Driving home from work tonight when I started to get symptoms of electrical power failure.

 

Firstly, the stereo started to cut out then went off altogether. Next the engine started to misfire under heavy throttle usage.

 

Next the Hicas system, closely followed by the ABS system shut down (i.e. warning lights on the dash). This coincided with the variable power steering assist stopping working (i.e. the PAS was continually at the same level whatever speed I was driving).

 

Managed to limp home. When I got home, the passenger side window refused to go up. When I cut the engine, the starter motor would only turn very momentarily before giving up.

 

Just tried it again now (1.5 hours later) and the car starts fine and everything works!

 

Anyone shed any light on this. The battery is obviously charged as it now starts the car. So I would presume this rules out the alternator. The battery certainly wasn't providing enough power to even close the window before but now it seems capable of starting the engine! What's that all about then? The battery's a few months old.

 

Thanks all.

Mike,the first thing to check is.....................

 

 

Are your battery terminals real tight?

 

does your earth lead coming from your battery to your earth, have a good contact and the nut is tight?

Mac's right in what he has said (should do, he is the Man that knows everything and everybody LOL!). If the terminals dont fix it then I would suggest removing the lower panel on the drivers side. Check the ignition switch for signs of burning (sure sign that the contacts are knackered), also check the large wires connected to the bottom of the fuse box with the bolt on terminals.

 

Good luck!!

 

Paul (SparkZ, because I'm a sparky!!)

Cheers guys. Checked the terminals and they're pretty tight. Just started it up now, in the dark, and there's a faint glow from the battery light on the dash.

 

As far as I know (which isn't saying much) this means there's more power leaving the battery than charging it? Which means alternator or wiring to alternator?

 

Anyone brighter than me agree or disagree with this?

I had a similar problem due to the alternator overcharging. It was giving off nearly 20 volts when engine revved. Caught it before it cooked the battery, but symptoms very similar. Needed new regulator.

 

Best of luck,

Simon

Alternator light glowing simply means that the voltage at the charging light is not the same as battery voltage. This can be caused by many things such as ignition feed to dash not at battery voltage (faulty switch or feed wiring), alternator output not correct (either under or over charging) or high resistance in wiring somewhere. Do check the ignition switch, preferably with a multimeter. Measure the battery voltage and then measure the output from the ignition switch while someone else is cranking the engine over, they should be the same. If the voltage at the switch is lower then check the permanent live feed to the switch while cranking, if that is also lower than at the battery while cranking then the fault is with wiring to the switch. If you cannot crank the engine steadily enough to get a reading then try without cranking but with all electrics switched on. Also worth mentioning is if there is an imobiliser which cuts the ignition feed then that would also be worth checking as they can suffer the problems you have described.

 

Let me know your test results and I will try and guide you from there. Sorry I cannot be more specific but it is the sort of fault I could probably diagnose in minutes with the car in front of me but could be a bit tedious using this method.

 

Good luck (again)

 

Paul (SparkZ)

Hi all.

 

Not had chance to do any comprehensive testing on it yet. Been re-tiling, re-carpeting, re-patio-ing, re-painting and re-wiring. Apparently new born babies love that kind of thing so I have to get it ready!

 

Charged the battery up with an external charger and the car runs fine for the moment. If I disconnect the battery while it's running, the car still idles fine. But when I try to drive the car with the battery disconnected, it dies as soon as it starts to rev harder.

 

Am I right in thinking the car should run fine without the battery? And if it's going to die, it should do it at idle rather than high revs?

 

I presume the car is running off the battery somewhat rather than the alternator, hence the good running at the moment (until it discharges again presumably!) Which I would presume means that the alternator is not functioning correctly? The wiring must (I think!) be ok as the car can run when it's draining some charge from the battery.

 

I know I need to do some better testing but that's all I've had time to do for now. Based on my somewhat sketchy results, would it seem likely that the alternator is at fault?

get a multimeter across the battery terminals, should be around 12.5 to 13v when the car is not running if its less than 12v then i'd say your battery is goosed(especially if your alternator voltage is ok). Around 13.5-14.5 with the car ticking over, if its not then it looks like your alternator.

I was told you should NEVER run an engine when it is not connected to a battery. The battery absorbs the variation in voltage the alternater put out. Without the battery the fluctuation in voltage can blow your electronics and a lot else.

Originally posted by Mike Duffy

Hi all.

 

 

 

Am I right in thinking the car should run fine without the battery? And if it's going to die, it should do it at idle rather than high revs?

 

 

I wouldnt fancy trying it, i once tried to drive a friends rover 213 without a stater motor and it set on fire, so now stuff like that scares me!!!

Cheers everyone.

 

Voltage across battery terminals is 11.91 with engine off. Drops to 11.69 with engine on. Alternator?

 

Oh, and no fires yet but thanks for the warning! Battery staying firmly connected from now on.

NEVER run without a battery but I guess you already have that message! Wouldn't fancy replacing all of those ECU's and control modules!!!

If your battery voltage drops when the car is started then the alternator is not charging the battery, but be careful. It does not mean the alternator is NFG. If there is a short on the D+ wire (feed to the charging light) then the alternator will struggle to excite and charge. If it does start charging with a short on this wire then the wire will start to burn because of the heat generated!!!! If you can get to the alternator easily with a ramp or stands then disconnect the thin wire (D+) and recheck the battery voltage with the engine running. If you still have no charge (battery voltage still below 12V) then it is pretty sure the alternator. If you are getting charge to the battery then you do have a fault on the D+ circuit.

 

 

Paul (SparkZ)

Cheers Paul

 

I'll try that tomorrow. Anyone know how easy it is to replace the alternator if that's at fault? And any ideas how much?

 

Mike