Technical Dummy car alarm LED draining battery

Ant65

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Aug 10, 2017
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Hello.
I hope someone may be able to help with this.

I have a 2004 Panda and have installed a dummy LED flashing red light. This worked correctly however it appears to have drained the battery after just a couple of days, when apparently it should have a minimal effect.

The details of the wiring done are as follows:

Red (positive) wire connected to Fuse F52 - Rear Window Wiper
[The power to this fuse seems to be always on]

Black (negative) wire connected to Fuse F51 - Body Computer Control Unit / Instrument Panel
[The power to this unit appears to be on only when the car is running]

Fuse taps have been used here.
No resistors used.
No relays used (only fuses)

The blinking LED works on 12v DC and draws 10mA

Any advice or thoughts would of course be welcome.

Thanks in advance
 

koalar

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Oct 24, 2016
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Could be a coincident but you have to measure the drain parasitic with an Amp meter.

I can't remember what it should be I have posted it on here before

Something like 100ma for 15 seconds ECU goes to sleep and it drops to 15ma

While testing be careful not to open a door or leave any lights on. The interior light is likely to damage your meter while in a low range.


https://www.youtube.com/watch?v=zdIKNnwEjIs
 
Last edited:

DaveMcT

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Sep 14, 2009
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17,671
It might be preventing the electronics from shutting down. It needs to be fed from a direct source straight off the battery. Use a normally closed relay triggered by an ignition controlled circuit to switch it off when the car is running.
 
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Ant65

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Hi Guys,
Great responses & very helpful.
After a lot of searching & head scratching DaveMcT is the attached layout anything like what you mean ?
(Apologies for the roughness of the drawing, this stuff isn't really my forte)

Ant

 

DaveMcT

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I would take a feed from battery +ve to the relay common contact. Take the normally closed contact to the LED and then the other side of the LED to earth (-ve). That completes the switched side.
Find an ignition controlled fuse and fit a piggy-back fuse holder to carry the original fuse. The wire goes to the relay coil and the other side to earth (-ve).

When the car is switched off, the relay is closed and the LED lights. When the ignition is switched on, the relay opens and the LED stop flashing. You might be able to find an electronic circuit to do the same thing but the wiring will be the same.


This is way over spec but its cheap.
https://www.ebay.co.uk/itm/Micro-Re...754490?hash=item523b922fba:g:BQ8AAOSwh7tcJMfb
This is the piggy back fuse. Check the fuse box. You might need to find one where the wire comes out of the top.

https://www.ebay.co.uk/itm/Add-A-Ci...228993?hash=item365e791ac1:g:EBYAAOSwIYdeXi-F

It's possible the car has a live fused circuit that goes OFF when the car is running. You would have to research for that.
 
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Ant65

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Good stuff. Thanks for the heads up. Will give this a try & let you all know.
 
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Ant65

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Hi there. Using the setup with a relay does appear to be working properly and the battery is fine and not draining at all. Good advice indeed thanks for putting me on the right track this.

I have put together some steps of what I had to do if anyone else with a Panda 169 (2004) wanted to do the same. Unfortunately I cant seem to see anywhere on the site to upload PDF files....?
 

Pickwick

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Oct 26, 2005
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I have put together some steps of what I had to do if anyone else with a Panda 169 (2004) wanted to do the same. Unfortunately I cant seem to see anywhere on the site to upload PDF files....?

You could attach the file to a new post in this thread. The maximum size allowed for a pdf is 23.84 MB and there's a guide to attaching files here if you need it (its main focus is on images but it applies to pdf files too).
 
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Ant65

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Many Thanks Pickwick. WOuld have struggled for hours to try & work that out.
Have posted the same note in the Guides section.
Thank You All.
 

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