st, then the Positive terminal?
Or is it more complicated than that? :confused:

Since I slightly hijacked TOKEUP's thread(apologies), I'll add that all MB's seems to be very sensitive to electrical inputs, and the battery is the heart of the electric/electronics systems. Spend the extra money and get EXACTLY what the vehicle requires.
 
#4 ·
Some things to consider!

If battery had low electrolyte it could be over charging.

If it sat for a while on low electrolyte the cells are probably sulfated. Hard surface which develops when exposed to air. Very difficult to remove. It will limit the currant available to start the car. Test alternator output with meter while operating. Should be 14.3 VDC. Not higher. At a minimun charge the battery for at least 24 hr after addition of distilled water. Let it rest a few hours. Test voltage again. It should be 12.6 to 12.8 VDC resting.

There should be a small round sticker on the battery top or end indicating the manufacturing build date. Something like 6/14 on the sticker. First number is mouth and second is year. Anything over 3 years plan on a new battery per spec. minimum.
 
#7 ·
I've replaced two batteries in 5 Mercedes. Went straight to the Interstate Battery Store and let them handle it. They plug a device into the port above the pedals. This fools the car and doesn't know the battery is not in place. If you don't do this you will probably lose your radio code. You do have it written down, right? And Thom and Merc-S600 are right. Never jump start one and never go cheap. I (Interstate) just replaced the battery in my Cl600. I bought a 5 year as big as they had (H-8) for $199. The Bosch battery that was in there was an 8 year battery and the replacement cost was $386!
These are not Corolla or Kia cars.
Anziani
 
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