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Old 19th January 2021, 18:33   #11
COLVERT
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Ok and thank you for your reply.

The battery only took about 15 mins to charge to 13.8v but I'll take your advice and take the charger with me tomorrow. The car is 50 yds from daughter's house. I'll take it inside n charge it. I got soaked working out in the street today.

Would a new battery be an option if this one is failing? I could take it n get it tested for faulty cell.
No battery will ever read 13.8 volts if left for several hours after charging for the true voltage to be obtained.--Even with a brand new battery it's highly unlikely to read more than about 12.6 or 12.7 volts.

It's probably not the battery that's failing but the way in which you are testing it.--

There are 6 cells in a battery.--Each one will give about 2.1 volts.--( six times 2.1 is 12.6 in total. )


If you would like to read a bit more about batteries then go to the thread on the main page that says---Really, really useful information.--I have three posts in there about batteries and their funny little ways.----Go have a read under the name of COLVERT.
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Old 19th January 2021, 20:26   #12
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No battery will ever read 13.8 volts if left for several hours after charging for the true voltage to be obtained.--Even with a brand new battery it's highly unlikely to read more than about 12.6 or 12.7 volts.

It's probably not the battery that's failing but the way in which you are testing it.--

There are 6 cells in a battery.--Each one will give about 2.1 volts.--( six times 2.1 is 12.6 in total. )


If you would like to read a bit more about batteries then go to the thread on the main page that says---Really, really useful information.--I have three posts in there about batteries and their funny little ways.----Go have a read under the name of COLVERT.
That was 13.8v after running the engine and warming up. As you say it'll settle out at a lower level. Took it for a 20 mile drive earlier and the restart was much better.

Thanks again.
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Old 19th January 2021, 20:37   #13
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Very unlikely to be the battery even though you have only quarter charged it.

When you say---starting procedure--- do you mean you have to use the starter motor for ten seconds ??

Give your battery a full charge as it must now be quite low using the starter for so long.

I get the impression from what you are saying that you have, maybe, low fuel pressure and it needs that long on the starter before the pressure is high enough for the ECU to kick in.
Yes, I'm running the starter motor for 10 secs. If Low pressure at the rail is causing it Is the low pressure from the UBP limiting the overall amount of pressure the high pressure pump can produce or is the high pressure side regulated and limited irrespective.

Last edited by Gizmo150; 19th January 2021 at 20:38.. Reason: Clarity
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Old 19th January 2021, 22:42   #14
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If it is low pump pressure it's most likely to be the HP pump or the sensor connection on it.--
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Old 20th January 2021, 00:35   #15
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Reading all the posts on this, I have a feeling that you have over-discharged the battery to below 8v by constant short charge times followed by draining it trying to start the car. Even when in this state it can still show 13v but won’t hold it long enough to start or keep the car running.
Sorry to say but it is looking like your only solution is to replace the battery as there is a good chance now that the one you have on the car has a buckled plate.
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Old 20th January 2021, 18:52   #16
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Reading all the posts on this, I have a feeling that you have over-discharged the battery to below 8v by constant short charge times followed by draining it trying to start the car. Even when in this state it can still show 13v but won’t hold it long enough to start or keep the car running.
Sorry to say but it is looking like your only solution is to replace the battery as there is a good chance now that the one you have on the car has a buckled plate.
Update. 20/01/2021
Since the 20 mile drive yesterday afternoon, the car successfully started twice in the evening and twice today. Start and end of daughter's NHS shift. I will check the battery again on Saturday when the car is here.

I've checked the battery every day since I started this post and not recorded a voltage lower than 11.7v. Would 8v destroy the key coding as suggested by COLVERT?
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Old 22nd January 2021, 23:52   #17
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Update. 20/01/2021
Since the 20 mile drive yesterday afternoon, the car successfully started twice in the evening and twice today. Start and end of daughter's NHS shift. I will check the battery again on Saturday when the car is here.

