BATTERY VOLTAGES

[Polly]

[Okay It used to be my old job as an Aircraft Electrician and battery charging room op decades ago!!]

Can a current expert advise me on my new std 70 ah EFB battery in my Cupra R.
As it is not being used with lockdown

Resting voltage as now.
Minimum before I need to recharge? If relevant
Just off battery charger Voltage. If relevant.
Car charging voltage [14. something]

 

[RUM4MO]

I'd cut to the chase and buy and use a smart charger as letting that battery drop down in charge level - more than normal, will be sulphating it and reducing its effective stats.

So, as these stop/start cars seem to at best be left at about 70% charged if used for long journeys, get something like a CTEK 5 Amp charger, nothing less than that for a 70AH battery, and either fit it and forget if you have the car parked in a garage or driveway, or fit it during the hours you are up and about until you have fully charged it, then top it up weekly.

I have a not much used Audi S4 and it lives/sleeps in the garage connected to a CTEK 5 Amp smart charger, that car has an AGM battery, my wife's 2015 VW Polo, that has an EFB also is kept in the garage, and weekly it is being treated to a "day time" recharge/top up with a 20 Amp CTEK charger/support unit. That Polo gets used maybe every 10 days right now for essential shopping, but obviously as that is done very locally, it still needs a bit of help to keep that battery in good condition.

 

[Polly]

Thanks Rum4mo. Great advice and have done that using the CTEK. Hard wired in with the plug and socket.
Brilliant bit of kit. Bought it when I had issues from NEW of the battery going flat. That was down to an undiagnosed cracked leaking cell!!

As I also have various multimeters just wanted to check what the voltages were or as expected.

 

[RUM4MO]

On voltages, if never topped up using a smart charger, the answer will be "disappointingly low, maybe 12.2 > 12.4Volts.

Now, have you ever plugged a DVM into the "ciggy lighter" socket and checked to see what happens during driving/accelerating and on the over run, I've forgotten what the highest charging voltage that I've measured there but it might be even 15.??V > 16.??V - that is a guess as it was done a long time ago, certainly 14.7+V anyway.

Edit:- rightly or wrongly I have finally convinced my older daughter with the end April 2019 Cupra to buy a smart charger, and she has bought the 5Amp CTEK and it is on its way to her, that battery in her car desperately needs a good bit of de-sulphating probably due to it being a pre reg in end of April, but only moved into the dealer's sales area in August with low voltage faults having been logged - then used mainly 5 days a week for in town 5 mile journeys. I was getting concerned that with her working from home, and being able to walk for essential food supplies, that that car might just end up with a dead battery and she would then would trouble getting the central locking to open all the doors so that she could open the bonnet - that has already happened to a newish Skoda Fabia owner!
The AA were called out and they have had enough experience of this on Skoda and SEAT cars, that they know that they can get rough with the internal bonnet release and open the bonnet without first getting the passenger side door open - now that is a Skoda and SEAT failing having the internal bonnet release on the passenger's side, so it is effectively blocked until you can get the deadlocks opened!

 

[Red ibiza]

car desperately needs a good bit of de-sulphating

How do you know this has happened, is there a way of reversing it, and how?

 

[martin j.]

I’m old to remember ‘battery reconditioning tablets’ , one was dropped into each compartment of the battery, these fizzed like denture cleaning tablets do-were probably similar ingredients-and supposedly kept the battery in tip top order, whether they did any good I don’t suppose anyone knows.

 

[ChrisM75]

Fords could charge at 18v for short bursts, Im assuming the 'regenerative braking' on the Seat does something like that. AGM batteries can handle a low charge state, so they should be ok for extended periods.

 

[RUM4MO]

How do you know this has happened, is there a way of reversing it, and how?

If the battery is generally in poor condition by virtue of its reduced capacity or its ability to take on charge or recover if recharged, if you test it using a battery analyser and its still quite new but low in effective CCA but the voltage when charged seems okay, then it probably has suffered from neglect/abuse due to how it has been used since new and that has lead to sulphating of the plates.
There is a school of thought that considers that most lead acid flooded batteries do respond/recover if a reconditioning charge program is applied to them every 12 months, I have seen improvement in the EFB in my wife's 2015 VW Polo after applying a recondition charge to it - if that had not happened, that battery was going to get replaced with an equivalent AGM battery.

 

[RUM4MO]

I’m old to remember ‘battery reconditioning tablets’ , one was dropped into each compartment of the battery, these fizzed like denture cleaning tablets do-were probably similar ingredients-and supposedly kept the battery in tip top order, whether they did any good I don’t suppose anyone knows.

