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[TheBoy]

Quickie question...

Can I use a non AGM battery in a car that was factory supplied with an AGM one?

[Raeturbo]

Can I replace a lead acid battery with an AGM battery?
Yes for the most part an AGM is a drop in replacement for your standard Lead Acid Battery. The charging voltages are almost identical. You are correct that they have a lower internal resistance and can be charged at a much faster rate.12 Jan 2015

[Raeturbo]

Yes for the most part an AGM is a drop in replacement for your standard Lead Acid Battery. The charging voltages are almost identical. You are correct that they have a lower internal resistance and can be charged at a much faster rate. This shouldn't cause a problem on the majority of vehicles as the wiring in the car is designed to handle the maximum rated output of the alternator.

[TheBoy]

Wrong way round Rae, can I drop in a non AGM batt into a car designed to tale an AGM?

[STEMO]

Wrong way round Rae, can I drop in a non AGM batt into a car designed to tale an AGM?

https://youtu.be/zGKk2SzYIig

[Raeturbo]

👍

[Andy H]

Stop-start gives the battery a work out - potentially causing a reduction in battery life

I thought that AGM batteries were developed in an attempt to try to make the battery last a bit longer.

My guess is that you won't notice any difference if you can manage to avoid using the stop-start. What we need is someone to drop a standard battery in and report back on longevity - can you think of anyone curious enough to try ? 

[johnnydog]

https://www.yuasa.co.uk/info/technical/start-stop-vehicle-battery-replacement-warning/

My AGM battery on my Audi failed under warranty, and was replaced by Audi, but the replacement AGM had to be programmed to the car. Certain electrical components won't function correctly without the programming. I understand that AGM and EFB batteries should be replaced with like for like. No doubt owners have gone against this recommendation, but that is the advice. The link above gives some insight into the reasoning behind it.

[Kevin Wood]

You might find it does some "mild hybrid" deeper cycling of the battery than is normal for a wet cell battery. That might involve charging it more aggressively than would be normal for a wet battery. Only one way to find out, though. The world isn't going to end, at any rate.

[TheBoy]

Stop-start gives the battery a work out - potentially causing a reduction in battery life

That piece of shit will be disabled whatever

[TheBoy]

You might find it does some "mild hybrid" deeper cycling of the battery than is normal for a wet cell battery. That might involve charging it more aggressively than would be normal for a wet battery. Only one way to find out, though. The world isn't going to end, at any rate.

Her battery sounds like its struggling, and I have a reasonable battery from my XJ in the garage, so its a no cost option to do something until batteries become more sensibly priced...   ...or I have to bite the bullet and splash down the wrong side of £150 for an AGM one

[Migv6 le Frog Fan]

well,if you buy one of these modern contraptions........

[Kevin Wood]

Stop-start gives the battery a work out - potentially causing a reduction in battery life

That piece of shit will be disabled whatever

It's particularly dumb on the XE. Always stops the engine just as I'm about to pull away.

Do you know if it can be permanently disabled? I'd be up for that.

You might find it does some "mild hybrid" deeper cycling of the battery than is normal for a wet cell battery. That might involve charging it more aggressively than would be normal for a wet battery. Only one way to find out, though. The world isn't going to end, at any rate.

Her battery sounds like its struggling, and I have a reasonable battery from my XJ in the garage, so its a no cost option to do something until batteries become more sensibly priced...   ...or I have to bite the bullet and splash down the wrong side of £150 for an AGM one

I can't imagine it'll do any harm, as long as it doesn't vent in the spare wheel well, of course.

The one thing you don't want in an XE is an unreliable battery, as it does a bloody good job of immobilising itself when it goes flat.

[Sir Tigger KC]

If stop/start cars with AGM batteries have beefier alternators, is there not a danger that a normal battery would get 'over cooked' by the alternator and go bang?   

[Andy H]

If stop/start cars with AGM batteries have beefier alternators, is there not a danger that a normal battery would get 'over cooked' by the alternator and go bang?   

the chemistry is still the same so the target voltage should be the same (14.7v?)

The impedance in the battery will probably limit the maximum current rather than the alternator.

[TheBoy]

Do you know if it can be permanently disabled? I'd be up for that.

I've been told how to do it, I forgot to do hers when I had the trim off (as her stop-start has never switched the car off, probably due to shagged battery), but reckon its doable without removing trim.

I'll email you a pic

[Marks DTM Calib]

There is a certain connector by the battery you unplug to disable stop start.

As for a non AGM battery, these work as a very mild hybrid so have a very high amps alternator and do not take the battery above 90% state of charge normally, it then boosts the battery voltage under braking and backs off the charge rate when cruising (and uses some battery reserve). Hence the need for AGM.

Have you given it a good charge and updated the PCM and BCM software?

[Kevin Wood]

Thanks both. I'd seen that mod but held back because I wondered what else would be affected by disconnecting the VCM. I'll give it a go.

[TheBoy]

Have you given it a good charge and updated the PCM and BCM software?

No, no and no. In that order

With 100A load, it drops to under 10v, but holds steady.

[Marks DTM Calib]

Have you given it a good charge and updated the PCM and BCM software?

No, no and no. In that order

With 100A load, it drops to under 10v, but holds steady.

So its either down a cell or all cells are at a low SOC so needs a bloody good charge

[TheBoy]

I'll go and put some electricity in it now.  But not holding out much hope.

Reason for asking about non AGM is I have the old XJ battery still, that comes out as OK on the 100A load, and was only changed because the XJ is particularly fussy and throws weird errors with non perfect batteries.