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1987 560SL (L.Tonk) [92,700 miles]
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313 Posts
Discussion Starter #1
My '87 560SL isn't getting much use, with the new baby and all, and now the battery doesn't seem to be holding a charge for more than few days. By 2 weeks it will barely move the power windows.

While I understand the basics of the charging system, I am sadly ignorant of a few basic facts. Opinions abound elsewhere on the internet, but I imagine older cars have different characteristics.

  1. Does jump-starting from another car or portable power source cause any damage?
  2. How long does it need to be driven after a jump to be charged?
  3. What's the lifespan of a battery that never sees temperature extremes (stays 40-80F year round)?
  4. How can I tell when it's time to buy a new battery?
Thanks for any info provided. I learn so much from you guys!
 

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1987 560SL (L.Tonk) [92,700 miles]
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313 Posts
Discussion Starter #3
That sounds perfect! :thumbsup:

This might be a dumb question but does the battery require open ventilation during this form of charging, or would it be safe if the trunk were closed and a non-waterproof cover was over it?
 

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Premium Member
1975 450SL
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2,440 Posts
Just a few notes on flodded cell lead-acid batteries:

1) When charging, they will emit hydrogen. There are vents and design features of modern batteries that derease the amount, but you still want to have a bit of ventilation to prevent gasses from buliding up. A slow or 'trickle' charger will emit the gasses at a very low level to prevent them from building up to dangerous levels.

2) Heat will cause the chemical reactions inside the battery to 'speed up', this can result in a shortened lifespan. The lifetime of a battery in Phoenix is notably less than that of one in say, Minneapolis.

3) Cold will cause the chemical reaction so slow down, resulting in less output from the battery. This is why the vehicle left outside in a North Dakota winter sometimes had difficulty in starting. When I was younger, there was a trick involving wrapping a 4 foot pipe heater around the battery and plugging that in at night. I don't know if that is still done.

4) If a battery just sits and doesn't get discharged, an insulating chemical slime will build up on the plates, this can be prevented and reversed by "using" the battery. Usually just starting the car up and driving it every few months will take care of this.

5) If a battery discharges, it will build up a coating of lead sulfate on the plates if not recharged promtly. This is fatal to the battery. Don't let this happen, it'e unnecessary and expensive.

6) The connections are important, too. How are you going to get the electricity to where you can use it? Keep the terminals clean and tight, make sure the cables and connections are not corroded. You can get a small packet of contact grease at the auto parts store for about 2 dollars that will let you coat the terminals and connections to exclude air and moisture to prevent corrosion. Coat the posts and inside of the terminal thinly, tighten them down, then give a not-so-thin coating on the exposed metal. Surprisingly, those little green and red treated felt discs that cost 79 cents do actually help.

Make sure the end of the wire going in to the connection is protected, sometimes the insulation can be damaged, and air & moisture can cause corrosion, this will be indicated by a swelling around the break in the insulation. If you open up the insulation, there will be a greenish white powdery substance there. This can be cleaned off with an old toothbrush and baking soda solution, but keep it way from getting into the battery. grease and tape the exposed area to prevent recurrence.


Sorry, "unloaded" again, what it comes down to is: Keep the connections claen and tight, keep the battery charged, and use it regularly.

Sorry for going off the deep end,:eek:
Scott
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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32,315 Posts
Thanks again Scott. You make it easy to understand.
I have the luxury of covered storage so I really never thought about the question of charging in an enclosed area. I think you may be leaning toward not doing this?
 

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Premium Member
450slc 1979 Honda civic type r 2002 53 ford f100 truck
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375 Posts
Battery

I used to have the same problem so I had my mec install an immobiliser, a switch was installed in the car out of view works a treat . also acts as an anti theft device, the only problem is I have to re set my clock each time. The only thing that stays connected is the radio so as not to loose the memory.
 

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1988 560SL (California Model)
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5,103 Posts
First off how old is the battery? Also you may want to check the output of the alternator to see if it is charging. With the car not running hook up a volt/ohm meter to the battery terminals. You should see a little over 12 volts. Start the car and repeat. Reading should be 13+ volts. I am guessing the battery.
 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
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29,492 Posts
I've got 7 plus years and 45,000 miles on my Walmart Everstart battery.
6 months cold and 6 months, well, not snowing.
When stored for the winter I start it up every 4 weeks or so and let it run for 20 minutes.
Summer.....I drive it!


Mine's still perfect.... but it sounds like your battery doesn't like you anymore.
 

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1978 450SL--117K
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1,374 Posts
Not driving the vehicle or not driving it much can wear the battery down. A slow charge from a trickle charger is better than a fast charger--goes in deeper and holds better.

Scott can probably verify whether there is any real difference between a "marine" battery and a car battery. Point is, is that all marine batteries in Minnesota, particularly those left at lake cabins for indeterminate amounts of time, are hooked up to trickle chargers to restore them as well as maintain them. Usually each boat will have two batteries for it. I always left my stored equipment on trickle chargers and do so with the 107's I now have. I see no difference between the trickle charger and the car's alternator.

"jumping" a car with another car will not hurt it so long as you get the connections right. Using a commercial type jumping device will harm your car. Those guys are in business to make money and the amount of voltage going from their gas powered starting unit to your car far exceeds what your car was built to handle. Your mileage may vary, but i consider them to be a last resort scenario.

Lastly, in Minnesota, you are doing well to get 4-5 years out of a battery. My relatives on the West coast get upwards of ten years out of theirs.
 

