Electrics: Should I fit a bigger battery?

[oragex]

If you got 10-20mAmps it should mean there's no drain. On my S60 with dr door, trunk & hood open and unlocked I was getting only a few amps before 10 min, like 2-3 if I remember well. But I did disconnect the trunk lights - for some reason mines wouldn't shut off after 10 min

[cheshired5]

Originally Posted by BlueRubber

when I re-connect the battery there is significant amp draw for a while as all the computers etc boot up, initially over 20amps, then down to 16amps

Sounds high. Was the key in the ignition?

[BlueRubber]

Originally Posted by cheshired5

Sounds high. Was the key in the ignition?

Yes the key was in position 2

[oragex]

We cannot measure for parasitic drain with the key in the ignition, because the car systems will not shut down. Just keep the key in POSII, connect the multimeter in series as explained (set to 10amp scale and 10amp plug), once the multimeter is connected, remove the key from the ignition and time 10 min by the second. At 10 min sharp all computers shut down (except as said perhaps the trunk lights). I had all doors unlocked, dr door, trunk and hood open. Mind you, if you undo some fuses you may get an SRS message (just a guess). When done measuring and connecting back the battery, may put back the key in POSII

[cheshired5]

Originally Posted by BlueRubber

Yes the key was in position 2

Aah, that'll be why. Key out for parasitic drain test.

[BlueRubber]

Thanks for all the replies.

I re-did the test with the multimeter inline and got a very similar result to the clamp meter, which showed there is no parasitic drain.

I bought a replacement battery for £59 and the car does seem a little happier with that. Plus the old battery still has enough life left in it for me to charge my model aeroplane batteries from it when at the flying field so win-win!

https://www.ebay.co.uk/itm/YUASA-PRE...72.m2749.l2649

[Samuel2709]

I was under the impression that a clamp current measuring meter will only measure AC current? DC you need to be in series using your cables

[BlueRubber]

Originally Posted by Samuel2709

I was under the impression that a clamp current measuring meter will only measure AC current? DC you need to be in series using your cables

Some clamp meters only measure AC voltage but others can measure DC as well.
This is the meter I'm using and it seems accurate to within about 2mA.
https://www.amazon.co.uk/gp/product/...?ie=UTF8&psc=1
UNI-T UT210E

[cheshired5]

Originally Posted by Samuel2709

DC you need to be in series using your cables

Good luck being in series with a multimeter to measure alternator output or starting current. At best you'll blow the fuse, at worst you'll blow up the meter.
As said, DC clamp meters are plentiful just a little more expensive than their AC only equivalents.

[BlueRubber]

Another quick update on this.

Before swapping the battery I would fully charge it and then it would go down to about 12.3v while connected to the car but the car being left unused for about 3-5 days.
The measurement was taken with the boot open via the cigarette lighter socket in the boot.

I repeated the same test with the new battery and it's holding around 12.5-6v.
Which leads me to conclude the battery was definitely the issue.