Possible Battery / Alternator issues?

Retrogamer

Ibiza 1.9TDi.
If left standing for a couple of days and it's a cold morning really struggles to start. Turns over slowly.
If you try and start it any morning with radio, heaters or any high amp device it won't turn over properly.
One started and ran, it's fine for at least 24 hours.

I got a loan of a device that goes into the cigarette lighter to measure the voltage.

After battery sat for 24 hours - 12.3v
Fresh off a long drive - 12.8v, but goes down to 2.4v within 30 minutes.

Now, if i start the car the voltage goes to 11.9v because of the ignition being on. If i let the car idle, the voltage stays there and the alternator isn't working.
If i blip the throttle to 1500-2000rpm the alternator kicks in and reads 14.4v at idle revs.


I'm thinking the alternator is just a bit tired with 115k on it, but sincle i don't let it idle for a long time and i do a lot of long motorway miles, that it should be getting charged enough each day to cancel out the 30s or so each morning i start it and it's not charging.

I'm thinking that the battery is struggling to deliver the amps needed and it's feeling a bit tired.

Any advice / opinions are welcome.

marlot

A garage or car parts retailer can do a 'drop test' on your battery - this measures it's ability to deliver a starting current. But it does sound as if it's knackered.

Your alternator may well be past it's best too, but changing the battery is the first step.

Strider590

Retrogamer wrote: »

Ibiza 1.9TDi.
If left standing for a couple of days and it's a cold morning really struggles to start. Turns over slowly.
If you try and start it any morning with radio, heaters or any high amp device it won't turn over properly.
One started and ran, it's fine for at least 24 hours.

I got a loan of a device that goes into the cigarette lighter to measure the voltage.

After battery sat for 24 hours - 12.3v
Fresh off a long drive - 12.8v, but goes down to 2.4v within 30 minutes.

Now, if i start the car the voltage goes to 11.9v because of the ignition being on. If i let the car idle, the voltage stays there and the alternator isn't working.
If i blip the throttle to 1500-2000rpm the alternator kicks in and reads 14.4v at idle revs.


I'm thinking the alternator is just a bit tired with 115k on it, but sincle i don't let it idle for a long time and i do a lot of long motorway miles, that it should be getting charged enough each day to cancel out the 30s or so each morning i start it and it's not charging.

I'm thinking that the battery is struggling to deliver the amps needed and it's feeling a bit tired.

Any advice / opinions are welcome.

Either the alternator is working or it's not and it does seem to be charging the battery, what can happen is the the regulator starts to break up at high temperatures, so check the voltage with the engine running just after starting AND after a journey.

Having just done a rebuild on a classic Lucas ACR type alternator, I know this ^^ to be true.

The voltage at the lighter socket might not be correct, sometimes this voltage comes in through a diode (which drops the voltage by around 0.6v) BUT it will tell you if the alternator is doing it's job.

So basically if the alternator is charging at the beginning and end of your journey, then the battery is knackered.

DO NOT attempt to keep charging and jumping a dead battery, it will only end in tears and does nothing but delay the inevitable. Only instead of buying a new battery cheap while the other one is still semi working, you'll end up stranded somewhere with the prospect of a breakdown service charging you double the going rate for a battery.

Marktheshark

Alternators do not get "tired" they either work or they dont.
batteries get Tired, especially when its cold as it is a chemical reaction and chemical reactions happen slower at lower temperatures.
Over time the Battery chemicals lose strength, the cold slows the reaction and you reach a point where these intercept.
A new battery is the solution, never let them give you the display one, look for date codes on the batteries and pick the newest one they have.
Euro car parts are unbeatable on new batteries at present and as they knock them out like hot cakes you get a fresh one.

colino

If a modern car isn't charging at a fast idle from start-up, the alternator is goosed. You need it checked over properly though as a large drain, either from a dying battery or another parasitic drain, could give the impression that there is only <12.5v at the battery terminals.


If you do need either a battery or an alternator, check out your local motor factor. We have had a very mild winter and stock-piled batteries and alternators have never been cheaper.

jbainbridge

Yes, start by replacing the battery. A good one won't cost much and you can probably do it yourself. If it is more than 6 or 7 years old it's done well.

Retrogamer

colino wrote: »

If a modern car isn't charging at a fast idle from start-up, the alternator is goosed. You need it checked over properly though as a large drain, either from a dying battery or another parasitic drain, could give the impression that there is only <12.5v at the battery terminals.


If you do need either a battery or an alternator, check out your local motor factor. We have had a very mild winter and stock-piled batteries and alternators have never been cheaper.

This is the thing. If i start the car and let it idle at 900rpm and never touch the throttle, the alternator never kicks in.

As soon as you rev it to 1500-2000rpm then the alternator kicks in and keeps charging regardless of the rpm after that so it's not a problem unless i sit and let the car idle for a really long time

jbainbridge wrote: »

Yes, start by replacing the battery. A good one won't cost much and you can probably do it yourself. If it is more than 6 or 7 years old it's done well.

It's a 2006 and i suspect this is the original battery so no shame i don't think.

Foxy-Stoat_3

Retrogamer wrote: »

This is the thing. If i start the car and let it idle at 900rpm and never touch the throttle, the alternator never kicks in.

As soon as you rev it to 1500-2000rpm then the alternator kicks in and keeps charging regardless of the rpm after that so it's not a problem unless i sit and let the car idle for a really long time


It's a 2006 and i suspect this is the original battery so no shame i don't think.

Sounds about right about the alternator, just change the battery and see what the multimeter says under load.

Strider590

If the battery voltage is too low to power up the alternators exciter coil, then the alternator will not work until it self excites at higher rpm.

colino

If the alternator was faulty in that fashion, the clue would have been the big red light glowing on the dashboard.

Retrogamer

Yep, no alternator light on at all and belt is nice and tight.

Took the gamble and went and got a new battery now. Slightly more amps than i need, but i want to keep the car long term so should be fine.
Since it's been fitted the alternator still doesn't begin it's charge unless the rpm goes over 2000.
But since it's been fitted, the car has never started as quickly as it has now and i've had it a year and a half.