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[Field Marshal Dr. Opti]

Using my trusty Gunson Sparktune I obtained these figures.The battery is off the car. She's been a little slow on the starter recently.

Battery on charger......14.7 volts
Immediately off charger 13.0 volts
After 15 minutes ........12.4 volts
After 3 hours..............11.9 volts.

The voltage drop appears to have now peaked.

Good battery or new battery?

[cem_devecioglu]

battery good, car donald change the car

[Andy B]

You need a proper auto spark with an olde fashioned type battery discharge tester

[Field Marshal Dr. Opti]

You need a proper auto spark with an olde fashioned type battery discharge tester

How much, Andy?

[Andy B]

....


How much, Andy?

The local proper auto spark local to me won't charge you for doing it, but won't refuse the cost of a pint! 

[Omegatoy]

I think the battery is losing a lot of its off the car,

best way when using voltage is to crank the starter while someone has the leads on the battery then measure the drop,

[Marks DTM Calib]

If that voltage after three hours is no load then you have issues!

[zirk]

If that voltage after three hours is no load then you have issues!

Agreed, battery is on its way out, just to double check, slow charge it again for 24hours then leave it on its own somewhere cold for another 24hrs and measure again, anything less than 12.5 / 12.6v battery is u/s.

I assume if its not Maintenance Free you have checked the fluid levels.

[Kevin Wood]

If that voltage after three hours is no load then you have issues!

Agreed. If the car isn't loading it (disconnect the terminals) then the battery has probably had it, but do check that the alternator has been charging it OK too.

[JasonH]

11.9V off the car, 3 hours after charging, means the battery has had it. Should be more like 12.7V.

It may seem like a small difference but it's the difference between a new battery and one that is virtually dead.

[Taxi_Driver]

Opti doesnt say how long the battery was on the charger 

5 mins charging and i could believe those figures.

A good few hours, then yes, i'd say battery is fubar.

[TheBoy]

Opti, do same test with battery off the car, in case car is draining it for some reason - stuck relays, duff power sounder etc.

If still the same, the battery is toast

[aaronjb]

Using my trusty Gunson Sparktune I obtained these figures.The battery is off the car. She's been a little slow on the starter recently.

I read that as the battery is already off the car .. in which case yep, it's donald.

[henryd]

Using my trusty Gunson Sparktune I obtained these figures.The battery is off the car. She's been a little slow on the starter recently.

I read that as the battery is already off the car .. in which case yep, it's donald.

+1

[TheBoy]

Ah, yes, reread properly. Battery is BF'd