I've checked the battery every day since I started this post and not recorded a voltage lower than 11.7v. Would 8v destroy the key coding as suggested by COLVERT?
NO.--It's not the low voltage but the sudden surges of voltage that does the harm.---They are called SPIKES in the trade. Voltages can be generated much, much higher than the battery12 volts.--( into hundreds. )
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Old 23rd January 2021, 12:37   #18
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Quote:
Originally Posted by Gizmo150 View Post
Ok and thank you for your reply.

The battery only took about 15 mins to charge to 13.8v but I'll take your advice and take the charger with me tomorrow. The car is 50 yds from daughter's house. I'll take it inside n charge it. I got soaked working out in the street today.

Would a new battery be an option if this one is failing? I could take it n get it tested for faulty cell.
What you have read there is 'residual' voltage, which is misleading, leave it to stand for an hour and you will find the battery is dead.
CHARGE the battery for 24 hours, then leave it disconnected for 1 hour then measure voltage, it should read at least 12.5V, start car and check voltage with engine running, should be 14.4V +, switch lights on, radio, demister and check again, should be near 13.8v any significantly lower readings, need a new battery, and your alternator is probably in need of attention, new regulator pack?. Good luck.
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Old 23rd January 2021, 13:28   #19
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What you have read there is 'residual' voltage, which is misleading, leave it to stand for an hour and you will find the battery is dead.
CHARGE the battery for 24 hours, then leave it disconnected for 1 hour then measure voltage, it should read at least 12.5V, start car and check voltage with engine running, should be 14.4V +, switch lights on, radio, demister and check again, should be near 13.8v any significantly lower readings, need a new battery, and your alternator is probably in need of attention, new regulator pack?. Good luck.
¿

Thank you.
Just to clarify, with engine running the terminal readings are 13.8v.
With battery disconnected after an hour it reads 12.3v. With battery connected to car and a spare battery attached in parallel it reads 12.6v. the increase in voltage makes no difference to the cranking time before the engine will run.

With the engine ticking over there's 13.8v. with headlights on it's still 13.8v. add rear screen demister it's 13.7v and adding climate control it's down to 13.6v and that at tick over speed.

With revs increased to 1800 rpm I've turned everything on and the voltage is steady at 13.8v
That's lower than I'd like and probably indicative of the alternator but not necessarily the starting problem.

I just tried an inline amperage test. There is a current draw of 0.34 amps. So I'm currently ( no pun intended) pulling fuses.

Under bonnet fuse box:
F8 removed value drops to .29a. with fuse back in and disconnecting the connectors on top of diesel heater the value drops to .14a. cleaning and reconnecting it remain at .14a. so still have a .14 current draw. Current draw is now .02a. I can deal with that.

Last edited by Gizmo150; 23rd January 2021 at 17:21.. Reason: Update
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Old 23rd January 2021, 14:36   #20
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¿

Thank you.
Just to clarify, with engine running the terminal readings are 13.8v.
With battery disconnected after an hour it reads 12.3v. With battery connected to car and a spare battery attached in parallel it reads 12.6v. the increase in voltage makes no difference to the cranking time before the engine will run.

With the engine ticking over there's 13.8v. with headlights on it's still 13.8v. add rear screen demister it's 13.7v and adding climate control it's down to 13.6v and that at tick over speed.

With revs increased to 1800 rpm I've turned everything on and the voltage is steady at 13.8v
That's lower than I'd like and probably indicative of the alternator but not necessarily the starting problem.

I just tried an inline amperage test. There is a current draw of 0.34 amps. So I'm currently ( no pun intended) pulling fuses.

Under bonnet fuse box:
F8 removed value drops to .29v. with fuse back in and disconnecting the connectors on top of diesel heater the value drops to .14v. cleaning and reconnecting it remain at .14v. so still have a .14 current draw. Current draw is now .02v. I can deal with that.
If after a 24 hour charge the battery voltage at rest is reading only 12.3V, that approximates to about 65% charged.
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