HELP! car won’t start

[Northy]

1 hour ago, carrpet said:

Thanks ! It is interesting that the voltage dropped to about 8V initially.

It would be helpful if you could repeat the test with a cold start without a drive first and publish the info from BM2 App

I would like to see how low the voltage gets with a cold start / cold engine etc.

I note that there appears to be CCA specification for this battery

What starter motor are you using and what ignition unit CDI CDI+ etc

Thanks

I’ve got a wasp starter and CDI+ 

This was a cold start this morning. 
 

[carrpet]

42 minutes ago, Northy said:

I’ve got a wasp starter and CDI+ 

This was a cold start this morning. 
 

Interesting result for Ian. Low cranking voltage but more than the threshold of 8V for the the CDI+ and looks like it fired up just fine as Jonny predicted.

It would be interesting to repeat the test tomorrow morning and see how close to the 8V threshold you get ?

Thanks Northy

Edited April 21, 2022 by carrpet

[Ian Comerford]

Thanks Lewis, Peter,

here’s my records from this morning and evening starts as well as a charging test.  Battery seems fine, charging is working but it all gets a bit sketchy when cranking.  I need to consider a different battery but do we really know how much is needed when your starter motor wants 330 CCA/a number of volts and the ignition system also wants power?

The voltage at cranking has also fallen over ten hours or so.  I’m going to leave it off the conditioner overnight and see how it performs tomorrow afternoon.  More to follow but thoughts appreciated on battery requirements for a 2kw, 330 CAA starter motor.  Thank you

 

[carrpet]

20 minutes ago, Ian Comerford said:

Thanks Lewis, Peter,

here’s my records from this morning and evening starts as well as a charging test.  Battery seems fine, charging is working but it all gets a bit sketchy when cranking.  I need to consider a different battery but do we really know how much is needed when your starter motor wants 330 CCA/a number of volts and the ignition system also wants power?

The voltage at cranking has also fallen over ten hours or so.  I’m going to leave it off the conditioner overnight and see how it performs tomorrow afternoon.  More to follow but thoughts appreciated on battery requirements for a 2kw, 330 CAA starter motor.  Thank you

 

Had the battery been on the CTEK conditioner up to just before you fired it up the first time shown above ?

Hi Ian

[Ian Comerford]

Hi Peter, no, I left it off the conditioner after we started it the other day. 

It was good to see there was little parasitic drain

Edited April 21, 2022 by Ian Comerford

[Northy]

11 hours ago, carrpet said:

Interesting result for Ian. Low cranking voltage but more than the threshold of 8V for the the CDI+ and looks like it fired up just fine as Jonny predicted.

It would be interesting to repeat the test tomorrow morning and see how close to the 8V threshold you get ?

Thanks Northy

I think when the battery is low, it's very likely dipping into 8.x volts. 

The 8v threshold would explain the symptoms I have experienced, where it doesn't start, smells of fuel and then fires straight up when a jumper battery is added.  This only really happens when it's not been started for a month or so in the dead of winter and the battery is low.

[Jonny Hart]

Well, I run a small odyssey 925 but I have a standard starter motor.   https://www.tayna.co.uk/industrial-batteries/odyssey/pc925/ 

I have never used a battery conditioner but my car has zero parasitic draw (I don't have a clock).  If the battery is low, it will fail to turn the engine over long before it fails to power the ignition and make a spark.

Anything below 9V for cranking is borderline.   The design spec for automotive electronics (ECUs etc) is typically 9v - 16V.

Ian, you could do a test on your starter cable during cranking to see how much voltage is being lost along the way:

Make up some long test leads for your meter and connect one end to the + connection at the starter.  Connect the other end to the battery +.  Set the meter range to 2V or something small.    Disable the ignition and crank the engine.  Look at the meter whilst cranking.   You are now measuring the voltage 'lost' between one end of the starter cable and the other.  This should be 0.5V or less.  If it is higher, go through the connections/terminals making sure the connection points are nice and shiny and that all crimped terminals are sound.   You can also do the same with the ground points in the front near the battery and also change the transmission earth strap.  Repeat the test and try to lower the voltage lost.

