To my mind (electrician and electronics technician, studying to be an engineer) I really think you are going head first down the rabbit hole... 12.2v static on a car battery these days is fine, especially if it had some current draw since last charging/driving as you have described your testing.

 

On a side note, I use the stop/start with the ac on and it does the stop/start as normal.

Only time it doesn't act as per normal is when I have the stereo pumping, which I would fully expect with my set-up.

On 01/06/2021 at 18:32, Kenny R said:

Stop/ start system batteries are normally only charged to approximately 80% by the system to allow for some capacity from the regenerative braking.

@Kenny R I read this with genuine interest. Does my Superb (150 TDI) with Stop/Start have regenerative braking then? I’d always thought that this needed at least a “mild hybrid” to allow the motor to become a generator under braking. Or is my starter motor also a generator under braking conditions?

Deleted double post. 

Edited 3 June, 20215 yr by Ivan8192
Edited due to double post.

3 minutes ago, Ivan8192 said:

@Kenny R I read this with genuine interest. Does my Superb (150 TDI) with Stop/Start have regenerative braking then? I’d always thought that this needed at least a “mild hybrid” to allow the motor to become a generator under braking. Or is my starter motor also a generator under braking conditions?

The micro hybrid 2 section is relevant in this link…

https://www.yuasa.co.uk/info/technical/micro-hybrid-hybrid-vehicles-explained/

1 hour ago, Kenny R said:

The micro hybrid 2 section is relevant in this link…

https://www.yuasa.co.uk/info/technical/micro-hybrid-hybrid-vehicles-explained/

@Kenny R Great info - so the alternator is shut down to take load off the engine, improving fuel consumption, once there is “enough” battery charge? And then when braking, the alternator is started up again to provide additional load, which will contribute to the engine braking effect slowing the car?

Sounds like you've grasped it. 

 

 

 

I think it's a bit of a stretch to refer to that as regenerative braking, but fair enough, I get the concept 😏, every little helps

I just tested with bonnet open and then closed and there is no difference. Both give a reading of 12.43v after the car hasn’t been running for nearly a week. It made me question the reading on Tuesday (12.3v) so I tried another multimeter and it gave 12.44v so well within tolerances.

It’s not a permanent drain given the reading today so I either didn’t lock the car or didn’t give it a full 30min on Tuesday. Anyway, it seems much better than the ~12.2v I was getting prior to the full recharge and battery reset. Thanks for all the info and I will keep an eye on it.

5 minutes ago, Alan_P said:

I just tested with bonnet open and then closed and there is no difference. Both give a reading of 12.43v after the car hasn’t been running for nearly a week. It made me question the reading on Tuesday (12.3v) so I tried another multimeter and it gave 12.44v so well within tolerances.

It’s not a permanent drain given the reading today so I either didn’t lock the car or didn’t give it a full 30min on Tuesday. Anyway, it seems much better than the ~12.2v I was getting prior to the full recharge and battery reset. Thanks for all the info and I will keep an eye on it.

 

good luck alan, i will do the same with mine till i get a service in 4 months and i will ask skoda to check system.

Just for comparison, i have a passat with a Varta AGM battery 680A EN rating. 4 years and 4 months.

 

i have a bluetooth battery monitor fitted and i can check battery voltage via my phone. When the car goes to sleep i usually get a resting voltage between 12.5 - 12.6v. Mostly around the 12.55-12.6.

 

i have a Topdon conductance tester. The results vary with temperature. With the warmer days i get a reading of 520 A ( rated 680A) and 60% SOH and a message “ good battery”. During last winter with cooler temps i’d get a reading of 430 ish A with a SOH 40-45% and a message “ replace battery”

 

i find the battery is an unusual beast. When temps are low say 0 degrees it can sound sluggish starting the car with a few errors like “ start stop error” on the dash with a fault code “ insufficient voltage” type code. Also the start stop might not work intermittently ( but mostly works)with the message “ power consumption high”.

 

However when temps are above 3 degrees battery works flawlessly. Start stop works all the time and i could leave lights on for ages it will still start, weird battery!

Edited 6 June, 20214 yr by Micky 32

1 hour ago, Micky 32 said:

Just for comparison, i have a passat with a Varta AGM battery 680A EN rating. 4 years and 4 months.

 

i have a bluetooth battery monitor fitted and i can check battery voltage via my phone. When the car goes to sleep i usually get a resting voltage between 12.5 - 12.6v. Mostly around the 12.55-12.6.

