Thread: What happened to your D3/D4 today?

Off to Repco for 20L of HPR5 with their yearly 30% off sale.

Originally Posted by V8Ian

Via Lake Perseverance?

I put the TRS into "grass, gravel, snow" yesterday in case I had to swerve for oncoming traffic as a lot of the double lane Seventeen Mile dirt road has devolved into single lane due to ruts and potholes. Perseverance Dam was spilling into Lake Cressbrook on my way up to Crows Nest.

Remind me again how long should an alternator last? I replaced mine in 2015 at 160 kms and now have 312 km on the new one. With a long trip coming up am I in the worry zone yet or did they improve and stop failing as don’t seem to read about it much anymore.

The alternators fail because the manufacturer uses main power diodes of the type that reverse conduct at high voltage to protect the various modules from high voltage spikes, initially triggering at around 30V. However the diodes degrade with usage causing the trigger voltage to lower which eventually gets down to normal operating voltage so the diodes cause a short circuit at battery voltage, immediately flattening the battery.

Other manufacturers use normal main power diodes and a separate circuit to shut down the alternator if a voltage spike occurs, but not the manufacturer that LR uses for its alternators.

Originally Posted by Graeme

The alternators fail because the manufacturer uses main power diodes of the type that reverse conduct at high voltage to protect the various modules from high voltage spikes, initially triggering at around 30V. However the diodes degrade with usage causing the trigger voltage to lower which eventually gets down to normal operating voltage so the diodes cause a short circuit at battery voltage, immediately flattening the battery.

Other manufacturers use normal main power diodes and a separate circuit to shut down the alternator if a voltage spike occurs, but not the manufacturer that LR uses for its alternators.

Worth trying/possible to rebuild?

I didn't consider rebuilding the one from my 4.4TDV8 L322 because it had shorted to ground being the usual failed Zener diodes which meant that the insulation on the windings would have been burnt.

Yes but is 16 km and 7 years the limit or people see more?

My L322's 240A version lasted 10 years but only 151K kms.