Is there a problem in my charging circuit (or starter)

J

Joe Shell

Member
Hi Guys,

Have a 36 Cabriolet with 13 year old Optima battery which does not seem to hold a charge. Ordered a new 6 volt from Optima which will be delivered day before thanksgiving.

Trying to take the car for a ride around the neighborhood so I put a 6 amp charger on the old Optima fo an hour and it starts right up. I removed the charger and let the car run fo about 30 minutes at high rpm to let the alternator put some additional charge in the battery. After the 30 minuted, I shut the motor and immediately trie to start the car. The starter hardly turned over. I let the car sit for two hours without being charged, I then tried to start and it started right up? I PUT A VOLT METER ON THE BATTERY at about 1500 rpm and the alternator is putting out almost 7 volts.

I know the battery needs to be replaced now I’m thinking could I have a problem with the starter. Checked the starter cable and it clean ant tight where it attaches to the top of the starter.

Any thoughts on why the starter won’t turn over after the car was running for 30 minutes but will turnover and start after the car sits for an hour or so without the charger on.

Thanks,

Joe
 
Hi Joe, Start by checking ALL battery and ALL ground cable connections, make sure that they are all clean and tight.
 
I would wait until you get the new battery installed before getting to worried. Hot engines can be more difficult to start than a cold engine. The issue could also be the coil or condenser.
 
As Meric suggested, use this opportunity to go through all your connections, cleaning and tightening. Seery is also correct, the warmer it gets under the hood, the more resistance there is in electrical circuits.
 
Thanks guys. Will check all connections and grounds in a day or two. When I do get the car started, it runs smooth and strong. Hoping I don’t need to change condenser. The coil is the more modern type mounted near the passenger side cylinder head so no problem changing that, Have this car for 8 years and it has never over heated.

We will see what happens when the new optima battery is installed. Thanks again. Have a happy thanksgiving
.

Joe
 
At 1500 rpm the alternator should be putting out 7.2 - 7.4 volts.


As others have said, check your connections and cables for corrosion. The best way to do this is a voltage drop test, where you connect the black lead of your meter to the NEG post of the battery and the red lead to the starter terminal, then operate the starter and observe the meter reading. The reading should be 0.4 volts or less.


If the reading is within limits, your starter may need new brushes and bushings.


If the reading is higher than 0.4 volts, either your cables are bad or your starter switch is bad. Move the red lead to the battery side of the starter switch and repeat the test. The reading should be 0.1V or less. If it is, move the red lead to the starter side of the switch and repeat the test. The reading should be 0.2V or less, if it is higher your starter switch is bad.
 
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