Classic cars forum & vehicle restoration.

[trampintransit]

Just aqcuired a Relaint Scimitar. First time with a plastic car. The wiring diagram is kinda weird ..there's loads of stuff that isn't really an earth but you just have to assume it is earther somewhere?

The last owner said it would fry alternators at high revs.

Battery seems OK, holds charge so no internal short.

Current alternator new, and pulley is correct size.

The wiring diagram shows the alternator case as earthed. ( via engine /chassis ) the unit itself, in the diagram has two wires coming from seperate spades on the back of the alternator both going to the same place in the wiring diagram ( 'Battey Spur') ...what's the point ...why have two wires going to the same point?

The third wire goes to the dash lamp and then to ign relay and ign switch

Could the burn out problem be due to the alternator 'seeing' a false 'raised' earth...
_________________
'60 Armstrong Siddeley Star Sapphire
'80 Reliant Scimitar
'47 Jaguar MKIV --- in bits!!!!

[DM]

The output of the alternator will be a higher amperage than a large lucar connector can take, hence two connectors and cables to share the load.

Is the alternator fan correct for the direction of rotation of the alternator ?

[trampintransit]

Never thought about examining the fan ...good point.
_________________
'60 Armstrong Siddeley Star Sapphire
'80 Reliant Scimitar
'47 Jaguar MKIV --- in bits!!!!

[trampintransit]

So the two spades are connected ...why not one spade and a heavy wire ..it's only going straight to the battery?
_________________
'60 Armstrong Siddeley Star Sapphire
'80 Reliant Scimitar
'47 Jaguar MKIV --- in bits!!!!

[trampintransit]

Also..there's a spade connector on the back of the alternator that's unused????
_________________
'60 Armstrong Siddeley Star Sapphire
'80 Reliant Scimitar
'47 Jaguar MKIV --- in bits!!!!

[DM]

[DM]

[trampintransit]

Well, I've left tthe wiring as standard for the moment. Given that it's a plastic car and the alternator earths through the engine to the chassis ....it won't have helped that there was no earth strap from engine to chassic . having put one in we'll see what happens once it hits the road in the next week or so
_________________
'60 Armstrong Siddeley Star Sapphire
'80 Reliant Scimitar
'47 Jaguar MKIV --- in bits!!!!

[alastairq]

An alternator overcharge was the factor that saw the demise of an old Volvo I had.

No indication of overcharge, aside from one or two 'hints' such as wipers suddenly going berserk, or the driver's window rising up occasionally at a alarming speed.

The car diod very regular journeys, with maximum mileage very much the same, day in, day out.

What I did not realise was, the battery was absorbing the alternator overcharge, until it would boil.

At that precise moment, I would have parked in the works' car park, and turned the engine off.

Thus the battery would take all day to simmer down.

This would be repeated come evening time.

Engine always turned over & started very well.

Until one day, I took a short diversion to get petrol.

A 3 mile diversion.

Thus, 3 miles from home, the battery exploded under the bonnet.....snot & acid everywhere.

At the precise moment the battery exploded, every electrical item in circuit at that brief point in time got a huge voltage overload [probably around 50 to 60 volts, it has been estimated]

Thus taking out ignition modules, fuel injection pumps, daylight running lights...in fact, pretty much everything.....including the alternator, of course.

Around £200 in parts, the labour being mine, to fix.

Then, over 200 quid in tax to pay at month's end.....


plus the free loan of a colleagues Skoda Felicia estate...meant no contest, the EOL man cometh...got around 110 quids or so for the Volvo [a 740]....

Sorry to see it go, but, no clue about the overcharging alternator was visible.......

[MVPeters]

I have a similar story of an Austin 10 with a stuck control box = blown battery!
One of the most useful tools I bought a few years ago is a digital volt meter that plugs into the cigarette lighter. It cost a mere couple of $$ shipped from abroad. It seems to be accurate to within 0.1 volt .
Just by keeping an eye on it I can get a pretty good idea of the health of the charging system & battery.
_________________
Mike - MVPeters at comcast.net
2002 MINI Cooper 'S'