Checking battery / charging / alternator

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rangiegal

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466
Location
Burton on Trent, East Midlands
What is the best way to check if an alternator is faulty or if the battery has a dead cell / is not holding a charge? Not specifically for the Rangie, but for any vehicle. Its just that two numpties at Kwik Fit type franchises gave really stupid "advice" when I had a recent battery problem on my travels in an elderly automatic car - luckily I had a jump starter in the boot, but stopped at two of these places as I was miles from home and had no test gear with me. :doh: The first insisted the battery was "fine" (I'd left the lights on about 2 weeks previously and had jump started it but not actually recharged the battery on the charger, so I thought it may be a bit low and as the car is a 3.0l it needed a higher cranking amperage). So off I drove, had to stop for a meeting, and it was flat when I tried to start later, needed the jump starter. Stopped at another place, guy puts a multimeter across the poles of the battery while car is running and says it needs a new alternator.....:doh: No warning lights on everything working as it should. I thought he was talking s**t - bought a new battery else where and car has been fine ever since.

Is the best way to put a load on, like putting the lights on, and check voltage on a voltmeter and if so, what should it be?

It may seem an elementary problem, but these two twits got me confused:eek::eek::eek:
 
you'll know on a p38 cos all feckin hell breaks loose if its alternator fault! (thats also true for any other minor fault on the p38 too! lol!)

One Simple Battery Test:


1) Connect the voltmeter directly across the "Battery Terminals". (NOT to the Cable Clamps)

2) While watching the meter, Start the Car.

3) The Battery Voltage should Never fall below about 10 Volts.
If it does:
a) The battery is either "Low in Charge".

b) Or The Battery is "Low in Water".
(The water leven in the battery should be about 1/4 of an inch, Above the Plates.)
"DO NOT" Fill it up FULL.

c) Or The battery has a "High Internal Resistance".
(Possibly Sulfided Plates and probably Time for New Battery?)



**NOW Repeat This Test BUT:

1) Connect the voltmeter directly across the "Battery Clamps on the Battery Cables".

2) This Reading should be Within 0.1 Volt Maximum, the Same as 3 Above.
***If NOT, Clean Battery Terminals and Clamps.

2a)If Necessary, Repeat Test to Varify it is now OK.



**NOW Repeat This Test Again, BUT:

1) Connect the Voltmeter Directly Across the Positive Terminal of the Starter and it Case Ground.

2) If the voltmeter reading is More than 1/2 Volts Lower than the Previous Test,
** You Probably have a Cable or Connectorp Problem!
Check the Connections between the Cable and the Cable Connectors. ON BOTH ENDS.




One Very Simple Alternator Test:


1) Start Car and run at a normal idle.

2) Connect a Voltmeter Directly Across the battery Terminals.

3) Turn on Headlights to High Beam.

4) check the battery Voltage.
*** The Battery voltage Should read between about 13.8 to 14.2 volts. (Possibly up to 14.5 Volts.)

5) Increase motor speed to about 1500 RPM. The Alternator should now produce a battery voltage between 14.2 and 14.6
Volts.
*** If it is Lower than 14.2 volts, the Alternator probably has one or more Bad Diodes.

6) Now, Maintain the 1500 RPM and Turn off the Headlights. Run this test for One Full Minute.
"The Battery Voltage should NEVER Exceed about 14.8 Volts".
***If it Does, the Alternators Voltage Regulator is probably Faulty, OVER CHARGING the Battery.
 
gavbriggs said:
you'll know on a p38 cos all feckin hell breaks loose if its alternator fault! (thats also true for any other minor fault on the p38 too! lol!)

One Simple Battery Test:


1) Connect the voltmeter directly across the "Battery Terminals". (NOT to the Cable Clamps)

2) While watching the meter, Start the Car.

3) The Battery Voltage should Never fall below about 10 Volts.
If it does:
a) The battery is either "Low in Charge".

b) Or The Battery is "Low in Water".
(The water leven in the battery should be about 1/4 of an inch, Above the Plates.)
"DO NOT" Fill it up FULL.

c) Or The battery has a "High Internal Resistance".
(Possibly Sulfided Plates and probably Time for New Battery?)



**NOW Repeat This Test BUT:

1) Connect the voltmeter directly across the "Battery Clamps on the Battery Cables".