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560SL,380SL
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4,012 Posts
I've got 7 plus years and 45,000 miles on my Walmart Everstart battery.
6 months cold and 6 months, well, not snowing.
When stored for the winter I start it up every 4 weeks or so and let it run for 20 minutes.
Summer.....I drive it!


Mine's still perfect.... but it sounds like your battery doesn't like you anymore.

I've been downright amazed that the batteries that came with my cars, age of the batteries unknown, have been fine for >7 and >5 years.
 

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1978 450SL--117K
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1,374 Posts
I've been downright amazed that the batteries that came with my cars, age of the batteries unknown, have been fine for >7 and >5 years.
Yeah, but look at where you live. It's perfect weather. I think. Jeez, I would never move to Minnesota--I had the misfortune of being born here and should have got out when I was young, now I have to wait until I'm old........
 

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1983 380SL
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56 Posts
I've been downright amazed that the batteries that came with my cars, age of the batteries unknown, have been fine for >7 and >5 years.
About 3 years ago, I replaced the old Die Hard battery in my 380SL with a new Die Hard. The sales clerk at the Sears Auto Center was amazed that old battery lasted 9 years.
Thank goodness for living in Florida.
We'll see if this current battery lasts just as long.
 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
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29,492 Posts
Thank goodness for living in Florida.
Underuse is probably the #1 killer followed by overheating.

I guess moderate temps would probably yeild the longest battery life.

Of course how do you explain getting 11 years out of a Honda Civic OEM battery but only 3 years out of a newer Honda Pilot OEM battery in the same climate.

I have quite a few Milwaukee cordless tools with batteries to match.


When they are in constant use, the batteries charge faster and last longer. When they are dormant or underused......the battery life shortens to the point that they need to be replaced or deep cycled.
 

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US spec MB560SL 1986, Audi A4 and A6, Ford Taunus 1964 17M and 2.0 1975
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1,419 Posts
Optima cell battery

I replaced 2008 the traditional battery by Optima yellow top cell battery, it has very tight height fit into battery box. These round cell style batteries do not mind low annual driving miles and resist better deep uncharging situations.

So far it has been OK in my W107.

I have also added main switch for easy winter storage periods.
 

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1978 450SL--117K
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1,374 Posts
Underuse is probably the #1 killer followed by overheating.

I guess moderate temps would probably yeild the longest battery life.

Of course how do you explain getting 11 years out of a Honda Civic OEM battery but only 3 years out of a newer Honda Pilot OEM battery in the same climate.
A bad battery--it happens. I'm not sure how bad your winters are there, but I'm guessing about the same or slightly milder than Minnesota due to your being closer to the Atlantic. Here, we get four years, sometimes five. Doesn't matter whether OEM or not. The only difference is that a cheap battery, like Interstate, will be lucky to get three years. It has something to do with going from say, -10 F to 196 F in the process of starting the car and warming it up. They do last longer if the car is garaged. Most people who store vehicles here (and boats) pull the batteries and bring them inside for the winter. They last longer that way.
 

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1987 560SL (L.Tonk) [92,700 miles]
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313 Posts
Discussion Starter #16
First off how old is the battery? Also you may want to check the output of the alternator to see if it is charging. With the car not running hook up a volt/ohm meter to the battery terminals. You should see a little over 12 volts. Start the car and repeat. Reading should be 13+ volts. I am guessing the battery.
I hooked up the multimeter and it read 2.9V. So that's one mystery solved!

In the meantime I've bought a Battery Tender so when I've got the new battery it will stay charged and ready to drive. I'll keep the trunk lid cracked a smidge for venting and get some contact grease on there too.

Thanks again for all the great info!
 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
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29,492 Posts
I hooked up the multimeter and it read 2.9V. So that's one mystery solved!

In the meantime I've bought a Battery Tender so when I've got the new battery it will stay charged and ready to drive. I'll keep the trunk lid cracked a smidge for venting and get some contact grease on there too.

Thanks again for all the great info!
Once you get your car running again.................put the meter back on the battery terminals .

It would be good to know your alt. is throwing the correct charge.
 

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1987 Mercedes-Benz 560 SL
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973 Posts
My Interstate Megatron MTP-93 just this month completes its 11th year of service in my SL. For about the last 5 years I've put it on a Schumacher battery maintainer over each winter (as it isn't being driven).

Good road,
 

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1987 560SL (L.Tonk) [92,700 miles]
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313 Posts
Discussion Starter #19
Just bringing the thread to closure...

Got a new battery and had the charging system checked when I brought it in for service. It all checks out.

Now I just need to find time to get the Battery Tender hooked up...
 

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'80 450SLC Afro RHD Ikonengold
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2,900 Posts
What may be very important is that alternators in Mercedes cars of the era cannot "equalise" battery and periodic, maybe 2-4 times a year, "equalise" charge is highly beneficial, specially for seldom used cars.
It could extend the life of seldom used battery as much as by 2 times, reduces sulphation and improves reliability.

"Equalise charge" is done at ~14.4-15V and it ensures that cells that are discharged disproportionally receive full charge - "equalising charge".
Trickle chargers can do that. Electrolyte loss will occur and level should be checked before and after.

____________________________________________


for $70 bucks I got waterproof desulphator, equaliser and float charger the size of a laptop ac-dc adapter... it is connected permanently and it revived my far from perfect 4yo secondhand calcium battery and "every-time-I-want-to-start-the-car" problem has gone with the wind.
That $70 already paid back as I had to get a new battery every 2 years.
 
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