So, last week i was messing around with the rear battery panel out of my 405.

Whilst it was open i looked at the supplementary battery and noted i had the "next size battery up" on the side in my workshop. It was a JLR Battery made for a Jag XE? XF? It was an inch longer than my original and was a 800ah rather than the 750ah and obviously an AGM so i thought "that might be a good upgrade"

NO! ten mins after fitting the dash was bonging up LOW BATTERY PLEASE START ENGINE and even after driving the car for 45mins the same bong of doom when turning off the engine...

Incidentally, when starting the car, the dash would flicker for longer than usual! So all together the car was unhappy with my upgrade! I left it on the Ctek overnight and in the morning was the same... Doooooh! So i changed it back to my original and all reverted to normal

I bench charged both my original and the larger battery after removal and off the car they both charged fully within a couple of hours... So both batteries are fine, it was the car that didn't like them!

Im only telling members here so they don't make the same or a similar mistake... Im guessing fitting a cheaply made after market battery may have similar effects?

Wow - thanks for the heads up

I'm always attracted to those kind of slight upgrades and would almost certainly have made that sort of mistake when it comes to needing a new battery

That is interesting, because I did the same mod. Removed the metal bracket to fit it, and I have no issue at all. I fitted a 900amp 100ah battery and it's fine. No issues at all. Are you sure something else is not causing a drain?

^ +1 There is no way installing a battery with a capacity 50Ah greater than originally specified will make the slightest difference to the car.

^ Agree. It shouldn’t make a difference. But maybe it does. Automobile magazine reported that their brand new Discovery 5 would throw up nasty error messages if they added generic, good quality Add blu instead of the (very expensive) JLR branded equivalent. Shouldn’t make a difference...

Bit of an update on this... Had LR Assist out today as my car has been getting more and more "low battery" bongs! The car was not starting after 3-4 days of inactivity... Both batteries were changed in July and it would appear the one under the spare wheel had failed! So, we put LR Assist on it today and the "battery management system" had faulted and was causing these issues! LR Assist guy ripped out the software and downloaded new and all seems to be well now...

Was this the result of me messing with the Aux Battery??? Don't know and i won't be messing any further!

Just thought you'd all appreciate the outcome...

wow. An LR assist guy that knew what to do ( was he actually LR? I thought they had subcontracted all of them to the AA now.)..... Apologies for my cynicism but my experience with them is not good. The last AA guy that came out to me as good as admitted he knew practically nothing about LR's.

Glad it's sorted though!

While perusing the CCF files, there are different options for the power of the main and Aux batteries.

I wonder if it would have been fine with the corresponding option enabled within the CCF?

is a supplementary battery standard on l405?

Bloody cars!!! Been out for a 30min drive early this evening and when i turned the car off...... Yep you guessed it BONG LOW BATTERY START ENGINE!!! Grrrrr

Buy yourself a L322

The battery capacity is the battery manufacturers minimum test when they come off the production line.
I am sure batteries are graded on the tests, and lower/different figure ones are sold off with different branding.

I just had a 900ah one tested and it came up with 960ah, so maybe fitting a used one might not have the capacity written on the tin, and with second hand ones, the capacity could be anything.

On the running costs of a RR, batteries are really quite a low outlay. Modern batteries just don't last, and buying a new one every 2 or 3 years
Tayna are doing Powerline 105Ah 895A £80.45 or a Lucas 110Ah 920A £96.99, That's £30 a year or so. Less with some scrap or ebay the old one.

Best wishes
Glen Previously......
Series 1 80, Series 3 88, Turbo 90, 300tdi 90, 110's with 200, 300, TD5
TD5 Disco, Disco 3, 200Tdi Disco - probably the best vehicle Landrover ever made,
Now 3x FFRR, some would say I should have learned by now......

If you replace ether of the batteries do you have to "code" the car in the same way that you would have to say on a BMW .

There is a BMS reset when either of the batteries are replaced, which I'm sure Craig knows about

I was thinking of changing both batteries as a precaution , is there a way of re setting the BMS without going to a main oil changer as its 6 weeks wait and even then its impossible to talk to a engineer -- just a receptionist who makes a note on a PC LOL