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2002 Petrol Mondeo - Faulty Alternator? - Battery Drain


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#16 wase16ll

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Posted 15 February 2014 - 12:00 PM

great answer from BOF

 

should also be noted your battery voltage is very low, bordering on flat

 

most common reason i have found with intermittent drains over the years have been, cigar lighters shorting, courtesy light switches and alarms...these would be the areas to check first...mondeo bonnet alarm switch was a very common problem, wondering if alarm is triggering overnight but your unaware as its not setting off the horn



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#17 PaulRandell

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Posted 15 February 2014 - 12:06 PM

Ok, I am now sure the alarm is working,  I set the alarm, waited 20 seconds and then tried to open the bonnet. Alarm went off Ok.



#18 wase16ll

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Posted 15 February 2014 - 12:14 PM

do you have access to anything that can communicate with the ECU's beyond engine...

 

when you previously said you couldnt seem to set the alarm off, what/how were you doing.

 

there is a data you can access via the ecu, which will give you not only faults within the alarm, but reasons for the last 5 triggerings..



#19 PaulRandell

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Posted 15 February 2014 - 12:23 PM

The only other thing that has been changed is the stereo it is currently a 5000rds tape stereo. Which means the steering column control stalk doesn't work.

 

Pretty sure its not this however as I have already disconnected the stereo completely and the battery still drained overnight.



#20 wase16ll

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Posted 15 February 2014 - 12:26 PM

was the battery connected last night, as that voltage is very low



#21 PaulRandell

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Posted 15 February 2014 - 12:30 PM

Sadly I don't have access or the kit for the ECU.

 

My other issue would be that I cant replicate the drain. Is it practical to just remove the fuses for Interior lights / Cigar Lighter / Alarm and see what happens over a longer period?



#22 PaulRandell

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Posted 15 February 2014 - 12:32 PM

no the battery was not connected last night.

 

I have a trickle charger which I a can put on now, what should the battery voltage be? Is it possible that the alternator is just no charging the battery enough, and the 0.09 drain is enough to stop the car starting?



#23 wase16ll

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Posted 15 February 2014 - 12:43 PM

12v or below is classed as bordering on flat...a fully charged battery should read at least 12.5v

 

may not seem a lot of difference, but if the voltage is low then it can play havoc with electrics..

 

if the alternator is giving the correct charge, all battery leads/connections are good, then it could just be a case of a faulty battery.

 

you will need a charged battery in order to get an accurate reading on drain test, the downside of trickle chargers are that they will never fully charge a calcium battery unless you have a specific calcium battery charger.

 

would ignore your readings for now, till you get battery charged



#24 wase16ll

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Posted 15 February 2014 - 12:45 PM

should add that a low amp drain will still flatten an already low/flat battery quite quickly



#25 BOF

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Posted 15 February 2014 - 01:03 PM

 

My other issue would be that I cant replicate the drain. Is it practical to just remove the fuses for Interior lights / Cigar Lighter / Alarm and see what happens over a longer period?

 

In principle, yes. In practice the difficulty is that whatever documentation you've got on which fuse does what is probably wrong and incomplete. It still might be worth a go, though...

 

At least, pulling out all the fuses that it seems safe to pull out and seeing if the drain goes away might be useful (oh: tip - take a photo of the fuse box(es) before you start, just in case you get confused about which fuse goes where later on; and of course, you'll need the radio code, but you must already have that).



#26 wase16ll

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Posted 15 February 2014 - 06:01 PM

i would forget about pulling fuses for now...there is a problem with the battery itself at the moment.

 

11.7v after being left disconnected overnight is a flat battery...slightly lower, maybe 0.5v,  and the car wouldnt have started..its actually taken a 5 mile run to get the battery to read above 12v, and at 12.06v is still very low charge

 

imagine the battery was connected overnight, soon as it drops below 12v, then its quite plausible the alarm will mistake this for a voltage drop, such as a door being opened, it may or may not have triggered the alarm, but it may increase the drain as it tries to deal with the info...not saying this is whats happening, but its one of a number of possibles

the battery will also struggle to maintain a charge at that voltage with a normal amp drainage.

 

first step has to be, charging the battery to an acceptable level...get it to at least 12.3v after charging and left for couple of hours.

from there, i would personally leave it disconnected overnight before taking another reading..any drop in voltage more than 0.2v i would suspect a battery fault..even 0.2 is pushing it, ideally you will want to see less than 0.1v difference

if battery has sustained an acceptable voltage, then you can carry out the drain test and get a truer reading...11.7-12.06v is way too low



#27 PaulRandell

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Posted 15 February 2014 - 06:55 PM

I purchased two batteries in Jan 2014, one for my mondeo and one for my wifes mondeo.

 

My battery is at 11.86v and my wifes is 12.37v, my battery is on charge and I will check the voltage tonight and then compare any drops in voltage on both tomorrow morning.

 

I'll leave the fuse pulling until as you suggest my battery is at an acceptable level. I am assuming that this issue has had a negative effect on the battery.

 

In hindsight I wish I had paid more attention to the voltage of the battery before.

 

Thanks for your help

 

Paul 



#28 PaulRandell

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Posted 16 February 2014 - 02:36 PM

Ok last night my battery after 4 hours of charge 11.30pm 12.76v  9.05am 12.68v

 

One 0.5m journey this morning battery now 12.51v

 

I have had one reading on my meter of 3.61a all morning, in that time I checked all the relays and all the fuses in the fusebox and no change to the drain, even F30 and R5 ??

 

I can't get either of the connectors off the back of the alternator, where would I find the the bat+ connection? 

 

The only fuses/relays I didn't get the chance to check were F11 F20 F21 F13 F15 F24 R1 R3 R2 R4

 

I will keep trying, not sure if I have isolated the alternator yet or not?

 

Paul  



#29 wase16ll

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Posted 16 February 2014 - 11:03 PM

are you saying that this morning you had a constant 3a drain or just a short time of 3a..if just a short time, when did it appear and for how long?

 

also, are you saying you have eliminated all the fuses in the fascia fusebox and most of the fuses in the engine bay, bar those you listed?

 

the BAT+ is the thick cable to the rear of the alternator...probably red in colour..if you cant access it, then might find the red thick cable to the back of the starter easier to remove, which will also isolate the alternator.

the battery cable goes from battery to starter to alternator

you will also need to remove fuse 30, that way the alternator is totally isolated from the battery, so if you still pick up a 3a drain with everything switched off, then you will have eliminated the alternator as a suspect



#30 PaulRandell

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Posted 17 February 2014 - 07:10 AM

After approx 4 hours of testing I had approx 4 minutes of finding the 3.61a drain and another 4 minutes of a 3.30a drain, in that time I checked most of the fuses in the engine bay, but none of the fuses in the glovebox.

 

I stated trying to replicate the drain (open doors, put on lights etc) but nothing really worked. I started thinking that it only drained in low temp?  or that it was something to do with the central locking as each time I touch the battery in line with my amp meter the locks click. Or that it is something that switches off/on after 20 minutes of no activity?

 

I have also searched on the internet and there are a few instances of the battery saving relay failing and causing a drain?

 

Pretty frustrating really, is something like this going to help?

 

http://www.ebay.co.u...=item27dace8b0d

 

I am pretty much committed to Mondeo's so something like this may well be an ongoing investment (looks a bit cheap but may help?)



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