Is it the Battery?

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richardpope50
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Is it the Battery?

Post by richardpope50 »

The same happened last year and I replaced the battery as the old one was five years old, New battery last September was a quality Varta 63ah so more than enough and conditioning charge all winter with a CTEK charge.

Used the car three times since 1st April when it went back on the road.
• First time all OK.
• Once starter used several times to start engine – it did, just - but then went dead with that usual ‘clunk’ sound of the solenoid. Left a while and starter started engine all OK.
• Once (yesterday) went to start and just that usual ‘clunk’ sound of solenoid. Left it a while and flashed light – OK. Tried to start and just that ‘clunk’ from the solenoid. Jump started it with full charged spare battery. Still ‘clunks’ a few times but assume jump leads not tight enough as then it started fine.
• After ‘clunks’ no power to instruments nor lights unless left a while, say an hour but multi-meter shows 12.62v.

Is the battery going again? It is only seven months old.


Richard.
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DaveEFI
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Re: Is it the Battery?

Post by DaveEFI »

Sounds more like a poor connection - most likely the ground. Connect a voltmeter between battery negative (onto the post, rather than clamp) and starter body. Operate the starter The reading will be the voltage drop. Ideally, a fraction of a volt.
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Re: Is it the Battery?

Post by ChrisJC »

Alternatively get somebody to hold a voltmeter between the battery posts, and then try to start the car. The battery voltage should dip a bit, but perhaps stay above 11V. If it drops to pretty much zero, time for a new battery. If it holds up, but no cranking action, then suspect a bad connection.

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Re: Is it the Battery?

Post by stevieturbo »

ChrisJC wrote:
Fri Apr 30, 2021 6:18 pm
Alternatively get somebody to hold a voltmeter between the battery posts, and then try to start the car. The battery voltage should dip a bit, but perhaps stay above 11V. If it drops to pretty much zero, time for a new battery. If it holds up, but no cranking action, then suspect a bad connection.

Chris.
Not really sure how valid a test that is, other than for a no start.

I was actually scoping current/voltage on some of the generators in work and was shocked to see battery voltage drop to 5.8v !! And that's a decent sized diesel genset on one 12v battery. Was testing a new clamp....and couldn't get it to work right, so didn't get a current reading.
For almost the entire duration cranking before start it was below 10v. Although with a petrol they may be more fussy with voltage drop in terms of fuel system and ignition system, plus they'd take far less ooomph to start than these generators.

Haven't tried it on my own car yet though but will do soon as always been curious to see what sort of current it pulls.

Whether you'd pick that up with just a multimeter I don't know, but it did start perfectly fine.

But as always, check all connections, wiring, grounds to body/engine block etc

Or even get a proper set of jump lands ( 35mm^2 welding cable and strong clamps ) and maybe test with the battery connected to the starter and engine block that way, to eliminate other wiring.
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Ian Anderson
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Re: Is it the Battery?

Post by Ian Anderson »

Have you got a master switch like this on it?
https://www.asap-supplies.com/products/ ... 31EALw_wcB

If so cut a circle of Manila card (cornflake box) that will fit in the hole before you insert the key. It will add pressure to the spring and help make better contact.

And yes it sounds like a solenoid clicking when it stops!

Don’t as me how I know!

Ian
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richardpope50
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Re: Is it the Battery?

Post by richardpope50 »

Thanks for replies.

Well, inconclusive so far ...

I did the following in this sequence yesterday.
1. Checked battery post clamps. Did not seem too bad but completely re-seated clamps and did up tighter.
2. Checked main connection to starter. Tightened very slightly so probably OK originally.
3. Checked earth to engine block. All seemed tight and no movement. Perhaps should have removed, cleaned and re-fitted but didn't.
4. Tried to start but nothing. Power to all instruments remained this time so perhaps post clamps were a problem before. This time I don't rember the 'clunk', just nothing.
5. Removed solenoid fuse - all ok. Put back and engine started. Hmm. Possibly the (30amp) fuse contacts but fues in dry box and proper fuse fittings so bit of a long shot if fault is here, me thinks.
6. Tried several time to start engine and worked each time!
7. Checked connection to solenoid. Was able to push connector further on very slightly. Agan, not convinced this was a problem.

I'm not convinced either fuse holder or solenoid connection is at fault. I would have preferred a more obvious test / fault. I've thought it could be a fault relay so will swap the current one.

Current plan is to see if it fails again - probably when I am far from home! - and re-set fuse. Not happy with this plan but no idea what else to do.

PS.
No, I do not have an isolator.
I have an after-market starter button but doubt that is at fault.
Richard.
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richardpope50
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Re: Is it the Battery?

Post by richardpope50 »

I have a WOSP hi torque starter motor.
Richard.
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Re: Is it the Battery?

Post by DaveEFI »

The power to other things disappearing when you operate the starter is a clue. You'd need to see if non ignition controlled things like the lights go out too as a help to diagnosis. As I remember, you have a rather non standard harness with lots of fuses and connectors. Did you draw out the diagram? If so, should be possible to work out just where the break is happening. Often, a standard switch operating a relay can get dirty, as the very low current the relay takes doesn't self clean the switch contacts.
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richardpope50
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Re: Is it the Battery?

Post by richardpope50 »

Dave,

First post when solenoid 'clunk' all power was lost so I suspect I did have lose post clamps. On Saturday I don't recall hearing solenoid 'clunk' and all power was there but starter button did nothing when pressed. Fine after fuses checked, though.

Yes, wiring loom all my own work. Yes plenty of fuses and reays. Yes I have full diagrams and details. Nothing has changed apart from time! IMHO break can only be fuse to starter button to relay or power fuse to relay to solenoid as not much else (or battery posts).

Forgot to say battery was 12.6v all the time except when cranking when it went down to 10.6v thus it's not the battery, I suggest.

I also like positive tests so I just do not feel that the fuse connection was at fault nor the solenoid wire connection either. Just not confident these are at fault.
Richard.
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Re: Is it the Battery?

Post by stevieturbo »

And are you sure the starter itself is good ?
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Re: Is it the Battery?

Post by DaveEFI »

If other things go out when you operate the starter and it's pretty certain the battery is good, a connection common to them must be giving up?
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Re: Is it the Battery?

Post by Ian Anderson »

A bloke in theGt40 club had a problem somewhat similar.
He would turn the key in the ignition and press the button, sometimes start sometimes not.

It turned out that his key ignition switch had faulty contacts inside and not making a good contact, he swapped the Lucas one for something more beefy, and I believe also put it through a relay as the current that flowed through the switch was actually rather excessive!

Ian
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richardpope50
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Re: Is it the Battery?

Post by richardpope50 »

I'm sure it's not the starter motor.
Could be the starter button having poor contacts inside but car stored in dry garage.
So far it has worked each time since Saturday!

I'll leave this post alone for now until I find the problem!
Richard.
Dax Rush 5.0l TVR V8, EFI with Megasquirt ECU and wasted spark, Racelogic Traction Control, ABS and Quaife LSD

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