Lotus Elan

Battery connection accidentally reversed.

PostPost by: bob_rich » Tue Mar 15, 2016 5:32 pm

Hi Again Roger

Hi you wrote (....duly replaced the 'cooked' brown cable........ to remind you this is the cable that runs from the fuse box and joins the main thick heavy duty cable that runs from the negative terminal on the battery and joins the starter solenoid......)

If you have an alternator I would have thought that it would be a negative earth system so did not the heavy duty cable cable run to the battery positive terminal?

As another post has said don't put a meter in series with a battery because at present you cannot be certain what the current flow may be and most DVM's won't read above 10A (maybe 20A with a higher quality unit) and if this current is exceeded it may damage the meter or at the very least blow its internal fuse.

A trick I have used when chasing shorts is to put a bulb in series with the battery live (positive) . Now when you connect up and the fault appears the worst that can happen is the bulb lights ( half of a old headlamp bulb with around a 6A current should limit the current to non destructive level) then various leads can be disconnected and then when the bulb goes out then that is the circuit to chase around for the fault.

Is the old control box the RB340 still in place? there may be some issue with this as a modern alternator may have an internal regulator. ( I have a +2S130 and while I have a Elan S4 circuit to hand I cannot be certain that the circuit I have is exactly what you have in your car.)

Hope this helps best of luck

Bob
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PostPost by: Chancer » Tue Mar 15, 2016 6:44 pm

A trick I have used when chasing shorts is to put a bulb in series with the battery live (positive) . Now when you connect up and the fault appears the worst that can happen is the bulb lights ( half of a old headlamp bulb with around a 6A current should limit the current to non destructive level) then various leads can be disconnected and then when the bulb goes out then that is the circuit to chase around for the fault.


I will never be too old to learn a (very usefull) new trick :D

I really like that one especially as it can be done at the side of the road without a meter or even any Tools just with what is already on the car.

Thanks!
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PostPost by: Craven » Tue Mar 15, 2016 8:33 pm

A test lamp is an old favourite, made up with longish leads and croc clips. Much easier to use than a meter for checking things like the opening of points in a distributor. You can hardly mistake a 21 watt bulb coming on even out of the corner of your eye, as you make static timing adjustments.
That is one wire on ? neg or CB of coil the other Chassis.
FWIW.
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PostPost by: billwill » Tue Mar 15, 2016 10:28 pm

Yes, I should have clarified, use an ammeter not just a multimeter, One salvaged from an old car and reading -60 to +60 amps would be best.
Bill Williams

36/6725 S3 Coupe OGU108E Yellow over Black.
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PostPost by: RogerFrench » Wed Mar 16, 2016 1:20 pm

If you have an alternator the thick brown wire should be Positive. Sounds like you're continuing to reverse battery polarity.
1967 Elan S3
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2005 Elise
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PostPost by: nomad » Sun Mar 27, 2016 2:39 am

When ever I'm working on a suspect electrical system I use a in line fuse holder available from any parts store. The kind that is commonly used on a radio hook up. One end of the wire is wrapped around the bolt on the battery cable clamp and the other end is attached to the battery terminal with a hose clamp. Now the entire system is fused and you can begin eliminating circuits till you find the troublesome one with a guarantee that no damage will be done. Best have a couple boxes of fuses though! :D

Kurt.
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