 

[Ian Comerford]

7 hours ago, Jonny Hart said:

Well, I run a small odyssey 925 but I have a standard starter motor.   https://www.tayna.co.uk/industrial-batteries/odyssey/pc925/ 

I have never used a battery conditioner but my car has zero parasitic draw (I don't have a clock).  If the battery is low, it will fail to turn the engine over long before it fails to power the ignition and make a spark.

Anything below 9V for cranking is borderline.   The design spec for automotive electronics (ECUs etc) is typically 9v - 16V.

Ian, you could do a test on your starter cable during cranking to see how much voltage is being lost along the way:

Make up some long test leads for your meter and connect one end to the + connection at the starter.  Connect the other end to the battery +.  Set the meter range to 2V or something small.    Disable the ignition and crank the engine.  Look at the meter whilst cranking.   You are now measuring the voltage 'lost' between one end of the starter cable and the other.  This should be 0.5V or less.  If it is higher, go through the connections/terminals making sure the connection points are nice and shiny and that all crimped terminals are sound.   You can also do the same with the ground points in the front near the battery and also change the transmission earth strap.  Repeat the test and try to lower the voltage lost.

 

Thanks Jonny, appreciate the advice, I will have a go at this once I get some wire and connectors.  The CDI+ arrived back this afternoon so thank you so much for the sterling service and help.  Do you think the 925 is man enough for my requirements?

[Ian Comerford]

This was Saturday after several days off the battery conditioner. Under 9v but still started happily.  This is also with the original CDI box fitted.  Confused…

[Ian Comerford]

And this was yesterday’s start when I left for Bicester after 12 hours on the conditioner

 

[carrpet]

9 minutes ago, Ian Comerford said:

And this was yesterday’s start when I left for Bicester after 12 hours on the conditioner

 

Hi Ian

The test time referred to above is 7.17am and I think you fired up just after 6am. Did you stop for petrol ?

Peter

[Ian Comerford]

Good spot.  No idea of why that is but we didn’t stop on the way down.

[Roy M]

Maybe of interest - I bought one of the testers shown here and ran it today on my daily. Quickly showed battery was on the way out (it's an AGM so not as easy as normal one to notice) but that the alternator was ok. New battery ordered with confidence and tester was less than £20. When battery arrives and is ok tester is going on the 911. May even get another for the Boxster.

[Ian Comerford]

I neglected to finish off this story with what seemed to be the problem/solution.  Peter Carr wins the prize for spotting the mismatch between what the new starter motor needed in terms of power and what the battery was able to consistently supply.  Interestingly it always started when warm, say after a break from driving, which I guess means the extra friction when cold was just enough to tip the balance between starting and not.  I replaced the Odyssey 680 with a 925 which has nearly twice the CCA of the smaller battery and all has been good since.

 

[GaryH]

20 hours ago, Ian Comerford said:

I replaced the Odyssey 680 with a 925

Oof ! YFB

(twice the CCA at almost twice the weight !)

You'll be excommunicated from The Church 😟

 

 

Edited July 24, 2022 by GaryH

[Ian Comerford]

9 hours ago, GaryH said:

Oof ! YFB

(twice the CCA at almost twice the weight !)

You'll be excommunicated from The Church 😟

 

 

I know but I’ve lost weight elsewhere so it’s all ok Gary

[GaryH]

6 minutes ago, Ian Comerford said:

I know but I’ve lost weight elsewhere so it’s all ok Gary

Then Bless you my son.

[Ian Comerford]

4 minutes ago, GaryH said:

Then Bless you my son.

Thank you Father….

[Beaky]

 

37 minutes ago, Ian Comerford said:

I know but I’ve lost weight elsewhere so it’s all ok Gary

30 minutes ago, GaryH said:

Then Bless you my son.

I think I must have caught all the weight loss, forgive for I have sinned!