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Discussion Starter · #1 ·
Hi,

my coupe which ive owned for about 3weeks now has never had any problems starting or anything.

Today, after the car was driven to my workplace, it was parked up unlocked for no more than 15mins. When i went to start it, it struggled! I stopped the engine and tried again and it wouldn't start....battery flat. Jumped it off and it started no problems.

Checked the battery terminals and was getting 13.5v on tickover.

Gave the car a good ride home, 80mph on motorway for 20mins.

Arrive home, turn off and tried starting and it was slow but started. Tested the battery terminals again.....11.45v at tickover and 11.85v at 2k rpm.


Is my alternator on its way out? There are no warning lights on the dash to indicate a charging fault.

TIA>

Dan
 

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Discussion Starter · #4 ·
Checked the output voltage and was getting 13.6v out of back of Alternator.

got a new batt delivered at work but wrong size! fitted anyway and started car...on idle i was getting 13v at the battery...still a little low but much better than the 11.5v!!

So think Alternator is best getting replaced?!?!?!

Dan
 

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Its hard to say, maybe see how it is for a few days? Whatever you choose, I'd recommend getting it checked out so you know if you need anything or not. You don't want to get stranded somewhere at a later date and be kicking yourself. :thumbsup
 

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If you are going to leave it a few days and see how it goes, I would take regular readings of the charge rate at the rear of the alternator as well as at the battery, as the readings you're getting are a bit random. This could be the result of the alternator breaking down, and probably is, but could also be down to a poor connection. If the charge rate is always steady at the alternator but varies at the battery then the wiring needs to be checked.
 

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Discussion Starter · #8 ·
Right..........NEW problem........i guess the alternator is little low in voltage output.

With new battery on car i went to start it this morning and its FLAT! even with the old battery attached along with new one...still not enough power to start or even turn the engine.

So,

1, The alternator has failed??

2, There is a mega drain on the system somewhere?

Trying to get someone out to bump car off but with work commitments i'm not going to be able to get it checked thoroughly until next sat now.

My aftermarket alarm stopped locking the driver door about a week before this happened, could the alarm be causing a drain? it has immobiliser incorporated into it. which still works fine.

Dan
 

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Discussion Starter · #10 ·
Mega drain easy enough to test. Set multimeter to DC amps, disconnect battery negative cable. One multimeter lead on disconnected negative cable, the other lead on battery negative post. Reading on meter should be not much more than 50mA approx

is this with engine running or off? Will try this when batt charged up.

Cheers
 

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Discussion Starter · #11 ·
Also, just bumped car off.

its been running for about 3mins. batt voltage is 12.7v on tickover.....13.4v revving approx 2k.

just touched the alternator casing and its red hot! is this normal??

Will remove and fully charge battery then run voltage drop test in morning.

Also checked the boot light but this went out when boot shut :-(

Dan
 

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Also, just bumped car off.

its been running for about 3mins. batt voltage is 12.7v on tickover.....13.4v revving approx 2k.

just touched the alternator casing and its red hot! is this normal??

Will remove and fully charge battery then run voltage drop test in morning.

Also checked the boot light but this went out when boot shut :-(

Dan
12.7 volts means alternator isn't charging. ;)

That is just the battery voltage showing. The alternator shouldn't be red hot either, you need a new one if you were checking voltage from the rear of the alternator
 

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Discussion Starter · #15 ·
I carried out a voltage drop/drain test.......

something is sucking a whopping 3.2 amps out of the battery and that was with only a booot light been on. with the bulb removed, it went to 3.1 amps!!!

Maybe?!?! the short is within the alternator.

I'm going to get it properly checked and replaced if required.
 

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Discussion Starter · #19 ·
Right, finished ealry today so measured battery again and getting a 4.2amp draw.

disconnected the alternator live wire from back of alt and batt reading gives a 1.2amp draw.

1.2amp?? this normal? only thing working will be the immo/alarm. car was unlocked too at this time.

will try again now...with car locked.
 
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