Accessory Switch

Quinten · 05-08-2003, 11:18

Question for our in-house ICE-men (women welcome too)... I've run a big power cable from battery to boot and are going to hook up an mp3 player to it (see separate threads for that), but because it is not hooked up to the accessory position on the ignition, it will always be under power. I dread the day I forget to switch the mp3 player off and it runs my battery dry

!

Would it be possible to incorporate some sort of automatic switch (or even use the accessory switch itself) as to have it automatically switch off the power to the mp3 player when I remove the key out of the ignition?

Q.

**robmawer** · 05-08-2003, 11:26

I shouldn't imagine an MP3 player will use all that much power, so unless you're leaving the car a few days you should be alright...

Not sure on how to wire it to the accessory switch, unless the MP3 player has an input for this, or the power was connected in serial from the head unit - I'd imagine neither of these are the case.

As for an automatic switch - on my fridge I have a 12v socket splitter (tenner from Halfords), which incorporates a cut off, so if the voltage from the battery drops beneath 10.8V it'll stop the accessories connected to it drawing power. Maybe you could cannibalise one of these, or find out how they work?

Rob.

Quinten · 05-08-2003, 11:32

That might actually be the solution, put one of those 12V socket splitters in between. Or (and I'm just making this up as I go along) could there be a point on the battery (as there is a little small distribution block on top of it already) which contains the accessory switch power? Big k?

Stimps · 05-08-2003, 12:19

Q,

Most after-market head units feature a "remote" wire - this carries 5v when the head unit is turned on. Typically it connects to an in-car amplifier to 'switch it on' when you start listening to the head unit.

I'm sure I've seen remote switching units that use the remote feed as an input to switch a relay, and thus supply power to everything only when needed...

Tavia4x4 · 05-08-2003, 12:24

The accessory feed wire is 12v in itself....

I've done the same, used a permanent 12v from the boot power socket. Forgot to turn the mp3 player off once, didn't do anything to my battery.

Tavia4x4 · 05-08-2003, 12:25

The mstation *really* doesn't like power blips tho, so I would try and stay with a perm feed and on \ off direct.

**robmawer** · 05-08-2003, 12:29

Think the standard battery is rated at 60/70 Ah, so it would take a while for it to drain off an MP3 player!

Rob.

Quinten · 05-08-2003, 12:46

Stimps, that sounds more like a 'proper' solution which I'm duly going to investigate

Rob, ofcourse it would take some time, but as Murphy's Law dictates, if anything can go wrong, it will

Q.

Oh, and Ian, what would cause power blips? Starting the engine for instance?

Stimps · 05-08-2003, 13:02

Quote:

Originally posted by Tavia4x4 in this post
The mstation *really* doesn't like power blips tho, so I would try and stay with a perm feed and on \ off direct.

If you had a nice fat capacitor somewhere that would help to smooth any blips in the power...

KLB · 05-08-2003, 13:56

Quote:

Originally posted by Quinten in this post
Stimps, that sounds more like a 'proper' solution which I'm duly going to investigate

Rob, ofcourse it would take some time, but as Murphy's Law dictates, if anything can go wrong, it will

Q.

Oh, and Ian, what would cause power blips? Starting the engine for instance?

Are you sure it's Murphy's Law, not Ohm's Law?

Kentish · 05-08-2003, 14:46

Quote:

Originally posted by KLB in this post
Are you sure it's Murphy's Law, not Ohm's Law?

Now your being "resistive".

Andy

KLB · 05-08-2003, 15:16

I feel a right Henry, 'cause I don't know Watt you're talking about.

***DGW*** · 05-08-2003, 16:22

A case of being 'ampered by lack of knowledge?

redbaron · 05-08-2003, 16:38

FYI left the car fridge in my mums 3 series overnight and it pancaked the batt wouldnt even unlock...

Kentish · 05-08-2003, 16:59

It would do as the current drawn by those fridges is quite a bit so without the engine running it will run down.

I think this thread is "volting" around too much and needs some impeidance, although the "current" direction could be polarised, and take it "farad farad" away from the dribble I,m spouting.

