Something seems a little odd to me when it comes to the 12v battery on the IS300H or most Lexus hybrids due to there being no "starter motor" why would battery suppliers insist it needs a stop start battery it only powers the electrics and signals the Traction battery system to work . 

Surely you can just fit a AGM battery that is suitable for non Stop Start or am I missing something ?

 

It’s because the batteries suppliers don’t know what they are talking about. 

As long as its AGM, fits and has the correct polarity arrangement on the terminals, it should work. 

Battery makers call these auxiliary or secondary, the main difference is their typically lower capacity, eg 45Ah, lower cranking performance. But not different in construction as far as I’m aware.

33 minutes ago, DBIZO said:

But not different in construction as far as I’m aware.

Stop/Start batteries may have different quantities and construction of the plates inside the battery which makes them more expensive - this is unnecessary for a Lexus aux battery. A standard AGM battery is fine.

6 hours ago, ColinBarber said:

Stop/Start batteries may have different quantities and construction of the plates inside the battery which makes them more expensive - this is unnecessary for a Lexus aux battery. A standard AGM battery is fine.

Are these different qualities and construction not because they're EFB or AGM batteries though? OP is specifically asking about AGM replacements as opposed to a typical Lead-Acid 12V so I'm not entirely sure those differences are applicable in this scenario

I'm lead to believe AGM itself is well suited to S/S as it is, thus it doesn't seem particularly likely that a S/S AGM will have much in the way of differences beyond capacity and perhaps amp output as most, if not all, of the more complicated lark is likely handled by a BMS within the car.

5 hours ago, TheMcSame said:

Are these different qualities and construction not because they're EFB or AGM batteries though? OP is specifically asking about AGM replacements as opposed to a typical Lead-Acid 12V so I'm not entirely sure those differences are applicable in this scenario

I'm lead to believe AGM itself is well suited to S/S as it is, thus it doesn't seem particularly likely that a S/S AGM will have much in the way of differences beyond capacity and perhaps amp output as most, if not all, of the more complicated lark is likely handled by a BMS within the car.

 

My issue is the hype around the battery from manufacturers and Lexus insisting on nearly £250 for a battery for the IS300h a standard JIS battery uses generally a JIS pencil pole found on Nissan,Honda etc the very thin JIS type.

These are on the IS300h battery with a 45ah output I have searched around and you can buy a much bigger ampage for less than £100 with these type of terminals which are not Stop/Start and seeing as the IS300h is not Stop/Start I feel a standard high output AGM battery equivalent will work . 

Also if you cannot find a pencil pole type you can buy a bigger pole type and fit conversion kits as below

SAE to JIS Pencil Post Automotive Brass Battery Terminal Conversion Pair | eBay UK

I cannot see the issue with this do you agree ?

16 hours ago, TheMcSame said:

Are these different qualities and construction not because they're EFB or AGM batteries though?

No, AGM batteries are not all the same. You get ones specifically for Stop/Start.

 

10 hours ago, Rod300h said:

I cannot see the issue with this do you agree ?

There is no issue not using a S/S battery. Ideally AGM but EFB would probably do too (it is what Lexus are now using on all their new models).

11 hours ago, Rod300h said:

My issue is the hype around the battery from manufacturers and Lexus insisting on nearly £250 for a battery for the IS300h a standard JIS battery uses generally a JIS pencil pole found on Nissan,Honda etc the very thin JIS type.

12v OEM battery is £185 from Lexus Parts Direct

Is this a joke? or have they priced it wrong?

 

Im gonna need someone's kidney to buy it!!

why so expensive... i would expect a price range of £180-230.... NOT £528!!!

🫣

2 hours ago, agent_dess said:

Is this a joke? or have they priced it wrong?

 

Im gonna need someone's kidney to buy it!!

why so expensive... i would expect a price range of £180-230.... NOT £528!!!

