Technical Battery drain

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Technical Battery drain

branton rhino

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Feb 2, 2006
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Hi,

After about a week my daughters car won't start due to flat battery.

The battery has been replaced because it was tested by a well known national garage and they told me it was kaput but I think I was ripped off as I still have the problem.

I notice there is a 104mA drain on the battery and if I remove fuse 15 the drain is elliminated. However to completely flatten a 40AHr battery with this discharge would take 400 hrs so I don't think this is significant.

When the engine is running and all the electrics on I still get 14.75 volts across the battery so I thought the alternator is donig it's job.

Has anyone any ideas how I should try and find the problem?

Thanks
 
Hi,

Thanks. No alarm fitted. I suspect the alternator but don't know how to test it and I understand it's a pain to swap it. Even so I thought 14.75 Volts indicated a good alternator.
 
Hi, I would find out what fuse 15 relates to lights radio ect cannot be all that much as its very small drain taking place on your battery. Otherwise take your car to an auto electrian. good luck.
 
Thanks

Yes, aftermarket sound system. Fitted it myself. direct raplacement into existing plugs. No additional Amp or speakers, just a simple radio / cd with a usb port for ipod connection.

Sound system does not turn off automatically, maybe it should? The 104mA drain was with the sound system turned off but the removeable face plate was in place.
 
Hi,

Thanks for all the replies. I'll do the sound system mod as per guide and see if that reduces the drain on the battery with multi-meter.

If that does not help how can I check for a leaky diode?
 
Hi, done the mod so now the sound system turns off with the ignition. Battery drain reduced from 104mA to around 10mA which I assume is the clock, head unit memory etc so hopefully the problem is solved. Thanks for your suggestions.
 
still a question (hope someone is reading it still).

My battery was also draining, also caused by fuse 15.... Doesn't matter whether turn it off by taking off the frontpanel, or by holding the off-button for a few secs which should really turn it off (according to the manual)
When measuring the connection, it showed out that indeed both red as well as yellow cable are under constant power - so identical to what you describe.

However, when testing with multimeter the connection to the radio (Sony XPlod) it turns out that:
- red+yellow connected: battery drains with 120 mAh
- only yellow connected with red de-connected: 120 mAh
- red connected and yellow taken out, drain is almost nothing.
(to prevent battery drain, i now de-couple yellow every time i leave the car, and connect them again when starting to drive. In this way, the battery doesn't drain - but instead all radio memory is gone but that's better than not driving at all).
SO the advise given to 'tap' the red power from electric windows, leaves yellow connected to the radio at all times. And exactly yellow is the big eater of battery in my case. (n)
Is this the same with you guys ? Or :confused:
Does this really resolve the battery drain ??
 
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My stereo was only using about 30mA and the alarm 10mA but still managed to drain the battery in a week.
I did some calculations and it worked out abot right.
 
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