E Class battery durability

[C7pg]

Looks like I'll be parking my 15 plate E 220 bluetec for a couple of months while we're away, will the battery or batteries have enough left to start it up again after this length of time? How many batteries has it got anyway, I know there's one under the bonnet passenger side, but is there another one for the stop start mullarkey?

 

[Tiim533]

Think it's only the one battery. They cost an arm and a leg as well because of the stop start mallarky! I always disable it as soon as I switch it on!

 

[whitenemesis]

Where will you be parking? Will there be power available?

I would try and connect a trickle charger for that duration.

 

[190]

If all is well the quiescent current that the car draws when asleep shouldn't exceed 30ma.

30ma = approx. 45 Ah over 2 months

Batteries also have an internal self discharge rate which varies according the age and type of the battery and storage temperature. At worst it could double up on the quiescent current. At best with an AGM battery it can negligible.

Clearly 2 months storage is unviable without charging. Even if it started OK the batteries life will be shortened by sulphation.

 

[C7pg]

Thanks. The car will be on our drive so I suppose I could ask a neighbour to put the charger on it for a few hours every couple of weeks. I have got a ctek charger but over long periods it has knackered batteries on another car. I'll get something sorted out.

 

[whitenemesis]

The Ctek should be fine over extended periods. Which model do you have. Mine, MXS5, can be left indefinitely without detriment

 

[Smart320]

Have used a CTech charger connected many times over 3 month period, never a problem as they are designed for this. Maybe yours is faulty?

 

[Benzmanc]

This will keep it topped up

Ring Solar Power Battery Maintainer Boat Car Bike JetSki Caravan Water Resistant

 

[190]

If there is a choice, I'm not a fan of leaving a charger permanently connected and not surprised to hear that one has knackered a battery. They can work safely if the voltage is just right for the particular type of battery it's connected to.

Unregulated solar chargers are another possible risk of overcharging as while they are marketed as being nominally 12 volts they can generate anything up to 18 volts if the current falls low enough. If anyone has one, measure the no load voltage with a digital meter to check if there is any built in regulation A 1.5 W panel might be safe enough as it will struggle to match the 30mA draw over a 24 hour period which will probably keep the voltage at a safe level.

 

[C7pg]

Thanks. Yes it's a mxs and it's done for a small battery on.my Caterham, it only stays charged for about 2 weeks due to the alarm on it. Now I disconnect it but presume that's not an option for the Merc?

 

[whitenemesis]

There must be something wrong with your Ctek, they are designed to be left connected indefinitely. There are rebadged as MB chargers and many high end models come with charge points installed to make connections easy.

I've left my Ctek connected to my CLS for weeks without issue. Once the battery is fully charged to Ctek goes into maintenance mode.

 

[SW18]

Unregulated solar chargers are another possible risk of overcharging...

Does anyone know if there is a regulated solar charger on the market, that will work like a Ctek and maintain a safe charge level?

I am interested in a charger as I use my car only for long trips, often interspersed with it being parked for 1-3 week periods. But having no driveway I cannot use a mains-powered charger. That said, I rarely drive less than 10 miles at a time and usually much more, so the battery should always get a good top-up.

 

[190]

I've never seen a panel with voltage regulation built in but that doesn't mean they don't exist.

Someone already mentioned on another thread that they used a charge controller in conjunction with a solar panel which is normal method and absolutely necessary for bigger panels.

It isn't usual to use a charge controller with a very low wattage panel e.g 1.5 Watts not least because the controller would cost more than the panel. I would want to do a voltage check with the panel hooked up to a fully charged battery to be sure it doesn't exceed the safe float voltage for the battery which is usually not more than 13.8 volts.