Thread: 300tdi Alternator output

Originally Posted by TOR

..... The previous owner has upgraded the alternator to a 100amp unit. ....

My understanding is that a 300 Tdi is a 300 Tdi, is a 300Tdi (ie. no matter the vehicle it was used in) .. so they will all be 100A alternators from the factory.

I think the Defenders came standard with 70Amp alternators while the D1's came with 100Amp, which many Deefer owners then upgrade to.

Originally Posted by cripesamighty

I think the Defenders came standard with 70Amp alternators while the D1's came with 100Amp, which many Deefer owners then upgrade to.

Wasn't it even smaller than that?

I have in my head it was only 65amps?

And it ran that tiny little needle roller at the back directly on the hardened shaft, which had to be regularly greased.

I replaced the one in my old Deefer with a 100amp Disco one and didn't bother upgrading the cabling and it was never an issue.

If you want to be sure it is way to add an additional wire in parallel between the alternator and battery (or starter terminal). No need to touch the factory wiring then beyond installing the new wire tidily.

I did this on my D1 after I upgraded to the 120A P38A alternator. And ran a direct earth cable from alternator to battery. Seemed to make it better

Hi TOR, those voltages are not bad, and if you take into account that you have the thinner cable, plus your new cranking battery is most likely nowhere near fully charged and last but not least, your motor would be at idle while you were taking the voltage readings. Again, those voltages are not a problem.

As also suggested above, installing thicker cables, or as was suggested, just double up on what you have, will give you a number of benefits. Such as faster recharging of your cranking battery.