havent started the car for a few days untill today when i find there is only enough power in the battery to struggle to turn the engine twice before packing up. :confused: jumped it and it started straight away.

i have got the usual sub and amp wired up and am thinking that they might be drawing power from the battery when the car is switched off, and with it being stood a couple of days took its toll on the battery. ive wired amps up before and never had any problems but this is all i can think off.

the car is a 04 plate with 30k so the battery should be ok, shouldnt it?

Daz

it does sound like something is killing the battery

i would disconnect one of the battery leads and measure the current draw between the lead and the battery with a multimeter set to Amps

this will give you an idea if there is excessive current being used

try pulling the fuses to the subs etc to see if the amps draw drops

havent started the car for a few days untill today when i find there is only enough power in the battery to struggle to turn the engine twice before packing up. :confused: jumped it and it started straight away.

i have got the usual sub and amp wired up and am thinking that they might be drawing power from the battery when the car is switched off, and with it being stood a couple of days took its toll on the battery. ive wired amps up before and never had any problems but this is all i can think off.

the car is a 04 plate with 30k so the battery should be ok, shouldnt it?

Daz

Hi Daz

I think you have answered your own question !

I asume you have give it a quick run round, and it restarts ok? if so seems as you say the amp etc are drawing current, and as you have left it a few days then the capacity is just not enough to hold out.

Sound like you don't leave it like this on a regular basis, but might be an idea putting a relay in the ignition, so it cuts the power when the keys are out, or a manual switch to do the same.

Radiotwo

ps, don't think the battery is knackered(unless the car did not restart)

ok, ive just been back out there to start the car and it started fine.

had a look at the amp with the engine running and off and the amps light was on both times. so.....how easy is it to wire in a relay and what sort of material am i going to need?

Daz

ok, ive just been back out there to start the car and it started fine.

had a look at the amp with the engine running and off and the amps light was on both times. so.....how easy is it to wire in a relay and what sort of material am i going to need?

Daz

Hi Again Daz

Sounds like the battery is ok!

I assume there is not a switch on the amps? if not the wiring of a amp via a relay is easy(if you know what to do)

First of all, you need to know what the Amps draw(ie current), I have not got a clue what they draw, but should say on the amps somewhere like Amps or watts( I don't mean Output watts) I mean input !

If it gives you a input rating of say 50 watts then it would be about 4 Amps, you just need Ohms law (I=P/V (50Watts/12Volts=4Amps))

so once you have the current, then get a Automotive relay rated above the current of the amps.

then here comes the easy bit ! take a supply from the IGN feed (say from the back of the radio) then through the coil of the relay and to earth, so the relay clicks on when the ign is switched on, and clicks again when switched off, then just get the wires from the amp, and break the connection via the last two connectors on the relay.

So when you switch on the ign the amps come on and when you switch off the amps go off.

Relays, Single Pole Double Throw (SPDT), Automotive Relays

Just have a look at the link above, it will show a bit more what I mean.

Hope this helps, if not please ask !

Radiotwo

When I have repaired car amps ,I have always found they are fitted with an electronic circuit which lowers the quiesent current (current taken when the amp is powered with 12 volts on the amp supply ,and the on/off input another switched 12 volt supply is disconnected ) is very low about 3 to 10 milliamps. Only when the 12 volt on/off line is connected to the 12 supply by the radio on switched ,or the ignition switch, does the actual amplifier circuit turn on , and draw high current.

It would be better as one of the previous post mentions to find out what is pulling the battery down by fitting an ammeter between the battery +ve and the wires which were connected to this connection. Fitting relays etc to cure the problem I would call a 'Bodge' . Perhaps the amp is faulty or wired incorrectly ?

Daz, I am having a similar problem, just done 30,000 miles in an 04 Fabia VRS, also have a sub and amp in the boot. 2 months ago had a flat battery, AA boosted it got me going.

Got it checked on 30,000 service as they suggested retailer said everything OK.

Xmas Eve car had been in garage 3 days - dead. AA this time said flat battery but didnt think it was holding charge. Had to put a lower 62ah battery on as a temp measure until I get it looked at a retailer again in the new year as there was nowhere open and I needed the car over the holidays.

There has been a thread on here about the VW wiring feed into the H/U (and amp) being unusal and if wired wrong might be drawing power all the time will ask that get that checked as well. But I cant find that topic at the moment.

Bit of a coincidence that we both got 04 plate and 30,000 miles, maybe the batteries only last 3 years? be interested in what you find.