|
||
|
11th October 2021, 08:43 | #1 |
This is my second home
Rover 75 Saloon & Tourer Join Date: Sep 2012
Location: Lincoln
Posts: 14,926
Thanks: 1,630
Thanked 3,032 Times in 2,181 Posts
|
Have I a duff battery
I took the battery off the car and put it on charge for a few days in the garage.
As soon as I took it off charge I measured the voltage and it was 12.8v, another battery that had been off charge for about a week measured 13.2v. The above was about 3 or 4 days ago, I have just measured the suspected duff battery again and it is 12.57v. Not a lot of drop but as it was 12.8 when it came off charge I am suspecting it is duff. Your thoughts please. If you too think it may be duff I will take it back and the shop can try a drop test. macafee2 |
11th October 2021, 10:20 | #2 |
This is my second home
Rover 75CDT, Jaguar XF-S 3.0V6, V'xhall Omega V6 Estate, Twintop 1.8VVT, Astra Estate and Corsa 1.2 Join Date: Dec 2007
Location: Suffolk
Posts: 7,084
Thanks: 283
Thanked 624 Times in 440 Posts
|
I wouldn't say the voltage you have measured necessarily indicates a duff battery.
I would put a mild load on the battery for a while and recheck the voltage. An old 55W 12V headlamp bulb consumes nearly 5Amps and makes a good test load. |
11th October 2021, 10:39 | #3 | |
This is my second home
Rover 75 Saloon & Tourer Join Date: Sep 2012
Location: Lincoln
Posts: 14,926
Thanks: 1,630
Thanked 3,032 Times in 2,181 Posts
|
Quote:
macafee2 |
|
11th October 2021, 11:19 | #4 |
This is my second home
Rover 75CDT, Jaguar XF-S 3.0V6, V'xhall Omega V6 Estate, Twintop 1.8VVT, Astra Estate and Corsa 1.2 Join Date: Dec 2007
Location: Suffolk
Posts: 7,084
Thanks: 283
Thanked 624 Times in 440 Posts
|
I would put the bulb on for 30 minutes. This will remove approximately 2.5Ah of charge from the battery which will have a capacity of around 70Ah for a 096 type when new.
You should get at least 12.5V which would indicate that the battery is at >90% fully charged. If it drops to less than 12.5V, the battery is not as healthy as it should be. |
9th November 2021, 22:34 | #5 |
This is my second home
Rover 75CDT, Jaguar XF-S 3.0V6, V'xhall Omega V6 Estate, Twintop 1.8VVT, Astra Estate and Corsa 1.2 Join Date: Dec 2007
Location: Suffolk
Posts: 7,084
Thanks: 283
Thanked 624 Times in 440 Posts
|
What was the measurement or conclusion in the end?
|
10th November 2021, 07:08 | #6 |
This is my second home
Rover 75 Saloon & Tourer Join Date: Sep 2012
Location: Lincoln
Posts: 14,926
Thanks: 1,630
Thanked 3,032 Times in 2,181 Posts
|
Result, undecided about the battery. The voltage seemed not to drop any further, always staying above 12v. I am wondering if the fault is on the car. I kept a headlight bulb connected for well over an hour as suggested but the voltage stayed above 12.
I have just taken the battery off charge and it is showing 13.04v. macafee2 |
10th November 2021, 14:35 | #7 |
This is my second home
R75 Saloon. Join Date: Feb 2009
Location: France/or Devon.
Posts: 14,003
Thanks: 3,851
Thanked 2,167 Times in 1,816 Posts
|
The reading off charge won't be accurate.--It needs to be left for a few hours to settle.
12.57 is normal for most batteries.--- The very best way to check a sealed batteries capacity is to have a drop test done at a local garage. Oh for those filler caps where you could test the specific gravity of the acid. Last edited by COLVERT; 10th November 2021 at 14:38.. |
10th November 2021, 16:08 | #8 | |
This is my second home
Rover 75 Saloon & Tourer Join Date: Sep 2012
Location: Lincoln
Posts: 14,926
Thanks: 1,630
Thanked 3,032 Times in 2,181 Posts
|
Quote:
macafee2 |
|
10th November 2021, 18:48 | #9 |
Posted a thing or two
Rover 75 club se tourer CDT and a Connoisseur SE Diesel Auto Saloon Join Date: Nov 2006
Location: Houghton - le - Spring
Posts: 1,418
Thanks: 618
Thanked 333 Times in 197 Posts
|
An old way that the AA used to test batteries was to charge by running the engine for 5 mins , then disable the engine by pulling a fuse so that the car would crank but not start. Crank the engine for 15 seconds and listen to the cranking speed , and if it starts to drop , the battery is unserviceable . That is a live drop test and is pretty conclusive.
|
11th November 2021, 08:16 | #10 | |
This is my second home
Rover 75 Saloon & Tourer Join Date: Sep 2012
Location: Lincoln
Posts: 14,926
Thanks: 1,630
Thanked 3,032 Times in 2,181 Posts
|
Quote:
15 seconds continuous cranking seems a long time, I just timed it my goodness that is a lot of cranking macafee2 |
|
|
|