If you are replacing an AGM battery with another AGM battery then you don't need to do anything, except install it properly. If you are putting an AGM battery in for the first time then it is advisable but not absolutely necessary to do a reset. You can do this reset using an IID tool or get a garage with the right tool to do it for you. Obviously they will charge you. No pun intended

I had ats put a new 110ah in this spring - think it was about £100 - plus bonus of not needing to wrestle it into place myself...

Landphil wrote:

If you are replacing an AGM battery with another AGM battery then you don't need to do anything, except install it properly. If you are putting an AGM battery in for the first time then it is advisable but not absolutely necessary to do a reset. You can do this reset using an IID tool or get a garage with the right tool to do it for you. Obviously they will charge you. No pun intended

That's shocking news

So I assume that the reset is to preset the charging voltage.. as an AGM battery needs a slightly higher voltage to function properly, 14.5v min from memory, where the standard batteries charge at 14.1v max .. either way if you fit the wrong type it could potentially end in tears or a lot of

Another vote for the IID tool then... they really don't take long to pay for themselves  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

Mine is typically 14.7 or 14.8
I have seen 15 during winter.

A lead acid battery will not like those voltages for long.....

Sticking a lead acid battery into a system specc'ed for AGM is going to be "sub optimal" and/ or will lead to premature battery failure.

I just squeezed a Varta H15 into mine. Why would a reset be necessary? If the car doesn't know about AGM batteries natively (which it won't I guess for a 2007 model), what will it do differently?

BTW to those fitting one: It only just fits in the tray, and unlike the old one that came out slightly diagonally you need to get on top of the recess and drop it straight down. I found some old thick carpet underlay on the area in front of the suspension strut helped me rest my leg there.

Unsolicited

Nice photo !

IMHO you are correct. If your OEM equipment was lead acid, then no reset necessary, and enjoy the 110ah power.
If your OEM was AGM and the more complex charging arrangements, I personally would not install lead / acid but would still with AGM.
I think the switch was 2010.

That Varta H15 AGM battery in the link is 105ah.

I have 03 V8 model, is the 105ah AGM going to give me better performance than the 110ah lead acid battery? I think I may be in need of a new one as if I haven't driven it for a few days I sometimes get the "trans fail safe" message if I turn on all the heated seat, heated steering wheel, heated screens etc before I drive off. 2004 RR 4.4 V8 Autobiography

DIDLEY

I am putting in the H15 Farta AGM 105AH
as shown in Miggit link from pure drive.
At the same time I intend to increase my FBH
cycle time to 25mins.
THIS is why the 105 is better than the 95.
Hopefully it will fit.
As it is the same dimension as the lead acid 020 it should.

PaulM wrote:

That Varta H15 AGM battery in the link is 105ah.

I have 03 V8 model, is the 105ah AGM going to give me better performance than the 110ah lead acid battery? I think I may be in need of a new one as if I haven't driven it for a few days I sometimes get the "trans fail safe" message if I turn on all the heated seat, heated steering wheel, heated screens etc before I drive off.

I'm not too sure how well the battery will respond to being charged at 14 volts... the later cars charge the battery at nearly 15 volts, personally I would stay with the lead acid battery, and if your looking for larger capacity then get an 020, which is a 110 Ah battery. Plus there is the added bonus that the lead acid batteries come with up to a 5 year warranty, the AGM batteries only carry a 3 year warranty, and there is a noticeable price difference between the 2 types of battery

FYI before my DSP amp fubar'd the battery it would sit for best part of a fortnight and start without any issues, if the truth is really known it sat for 3 weeks in the summer and still started, all be it with the screen of doom telling me everything had pact up, HDC,EAS etc.... but it did start, and was normal after a lock top lock turn of the steering wheel and a blast up the road  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

AGM batteries can take a higher charge voltage and so charge up quicker HOWEVER AGM's batteries (or any VRLA Gel type) should not be float charged above 13.8V as they can be damaged.
The standard nominal charge voltage of 14.4V for a flooded cell lead acid equipped L322 could damage an AGM battery on a long run where the battery becomes fully charged.
That is the main reason why the ECU needs updating, the charging criteria would be altered (higher voltage allowed while bulk charging, limited voltage on float charging).
Likewise a conventional flooded cell lead acid battery shouldn't be charged over 14.7V (L322 is limited to around 14.4V for conventional) so again if swapping from an AGM battery to conventional flooded cell then the charging regime would need to be altered as the higher bulk charge voltage allowed for AGM can damage it (gassing and plate damage).

AGM batteries are superior to conventional flooded cell lead acid types, they can be charged up faster, cycled a lot more, can be deeper discharged without reducing their lifespan (up to 80% discharge without damage compared to 50% for flooded cell) so that is the reason why they are specified for Start/Stop equipped vehicles.
If you don't have Start/Stop you don't necessarily need an AGM battery and personally I wouldn't fit one without altering the ECU control of the charging.

When I changed my battery I put on a conventional 020 sized 110Ah battery about 3-4 years ago. It has been fine since on '02 4.4 which may sit for 3-4 weeks without use and gently reminds me after that time it needs charging with the 'HDC inactive' warning. It then gets fully charged up with a battery charger if I've not already done it.

If you want any lead acid battery to last it needs to be keep as full as possible, discharging deeply and cycling ages the battery. So if you are doing lots of short trips or the vehicle is not used very often invest in a decent charger and top the battery up fully now and again. Charging a low battery from the alternator is no where near as kind and takes a lot longer than you would think.

I'll try and do another post about batteries as there seems to be a lot of confusion about them.
Interesting fact: Every 8C rise above room temperature halves a lead acid batteries working life (not nice when the air-con fails in a UPS room in the height of summer (50C+) and 100+ batteries get cooked and you get the job of ripping them out ).

In practice for the AGM L322s, the normal voltage you will see is around 14.7 or 14.8v. Occasionally 15v.
Very rarely on a long run I have seen it drop to 13.7v.
But having a fully charged AGM battery is a bit of a rarity.
Or more accurately having your vehicle think the battery is fully charged is rare....

I had an OE spec VARTA battery fitted 2 years ago (£150 I think) to replace a genuine LR battery which was on its way out. It was never quite right afterwards, more sluggish to start and touch and go in really cold weather - also numerous spurious fault codes for suspension etc. Mentioned it to my Indy a few times and they checked it and it passed the test many times to my irritation.

In the cold snap a few weeks ago it actually didn't start one morning and I took it back and demanded a replacement. They fitted a genuine LR battery under warranty and its back to perfect again. Starts on the button and no spurious beeps. Lesson learnt for me.

They said the LR battery was £176.

Cheers, Jon.

Well after reading threw the posts I am still holding out purchasing a new battery just yet.(its been behaving) I placed a ctek charger on and all has been well since. However if left for a couple of weeks and then install the ctek the unit shows only 3 lights out of 7 lite up. I see the inevitable is going to happen right when I don't want it too.

AGM batteries only carry a three year warranty, and looking at the age of your car, you is on borrowed time Pal Baring in mind that no manufacturer is going to give a warranty that it can't achieve easily i.e if Varta give a 3 year warranty on the AGM battery then they will have tested them to at least 4.5 years... a rough rule of thumb is they expect the item to go an extra 50% of the warranty period, that way they are only liable for real duds  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

Diddley wrote:

Well after reading threw the posts I am still holding out purchasing a new battery just yet.(its been behaving) I placed a ctek charger on and all has been well since. However if left for a couple of weeks and then install the ctek the unit shows only 3 lights out of 7 lite up. I see the inevitable is going to happen right when I don't want it too.