I've got a 6n2 as a daily driver. A couple of days ago, it didn't have enough juice in the battery to turn the engine over, so I recharged the battery for the day and popped it back in. It's started fine a couple of times, but I've noticed there appears to be symptoms of low power; e.g. the heater blower and windscreen wipers run slowly.

 

Anyway, I nip into town today. It starts fine and when I come back to the car 5 minutes later, it doesn't have enough power to turn the car over again! After a push start, I get it back home and there still isn't enough to turn it over again. I've tested the battery which shows 12.2 volts. I thought this was plenty enough to start. The battery is about 5 years old. Does this sound like a dying battery or something like a poor earth?

Have you checked the alternator is charging the battery ?  with the engine running and headlights on the voltage should be around 14.4v

 

 

I didn't give that a try. Will give that a shot at the weekend. Thanks :)

Thank you for your help. I couldn't do step 2 and 3, but I recharged the battery for a couple of hours and am getting the following voltages from the battery:

 

Engine off: 12

Engine on: 10.93

Engine and all electrics on: 10.4

 

Interestingly, this is about 0.5v lower than when I checked about 10 minutes earlier but didn't note down the results, so it sounds like the battery isn't charging whilst the car is running. The charge light illuminates when I turn the ignition on, but isn't showing when the engine is running. Do you think this sounds like a duff alternator or wiring fault as opposed to the battery being at fault?

 

 

Edited 4 June, 20179 yr by dabigginger

That does look like the alternator isn't charging, before replacing the alternator, have a good look at the fusebox on top of the battery, the flat fusable links, they can fracture but look OK, so remove them and make sure they haven't fractured, then have a close look at the connections on the rear of the alternator as again the main fat cable has been known to fail.

Thanks for your help. Will take a look this evening. At the very least, you've saved me money on a new battery that it looks like I didn't need!

Edited 4 June, 20179 yr by dabigginger

I haven't had a chance to get underneath yet, but the fuses are definitely fine. Interestingly, as soon as I start the car, the voltage hits 13.8v, but then quickly starts running down with the car idling. Switch on all the electrics and it drops below 12...

That is classic either, alternator failure, or the big thick cable from the Alternator to the fuse on the top of the battery failing 

It was the alternator; thanks for the help!