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Start-Stop Batteries - AGM? EFB? WTF?


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So New Yaris has one of these new-fangled start-stop engines that turn off when you are stopped. At least it is supposed to; So far it's very rarely done it!

I suspect the Battery hasn't been changed in a while, and I'm aware that petrol engines tend to work their batteries harder so they don't last as long as on diesels so I've been researching replacing it.

What a mine field!

Now, apparently it comes with an EFB Battery, but I was going to 'upgrade' it to an AGM Battery on account of them just being 'better' and thus hopefully working better with the start-stop system.

However, the salesperson insisted that I couldn't use an AGM Battery and could only use an EFB, but was reluctant to explain why. Eventually he came up with this shocker that EFB and AGM batteries need to be coded to the car when installed and a car with an EFB can't be coded to take an AGM Battery - Is this really a thing or was he just BS'ing me?! :eek:

I've never heard of a car Battery needing to be coded to the car when installed - I thought it was just unscrew the terminals and bracket, remove old Battery, put in new one, screw everything back on, done!

But apparently on modern cars you need to somehow enter a Battery code to reset... *something*.

Is this really a thing?! Can I actually not change my Battery without going to a garage or buying some sort of Battery code ECU entery thing?! :eek:
 

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The stop/start system has certain parameters within which it will operate. Cold temperatures, electrical loading of the car's system, and Battery charge may prevent the system operating.

Toyota dropped the stop/start system from the third generation Yaris due to cost reasons.

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My CTEK charger has a setting for charging AGM batteries, so I assume something such as charging voltage is different to that for a normal lead acid.  That being the case, it would suggest to me that somehow you would need to tell the car when a new battery's been fitted, though this shouldn't be needed if the new Battery were the same as the old one.

You would think with all the technology they insist on loading into cars nowadays, that they'd give it the intelligence to work out what's what of the new Battery for itself!

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7 hours ago, Notoyboy said:

My CTEK charger has a setting for charging AGM batteries, so I assume something such as charging voltage is different to that for a normal lead acid.  That being the case, it would suggest to me that somehow you would need to tell the car when a new battery's been fitted, though this shouldn't be needed if the new battery were the same as the old one.

You would think with all the technology they insist on loading into cars nowadays, that they'd give it the intelligence to work out what's what of the new battery for itself!

That sounds like a more likely explanation. Shame the salesperson wouldn't divulge this information, or if they weren't sure, at least offer to find out. It would help an owner make an informed choice on what to buy.

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The fixed price repair cost of a new Battery from Toyota is £100 - https://www.toyota.co.uk/owners/service-mot-maintenance/repairs.json

Is the Battery covered under whatever warranty you had when you bought the car? If so, may be as well to ask the dealer to test it.

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Batteries on stop start vehicles are different for ALL manufacturers, and always more expensive, as mentioned above, the Toyota fixed price is £100

Kingo :thumbsup:

 

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Thanks for the replies guys - After getting over my incredulation at such a stupid idea (Coded batteries!?) and doing yet more research, it turns out this is actually a real thing!

Apparently with mostly German cars that use EFB/AGM batteries, they DO need to be coded in when they are replaced otherwise the car runs in a more conservative mode (Whatever the heck that means!). Apparently there is a QR code on new batteries that needs to be scanned or manually entered in to the ECU to tell the car things like charging profile and such and to reset the infotainment and start-stop etc. systems to work in a 'full' mode.

(This is kinda dumb since the charging electronics should be able to figure this out itself - We've had that kind of tech in our server UPS's for decades!!)

HOWEVER, on the plus side, it seems this is not applicable to Toyota cars; I assume the ECU senses Battery state and acts accordingly like it should. Thank smeg for that.

So, theoretically at least, I should just be able to stick in an AGM Battery instead of the stock EFB and it should Just Work.

That all said, I will hold fire for now - My friend has pointed out that I would have to be a special kind of idiot to replace an otherwise working Battery just to make the start-stop work more, since at best I'd save maybe £20 of fuel vs. paying £100+ for the Battery! This is actually a good point... :blush:  (When the time comes tho', I will let you all know if it dies within a week or blows the car up or something :biggrin:)

 

re. warranty, the Battery *works*, so I doubt I'd get anywhere just whinging to the dealer that the start-stop doesn't work all the time. From posts I've read here in the past, even Mr T considers this irregular behaviour 'normal', and 'subject to conditions' (Presumably all the conditions Frosty keeps mentioning! :laugh:).

re. the CTEK charger, AGM batteries operate basically the same as normal flooded cell batteries - There is a slight difference in preferred charging voltage but it's like 0.3v difference IIRC; The only real difference is they don't like being held at constant trickle/float voltages to keep them topped up - It makes them vent over time and tends to shorten their lives prematurely. They much prefer cyclic charging as it gives the hydrogen/oxygen a chance to recombine so they don't have to vent. Flooded batteries are always using up a little electrolyte when they are charging - I assume with EFB's they just stick in more electrolyte so they last longer!


