Ok, but what about the cranking time? Is there any proof it also impoves or no impact in that matter?

Post a video for the forum if you can SOLD | Tuned MY 2011.5 Range Rover Autobiography 4.4 TDV8 Orkney Grey | e-diff | ACC

New Toy: Unimog U1550L/37
New : G350D

A video of what do you mean?

record the crank cycle, from the dash and the engine bay SOLD | Tuned MY 2011.5 Range Rover Autobiography 4.4 TDV8 Orkney Grey | e-diff | ACC

New Toy: Unimog U1550L/37
New : G350D

Ok, will do later.

Here's comparison of the cranking test between the old and the new battery.

Click image to enlarge

Click image to enlarge

Has the battery swap fixed your issue? SOLD | Tuned MY 2011.5 Range Rover Autobiography 4.4 TDV8 Orkney Grey | e-diff | ACC

New Toy: Unimog U1550L/37
New : G350D

10.07VDC at cranking is a little low, various modules will shut down below 10.50VDC

It could be how/where the system voltage is monitored is reading low.

ffrr14 wrote:

Has the battery swap fixed your issue?

Phoenix wrote:

10.07VDC at cranking is a little low, various modules will shut down below 10.50VDC

It could be how/where the system voltage is monitored is reading low.

9.5VDC at cranking is not a healthy voltage, whatever the documentation that came with your voltage monitor says.
There are several diagnostic screens on SDD that mention the 10.5VDC threshold and this is common across many vehicle manufacturers, some lower it to 10.0VDC. the key measurement is at the module which is where it matters, there will be volt drop, probably less than 0.5VDC depending on the module and CSA of the wiring to it - relays will also drop out / fail to pull in at below 10.0VDC (type dependent). Not everything is in the workshop manual as it is aimed at a level of understanding and training that workshop staff are expected to have as a minimum requirement. I think the reference to 9.5VDC being 'OK' goes back to an era of ignition coils and ballast resistors mounted on the inner wings of vehicles, where cranking voltages of 8 or 9VDC were common.

As a rough indicator, if your navigation screen reboots when cranking, then the battery voltage is getting quite low, if it flickers but goes back to the same screen, then it's OK but less than optimal, a fully charged battery won't affect the screen at all during cranking.

I haven't measured my cranking voltage recently and it may not be directly comparable as I have the 3.6 TDV8, I'm in work tomorrow so I'll record a trace of it, just for morbid curiosity.

ETA - I found these traces, the vehicle (non-JLR) was having transmission issues caused by lost comms between the central gateway & the TCM during cranking (the oft-ignored 'U codes'). Replacing the starter battery rectified the concern. A fairly straightforward and common diagnosis.

Thank you for the informative answer.
No issues with any modules, no interruption in navigation screens work etc. Altough I noticed it with old battery. Both old and new batteries are Bosch S5 A13 850A 95Ah AGM batteries, the ones they use in official workshops.
And you are right - 4.4 and 3.6 are not comparable because of the differences in charging and starting systems.

I got roughtly the same result with Picoscope, so the Topdon battery tester is pretty accurate.

I might need to do a new test tough, because when I did the test, the new battery was been on just two days and the BMS was on initial discharging cycle, meaning intentionally draining battery to certain point by appling just 12.25V charging voltage.
Also it was -15 degrees outside and blower, radio, interior and exterior lights were on.
So worth doing new test now.

Here's a couple of traces
First one, vehicle used for 2 x ~4 mile journeys per day, pre-heat used and stop/start traffic with heated seats etc. used every day. Ambient this morning was -2deg. C.

Nav. screen rebooted and ABS amber warning / 'Special programs off' message appeared, which is normal towards the end of the week with the usage pattern - i.e. depleted battery not fully recharged due to usage cycle, second & third starts still rebooted the Nav. screen but presumably the capacitors in the other modules had enough time charging to prevent any brownouts, the higher voltages during crank are probably due to quicker starting after the initial one.




Second one, after driving the 4 miles or so to work and ~1 hour on a Ctek 60Pro charger, Nav screen flickered but went back to the previous display, not the LR logo, no other warnings.



In case you're wondering, I got a lift into & back from work with the voltmeter etc. to record a true 'cold start'. In both instances, I didn't wait for the glow plug light to extinguish.

Yeah, I'm using the car also with all accessories on and only 5-10 min trips so it doesn't get warm even. The ambient temperature here swings between -10 to -20 degrees so after startup, all window defrosters, heated steering wheel, and seat heater get turned to the max.
But never had any warnings on the dash nor any modules shutting down. Only some low voltage codes in some modules occasionally when reading codes.

There are at least two remarkable differences between our tests.

One is that your initial voltage was around 12.8 and mine was 12.25 hence it was discharged by BMS at the moment of testing.

Another one is that these are two different cars in different environments. It is obvious that a 22% bigger engine (4.4 vs 3.6) which has thicker oil in it (-15 vs -2 degrees) is much harder to turn around, which results in a bigger voltage drop.

Of course, technically this original cable from the relay to the starter has more resistance than the upgraded one and hence causes more voltage drop, but it is paltry compared to the reasons mentioned above.

Do you have any precision measuring tools to determine the cranking time like a scope?

Cheers
Keijo

Yep, I can 'scope it - all the measuring equipment is checked and calibrated every six months and meets the minimum accuracy requirements of the brands my employer works for. It'll have to be next weekend though, weekdays are just too busy for me.