alternator question

What you are asking for is an ALTERNATOR OUTPUT PERFORMANCE CURVE. The term is used and understood industry wide.

To cut to the chase, go online or to the telephone, and query OEM the MANUFACTURER of your alternator for the output performance curve. It is a graph showing speed vs max output potential.

COLD output is considerably higher than HOT output. It's a fairly useless value, but if COLD output is all you can get, so be it. Just don't bank on getting COLD output performance when the alternator is loaded. If you're going to charge batteries while stationary, raise the hood. I even placed a 12 volt fan blowing down on to the alternator.

For extremely technical jargon, dealerships remind me of trying to discuss phasor algebra with a chimp.

Hi,

My understanding of "high idle" on diesel is that it is more about sufficient oil pressure to prevent damage to the motor, than greater output from the alternator.

The common garden variety alternators are rated at their peak output. This is a far higher number than the continuous duty output. I derate my 130 amp by 1/3 and call it about 90 amps maximum. Even at that level I sometimes see the voltage start to drop which is a BIG signal to lower the load. Ignore the signals and soon there will be a bill to pay for a new alternator.

If the voltage hits 12.9 I lower the load on the electrical system right away.

RWDIII wrote:
If an alternator is rated 200 amps,why cant they tell you at what RPM this rating is good.At idle,650rpm, or at cruising,1950 RPM.
If you get a diesel rig,there is a high idle setting to get more amps
but is not available for gas rigs,Ford,.
When I got my truck serviced at the dealer,I asked and all I got was a stare LIKE I was speaking Chinese. :h