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TR2/3/3A Is it time for a new alternator???

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K

karls59tr

Obi Wan
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Converted to alternator years ago. When I turn the ignition key on the red dash light does not come on. The voltmeter gauge often does not go beyond 12/13 volts. I took a long drive today with no issues. Parked the car for about 2 hours. Went to start the car and got nothing when I turned the key on? Boosted the battery and ithe motor started and the gauge showed it was charging? Any thoughts on this?
 
There are lots of reasons why the ignition light won't go on. If it's like the TR4, the socket is trash and regularly fails to make good contact. A bad connection is possible lots of places. And, of course, the light can be burned out.

If you see charging on the ammeter, the alternator is OK. But there are lots of places where you could have a bad connection, and of course you need to drive the car enough to keep the battery charged. I often recommend the use of a "float charger," a low-current smart charger that you can connect to the battery when the car is parked. That will keep the battery well charged and extend its life.
 
Battery is fairly new. The odd thing is that after this no start incident I tested the battery and it showed 12 volts. I think there may be a wiring problem at the ignition switch. Very odd to turn the key and get nothing when it first failed to start. I started the car recently with no problem I did not even have to charge the battery wirh a charger
 
Measuring the battery voltage doesn't tell you much about its condition. A load test is more revealing. Also, the battery can be nearly flat and it may still start the car. I think I'd give it a full charge on a modern charger, then do a load test. Check and redo all questionable connections. If all this checks out, you should be ok.
 
A battery that measures 12 volts is not in very good condition. There are 6 cells in a battery and each is 2.2 volts, so a good battery should measure 13.2 volts. Put a charger on it and if it doesn't measure better than 12 volts after being charged, then it's time for a new battery.
 
I tend to always look for something really difficult to resolve a problem. I had similar issues a couple of years ago and checked every connection that was in the electrical system. Even checked ignition switch for a fault. In my case it came down to a simple issue. I had not cleaned the battery posts as part of my spring start up. I do that more frequently now. Also had my battery bench tested. It is getting older but still has 550 cold cranking amps and holds a charge of 12.8 over long periods of no charging. Hope you find the issue.

Frank D…..
 
One simple way to see if the alternator is chaarging,
let the car idle , switch the headlights on, then bring the revs up, the headllights should go a lot brighter.
An alternator charges as 14 Volts,
If you have a volt meter just put it on the battery and see if it is charging at 14 volts
 
Another really simple way to find out if your alternator is charging is to remove the negative terminal from the battery while the engine is running. If the alternator is bad the engine will die.
 
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