Alternator output

[SD1too]

Edward,

The information I've given you is from RAVE for the four and six cylinder engines. It occurs to me that your V8 might be different. Have you tried asking on the club's section for these cars?

Simon

[COLVERT]

Edward.----Now for something that might be a major factor in this search for what is making your battery go flat in only 48 hours, approx.

How do you know your battery is in good condition ???

If your battery is near the end of its working life and you are using a smart charger all the charger will tell you is that the parts of the cell plates that will take a charge are charged.

For the sake of argument lets say only 10% of the plates become charged. The green charged light on your smart charger may light up but that won't tell you how much electricity is stored up in your battery.----Just that the 10% is fully charged.

A small amount like this will soon be used up even with a small continuous discharge. ( 48 hours you say. )

It could simply be that it's your battery itself that's giving you all this stress.---

[edwardmk]

Thanks Colvert,

I'm inclined to agree. I'd assumed that a big beefy battery with a five year guarantee only a year old couldn't be the problem. The voltage this morning was 12.07v which is disturbing after a full charge and not using the car. The resting current was fluctuating 0.05-0.1a, so in less than 10 hrs it looks more likely the battery isn't holding it's charge well. I'll report back again tonight.
thanks again to everyone who posted. The pointers have all been invaluable to me .

[COLVERT]

Originally Posted by edwardmk

Thanks Colvert,

I'm inclined to agree. I'd assumed that a big beefy battery with a five year guarantee only a year old couldn't be the problem. The voltage this morning was 12.07v which is disturbing after a full charge and not using the car. The resting current was fluctuating 0.05-0.1a, so in less than 10 hrs it looks more likely the battery isn't holding it's charge well. I'll report back again tonight.
thanks again to everyone who posted. The pointers have all been invaluable to me .

Sometimes, ignoring what your charger is telling you is to charge your battery for at least 24 hours.

30 is better if you can. Then let your battery settle overnight before you check the voltage.

However a garage Drop Tester is the only way nowadays to get some idea of how much charge is in the battery.

In the older type of battery with removable filler caps it was always very easy to get an accurate assessment with a hydrometer.

[COLVERT]

Originally Posted by pletevl

OK. So different opinions.
My other cars are around the 13.5 mark too.
Would this voltage kill my battery?

Well, there you go Pete.---You'll now find lots of useful information in the thread you started.---




Especially all the bits in blue print.-------

[SD1too]

Edward,

Some good thinking by Colvert there, but it doesn't explain the current draw after the ECUs have entered 'sleep' mode which MG Rover's bulletin says should be 30 - 45 mA. Yours appears to be high at 100 mA and it's odd that it fluctuates.

Have you checked that your sat. nav. disc drive LED extinguishes?

Originally Posted by edwardmk

I'd assumed that a big beefy battery with a five year guarantee only a year old couldn't be the problem.

How often do you use the car Edward? When you do, how long are your journeys? Even a big beefy battery with a five year guarantee will go flat if it's not kept fully charged and few are. Car batteries also don't like deep discharge so if yours has been in this condition a few times it's life will be shortened.

Simon

[edwardmk]

Now convinced my battery isn't what it should be.
Voltage is 11.97. It's slowly dropping. The car hasn't been driven this week since it was parked after the 20 mile run on Monday.
I tried starting just now and it didn't turn over so easily, but still started at under 12v. I'll take the battery to Halfords tomorrow under warranty and see what response I get!
I think the next battery might get left on the CTEK permanently when the car isn't in use!

[COLVERT]

Originally Posted by edwardmk

Now convinced my battery isn't what it should be.
Voltage is 11.97. It's slowly dropping. The car hasn't been driven this week since it was parked after the 20 mile run on Monday.
I tried starting just now and it didn't turn over so easily, but still started at under 12v. I'll take the battery to Halfords tomorrow under warranty and see what response I get!
I think the next battery might get left on the CTEK permanently when the car isn't in use!

Good idea about a trickle charger.

As I live in France and we get a good amount of sunshine here I have my battery permanently on a solar charger when the car's not in use.

When the battery gets checked it's always over 12.6 volts at rest.---

[SD1too]

Originally Posted by edwardmk

I think the next battery might get left on the CTEK permanently when the car isn't in use!

That's exactly what I do with my SD1 Edward.

Simon

[COLVERT]

Edward.---Now don't forget. Come back and tell us the outcome of all this.--