Battery woes

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ashenfie

Active Member
Joined
Jan 17, 2017
Messages
128
Car
Merc C180 1.6
My 4 year old 1.6 CGI Merc W204 on Friday had a totally flat battery after being left for 5 days. On testing the battery had 10v and was so dead I couldn't use the portable battery jump starter which to be fair had been sitting unused for two years.

I attempted trickle charging but the charger stopped saying the battery was charged and on testing only had 11.5 volts.

This car has start/stop, but I would expect an 80A 800CCA VARTA battery to last better than that and not go totally dead like that. Its not as if its a big engine to turn over.

A new battery seams to have done the job. That was very confusing to as using the reg applications kept returning the incorrect batteries. I wonder how many people having installed a non AGM battery in there Merc.

I wonder if other have found the same?
 
i fitted a non agm bosch s4 to my e class and it wasnt upto the job tbh. trickle chargers dont charge flat batteries btw, you should of used a standard 4 amp charger for 24 hours.
 
Sadly despite the costs, the AGM batteries fitted to modern cars are not as durable as they used to be.
This is mainly down to the way a stop/start equipped car charges the battery, and it rarely getting fully charged by the car.
You could put a standard/calcium lead-acid battery in and it would work fine for a while, but in the long run it shouldn’t last as long as the correct AGM battery. It also would not make the same power output for its size, usually about 100cca down.
 
This is mainly down to the way a stop/start equipped car charges the battery, and it rarely getting fully charged by the car.

It seems to me that modern ECU controlled charging systems including those on non start/stop models, have been slightly compromised towards headline MPG and emissions figures rather than maintaining a fully charged battery. They keep a battery above 80% charge but never fully charged it. Regardless of the length of journey mine will always need a charge for a couple of hours which I do once per week. This may have helped as I'm still on the original 8 1/2 year old battery and expect it to last a while longer yet.

Most owners quite rightly expect the car to just work and as long as it starts never give a thought to the state of charge of the battery. It seems ironic that such a sophisticated charging system actually needs some manual intervention to get the best out of the battery. Compare that with my 40 year old motor cycle battery which is always fully charged because it finishes a run fully charged, has zero current draw when not in use and the AGM battery has astonishingly low self discharge rate. I never need to go near it with a charger.
 
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Get a Ctek charger and 2x sets of the fly leads - one on the main battery one on the Aux battery and bring both up to 100% on a regular basis. I don't have stop/start or Aux battery but I bring my main battery up to 100% charge with a Ctek 5-6 times a year.

AGM batteries require a different charging regime to lead acid. Ctek charger will happily charge AGM/Lead acid and almost all 12v batteries.
 

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