Radio with engine off

[Petrol Pete]

Deep cycle leisure battery as an auxiliary power supply for ICE with a split relay fitted might be an option. Space permitting.

 

[paul73mt]

my command varies from time to time i can watch a dvd for an hour and will still be fine but have started to wash the car and within 10mins or so with the radio on the command unit switches its self off to preserve the battery

 

[Bobby Dazzler]

Exactly mate. Quick q do all 164s have electric tailgate or was it optional extra?
Cheers

Not 100% but I believe it was an optional extra for most trim levels, and standard on higher spec models. Best check on each individual car, just to be sure.

As soon as you release the boot lid the electric motor will take over and control the opening. To close again, hit the button exposed on the bottom edge of the tailgate when open.

 

[PobodY]

Deep cycle leisure battery as an auxiliary power supply for ICE with a split relay fitted might be an option. Space permitting.

With the added advantage that it's designed to be almost completely discharged and recharged.

 

[TheFoX]

How long do you actually have to listen to the radio for before you kill your battery?

How long is a bit of string?

Firstly, the battery condition is a major factor. New batteries will retain a charge better than older batteries. Eventually, the battery will stop holding a charge efficiently, requiring replacement.

Secondly, the battery rating, in amp/hours, determines how much of a charge it can hold. A smaller 35 Ah won't last as long as a 70 Ah with a constant drain from your radio. Bigger Ah's are for bigger engines or those with more auxilliaries running from them. The biggest single drain to any battery comes from starting the car.

Most cars have a standby drain from things such as alarm systems, trackers, and other auxilliary components that need to be powered constantly, but these are usually low wattage devices.

A properly conditioned and reliable battery should hardly be affected by your radio and amp for a few hours or so, but if the battery does show signs of failing, this could be an indication to change it. I noticed this once when parked and using my BlueTooth handsfree to make a call lasting about 25 minutes, then the car struggling to start. The battery was no longer able to hold a decent charge.

So, if you have a fully charged and fully conditioned battery, say in the region of a 70 Ah, you would probably find your battery would last a week playing music constantly before needing a recharge. Mind you, depends on the radio and amp combination as well.

 

[Deleted member 6183]

I think that modern cars start closing things down long before the battery is properly run down.

My old 5 series had a problem and would start disabling electrical functions to retain enough starting power.

 

[TheFoX]

I've also noticed that some of the newer Mercs now have two batteries, obviously to split the load of all those components requiring power.