🫣

Not sure if that is a Japanese sourced original battery - or some weird pricing when you couldn't get one a couple of years ago, but they have an alternative:

https://lexuspartsdirect.co.uk/product/lexus-is-phase-3-auxiliary-12v-starter-battery/

 

11 hours ago, ColinBarber said:

Not sure if that is a Japanese sourced original battery - or some weird pricing when you couldn't get one a couple of years ago, but they have an alternative:

https://lexuspartsdirect.co.uk/product/lexus-is-phase-3-auxiliary-12v-starter-battery/

 

Every time i search i only get the £528 option but if i search using the terms:
"Lexus IS Phase 3 Auxiliary 12V Starter Battery"

Then i get 2 hits:


£185
https://lexuspartsdirect.co.uk/product/lexus-is-phase-3-auxiliary-12v-starter-battery/

£528
https://lexuspartsdirect.co.uk/product/lexus-is-phase-3-auxiliary-12v-starter-battery-2/

The reason for bringing this up is that i had my 100k/10 year service yesterday.... Bloody expensive that was! 😬

For the hybrid check while they passed it they noted:
Auxiliary Battery Charging:
We detected a drop in performance of the conventional 12v battery.  Please consult service provider.

They didn't actually advise on any replacement but given the car is 10 next month, im not sure if the previous owner ever replaced it, i do know its a Toyota branded battery so does look original.  

So maybe time to source a new battery over the next 6 months.

2 hours ago, agent_dess said:

So maybe time to source a new battery over the next 6 months.

Yeah, get one in the autumn once it start to turn cold again - you should be fine over the summer when there is less strain on the battery.

The wild lives some people lead...batteries that never been changed after 7-8-9 years...I wonder what else you're up to...

Mine is turning 4 this summer, reading 12.2-3 in accessory mode, and I'll get it replaced by the winter, let me tell you!

I need my beauty sleep.

Just now, DBIZO said:

The wild lives some people lead...batteries that never been changed after 7-8-9 years...I wonder what else you're up to...

Mine is turning 4 this summer, reading 12.2-3 in accessory mode, and I'll get it replaced by the winter, let me tell you!

I need my beauty sleep.

My 12V battery is original fitment on my IS 300h - car is now 10.5 years old and has done 162k miles. No issue with the 12V battery and recently left for around 10 days and started just fine. If they've been looked after (so not discharged) I think the original 12V batteries in the IS 300h are very durable. 

1 hour ago, wharfhouse said:

My 12V battery is original fitment on my IS 300h - car is now 10.5 years old and has done 162k miles. No issue with the 12V battery and recently left for around 10 days and started just fine. If they've been looked after (so not discharged) I think the original 12V batteries in the IS 300h are very durable. 

That's some hardy specimen.

I'd be much more comfortable extending the service life of a 12V if there was clear public guidance what is the amount of discharge rate and capacity required by the hybrid system to start up. The commercial practice for useful life definition is 80% of design capacity. My 4-year old battery is already around this level of wear, which is normal from VRLAs, AGM or not. 

That appears to be enough for extended periods (weeks) of parking.

Would it be able to operate the car for years to come? Likely yes. I suspect even say 40% capacity is plenty.

Is it worth the gradually creeping risk of no-start after a couple of weeks of parking in the cold, given the relatively modest cost of getting it replaced?

Not for me.

 

4 minutes ago, DBIZO said:

That's some hardy specimen.

I'd be much more comfortable extending the service life of a 12V if there was clear public guidance what is the amount of discharge rate and capacity required by the hybrid system to start up. The commercial practice for useful life definition is 80% of design capacity. My 4-year old battery is already around this level of wear, which is normal from VRLAs, AGM or not. 

That appears to be enough for extended periods (weeks) of parking.

Would it be able to operate the car for years to come? Likely yes. I suspect even say 40% capacity is plenty.

Is it worth the gradually creeping risk of no-start after a couple of weeks of parking in the cold, given the relatively modest cost of getting it replaced?

Not for me.

 

I think it's always wise to carry one of the lithium power packs to start the car just in case - given that I have one of those, then I don't have any concerns - when the 12V battery finally fails I'll get a new one fitted but should be able to get the car going again with the power pack in the meantime.