Flat Battery I Think I Can Guess Unfortunately

[Chamber66]

So Yesterday out of the blue I had a flat battery, now I know its a good one and fairly new. The car jumpstarted no problem the out of the blue my dashboard lights started coming on an off.

Now to me this says alternator, but do they actually go that quick?
Just in case anything else it could be before I dive in to the engine bay?

 

[t-tony]

Easy to check alternator output?

Tony.

 

[Fender2004]

Make sure the boot light isn’t staying on?

 

[Chamber66]

Make sure the boot light isn’t staying on?

I don't appear to have one on y 2.8?

 

[Fender2004]

I don't appear to have one on y 2.8?

Unless a previous owner has removed it, my 97 2.8 has one.

 

[colb]

Alternators go bad without any warning, happened to my Z4 and Z3, simple to check if its got any output. Put a voltmeter on the battery terminals with engine running you should see around 13-14volts if its charging ok. I fitted combined voltmeter/USB sockets on both my cars after my episodes so I can monitor the battery and charging.

12V-24V Dual USB 2 Port Car Boat Charger Socket Voltage Digital Panel Volt Meter | eBay

Suitable for. 【Waterproof & Temperature Resistance】: The waterproof lid secures the USB port and leaves it able to work in splash conditions.

www.ebay.co.uk

Oblong type here

Pardon our interruption...

If you don't want to drill a hole get a unit that plugs into the cigarette lighter socket.

Pardon our interruption...

 

[Chamber66]

Unless a previous owner has removed it, my 97 2.8 has one.

Well I hadn't noticed that before lol
Surely it would take quite a while to drain the battery though?

 

[Chamber66]

Alternators go bad without any warning, happened to my Z4 and Z3, simple to check if its got any output. Put a voltmeter on the battery terminals with engine running you should see around 13-14volts if its charging ok. I fitted combined voltmeter/USB sockets on both my cars after my episodes so I can monitor the battery and charging.

12V-24V Dual USB 2 Port Car Boat Charger Socket Voltage Digital Panel Volt Meter | eBay

Suitable for. 【Waterproof & Temperature Resistance】: The waterproof lid secures the USB port and leaves it able to work in splash conditions.

www.ebay.co.uk

Oblong type here

Pardon our interruption...

If you don't want to drill a hole get a unit that plugs into the cigarette lighter socket.

Pardon our interruption...

Thanks Colin

 

[Pond]

Surely it would take quite a while to drain the battery though?

A 5w light at 12v is equivalent to a 100w at 240v, so around 1/2 amp an hour. About 5 days to flatten the battery.