Hello!

New to the forum, and forums in general come to it, so please bear with me if I am clumsy - But I am a quick learner...

I have just taken on a 2014 TD4 XS, spec, (my 5th Landrover over 35 years), which is fitted with "eco" stop start. From day one I suspected that the battery was failing, and my trusted local garage ran a check and confirmed it was showing a failing/failed cell. They fitted an 800 AH "YUASA" AGM battery, and hey presto, the stop start works, the cold cranking speed improved, etc.

I then fitted a voltmeter in the cabin, fed directly from the cigar lighter fuse (via piggy-back holder) so I can monitor the system and was startled to see that, once started, the system is running at 14.9V most of the time, occasionally 14.8 . That voltage decays to 12.2 very quickly when I stop the engine, which also surprised me but perhaps there are all sorts of systems that "run on"?. I have checked the displayed voltage at the battery terminals with an expensive meter and it totally agrees with the cabin unit.

I have only recently learned about smart charging systems (I was trained on electro magnetic regulators too long ago!), and I appreciate that an AGM needs a slightly higher voltage, but am still a bit concerned at 14.9. If it aint broke, I wont fix it, but if I am quietly cooking a brand new battery I would like to know!

Can anyone with knowledge of the FL2 electrical system offer an opinion?

Thanks in anticipation

Quite normal no problem

Should be higher than 12.2 with no load.

1. Charging is temperature dependent so the lower the temp, the higher the voltage when charging.
2. After ignition off, a lot of systems are still running, up until sleep mode, so it's normal for the voltage to drop without charging...

Wow! That was quick...

Sincere thanks to all.



Alex/Wonderdust - Just realised that the headlight delay was active, so 8/10 amp load for first 30 seconds. That was clumsy of me!

I hadnt realised temperature is a factor, and yes, its been consistently cold.

Denboy/ All - Thankyou, I really appreciate your help.

Hadnt realised just how smart this car is - Love it!!

1 Connect a voltmeter to the vehicle battery
2 Switch ignition state to on (engine off)
3 Turn off all electrical loads e.g. (blower, radio, interior lights etc.)
4 Start the engine, switch on the heated rear screen
Ensure the heated rear screen is on (see note above) and that the air conditioning system is off.
5 Wait 90 seconds
6 Record the battery voltage (V1) shown on the
multimeter
Does battery voltage (V1) = 14.8 volts or greater at idle?
Yes
Install a new generator. Refer to the warranty policy and procedures manual, or determine if any prior approval

Again, Thanks.

I assume that procedure came from a workshop manual?

I followed the procedure rigorously, twice. The first was from stone cold, gave me 14.5 initiallly, rising to 14.7

The second was 30 mins later, with another voltmeter (that agreed with the first) rose quickly to 14.74, then peaked at 14.79 after 90 seconds!

I have also done a road test and the 14.9V running drops to14.8 with the HR screen on. I really dont want to be buying an alternator, but dont want to damage the new battery either. I guess by the letter of the manual I am within spec - but only just, which bothers me a tad. I wish they had given an acceptable range...

Thanks again - much appreciated "If you want to manage it, measure it... Twice!

Forgot to mention - ambient temperature was/is 5C. Perhaps relevant to that test procedure? "If you want to manage it, measure it... Twice!

You worry too much... You are just fine.

Last edited by alex_pescaru on 27th Dec 2020 4:43 pm. Edited 1 time in total

^^^ I can also benefit from the above advice!!!
I just blame my OCD........

OK, point taken. Thanks for previous responses anyway. "If you want to manage it, measure it... Twice!

Hi,
might be worth doing a check of the voltage when your car has gone to sleep as well, easy if you have a twin tow socket,
its the S white plug or have a 13 pin socket,

recently replaced our battery, Replaced with a Yuasa YBX9115 and 4 year warranty

Just checked sleeping voltage before using today (its been 2 weeks since it was fitted and not used the car!) and it was 12.7v

 .
my first ever FL2 and I did keep it longer than most other cars!
But its now gone way up Norf

Sleeping voltage on my 2008 LR2 AGM is 12.76 volts; depending on outside temps, my alternator voltage is 12.9 all the way up to 14.8; current outside temps are -5C and the voltage will flick back and forth around 14.5-7.

I will add, if I am going to not drive my LR2 for 3+ days, I will connect a CTEK (56-958) MUS 4.3 POLAR to it.

Again, thanks to both. I only started to have doubts after finding a "wake up" voltage first thing in the morning of 12.5, on a 2 week old Yuasa YBX 9115 battery that had been on a 40 mile trip the day before. I had always believed that a healthy float voltage was 12.6+ or more, but I openly admit I dont understand smart charging systems - yet!.

I will check it again tomorrow, without waking the car up! "If you want to manage it, measure it... Twice!

Float means open circuit voltage after a 100% charge with equalizing in the final stage.
For sure not a situation on a car connected battery...