w163 battery or alternator problem

Gregjam

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I fear the worst as the car would not start despite being used an hour or so earlier. less than 12 volts across the battery on a meter did not bode well. I started the car by using jump leads from my bike!!! but this means I will now need a new 30A fuse as the bike's main fuse blew once the car was started.... but it worked.

With the engine running I was getting 12.5V showing on the meter whereas the bike shows 14.7 plus. The indicator light on the console in the car lights up when the ignition turns on but goes out once the car is running which seems weird. I am suspecting the alternator is on the way out but meantime am charging the battery.

This brings me on to my next question. The battery in question is a UNIPART GBA3017 EN730 A/hr 88 R/C 150. Is this the correct size for the car as it was a real pig to get out. It is 35cm long,19.5cm high and 18cm wide. This seems quite big but given the size of the engine it might be right. This is the first time I have had any problems in this regard.

Of late the air con has been running all the time and the car is used daily but trips tend to be fairly short and mostly around town. There is a lot of power usage and could this be a contributory cause.

Am I looking at a replacement alternator and can anyone tell me if there is an easy way to remove the battery (if it is the correct size).

Somehow I see a trip to S.A.M/UNIT is on the cards. Anyone got any ideas?

Thanks.
 

Cole@MBS

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Battery is to small!! should be a 100amp an hour, hate to be the bearer of bad news but just done a alternator on a ml, £700 for the part!!

12.50 volt across the battery is battery voltage, its not charging!!!

You have my number sir!!
 

Mark A

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Changed the battery on the wife's ML a month or so ago. It was a 100Ah jobbie.

I found MB were able to supply the new one cheaper than my local motor factor could.
 
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Gregjam

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Arrangements made now for it to be checked out. Looks like the alternator is fairly new so will get that checked out. One of the hidden surprises buying secondhand. Initial checks show that no charging is taking place so first attach is the voltage regulator which looking on some US forums was subject to a recall earlier on (not applicable to mine according to MB dealer).

I am still surprised that the battery charging failure light is still not coming on so perhaps this is something to be wary of for other owners. I will post any findings as I am cautious given the less than top quality installation of the hands free system (coming out the first time the dash has to be removed for anything).

Oh what fun driving with due regard to the battery. Lovely sunshine and hot weather with no air con or fan to save on power usage. Reminds me of the good old days in a Singer Chamois Sport!
 

wireman

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Does the lamp come on before the engine is started? if not replace the bulb before you spend any more money, without this vital part of the alternator circuit no charge will be generated.

At 14.7v your motor bike battery will eventualy be destroyed due to excessive charging.

expect 12.8 for a freshly fully charged battery without charging (ie engine stopped)
expect 13.8 to 14.2 v on charge, if its over 14.4 it is too much.
Never discharge below 10.8v, this will reduce the life of your battery.
 
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