Thread: D3 battery

I spoke too soon in post #11.

The auxiliary battery died a couple of weeks ago and the Delkor had been showing signs it was not in good health. I put the multimeter on it before my wife turned the ignition yesterday and it dropped to under 11V as soon as it when to accessories. New battery installed yesterday evening and a new auxiliary due to arrive Monday.

August 2017 I paid $243, February 2020 I paid $253.

I just posted up this info in another thread on starting batteries, and could save some money for D3 and D4 owners.

Just in case someone is thinking of it, a word of caution.


DO NOT CONSIDER USING LITHIUM CRANKING BATTERIES.


Most lithiums can be charged directly from an alternator and if it’s the auxiliary battery then it’s not likely to be a problem, even in vehicles with SMART alternators.

How you set up a vehicle to be able to separate the lithium auxiliary battery from any lead acid batteries ( including the cranking battery ) when the motor is not running, that is the only real issue.

But there is a MAJOR potential problem when using a lithium battery as a cranking battery.

Again, while charging the lithium from the alternator is not likely to pose a problem for a lithium cranking battery, but there is a very high possibility of damaging both the alternator and the vehicles electronics.

The the problem is not from overloading the alternator but the exact opposite.

There have been a number of issues where the lithium battery’s BMS has shutdown while the lithium cranking battery is being charged. Be it from over voltage, or the battery reaching a fully charged state, or the lithium battery’s BMS failing.

Regardless of what causes the sudden shutdown, you now have a free-wheeling alternator, and in any situation, an alternator running without a battery connected to it, will allow the alternator to generate very high voltage spikes.

These spikes are being generated by all alternators at all times, but the cranking battery, because of its very size, acts as a massive spike suppressor.

With a lead acid cranking battery, even if it’s stuffed, it will still suppress these high voltage spike, and thus, protect the vehicle’s electronics.

With the lithium cranking battery removed from the alternator, these high voltage spikes will quickly destroy a vehicle electronics, including the alternators voltage regulator.

This is the REAL potential problem of using a lithium battery as a cranking battery and the potential of damage being caused, is even greater in newer vehicle, like Land Rovers, with their huge amount of electronics.