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Discussion Starter · #1 ·
Just to show how one thing leads to another again.

After researching the "Auxiliary batteries for dummies" post I did in the "Accessories" section of the forum, I realised the importance of even a 0.1 volt drop in the charging system. I had never been that fussed about such a small drop in power.

So I decided to go check the Rangie. I am using a standard 85 amp alternator from my 93 Rangie. I also believe that I used the same cable from the 93 that runs between the alternator and the battery. This cable had a copper core of around 6mm with the individual strands of cable being 0.7mm. It looked more than big enough.

But when I checked the voltage, with no real electrical load on the system, I had slightly less than 0.1V drop between the alternator and the battery. But when I loaded up the electrical system (Air-con on full, thermo fans on, headlights and HID driving lights on, etc) the difference in voltage increased to 0.5V. The resistance in the cable had increased from basically zero to nearly 500ohms.

It was obvious that the cable I was using from the alternator was not good enough for even my 85 amp alternator. So I went overboard like usual and installed a 0B&S cable between the battery and alternator. This cable is rated to handle 100 amps over 8 metres. The copper core of the cable is around 8mm and each strand is only 0.3mm.

I now only have no more than 0.05V drop from the alternator to the batteries when the alternator is at maximum output.

Will I ever run out of things to check and modify?
 

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Good info, and no you won't Ian
 

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Discussion Starter · #3 ·
I was just talking with my Land Rover Mechanic friend and he states that most vehicles he checks have a voltage drop between the alternator and battery. So it is definitely worth people checking. It is no use having a 100amp alternator if the wiring limits its supply to 50 amps.
 
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