2) This Reading should be Within 0.1 Volt Maximum, the Same as 3 Above.
***If NOT, Clean Battery Terminals and Clamps.

2a)If Necessary, Repeat Test to Varify it is now OK.



**NOW Repeat This Test Again, BUT:

1) Connect the Voltmeter Directly Across the Positive Terminal of the Starter and it Case Ground.

2) If the voltmeter reading is More than 1/2 Volts Lower than the Previous Test,
** You Probably have a Cable or Connectorp Problem!
Check the Connections between the Cable and the Cable Connectors. ON BOTH ENDS.




One Very Simple Alternator Test:


1) Start Car and run at a normal idle.

2) Connect a Voltmeter Directly Across the battery Terminals.

3) Turn on Headlights to High Beam.

4) check the battery Voltage.
*** The Battery voltage Should read between about 13.8 to 14.2 volts. (Possibly up to 14.5 Volts.)

5) Increase motor speed to about 1500 RPM. The Alternator should now produce a battery voltage between 14.2 and 14.6
Volts.
*** If it is Lower than 14.2 volts, the Alternator probably has one or more Bad Diodes.

6) Now, Maintain the 1500 RPM and Turn off the Headlights. Run this test for One Full Minute.
"The Battery Voltage should NEVER Exceed about 14.8 Volts".
***If it Does, the Alternators Voltage Regulator is probably Faulty, OVER CHARGING the Battery.
Click to expand...

wasnt a p38 you numpty.
 
Perfect Gav thanks. :D You forgot to mention the special P38 test - "If all hell breaks loose and every available fault light shows plus unpredictable things happen.....check the battery!!!"

Seriously, thanks for clarifying - the clots at Kwik Fit weren't entirely sure what they were doing then. Now there's a surprise:eek:
 
rangiegal said:
Perfect Gav thanks. :D You forgot to mention the special P38 test - "If all hell breaks loose and every available fault light shows plus unpredictable things happen.....check the battery!!!"

Seriously, thanks for clarifying - the clots at Kwik Fit weren't entirely sure what they were doing then. Now there's a surprise:eek:
Click to expand...
thats y they fit em quick :D
 
rangiegal said:
Perfect Gav thanks. :D You forgot to mention the special P38 test - "If all hell breaks loose and every available fault light shows plus unpredictable things happen.....check the battery!!!"

Seriously, thanks for clarifying - the clots at Kwik Fit weren't entirely sure what they were doing then. Now there's a surprise:eek:
Click to expand...

you mean, "If all hell breaks loose and every available fault light shows plus unpredictable things happen.....check the coolant!!!!"
:D:D:D:D:D:D
 
rojbarker said:
The noggins at Kiwik Fit wouldn't change a tyre on my imported Camaro as they "didn't have the torque values for the wheel nuts" :)
Click to expand...


thats a load of bole-axe cos, according to every wheel monkey round here the 'torque value' for any wheel nut from a bycycle to a jcb is just a little tighter than you can manage to get off on the hard shoulder or put more simple ' tight as fcuk':doh::doh::doh::doh::doh:
 
gavbriggs said:
...

One Very Simple Alternator Test:


1) Start Car and run at a normal idle.

2) Connect a Voltmeter Directly Across the battery Terminals.

3) Turn on Headlights to High Beam.

4) check the battery Voltage.
*** The Battery voltage Should read between about 13.8 to 14.2 volts. (Possibly up to 14.5 Volts.)

5) Increase motor speed to about 1500 RPM. The Alternator should now produce a battery voltage between 14.2 and 14.6
Volts.
*** If it is Lower than 14.2 volts, the Alternator probably has one or more Bad Diodes.

6) Now, Maintain the 1500 RPM and Turn off the Headlights. Run this test for One Full Minute.
"The Battery Voltage should NEVER Exceed about 14.8 Volts".
***If it Does, the Alternators Voltage Regulator is probably Faulty, OVER CHARGING the Battery.
Click to expand...

Thanks gavbriggs, finally I found that my alternator is not fine :mad:, but found where is the problem (13,54 V with no lights on):).
(I hope that my door lock/unlock syndrome will be gone, since the problem started after a flat battery and is more recurrent in the night (lights on)).
Thanks
 
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