Mike disco Posted May 22, 2010 Share Posted May 22, 2010 Hi, can any body help how do I check to see if the aternator is charging. mike allenby, mike disco. Quote Link to comment Share on other sites More sharing options...
berti1554 Posted May 22, 2010 Share Posted May 22, 2010 Take a voltmeter and connect it to ground an + while engine is off. Voltage should be around 12 to 13V. Then start the engine - voltage should go up to approx 13.5 to 14V. Switch on lights, fan and everything else - voltage should be stable (might need higher revs). Quote Link to comment Share on other sites More sharing options...
crwoody Posted May 22, 2010 Share Posted May 22, 2010 You need to put a voltmeter across the battery and check the voltage while the engine is running. You should see around 13.8 - 14.2 volts when charging and about 12.5 with the engine stopped (may be less when not charging depending on age and condition of battery.) Any less than 13.8 volts charging would suggest the alternator is U/S but there could be wiring issues that can affect it too so don't condemn the alternator straight away if it's outside of the limits above. Edit; must type faster Quote Link to comment Share on other sites More sharing options...
landyash Posted May 22, 2010 Share Posted May 22, 2010 Hi Mike the best way I know is to start up your landy then remove the negative terminal off the battery,then put your lights on and see if it cuts out. If it does the alternater is no good Cheers Ash Quote Link to comment Share on other sites More sharing options...
Aragorn Posted May 22, 2010 Share Posted May 22, 2010 disconnecting the battery with the engine running isnt wise, as it can stop the alternator regulating the voltage properly. Quote Link to comment Share on other sites More sharing options...
reb78 Posted May 22, 2010 Share Posted May 22, 2010 I'd do it the way crwoody and berti have described. That will tell you the answer. Quote Link to comment Share on other sites More sharing options...
landyash Posted May 23, 2010 Share Posted May 23, 2010 disconnecting the battery with the engine running isnt wise, as it can stop the alternator regulating the voltage properly. If the Alternator is no good it wont matter Tried it lots of times and never had a problem. If the Alternator no good, it can't keep the engine running because it can't produce enough power to power the pump Ash Quote Link to comment Share on other sites More sharing options...
crwoody Posted May 23, 2010 Share Posted May 23, 2010 Quote "If the Alternator is no good it wont matter" Indeed it wont matter at all - however if the alternator is working properly, the unregulated output can rise to 18 volts or more and you're seriously in danger of frying the cars electrics, especially if it's a later one with various ECU's, these electronic modules can be quite sensitive to over-voltage. Quote Link to comment Share on other sites More sharing options...
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