Running the car just before with everything on (headlights, air con going, blower fan, windscreen wipers, stereo up) the voltage at the battery wouldn't go past 11.8V. Before starting the car it had been 12.5V.
After turning the car off it wouldn't start again for a good 10mins (engine not turning over, battery low).
'89 Brumby dim lights/low power at idle
Got it. Had a bad voltage drop from in the alternator wiring and upgraded a few other wires (battery neg to block etc). Also idle up valve for a/c was defective which was causing engine to idle VERY low when a/c was on -> alternator not generating power. I now have the opposite problem, I'm getting 14.8V at idle (right on max rating for battery) which drops to 14.5V with radio/blower/headlights on and apparently goes to 13.8V with the a/c on as well (compressor just came out so I can't check that). Unfortunately my battery is not holding charge very well and will need replacing soon, possibly damaged by the flogging it's had in the last few weeks.
Thanks for the replies.
Thanks for the replies.
All please note that a 12 volt system is not actually 12 volts.
A battery is a number of cells hooked together,each cell should supply 2,2 volts with automotive lead acid technology,remember all modern batteries are still just a variation such as AGM (Absorbed Glass Matt)Calcium etc.
Therefore a fully charged 12 Volt system should be 13.2 Volts not 12 and following on from this you should aim for a charge rate of 1~1,2 volts above that.
This means a properly working charging system should read at the battery and alternator output connector between 14,2 and 14,4 volts,above 14.6 is starting to overheat the plates and destroy the battery.
This is important because a drop of just 1 volt will decrease output from your headlights by 10~20% depending on type as well as ignition issues as all ignition systems amplify input voltage to produce a good spark.
A drop of say 1.2 volts doesn't sound like much around 10% roughly,but then equate that to say the ignition coil at say 50,000 Volts output loose 10% of that and it suddenly seems much more important when you are talking 5,000 volts less ignition output.
Remember it is a system and it affects all aspects of your vehicle from lights,ignition door locks brakes etc these days,voltage drop as it is known is to be avoided as much as possible therefore good earths and clean connections and correct power supply would solve many issues people have that may not at first seem related to the electrics.
A battery is a number of cells hooked together,each cell should supply 2,2 volts with automotive lead acid technology,remember all modern batteries are still just a variation such as AGM (Absorbed Glass Matt)Calcium etc.
Therefore a fully charged 12 Volt system should be 13.2 Volts not 12 and following on from this you should aim for a charge rate of 1~1,2 volts above that.
This means a properly working charging system should read at the battery and alternator output connector between 14,2 and 14,4 volts,above 14.6 is starting to overheat the plates and destroy the battery.
This is important because a drop of just 1 volt will decrease output from your headlights by 10~20% depending on type as well as ignition issues as all ignition systems amplify input voltage to produce a good spark.
A drop of say 1.2 volts doesn't sound like much around 10% roughly,but then equate that to say the ignition coil at say 50,000 Volts output loose 10% of that and it suddenly seems much more important when you are talking 5,000 volts less ignition output.
Remember it is a system and it affects all aspects of your vehicle from lights,ignition door locks brakes etc these days,voltage drop as it is known is to be avoided as much as possible therefore good earths and clean connections and correct power supply would solve many issues people have that may not at first seem related to the electrics.