 

i have a Topdon conductance tester. The results vary with temperature. With the warmer days i get a reading of 520 A ( rated 680A) and 60% SOH and a message “ good battery”. During last winter with cooler temps i’d get a reading of 430 ish A with a SOH 40-45% and a message “ replace battery”

 

i find the battery is an unusual beast. When temps are low say 0 degrees it can sound sluggish starting the car with a few errors like “ start stop error” on the dash with a fault code “ insufficient voltage” type code. Also the start stop might not work intermittently ( but mostly works)with the message “ power consumption high”.

 

However when temps are above 3 degrees battery works flawlessly. Start stop works all the time and i could leave lights on for ages it will still start, weird battery!

 

That’s strange, almost the reverse of my situation with lower voltage but good cranking amps. To be fair, I never get the slightest hesitation at turnover even in cold weather or any errors. I also never use start-stop though.

An AGM should perform better than a standard battery in cold weather so it might be a good candidate for a charger than has a desulphation cycle or at least a recondition mode.

I resurrected an old Clarke 900 jump starter with a Ctek MXS 5.0 about 6 months ago that was refusing a charge from another smart charger and the simple Clarke charger. IIRC the Ctek was in the initial desulphation cycle for about an hour before going on to fully charge it.

6 hours ago, Alan_P said:

 

That’s strange, almost the reverse of my situation with lower voltage but good cranking amps. To be fair, I never get the slightest hesitation at turnover even in cold weather or any errors. I also never use start-stop though.

An AGM should perform better than a standard battery in cold weather so it might be a good candidate for a charger than has a desulphation cycle or at least a recondition mode.

I resurrected an old Clarke 900 jump starter with a Ctek MXS 5.0 about 6 months ago that was refusing a charge from another smart charger and the simple Clarke charger. IIRC the Ctek was in the initial desulphation cycle for about an hour before going on to fully charge it.

 

This morning ( car hasn’t been touched since 11pm last night) is reading 12.66v ( outside temp 13 degrees). Doors locked in sleep mode. My Bluetooth monitor often records low cranking voltage. . Sometimes drops below 9v first start of the morning. The lowest i have seen is 7.20v. It made the starter actually pause before starting and putting up a start stop error on the dash. It was approx -1 degrees at the time. I had just driven the car 10 miles and stopped briefly at a shop. However my fans were running due to a regen but it was no longer than a few mins. My battery was charging fully for the 10 miles. My Bluetooth monitor records graphs. My battery just hates the cold.
 

You could try  lifting  the bonnet and then lock the car. Wait 20 mins and take a reading from the battery. It will give a fairly accurate open circuit reading.
 

Sometimes my starter will sound like it hesitates for a split second when first activated in the morningbut then can ramp up normally.

Edited 6 June, 20214 yr by Micky 32

Do you know what level of battery drain your Bluetooth thing causes? Does it come with any such info? It may well be negligible, but as a plug-in thing that's presumably permanently powered it's worth knowing.

Or is it self-powered with its own battery?

Edited 6 June, 20214 yr by Wino

I'd not bother using a "recon" or desulphate charging program on an AGM battery, that stuff is intended for wet/liquid batteries, the trouble seems to be that many CTEK chargers have a "normal" and an "AGM" program, when you read their bumf, the "normal" is to be used with wet including EFB and normal AGM, the AGM program is for specialised AGM batteries only.  It has taken me a while to wise up to that I must confess.

Colder weather will always result in lower battery health as they are just mini chemical factories, so carrying out battery testing at -10C will always give you poor results when compared with testing at 25C - both temperatures given being battery as well as ambient temperature.

Using a smart charger in recod program, CTEK for example on an older poorly EFB does seem to liven them up quite a bit, I do that once a year with the EFB in my wife's 2015 Polo and it is still claiming to be in very good condition when tested using my CTEK battery tester - though I only tend to test it at its annual service time in late July/early August. I tend to stick with recharging with a CTEK charger on recon program over night, remove the charger at 08:00ish, and carry out a test after 8 hours has passed.

 

Edit:- for anyone who is curious or concerned about what is actually happening battery charge wise while driving, maybe consider visiting ebay and buying a cheap (£5) plug-in DVM, regardless of its overall accuracy, it will give you an idea of what the charging level is and when the charging IS and IS NOT happening - these DVMs are have a "ciggy lighter" plug built into them, so easy to live with.

Edited 6 June, 20214 yr by rum4mo