Hi all.

May of found a problem with my new 3 door. Basically im having problems with battery or alternator.

Car battery is/was flat. Put it on jump start for 10 or so mins then turned it over. Then after 10/15 mins of ticking over the car cut out and wouldnt turn back over. Done the same with the jump leads again and it would start for abit, then cut out. Also when putting wipers or rear screen heat on it would also make car cut out.

Also battery light on dash ignites as it should but never goes out.

Basically, is it the alternator not charging the battery or is the battery that fucked t wont take the charge off alternator???

Im putting the battery on charge for 3 full days and im going to go from there.

Also, can someone recommend me a mint battery for my 3 door. I want the best one possible.

thankyou.

 

when its running test the voltage at the battery

 

What should it be? 12 or 12.5 volt?

 

2.5 -12.8 not running
13.8 -14.5 running i think

 

To define a charge the reading must be higher than the open circuit voltage of the battery, so a good battery will be a good 12.40V, so with the car running ideally you should be seeing 13+ V, under load ideally you don't want the figure to go below 13V.

To answer your question it's your charging system at fault, the battery is fine!

Thats the very purpose of the battery light to indicate no charge, so it would be best to consider a recon alternator, only other thing it may be is the "regulator".

Martin

 

Any advise on how to 'test' the alternator to find out if it is that or not?

Im still going to replace the battery anyway, as I dont know its condition tbh.

Also, where is it possible to pick up an alternator or can i get my own one recond?

 

You just need to put a multimeter over it with the engine running, you can replace the battery but it seems kind of pointless as it's most likely perfectly fine.

You want to be seeing 13.xxV with the engine running, I suspect a reading of 12V or lower, if so this confirms no charge!

Depends on if you know anyone decent who can do it for you on an exchange basis or who will recon yours, you could do so yourself if you got the brushes etc to do so.

Martin

 

Thanks Martin.

With the car runnning I need to take a reading from where. The battery terminals or the alternator?

If its 12v or less at said point it means there is no charging happening?

 

battery terminals

 

Terminals, yes anything below 13V would mean no charge.

Martin

 

Spot on.

When the battery has been on charge, should I quickly check its output just so I know what its giving? This may also tell me if its fucked or not and has accepted its charge right?

Once connected back up and im check for the 13v or above. Should the car be idle or revving? if revving, upto what RPM? Sorry for all the questions but I want to make sure im doing this right before I fork out for al/batt.

 

Just allow the car to idle mate check on the battery terminals if you don't see 14 volts there then really need to check on the back off alternator as it could be a wiring fault

 

Not really, tbh the reading doesen't really mean anything as a faulty battery as you are testing under no load.

Martin

 

Sorry Martin, dont understand your last post there?

 

The battery reading is irrelevant as it's when a load is placed on the battery it will show itself, so for example, a bad battery may show 12.10V, it dosen't mean that battery is good, it merely means it has that power at that moment when you tested it!

For your purposes you should see around 12.40V + when you have fully recharged it.

Martin

 

Great. And when on the car, idleing, i shoud see 13v plus. If not i then need to get the alternator seen to/tested?

 

Yes, the fact your battery light is on suggests it to be an alternator problem, but confirm no charge first!

Martin

 

Thanks.

Apart from the alternator itself, what else is in the path which could cause an issue?

 

Connect the battery up and put lights on for 2 mins to stabilise it.

Turn the lights back off, take a reading with a multimeter set to DC across the two big battery terminals, expect 12.5volts ish, but it doesnt really matter what it is in this case, but you want it for reference.

Now fire the engine up, rise revs to over 3k to ensure the alternator is kicked into operation then allow to idle.

Now Take another reading from the same place and expect 13.5V +
What you are now reading is your alternators power output.

I suspect the reading will still be nominal battery votage, indicating your alternator output is zero.

 

Fantastic help Stu.

Is there anything else, "in the line" which could cause the non charging of battery apart from the alt itself and cable?


Thanks alot.

 

I can only see it being the alternator mate... If I was closer I would have checked It you.

 

That would of been very kind of you Mat.

If it is, there is an excellent place round mine that recons them. As i dont fancy trying to source a new one. Can you still get um?

 

Assuming the alternator is good, then it requires a working regulator which is usually screwed to the back. A good earth to engine, the engine earth itself to chassis to be good and the live wire from alternator to battery to be good.

The only other part of the circuit is the exciter lamp which in your case appears to be working.

However, on your car, you may also have the Ford active charge technology which means the ECU has control of the charging circuit, that requires further investigation if the usual causes of no charge are ruled out.

 

Top advice.....

 

Thanks again. I will be sure to check all of those out.

 

Not on a Sierra/Cosworth you don't, unless he has aftermarket management?

Martin

 

Nope. Just a 3 door cosworth with L1.

 

Sorry, only saw 3 door in your original message, and your siggy has a 3 door Fiesta in it so I assumed it to be that vehicle.

 

My apoligies for not being clear enough.

So i can disregard that ECU comment you made earlier?

 

Yes mate

 

Found this to be alternator.

Bought a brand new one, off ebay, for 59 pound delivered with a 2 year warrenty. After a quick change of pully on it went. Battery light now ignites when ignition is on and extingushes as soon as engine is started.

No need to rev it past a certian rpm or anything. Seeing 14.2v at the battery now.

Thanks for all the help guys.

 

No problem, glad it's sorted.

Martin