Thread: D4 Alternator Question

Originally Posted by baldivistribe

Hi all
Have had our Discovery for a month now and am constantly getting the low voltage stereo will turn off in 3 minutes thingy. We brought the vehicle home from Albany (4 odd hour drive) i would have thought the drive would have charged the vehicle battery enough not to get the warnings. I have since stuck my cteck 5 amp charger on and left it on for 2 days (took overnight to progress through the stages). Now i have just flicked my solar panel on the battery and the regulator today showed a SOC of 80%. I would have thought the Alternator would have done a better job of charging the battery. I would hate to go camping and leave the fridge on for a couple of days. My queries are does anyone have an understanding of how the alternator works.

Hi Steve and the problem is not the vehicle, it’s the battery.

Calcium/Calcium batteries can be a big problem to charge and if they have been sitting around for weeks on end and not being charged, ( like when being transported out here ) it can be fair sort of job to get them into a fully charged state.

Add to this your driving habits.

If you do lots of short drives, your are just exacerbating the problem.

An occasional long drive is always good for these batteries but if your solar panel has a adjustable regulator, set it to 14.7v and leave it on your battery as long as you can.

Originally Posted by sniegy

Generator !

How about Dynamo? - may as well be as I think these new alternators in combination with newer design batteries and control systems are so far away from functioning like anything most of us are used to, that a new, (or old), name should be applied.

Drivesafe is understating it when he says these new CaCa batteries are not like the conventional Lead Acid of yesterday. That and some combination of fuel economy and energy saving design philosophies or maybe just a "we can do it", kind of thinking leads to different operating requirements.

About twice a year, I put my CTEK charger on each of my two batteries separately and top them up. I would say that for the main starting battery, an Interstate, it takes about a week of nights for the CTEK to get to where it says the Interstate is fully charged. I think it is a combination of there always being a draw on the battery from the computer systems, the small size of the CTEK, and in my case, city driving.

I also use the cold weather setting on the CTEK which is the higher charge voltage, 14.7 volts and 3.3 amps.

This morning I was meant to attend a Range Rover Club course so at 0615 a cold morning, I start the D4, however after a lot of flashing lights it pops up with the message that the smart key is not found yet it is right there. This happened a couple of times so we get out, lock the car wait 5 mins and still the same but then there is a lot more noise like relays going off an on. After a while I check the battery and it only has 9 volts. I try to jump start it with my fridge battery to avail. So a call to Land Rover Assist and NRMA battery guy arrives. He tries to jump start and that also fails. He puts a new battery in and after about a dozen goes at pressing the brake and on button it starts.

The NRMA guys says the alternator is running about 15.1 volts and suggests that is too high and this may have been the reason why the prior battery only lasted 3 years. Does any one know what the alternator should put out at? Is 15.1 volts too high?

Hi Orangi, if you have an AGM cranking battery then yes it is way too high and should not be over 14.7v.


High voltage like that is a software issue and you need to get it fixed, ASAP.


Keep an eye on the voltage to see if it does drop once you have been driving for 30 or more minutes.


If the voltage does not drop, whether you have an AGM or a Calcium/Calcium battery, you must get that fixed. That high a constant voltage will eventually cook any battery.