I always wondered about using them, but as I was running Ford cars during that period, the newer versions of Ford batteries had a bad habit of suddenly suffering from internal shorts - again maybe slag falling off the plate(s) and causing a big enough drop in performance that if the car was stopped, it would not start maybe 15 minutes later - so that for me was always "game over" - new battery needed, and so no chance to experiment with these special tablets.

 

[RUM4MO]

Fords could charge at 18v for short bursts, Im assuming the 'regenerative braking' on the Seat does something like that. AGM batteries can handle a low charge state, so they should be ok for extended periods.

Oh yes, I've forgotten the exact highest voltage I've spotted during "over run cramming" or "regenerative braking"

Unfortunately many, or too many VW Group cars with Stop/Start and "regenerative braking" get fitted with crappy cheapie EFB - and while they do tolerate a bit of that, they do degrade quite quickly when compared with AGM equivalent capacity batteries - I'm aiming to increase the Polo battery capacity up to the Cupra size if/when I need to replace the original EFB with an AGM - maybe curiously, by moving a size up means the more popular size is cheaper!!! In the Polo that means replacing the battery tray though and insulating cover, which adds in another £55.

 

[RUM4MO]

[Okay It used to be my old job as an Aircraft Electrician and battery charging room op decades ago!!]

Can a current expert advise me on my new std 70 ah EFB battery in my Cupra R.
As it is not being used with lockdown

Resting voltage as now.
Minimum before I need to recharge? If relevant
Just off battery charger Voltage. If relevant.
Car charging voltage [14. something]

Just one other thing about measuring battery voltages, if you unlock a car that has smart modules, then measure the battery voltage, what you are measuring is not an isolated out of circuit voltage of a battery - is an in circuit voltage of a partially loaded battery, so the measured voltage will normally be lower than if you left it until the smart controllers had gone to sleep and massively reduced the current draw on that battery.

That was how I ended up checking if the controllers in my older daughter's old late 2009 Ibiza were going to sleep as intended after stopping the car and locking it up with a remote test lead across the battery - I checked the battery voltage soon after stopping and locking the car up, if the battery voltage increased with time, maybe after 20 minutes, then I knew that the controllers had been forced into sleep mode.

 

[Crossthreaded]

I’m old to remember ‘battery reconditioning tablets’ , one was dropped into each compartment of the battery, these fizzed like denture cleaning tablets do-were probably similar ingredients-and supposedly kept the battery in tip top order, whether they did any good I don’t suppose anyone knows.

Now there's a memory Martin. I never tried them either but back in those days you would see them all over the place from Halfords to the likes of Sunday markets.

I have been the "proud" owner of a CTEK XS 7000 7amp charger for a few years now and used it on the older cars in the "family fleet" ('07 Astra, '08 Jazz, '10 Panda, etc.) I have not yet hooked it up to the Ibiza (2016 Ibiza 1.0 95hp CHZB engine with lots of "clever" stuff like regenerative braking, stop/start, battery monitoring - I think - etc, etc.) With the older chargers (transformer type) it was always recommended to isolate the battery by disconnecting the leads before charging because these older chargers could deliver "spikes" which might damage electronics. I bought the CTEK because I understood it to be safe to connect without isolating the battery first. I've successfully charged the older family vehicles without isolating and had no problems, in fact the Panda, very much a "shopping car" is often connected. Now, with this enforced isolating in place, the Ibiza hardly being driven at all. I feel it's battery would benefit from being hooked up to the CTEK for a day or so. I don't want to disconnect it and risk unexpected/unknown consequences but worry about whether any damage might be caused to this car which has so much more in the way of electronics compared to the older cars I'm used to working on. Anyone able to advise me?

 

[RUM4MO]

@Crossthreaded , just connect it up as CTEK suggest, which should be +VE to battery post -VE to the domed nut that connects the battery earth to body near the battery - then plug in and switch on - enjoy!

My 2011 Audi S4 quietly sleeps in the garage with a 5Amp CTEK connected to it at all times, I have just connected my 20Amp CTEK charger/support unit to my wife's 2015 Polo for its overnight "weekly refresh" - though as it can hand out 20Amps, I'd think I can remove it after a few hours, it is certainly indicating "fully charged" - so I'll remove it tomorrow.

Edit:- okay the instructions from CTEK that I read seem to predate cars with BCM dongles on the -VE side, so connect as I suggested not just across the battery as CTEK suggest.

