Mystery high current device.
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While sorting out some speaker wires behind the left hand panel, I noticed after all this time (43 years ? ) that there was a mystery electrical object mounted in the main fat battery cable with the terminals covered with insulation tape.
It didn't seem to be doing anything useful there so (after disconnecting the battery in the boot) I took it out and bolted the resulting two ends of the battery cable together and taped them up.
The operating handle was evidently on a fine stem and has broken off, so I cant really tell if it was a push-pull switch or a rotary one. I tried both actions using an ohm meter and the two fat terminals seem to be always connected and the other terminal never connected.
Has anyone seen one like this before?
It is maybe a relic of when Malcolm Ricketts owned the car for its first year and did some hill climbing events (I think). Perhaps it was a batter isolation switch and the handle broke off.
The small terminal is labelled C-B, the large copper one near it is labelled B and the other fat one is labelled E. It appears to be made by LUCAS, but I cannot make out the part number. There is a number which might be 76605B4482
It didn't seem to be doing anything useful there so (after disconnecting the battery in the boot) I took it out and bolted the resulting two ends of the battery cable together and taped them up.
The operating handle was evidently on a fine stem and has broken off, so I cant really tell if it was a push-pull switch or a rotary one. I tried both actions using an ohm meter and the two fat terminals seem to be always connected and the other terminal never connected.
Has anyone seen one like this before?
It is maybe a relic of when Malcolm Ricketts owned the car for its first year and did some hill climbing events (I think). Perhaps it was a batter isolation switch and the handle broke off.
The small terminal is labelled C-B, the large copper one near it is labelled B and the other fat one is labelled E. It appears to be made by LUCAS, but I cannot make out the part number. There is a number which might be 76605B4482
Bill Williams
36/6725 S3 Coupe OGU108E Yellow over Black.
36/6725 S3 Coupe OGU108E Yellow over Black.
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Aha, I found it.
It is indeed a battery isolator, though not much use now with the knob broken off.
https://www.autoelectricsupplies.co.uk/product/834
The extra contact would be used to short the contact-breaker to earth (i.e. permanently close the distributor points) to abruptly stop the engine.
It is indeed a battery isolator, though not much use now with the knob broken off.
https://www.autoelectricsupplies.co.uk/product/834
The extra contact would be used to short the contact-breaker to earth (i.e. permanently close the distributor points) to abruptly stop the engine.
Last edited by billwill on Mon Jun 19, 2017 5:18 pm, edited 1 time in total.
Bill Williams
36/6725 S3 Coupe OGU108E Yellow over Black.
36/6725 S3 Coupe OGU108E Yellow over Black.
- billwill
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Yes, that is the same thing, but a modern replica version.
The original that I have here is a stupid design the bit that broke off with the knob is a mere 2mm diameter at the centre of a 4mm square shaft. It was bound to break.
Bill Williams
36/6725 S3 Coupe OGU108E Yellow over Black.
36/6725 S3 Coupe OGU108E Yellow over Black.
- billwill
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From a safety perspective, it was important to have the engine cut out circuit included or the engine would continue to run with the switch off and battery disconnected - the dynamo would power the ignition coil.
I recall seeing exactly that switch a long time ago in an Aston Martin DB5 boot next to the battery. I think it was a standard fitting. My father was considering buying the Aston, but at ?5000 thought it was too much for an old car that needed some work.
I recall seeing exactly that switch a long time ago in an Aston Martin DB5 boot next to the battery. I think it was a standard fitting. My father was considering buying the Aston, but at ?5000 thought it was too much for an old car that needed some work.
68 Elan S3 HSCC Roadsports spec
71 Elan Sprint (being restored)
32 Standard 12
Various modern stuff
71 Elan Sprint (being restored)
32 Standard 12
Various modern stuff
- Andy8421
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With a battery isolator it is also advisable to wire the alternator output to the battery side of the switch. Otherwise if the switch is turned with the engine running not only can the engine keep running due to alternator output power still going to the ignition but you can also cause the alternator controller and rectifiers to fail with over voltage with the sudden loss of load when the battery is disconnected or for other electronics in the car to be damaged. See the attached description of options
http://www.adaptronic.com.au/battery-is ... ge-spikes/
cheers
Rohan
http://www.adaptronic.com.au/battery-is ... ge-spikes/
cheers
Rohan
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rgh0 - Coveted Fifth Gear
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Clearly then under some conditions problems,
But in the illustration of a single pole switch the alternator always has a load, However in the 4 pole switch solution the alternator has no load AT ALL definitely a No No. Also safety wise, a direct high current route from the battery to engine bay still exits by returning the alternator to the battery, re an Elan.
Ron.
But in the illustration of a single pole switch the alternator always has a load, However in the 4 pole switch solution the alternator has no load AT ALL definitely a No No. Also safety wise, a direct high current route from the battery to engine bay still exits by returning the alternator to the battery, re an Elan.
Ron.
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Yes - no simple complete solution
1. fully disconnect the alternator from both ignition and battery and may blow is internals
2. leave alternator connected to car ignition and may blow alternator and electronics in car and car may keep running
3. leave alternator connected to battery and alternator OK and car stops but still live wires inside engine bay.
I use option 3
cheers
Rohan
1. fully disconnect the alternator from both ignition and battery and may blow is internals
2. leave alternator connected to car ignition and may blow alternator and electronics in car and car may keep running
3. leave alternator connected to battery and alternator OK and car stops but still live wires inside engine bay.
I use option 3
cheers
Rohan
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rgh0 - Coveted Fifth Gear
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If your battery cut-off switch is there to comply with MSA or other similar competition regulations you need to take account of what Rohan refers to because it may be someone other than you who turns it off in an emergency when the engine is still running.
You can get isolators with auxiliairy switches for this purpose.
You can get isolators with auxiliairy switches for this purpose.
Robert
- rcraven
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I fitted the following cut-off switch just recently at the tail end (hopefully) of my restoration. Obviously worried about protecting the effort (and money) put into the car over the last 2 years. Not on road yet.
https://www.pegasusautoracing.com/produ ... RecID=1464
I think this switch hopefully covers the bases that Rohan outlined.
https://www.pegasusautoracing.com/produ ... RecID=1464
I think this switch hopefully covers the bases that Rohan outlined.
'69 Elan S4 SE
Street 181 BHP
Original owner
Street 181 BHP
Original owner
- 1owner69Elan
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11 posts
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