Minimum voltage needed to start - please help !

[happy_harris]

Hi

Does anyone know what the minimum battery voltage to start is - left interior light on last night and voltage is saying 11.8 today (usually 13.8 - (haven't started it yet as need car tommorrow so dont want to reduce it further by trying) but want to plan my journey to either include RAC call out or not i hope !

Any experiences would be a huge help !

[GreenV8S]

That's effectively a flat battery. The off-load voltage doesn't drop much until the battery nears total exhaustion.

[oxbow]

Been always able to start mine on old battery when reading approx 9!

[happy_harris]

MMM interesting ! any deciding votes ?! I will obviously post tommorrow with the answer !

[whitey]

It will only read 13.8 with the engine running and charging.

With the engine off, mine reads about 12.0-12.2 when nicely charged. If it reads more than about 11.2 after a couple of weeks it struggles to start, any less than that and it's jump start time.

I usually get just over 3 weeks sitting before it's jump start time.

Cheers
Whitey

PS. Yes I know I should drive it more!!

[happy_harris]

Thanks for this - not sure how accurate readouts are on volts - any views ? - but looks like i may avoid a jumpstart !

[J_S_G]

Accidentally left the sidelights on for a full day (8 hours) at work the other week. Car was veeeeery slow to turn-over. There's no way I'd have got a second chance if it'd stalled, but it did just start.

[PhilWattis]

I managed to start my car the other day when it was complaining that the voltage across the battery was zero

Phil.

[Apache]

Forget what voltage you have. Batteries are rated in A/Hr, you need to know ie how much current it can deliver. the only way of knowing this is to drop a choke across it with an ammeter. You can have a nearly dead battery with dead cells reading 12 volts but it won't be able to do anything

[happyharris]

well the answer is - YES IT STARTED ! Didn't struggle too much to turn over - so 11.8volts was enough !

thanks for all the feedback hope it helps someone else soon.

Anyway after i started it the bloody heater stopped pumping hot air - so guess its time for another thread !