Andy................sculking

**robmawer** · 06-08-2003, 09:27

Yeah, those fridges draw a lot of current, I reckon it could kill the battery in as little as 2-3 hours. Hence why I invested in the "cut off" splitter, so as not to have to make an embarrassed call to the AA!

Insulates quite well though, so holds the temperature for about 8 hours, which is nice...

Rob.

neilcaldwell · 07-08-2003, 12:19

Doesn't the 12v socket in the boot have some kind of time out on it several hours with ignition off, or am I mistaken?

**robmawer** · 07-08-2003, 12:28

It might well do, though some of us don't have 12v sockets in the boot anyway...

Rob.

redbaron · 07-08-2003, 13:08

ah rob you must have the "sports" model not the agricultural spec product?

**robmawer** · 07-08-2003, 13:13

Well, it certainly looks like a Coupe, albeit an American one...

Rob.

05-08-2003, 11:18	#1
Quinten playing dadsie Join Date: Apr 2003 Location: fast lane Posts: 10,013 Thanks: 16 Thanked 41 Times in 38 Posts	Accessory Switch Question for our in-house ICE-men (women welcome too)... I've run a big power cable from battery to boot and are going to hook up an mp3 player to it (see separate threads for that), but because it is not hooked up to the accessory position on the ignition, it will always be under power. I dread the day I forget to switch the mp3 player off and it runs my battery dry ! Would it be possible to incorporate some sort of automatic switch (or even use the accessory switch itself) as to have it automatically switch off the power to the mp3 player when I remove the key out of the ignition? Q. __________________ Awooga!!!

05-08-2003, 11:26	#2
robmawer Briskodian Join Date: Jan 2003 Location: Rochdale Posts: 12,371 Thanks: 2 Thanked 63 Times in 56 Posts	I shouldn't imagine an MP3 player will use all that much power, so unless you're leaving the car a few days you should be alright... Not sure on how to wire it to the accessory switch, unless the MP3 player has an input for this, or the power was connected in serial from the head unit - I'd imagine neither of these are the case. As for an automatic switch - on my fridge I have a 12v socket splitter (tenner from Halfords), which incorporates a cut off, so if the voltage from the battery drops beneath 10.8V it'll stop the accessories connected to it drawing power. Maybe you could cannibalise one of these, or find out how they work? Rob. __________________

05-08-2003, 11:32	#3
Quinten playing dadsie Join Date: Apr 2003 Location: fast lane Posts: 10,013 Thanks: 16 Thanked 41 Times in 38 Posts	That might actually be the solution, put one of those 12V socket splitters in between. Or (and I'm just making this up as I go along) could there be a point on the battery (as there is a little small distribution block on top of it already) which contains the accessory switch power? Big k? __________________ Awooga!!!

05-08-2003, 12:19	#4
Stimps Briskodian Join Date: Jan 2003 Location: Colchester Posts: 5,091 Thanks: 0 Thanked 0 Times in 0 Posts	Q, Most after-market head units feature a "remote" wire - this carries 5v when the head unit is turned on. Typically it connects to an in-car amplifier to 'switch it on' when you start listening to the head unit. I'm sure I've seen remote switching units that use the remote feed as an input to switch a relay, and thus supply power to everything only when needed... __________________ Steve « Nature Green 1.4 16v Fabia Comfort »

05-08-2003, 12:24	#5
Tavia4x4 Briskodian Join Date: Oct 2002 Location: J5 M61 Posts: 5,294 Thanks: 0 Thanked 0 Times in 0 Posts	The accessory feed wire is 12v in itself.... I've done the same, used a permanent 12v from the boot power socket. Forgot to turn the mp3 player off once, didn't do anything to my battery. __________________ Ian __________________ Nice to be important, but more important to be nice...

05-08-2003, 12:25	#6
Tavia4x4 Briskodian Join Date: Oct 2002 Location: J5 M61 Posts: 5,294 Thanks: 0 Thanked 0 Times in 0 Posts	The mstation really doesn't like power blips tho, so I would try and stay with a perm feed and on \ off direct. __________________ Ian __________________ Nice to be important, but more important to be nice...

