Upgrading Alternators - Amp Ratings?

**JZA70 R** · 16-08-2010, 05:15 PM

Originally Posted by sil80 1J

do fuel pumps draw more current as rpm increases?

Additional load is placed on the pump as boost increases but this is not proportional to rpm, so no. I would assume that the power draw from this extra load is marginal. Generally alternators produce more current as rpm increases, so its very strange you are losing voltage as rpm increases.

**oldcorollas** · 16-08-2010, 05:35 PM

where is the voltage being sensed from? perhaps it is the "ground" that is increasing, rather than the alt output voltage decreasing

**sil80 1J** · 16-08-2010, 07:56 PM

i am yet to investigate the problem, i was more interested in alternator outputs from various engine variants so as i could make the decision to go to another alternator or rebuild mine

the earth issue is a great point, everyone gets so tied up in sender wires they rarely put much thought into the grounding of the device, i was pretty generous with my grounding but another look will not harm anything

**oldcorollas** · 16-08-2010, 08:17 PM

if you can, measure voltage from the alternators output post to the case of the alternator.. if that is stable, you have wiring issues

how old is the battery? could it be having issues accepting current?

**sil80 1J** · 16-08-2010, 08:28 PM

Originally Posted by oldcorollas

if you can, measure voltage from the alternators output post to the case of the alternator.. if that is stable, you have wiring issues

at idle or when im getting the loss?

battery is ok, not that old, what makes me rule out the battery iis the voltage is good at idle, is a coil pack is on the way out could it cause extra draw as it struggles to ignite?