bolarbag Posted August 28, 2008 Share Posted August 28, 2008 Anyone know the output of the 6speed Alternator on idle? I'm sure I've heard 90Amps - anyone know the usual Voltage? Quote Link to comment Share on other sites More sharing options...
JustGav Posted August 28, 2008 Share Posted August 28, 2008 Voltage wise it should be about 14v, at idle however I'm not 100% sure... The current draw will obviously only be as much as is required up to the limit. Quote Link to comment Share on other sites More sharing options...
Lee P Posted August 28, 2008 Share Posted August 28, 2008 About 45 amps on idle but if the alternator is old and tired it could be less, can be a real problem on a supra when running fans, 2 pumps etc Quote Link to comment Share on other sites More sharing options...
bolarbag Posted August 28, 2008 Author Share Posted August 28, 2008 I have a new uprated phr alternator but need minimum requirements for a battery I'm buying, 14V supply from the Alternator is really required I have an electric water pump too - thats not going to help things Quote Link to comment Share on other sites More sharing options...
Lee P Posted August 28, 2008 Share Posted August 28, 2008 Its not really the voltage thats important its the amperage, the more equipment you run in the car the more it will draw on the alternator. The problem is supplying it at idle. You will get 14.4 volts or so off the alternator when cold but as it gets hot that will drop to 13s even with a high power alternator. What battery are you running? If its a dry cell like mine its always best to top them up every now and again off a mains charger anyway. Im running a stinger 1000 in mine Lee Quote Link to comment Share on other sites More sharing options...
bolarbag Posted August 28, 2008 Author Share Posted August 28, 2008 Voltphreaks VP900, Nano-Lithium I think it should be ok, I'll get a condition mapped in the motec if it goes below 13.8or something Cheers! Quote Link to comment Share on other sites More sharing options...
georigg Posted August 29, 2008 Share Posted August 29, 2008 In its very basic terms, an alternator produces an "alternating" current(similar in wave form to normal household AC supplies) which is then rectified down to a DC Voltage normally through a full wave bridge rectifier circuit. Most alternators generate a 3-phase supply. An alternator will basically supply its full rated current at 750RPM and above but if you draw "full rated Current" at or near to 750RPM(tick-over revs), then the voltage generated will tend to be slightly lower as it will compensate the lower RPM by dropping the voltage generated. In general terms if your alternator is rated at 45 Amps, that is what it is capable of supplying. Another thing to remember is that the car battery provides power to the car. The alternator senses battery output and boosts the charge rate to "replace" the power used, so switch everything electric on at tick-over, the load is powered from the battery and the alternator re-charges the battery replacing the power used. This is why if you have a knackered battery with a failed cell, the alternator senses the lower voltage output from the battery and continues the chagre process, cooking the battery further, but still supporting the battery in running the engine/car. A bit of a simplistic explanation but may help to understand the way alternators work. Quote Link to comment Share on other sites More sharing options...
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