Aftermarket speakers draining car battery - mk1 octavia

[gilmo]

Hi,

Anybody ever had a problem with aftermarket speakers draining the battery? I installed some old infinity kappas w/ xovers in the doors of my car because I had them and one of the stocks was done.

 

I want to stress I am talking about the speakers here not the head. I have had the same Alpine cde 9881 head in for a year and it works fine. I changed the speakers and the car battery goes flat overnight. I disconnect them and the battery doesn't go flat over night. I can't really understand this because I there is no power going to the head when the car is off (i lose presets  - no big deal).

 

Pretty sure i got the polarity right too: brown is -ve.

 

it's like there's a ground through a big resistor

 

Any thoughts coz I'm stumped?

 

battery is < 1 year old btw

[Cocain]

To my limited knowledge this is not possible in the situation you have described unless your head unit is not wired as you have stated or is not operating as you have stated. 

Either the head unit is connected or it isn't. the speakers cannot draw power/signal/energy without power being connected to them. 

Use a multimeter at the speaker connection with car on off and harness disconnected but the result will be it's not the speakers

Edited 8 February, 2022 by Cocain

[gilmo]

Thanks. That's exactly what I thought - I am not electrically illiterate but my car battery started dying after I changed the speakers. I guess it could be something else and the speaker change is incidental.

 

I also know that my radio isn't quite wired correctly - I've been reading around and recon it's a canbus issue.

http://forum.autopumpkin.com/viewtopic.php?t=161

Like I say though, the radio was functional and wasn't draining the battery before I changed the speakers. 

Having posted this I removed the wiring harness from the back of the radio completely and the car was fine for a few mornings but then died overnight one morning. Maybe there's a slow short to ground. I've been disconnecting the battery every time I leave the car for the last few days...

[Cocain]

So it seems like you have a paresetic draw from somewhere. Find someone near you to scan it and see if you have any fault codes present. For example I don't know what spec car you have but if you have touch door opening sensors and one dies Irfan make the car wake-up and not shut down properly. Same goes for a lot of other sensors that have to be working for the car to sleep.

[Cocain]

And get Ur battery tested

[gilmo]

Yes I do...

Had a poke around with the multimeter last night/today

• Float 12.7 VDC no drop this afternoon after sitting with battery disconnected all night
• 14.8V on idle so alternator good
• no AC on terminals so Diodes good
• 650mA parasitic drain with radio yellow and red wires out
• 480mA parasitic drain with radio totally disconnected.

probably time to start bulling fuses...

 

 

[KenONeill]

2 hours ago, gilmo said:

14.8V on idle so alternator good

If your multimeter is right then your alternator is overcharging.

[gilmo]

Really?

car wouldn't start - float dropped to 12.3. that was with the neg disconnected.

Multimeter was a good one (fluke) and we get them calibrated at work every year

 

what should it be when charging? and why would it be overcharging?

thanks

[gilmo]

also parisitc draw stabalised to 0.03/4 mA when I left the DMM connected for a bit

[J.R.]

3 hours ago, KenONeill said:

If your multimeter is right then your alternator is overcharging.

 

14.7v is the correct charging voltage and what I would expect to see after starting the engine or if the battery has been discharged.

[gilmo]

We do a lot of DC power systems - I would have thought 14 ish is good. In fact 12.6 seems like a low float...

regardless the battery drained itself having been disconnected for ~18 hours.

 

thanks for the input guys much appreiated! 

[gilmo]

FWIW, I borrowed a discharged battery to run as temp while I get a new one. It was pretty empty at 12.3V. Sitting on the mains charger at 14.4V