Alternator Output

  • Thread starter Thread starter MHolland
  • Start date Start date
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MHolland

I bought a '92 Civic in August. Within a week the battery died. Since then I
have replaced the computer, and the distributor. Today my daughter drove it
to work. When she tried to drive it home the engine would not crank. I
jumped it, and it started right up. After disconnecting the jumper cables I
checked the voltage at the Civic's battery terminals with a voltage meter
and it read 14.2 volts. When driving it home I heard a high pitch whine that
seemed to come from under the hood. I took it to Autozone and had the
charging system checked. They said the alternator was putting out 62 amps at
2000 rpm and 35 at idle. I think that should be good enough to keep the
battery charged. Here in Arizona batteries are usually failing because of
heat (bad cells). This acts like a bad cell to me.

Thanks
 
Hi,
Make sure you have good main ground connection from battery/alternator
to car chassis. Hot weather is harder on batteries than cold climate.
I live in Alberta. Used to go down to PHX a lot. (retired from
Honeywell). Once I suffered a bad battery on a new rental car. Battery
literally boiled over.
Tony
 
So 62 amps is ok?
Tony Hwang said:
Hi,
Make sure you have good main ground connection from battery/alternator
to car chassis. Hot weather is harder on batteries than cold climate.
I live in Alberta. Used to go down to PHX a lot. (retired from
Honeywell). Once I suffered a bad battery on a new rental car. Battery
literally boiled over.
Tony
Click to expand...
 
So 62 amps is ok?
Click to expand...

It could be that the rectifier in the alternator itself is draining
the battery while it's parked. Mine did that. It put out 14.3V while
engine was idling, which was normal.
 
You need to isolate the problem to the battery or a drain on the system.

A. To check the battery for bad cells, have it load tested at AutoZone with
a resistive load. You can also pry off the inspection caps and measure the
voltage of each cell with your voltmeter. The cell that reads a lot lower is
the problem area.

B. To check for loads that drain the battery while parked, try removing the
fuses from the fuse block. See if the problem goes away. IF it does you need
to figure out which circuit is "stuck on" Look at the brake lights, glove
box light, etc. To see if the alternator is at fault, you will need to
disconnect the wires while parked and see it the battery stays charged with
your voltmeter.


Good luck.
 
MHolland said:
So 62 amps is ok?
Click to expand...

It sounds sufficient. The official spec for my '88 Civic is about 35 amps @
2000 rpm when hot and about 45 amps @ 2000 rpm when cold.

Eric
 
Hi,
What is the alternator capacity?
What is the voltage with engine shut off?
Usually when charging system is acting up, radio in AM mode
will show lots of whiny noise regarless of tuning dial position.
Tony
 
Autozone load tested the battery I bought 3 months ago. A possible weak cell
appears to have been the problem.

Thank You
 
MHolland.
Here is a suggestion on how to check for elect. system drain on battery.
Simply disconnect the Neg. battery cable end and connect a test lamp between
the two. Touch the post and cable end together while the test lamp is
attached form one minute to reset the computer. Now move them apart and
check to see if the lamp illuminates, if so begin disconnecting fuses till
the light goes off. You will then know which circuit is causing you battery
drain. If the lamp doesn't illuminate you have no electrical system draw,
and it sound like the battery has a problem. Also charge battery and let sit
over night disconnected from car. If it is weak or dead the next day you
have an internal drain in the battery.
Mike the mechanic
 
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