FM transmitter - energy consumption?

[E38Ross]

Hi guys,

I've got one of these

http://www.amazon.co.uk/gp/product/B002S8AFE8/ref=...

now, my cigarette lighter always has power going to it when the car is switched off now, i'm wondering whether i can leave this plugged in when leaving the car. if you turn the music source off it switches itself off (i.e. stops broadcasting a frequency) after just 60 seconds but it still has a small green light active all the time, and not sure what else.

my only concern is whether it might drain the battery slightly.....i have no guesses as to how much energy it will draw? i'm lazy, and get fed up having to pull it in/out every time i want to listen to music

any guesses? i reckon it'd be fine but not sure. the battery is quite a big bd...110Ah and 830cca and my commute to work is 20 miles each way every day so should be getting a good charge.

Ross.

[G600]

unless you're leaving the car for weeks I wouldn't worry about it.

[Ozzie Osmond]

For goodness sake just find a switched circuit ..... like right behind the radio head unit.

OzOs

[E38Ross]

Ozzie Osmond said:

For goodness sake just find a switched circuit ..... like right behind the radio head unit.

OzOs

but the head unit is in the boot, and i need the cable connected to my MP3 player which i can have at the front underneath the arm rest!

[chazola]

I very much doubt it's drawing any more power than enough to keep the green LED on and a very low power standby mode, like you say it switches itself off and only really uses anything when transmitting. If your car is in regular use I wouldn't worry about it- I've got my TomTom charger permanently wired in, it's little green LED is always lit but only draws power when I connect the unit- I've never had any problems with that and battery drain in years. I suspect your unit will be similar.

[joebongo]

Open the boot and take the bulb out.

Open the drivers side window.

Put a multimeter in series and test the power drain when you switch off the engine.

Lock the doors leaving window open.

Leave the car 15-30mins so it goes out of sleep mode and switches off.

Test current drain again to see if it persists after sleep mode.

Reach in window and unplug transmitter.

Test current drain again.

IIRC the normal drain was 50milliamps on the E38 - I could be wrong but that will tell you how many times the drain is when transmitting and if it's above normal tolerances.

[Ozzie Osmond]

E38Ross said:

Ozzie Osmond said:

For goodness sake just find a switched circuit ..... like right behind the radio head unit.

OzOs

but the head unit is in the boot, and i need the cable connected to my MP3 player which i can have at the front underneath the arm rest!

No. That's why it's called the head unit. It's in the dashboard. And even if you've moved the gear to the boot the wiring is still in the dash.

[KingNothing]

I leave mine switched on all the time charging my ipod, never had a probelm yet.