Loosing power( electricity) after starting

[Sharkstu]

Im a little confused and whist waiting for my battery to charge thought to ask the question
V8 amazon 2000.
Starts on the button with a charged battery.
Within about 10 min of running it starts to misfire, a few min later it stops and will not start as the battery is flat.
Charge it up and get the same again.
New battery, same problem.
Any ideas what could drain it so fast when running? No lights fan or ac on.

 

[Chris]

Sorry I know so little about this particular model and its engine. If its petrol then it sounds rather like the alternator isn't charging. Without that, the battery is running the vehicle and will soon be flat. If it's a diesel then, I've not a clue! Some massive parasitic drain, but that shouldn't stop the engine. Unlike a petrol it will run with the battery disconnected.

 

[Sharkstu]

Chris
Thanks it is a petrol, I would not expect it to flatten a battery so fast, you are correct ut does sound like an alternator problem though, I will get a better idea once I can fire it up and test the alternator, but I won't have long before it dies.
It happens much faster than would expect.

 

[Chris]

Yes you won't get far on just the battery. It's not just the spark plugs that are firing but all the ignition electronics, ECUs and so on. There will be quite some amps associated with running a big lump like that.

 

[Sharkstu]

Yes, I guess you are right.
Assuming that when I firw it uo aging that I'm not getting charge voltage at the battery.
I need to work out the best way to check if the alternator is getting a signal, It looks really tight to get to the back of the alternator( if not impossible without hours and hours of parts removal 1st)
I have chexked the 2 fuses and both appear to be OK.
Im hoping that someone can point me to an easy option.

 

[Steve Wright]

Here are a things: first has it got twin batterys?
when you charge it,how long does it take to charge(at what amps)?
you have charged it and taken the charge leads off how long do you leave it before trying to start it?
Have you got DMM?
when you have charged it, put the meter on "amps" disconnect the neg lead and measure the current, and see what the current draw is?
then reconect neg lead set dmm to volts and stick the leads on the battery, start it and then watch the voltage?

and when you have done all that let us have the results

 

[Chris]

Well if it's not charging there will be a warning light on the dash for one thing. When it's running put a meter across the battery and see what the volt reading is. If it's 14.5 then you're charging. If it's 13.8 then it's a bit low so the alternator might be struggling but technically supplying current if it12v and dropping then your alternator is not charging. Also check that the connections on the battery are good and clean.

Let's just eliminate the really obvious stuff first.

 

[Sharkstu]

Steve
Single battery, 90ah, takes about a day to charge in a 6ah charger.
I have a multi meter yes, and going to do some checks in the morning once it is charged, I will start with your list.
I will report back.
Thanks

 

[Sharkstu]

I will check in the morning and report back.
Thanks

 

[Sharkstu]

Well , I have something to report.
Not quite what I was hoping though.
12.6 volt on the battery.
I tested from static drain 0.02 amp( I guess that's the immobiliser.
Starting volt dropped to 10.22
Then it picked up to 11.9 , not good.
However a few seconds after starting I had smoke bellowing out from the engine bay.....
It appears something on the aux belt is not turning, or the aux belt is not even moving al all.
However in my haste and the smoke it was hard to tell what it was.
The car has only done about 10 miles in the last 2 years, however up to now it has started every time I have tried it.

 

[qbartx]

Just take the belt off and see what's seized. If it's the alternator it isn't that hard to get it out on v8. Just make sure that after unbolting everything you push the p/s pump down and to the right, in front of engine to take alternator out, much easier than trying to pull it up.

 

[Sharkstu]

I have ordered a new belt today.
I thought the same as you, however its it melted I had best replace it, like you say whist I'm there I can see whats going on.
Is there anything I need to now about the removal and reinstall in the belt, I guess I het vask of the tensioner swap it out and put the mew one on and retention.

Do I need to remove the rad to get the alternator out?
Thanks.

 

[qbartx]

Just going by memory..y.ou don't need to remove the rad, just intake pipe/top of air filter, expansion bottle, p/s pump (don't disconnect it)

 

[BobMurphy]

Do I need to remove the rad to get the alternator out?

No you don't - but its a right fiddle and you'll need patience, long arms and a variety of tools. Its probably easier with the Air-Con pump removed, or at least loosened. Best tackled from below.

Bob.

 

[qbartx]

It's a simple half and hour job to replace that alternator. All from top no need to go underneath at all and a/c pump is on the other side of engine

 

[BobMurphy]

DOH ! Of course - its a 'V8', I have done this job on a 4.2 straight six - its a fiddle !

Bob.