 

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We had a Fiat500 before we had this Yaris Hybrid.  The F500 had SS but when we bought it secondhand at less than three years old, the SS wasn't very good at all.

I did some research and joined the Fiat Forum for advice.  The only thing to do, was to buy a new Battery and keep it fully charged permanently.

I bought the Battery @ £100 or so, and also bought a Battery charger with connections and a long lead so I could pop the bonnet every time we came home and connect up and leave it connected until we wanted to drive again.

We had that car four years eventually, and the new Battery worked faultlessly.  The main issue with the original Battery, was that the car is built and then left on a forecourt waiting for its first owner, but meanwhile the Battery is ignored and neglected.  I doubt the original owner when the car was new had the SS working perfectly.  By the time I fitted the new Battery and kept it maintained, it was PERFECT and worked perfectly for SS.  By the time the car was warm, it would remain stopped for the full three minutes every single time.

The old (original) Battery bench-tested fine with no issues whatsoever, but was rubbish as a SS Battery.  I took it to local garages and they tested it, and reported no issues and said it was a good Battery.  It eventually went into our elderly Clio and was brilliant as a "NORMAL" Battery.

SS cars have an uprated alternator and a bigger more efficient starter motor, let alone a bigger capacity and hugely expensive Battery.

Read this:  https://www.fiatforum.com/500/416006-stop-start-story.html?416006=#post3998414            20odd pages! 

Mick.

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I've had two Auris 1.33's from new - both with stop/start. Not had an issue with either of them over the 6 years 10 months of ownership.

Given the operational parameters, the stop/start performed as expected. Both around Birmingham and on long journeys - for example our annual 520 mile run up to the Isle of Skye at up to 48mpg fully loaded  and not driven with an eye on economy - they proved more economical than the previous Corolla 1.4. The stop/start was a boon in traffic - stopping and restarting smoothly - especially on my 6.5 mile commute each way into work, which depending on traffic density, took anything from 30 minutes to over 1 hour.

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The stop/start on my Auris seems to operate ever more infrequently these last couple of years. The original Battery is still 'fine' under all normal usage and test conditions. I have read on some of the big name Battery sites that fitting a conventional Battery can give a much reduced life, one manufacturer from memory quotes around 2 to 4 months !

In years past I drove vehicles that were used for field service work and we would do 16 calls or so a day in a very small area. That and other stops meant the starter was always operating and believe me, cars back then didn't start as instantly as a modern engine. I reckon the 1.33L starts when hot (the stop/start mode) in under 500ms. An old Ford or Vauxhall would be 4 to 5 times as long but we never had Battery issues  back then. The 1.1L Escorts we had were fitted with 28A Lucas alternators. No one ever had a flat Battery due to excess starting each day.

I know the above scenario is slightly different to stop/start cutting in several times in half a mile or whatever but I often don't see my stop/start cut in even after a 20 mile run. I never do short runs as a rule. Even from day one with the car and it didn't always operate when I would have thought it should. 

I had wondered what the small 'sensor' was on the Battery... it is something called IBS or intelligent Battery sensing. 

This is quite informative if you read down. A pity the pictures aren't a bit clearer though. 

Battery Management with IBS

  

    

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Well as Frosty says it depends on a lot of parameters - The Start-Stop system seems to be a very Goldlocks system, as we'd say. If the engine is too hot or too cold it won't work, it has to be just right! If the Oil is too hot or too cold it won't work, it has to be just right!

The only reason normal starter Battery shouldn't be used is they use very thin lead plates to give maximum surface area, and so a lot of cranking amps. Unfortunately, this means the Battery has to be kept as fully charged as possible. As soon as the charge drops the lead plates start dissolving - This is why a normal lead acid Battery drained past 50% loses a lot of capacity, and one drained to 0% is often virtually dead.

TBH, the fact that we're still using lead-acid is really stupid on modern cars - I don't understand why nobody is using lithium ion with a bank of super-capacitors by now!

The lithium Battery could easily hold 3 times the charge (Or take up a third of the space!) and be a lot lighter - On its own it would explode if you tried to crank a car engine, but if you add a capacitor bank that the lithium Battery keeps charged when the car is off, it could start any engine a lot easier than any lead acid!
 

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I agree totally.  Lead acid is silly in this day and age. So is 12v.  Years ago, some cars were even 6v!!

Why 12v?  Why not 24v or 48v?  Higher voltage means less current.  Less current means thinner and lighter conductors.

Why not AC?  Perhaps have a DC system for the starter, but AC for everything else?

Mick.

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4 minutes ago, Mick F said:

Why 12v?  Why not 24v or 48v?  Higher voltage means less current.  Less current means thinner and lighter conductors.

Bosch are selling a 48V system with mild hybrid characteristics - will be seen more and more in the latest cars.

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  • 3 years later...

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