W202 Battery not suitable for cars with Air Con.

Steed

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I suspect my 1998 C200 W202 needs a new battery.

When looking at battery specifications a number of them state not suitable for cars fitted with air conditioning, although the CCA appear similar.

Is it just that the air con requires more current or is there another reason that they may not be suitable?
 
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television

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The only thing that I can think of is if the battery tray is smaller, but that does not really stand up, the air con only runs from the engine, and has nothing to do with the battery at all. This kind of information looks to be very old to me.

As long as the CCA is the same and overall capacity is the same, that is all you have to worry about.

Do go for a well known make of battery, and not a house name, firms like ECP had some very good deals last year on batteries.

You would be hard pushed to find a 202 without any air con.
 
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Steed

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Thanks Malcolm,

Looking on the ECP website, it looks like they are suggesting a battery of 95(Ah) with 800(CCA) as being suitable for those with air-con and anything less e.g. 64(Ah) 640 (CCA) as not suitable.

Do you have any thoughts on the typical CCA required for a C200 Auto?
 

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The 95 ah must be more than adequate, with 800 CCA go for it.
 

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Battery tray is the same size regardless of age on a 202.
As the A/C/Climate Control is on by default, there will be additional load on the battery on cranking.
When I replaced my battery on my P plate C230K (no A/C) I was faced with this dilemma, I decided to go with the larger battery (same as my 202 V8 AMG) so both the cars had the same battery so if required I could swap around with no issues, though I never had to.
I have always historically been inclined to always buy the biggest option battery available for the car even more so if the car has been automatic, justifying the additional expense by the fact that the battery is not often replaced and the additional expense isn't much more for additional piece of mind.
For info, documentation I have read is that from the 202 facelift (late 1997) A/C was standard rather than an option, 202 prefacelift (up to MY 1996) cars with A/C were quite rare.
 

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This will be a clutch type A/C compressor, any load imposed must be neglectable, I have no idea if the clutch can or does engage at cranking RPM as pressure is required to operate the clutch.
 
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Steed

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Thanks Andy,

Looks like you and Malcolm think size is important! so I will look at changing my Mercedes 64Ah battery to something more substantial.
 

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I would go above that, my 2.3 V70R had a 75 amp battery.

There is a little more to this in that a ½ charged large battery is no where near as efficient as a fully charged small one. I would also say that one at 75-80 ah would be the best option. If the car always starts with the minimum of cranking, you will have no problems.
 
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Steed

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Just to complete this thread.

I suspect the reason that some batteries are not suitable for vehicles with air-con is to do with the heater at rest function.

When the 'rest' button is pressed without the ignition being switched on, the air-con blower starts and the panel illumination lights up, both of these create a drain on the battery.

It came to me, while waiting for my wife at the station this evening.
 

bigasotonuk

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The rest function is only on cars with Digital Climate Control, the standard A/C system on a 202 never had this function.
 
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Steed

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The rest function is only on cars with Digital Climate Control, the standard A/C system on a 202 never had this function.

Andy,

My car has non digital air con with the rest function.
 

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Just out of curiosity... is there a limit to the size of battery that a given alternator is able to (re)charge properly...? So say your car comes with a 70-80A battery from the factory, is it at all an issue that its alternator may have trouble charging a 100+ A battery...? Or will it merely take a bit longer, but work fine otherwise?
 

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When the engine is running with all electrical loads on, the alternator should still be able to charge the battery, so the battery size has no limit and it will charge only as much as required, whatever the size.
 
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television

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Just out of curiosity... is there a limit to the size of battery that a given alternator is able to (re)charge properly...? So say your car comes with a 70-80A battery from the factory, is it at all an issue that its alternator may have trouble charging a 100+ A battery...? Or will it merely take a bit longer, but work fine otherwise?

It is assumed that a average small/medium car uses 30amp for the engine, 30 amp for the car, and the minimum size alternator is a 70amp, so in this case 10 amps spare for charging the battery.

There are times when say in Winter the loading will use more current in the car with all heating on (the car blower can consume 15amp) In the summer, the engine fan could be on all the time. So variable needs on the electrics.

So from the above you can see that a 70amp alternator may never charge a 100 amp battery fully.

It is false economy to think that a large battery is best, the fact still remains that a battery has a charge curve, and a battery is only good when fully charged. A small fully charged battery is far more efficient than a ½ charged large one.

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There is so much more to this I will do a DIY on it. A low battery can cause your starter motor to burn out for instance.
 

Irresistance

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Thanks for that :) One more thing I guess... if I go on a long 500KM+ drive (which I do reasonably often) - would that 'spare' 10Amp charging capacity be able to change an 'excessively large' battery, or will it never be fully charged, regardless? I guess what i am wondering is... is this 'spare' charging capacity something that is 'inifinite' (so it could even charge a theoretical 500A battery, given enough charging time) or not? :)
 
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television

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Thanks for that :) One more thing I guess... if I go on a long 500KM+ drive (which I do reasonably often) - would that 'spare' 10Amp charging capacity be able to change an 'excessively large' battery, or will it never be fully charged, regardless? I guess what i am wondering is... is this 'spare' charging capacity something that is 'inifinite' (so it could even charge a theoretical 500A battery, given enough charging time) or not? :)

Indeed any battery can become fully charged no matter how large it is, so sure if you are doing very long runs, you could get it fully charged. It is not quite this straightforward though. Let us take bench charging, this will be a time verses current. So with a 10 amp charger, the battery will take that 10 amps until a point where the battery start to become charged, the internal resistance changes through the charging cycle and the max charge rate will start to drop, and probably drop to 2 amps, at this point one could say that the battery is fully charged.

With a battery in a poor state of charge, the voltage will be under 12.5 volts.
When you engage the starter motor there will be insufficient power in that battery to supply the 12 volt pressure (voltage is pressure) Starter motors are shunt wound, and the motor will have to get the power from somewhere owing to the way it is wound, so the current will increase. This is not good, increase the current, this means more heat and a current flowing greater than than the cars wiring etc can stand. Heat is the killer in all electrics as insulation breaks up and parts start to melt.
 

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Malcolm, useful even up in heaven, will try fit an a/c control panel and see if rest function works... Once I have her back
 

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