05-08-2003, 12:29	#7
robmawer Briskodian Join Date: Jan 2003 Location: Rochdale Posts: 12,371 Thanks: 2 Thanked 63 Times in 56 Posts	Think the standard battery is rated at 60/70 Ah, so it would take a while for it to drain off an MP3 player! Rob. __________________

05-08-2003, 12:46	#8
Quinten playing dadsie Join Date: Apr 2003 Location: fast lane Posts: 10,013 Thanks: 16 Thanked 41 Times in 38 Posts	Stimps, that sounds more like a 'proper' solution which I'm duly going to investigate Rob, ofcourse it would take some time, but as Murphy's Law dictates, if anything can go wrong, it will Q. Oh, and Ian, what would cause power blips? Starting the engine for instance? __________________ Awooga!!!

05-08-2003, 15:16	#12
KLB Discordian Join Date: Jan 2003 Location: Newport, Newport - so good the Post Office named it twice Posts: 1,962 Thanks: 0 Thanked 1 Time in 1 Post	I feel a right Henry, 'cause I don't know Watt you're talking about. __________________ Mike

05-08-2003, 16:22	#13
*DGW* BRISKODA Staff Join Date: Oct 2002 Location: Cambridgeshire Posts: 17,002 Thanks: 41 Thanked 148 Times in 112 Posts	A case of being 'ampered by lack of knowledge? __________________ Denis 2002 Octavia 1.8T 4X4 turbo Estate - rebreathed on by Jabba ... 31.93mpg 2007 Fabia vRS - CC, ESP, Jabba rear ARB, and full leather trim by Seat Surgeons ...48.01 mpg...

05-08-2003, 16:38	#14
redbaron Briskodian Join Date: Jun 2003 Posts: 9,242 Thanks: 9 Thanked 49 Times in 44 Posts	FYI left the car fridge in my mums 3 series overnight and it pancaked the batt wouldnt even unlock... __________________ ________________________________________ Some times I just feel like smiling.

05-08-2003, 16:59	#15
Kentish Briskodian Join Date: Feb 2003 Posts: 5,228 Thanks: 0 Thanked 3 Times in 3 Posts	It would do as the current drawn by those fridges is quite a bit so without the engine running it will run down. I think this thread is "volting" around too much and needs some impeidance, although the "current" direction could be polarised, and take it "farad farad" away from the dribble I,m spouting. Andy................sculking __________________ Andy Owner of a sense of humour.

06-08-2003, 09:27	#16
robmawer Briskodian Join Date: Jan 2003 Location: Rochdale Posts: 12,371 Thanks: 2 Thanked 63 Times in 56 Posts	Yeah, those fridges draw a lot of current, I reckon it could kill the battery in as little as 2-3 hours. Hence why I invested in the "cut off" splitter, so as not to have to make an embarrassed call to the AA! Insulates quite well though, so holds the temperature for about 8 hours, which is nice... Rob. __________________

07-08-2003, 12:19	#17
neilcaldwell Briskodian Join Date: Jan 2003 Posts: 15 Thanks: 0 Thanked 0 Times in 0 Posts	Doesn't the 12v socket in the boot have some kind of time out on it several hours with ignition off, or am I mistaken?

07-08-2003, 12:28	#18
robmawer Briskodian Join Date: Jan 2003 Location: Rochdale Posts: 12,371 Thanks: 2 Thanked 63 Times in 56 Posts	It might well do, though some of us don't have 12v sockets in the boot anyway... Rob. __________________

07-08-2003, 13:08	#19
redbaron Briskodian Join Date: Jun 2003 Posts: 9,242 Thanks: 9 Thanked 49 Times in 44 Posts	ah rob you must have the "sports" model not the agricultural spec product? __________________ ________________________________________ Some times I just feel like smiling.

07-08-2003, 13:13	#20
robmawer Briskodian Join Date: Jan 2003 Location: Rochdale Posts: 12,371 Thanks: 2 Thanked 63 Times in 56 Posts	Well, it certainly looks like a Coupe, albeit an American one... Rob. __________________

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