AGM or non-AGM Replacement Battery for W169?

[wongl]

Just been charging the wife's W169 overnight and once disconnected from the charger the battery voltage drops down to 11.8v to 12v. Given the factory fitted battery is now circa 10 years old, it is probably time to get a new Varta battery as a preventative measure.

Question is, is there any merit in getting a more expensive AGM battery E39 (£125) vs the normal battery E44 (£75)? Additionally, the AGM comes with a 4-year warranty while the non-AGM comes with a 5-year warranty. No bothered about the £50 difference if there is an advantage.

This car is use mainly for short journeys around the suburbs of London but does not have ECO start/stop function.

Opinions and reasons welcomed.

 

[markjay]

The AGM is a better battery, but given that the standard battery lasted for 10 years, I don't think that the AGM will have any tangible benefit for you.

 

[Will]

I’d buy another of exactly what you have currently fitted if it’s lasted ten years without trouble until now!

 

[grober]

AGM batteries have slightly different voltage and charging characteristics to their flooded battery brethern and your car's charging/electrical equipment will be designed/matched accordingly. Best to stick with the original type of battery. Go for the best non AGM Battery fitment from VARTA that's available. The CCA cold current cranking figure is a good guide to performance for batteries of the same amp hour capacity.
The e44 will be fine
Car battery finder from VARTA® - Find the best and most reliable battery for your car

 

[190]

AGM's are great batteries but in your application I don't think you need or will benefit from one given the performance of the original. Interesting that the AGM has a shorter warranty. That may be because while it should last as long as a standard battery, AGM's are a little more prone to sudden death syndrome. So while I do have a £32 generic AGM on the bike, I tend view buying a very expensive AGM as something of a lottery once outside the warranty and wouldn't buy one for a car that didn't need it. At the end of the day the AGM would have to last 40% longer than the standard just to break even.

 

[wongl]

Thank you everyone for all your opinions and advice. I agree that on balance I should stick with the non-AGM battery for the following reasons.

1. As mentioned, the charging circuit might not be optimal for an AGM battery.
2. We will probably keep the W169 for another 5 years more years due to its low mileage (assuming other expensive bits don't break and make the car uneconomic to repair) - so the 5 year warranty would be a better match with a lower price point.

Now, I wonder if ECP will price match Tayna for the Varta battery!

 

[wongl]

I’d buy another of exactly what you have currently fitted if it’s lasted ten years without trouble until now!

Buying one exactly the same would require sourcing one from MB. I will inquire the price tomorrow as dropping off the W205 for a warranty diagnostic. I doubt the MB price will be as low as £75.

 

[Deleted member 126251]

AGM batteries have slightly different voltage and charging characteristics to their flooded battery brethern and your car's charging/electrical equipment will be designed/matched accordingly. Best to stick with the original type of battery. Go for the best non AGM Battery fitment from VARTA that's available. The CCA cold current cranking figure is a good guide to performance for batteries of the same amp hour capacity.
The e44 will be fine
Car battery finder from VARTA® - Find the best and most reliable battery for your car

This^^

AGM is sensitive to over charging and if your old battery was the flooded lead acid type, the charge voltage will probably be too high and damage an AGM.

 

[Atavus]

Charging voltage is higher for AGM than flooded.

 

[Deleted member 126251]

Charging voltage is higher for AGM than flooded.

Should have said "float voltage" (which is when the damage occurs) not "charge voltage".....fact remains that it is not a good idea for him to use AGM.

 

[grober]

In sourcing a new car battery I would always favour a battery supplier with a high product turnover to ensure a minimum battery shelf life.