 

[Polly]

I asked the same question of CTEK due to my in depth knowledge/background ended up with the Chief tech officer and local Area Manager coming down and interviewing me!!
Yes all perfectly safe. Mine is a TIME TO GO version. They said instead of allowing the battery to run down a bit then charge up. It gives it small gentle pulses every so often to keep it topped up so can stay hooked up forever.

As to recon batteries 50 years ago I asked the client do you want a NEW battery or a recon for a few quid or a tip.
No problem to me labour was free. Materials available.

Guess what they wanted.
SO
Discharge
A reverse charge.
Full discharge
A full high voltage charge.
Discharge
A total flush out with a power wash FRESH water.

Leave to completely dry out.
Fill with a higher concentrate of acid [1280 SG or higher in lieu of 1275]
Full normal charge.

BINGO good for another few years.
Money back refund guarantee.

 

[Crossthreaded]

Thanks very much folks. I'm always pressed by the depth of knowledge on here. Being "old school" it's always the electronic knowledge (lack off) that leaves me feeling impotent!

 

[RUM4MO]

I deliberately told my older daughter to side step the "Time to go" version of CTEK, for 2 reasons, the version that you can command to do what you want plus "recond" is a few pounds cheaper. I thought that you @Polly with your back ground might have done the same, maybe not.

Recond is very handy for reawakening up these EFBs - and most of them will be getting used in a way that does end up with them getting sulphated.

Edit:- on the topic of reconditioning batteries years ago, probably batteries cost a lot more relative to a weekly wage back then and with their old style rough and ready construction they could benefit from a good wash out and refill, when I was a "boy" we tended to have mains radio LW, MW S1 S2 39M --- and they used a 1.5 wet cell to power the valve heaters. Among other stations there was the Trawler waveband and US forces in Europe stations, handy for Matt Dillan US Marshall - oh dear me!!

Edit:- sorry I got the RECND bit wrong, the Time to Go version also has RECOND!

 

[TheSwede]

Very interesting tread!

Have a couple of Ctek chargers (mxs 5 and zafir 45) which I use frequently. One Zafir 45 is connected 6 months per year to our winter stored Audi A4 Convertible. Works fine year after year (classic lead battery).

EFB and classic lead battery – If I run the RECOND mode with the MXS5 I suppose I must be able to add some water to the battery cells. My EFB battery’s are sealed so can´t add water (at first sight). I’m considering to run RECOND mode on my sons Golf R 2014 since the car is 6 years old.

So far I haven’t used the RECOND mode.

/Peter

Edit: Is it possible to run RECOND mode with battery connected to the car or should it be charged "stand alone"? RECOND uses 15,8V in pulses. As you have written earlier in this tread the charging should normally be executed via cable to the minus charging connecting point beside the battery in the car chassis.

 

[RUM4MO]

I've never given that connected/disconnected when running RECOND a thought, and CTEK does not say it should be disconnected, with these newer cars, when smart charging on the overrun/braking, the charging voltage is probably around that level - and remember this, that battery will be acting as a capacitor so the CTEK can throw 15.8V spikes at the battery but the rest of the car should never see these spikes as the battery will quench/sink them.

Unless someone has another idea, certainly I have run the RECOND on my wife's 2015 VW Polo 1.2TSI without anything nasty happeneing, as long as the 2014 Golf R has an EFB then running RECOD will be okay.

It seems that you can also run RECOND on normal AGM batteries, but not, I'd think, GEL batteries, I watched a CTEK tutorial covering all the operating modes of MXS 5 and it was used in AGM RECOND mode - prior to that I considered that RECOND mode was only suitable for wet, flooded batteries and so it would not be possible to select RECOND in AGM mode, not so it seems, so it must be only GEL and not just AGM batteries that can't be RECOND! Though the AGM battery in my sleeping 2011 Audi S4 tests prove/show that it is still in very good condition so probably does not need RECOND run on it.

Edit:- also the maybe light weight desulphating phase that is the normal first stage of charging will also be 15.8V - maybe, I have not checked the CTEK handbook.

Another Edit:- actually the main purpose of the RECOND is to "remix" the probably now stratified battery acid and so return more life to the battery, I don't know why I stuck with desulphating as the main benefit, though that would be why I was questioning the benefit of applying RECOND to an AGM battery that had the acid absorbed into the spun glass sheeting!

 

[TheSwede]

@RUM4MO Tanks! What do you think of filling dest. water to the sealed battery? Have you done that after running recond mode?

/Peter

 

[RUM4MO]

@RUM4MO Tanks! What do you think of filling dest. water to the sealed battery? Have you done that after running recond mode?

/Peter

No and I don't think that it is possible - well not possible with any VW Group EFB or AGM batteries that I have looked at.