The charging voltage of CTEK MXS 5.0 is unexpected higher, faulty charger or bad battery?

[Davidhee58]

As people recommended, I recently purchased a CTEK MXS 5.0 charger and tried to charge the AGM Battery on my Auris Hybrid.   on the car+AGM mode, the charging voltage at step 3 and step 4 was about 15.1v and was 14.06v at step 7, all of which were ~0.4v higher than the voltage as the manual specified (14.7v and 13.6v at step 4 and step 7, respectively). I tried standard Battery mode as well, again the voltage was ~0.4v higher (2nd photo, at step 4). All of my readings were from Fluke multimeter, which I confirmed is very accurate, compared to the displayed Battery voltage on the hidden  service manual.

I kept CTEK charger at step 7 overnight, but the battery was not fully charged (12.2v, 11.8v before charge) and I have no idea if it is a fault charger or is due to the bad battery. The battery died once a month ago but  was tested ok by Toyota  dealer, and
 just needs recharge.  I contacted CTEK, but haven't got any response yet, could you please help me to find the clues for the issue? all comments would be very appreciated.   

[Mooly]

I doubt there is a problem as such. 

Optimum charging voltages are not a fixed constant but also depend on temperature, colder equals higher. Any technical info supplied with the charger should state the temperature  at which any quoted voltages are measured. Typically this would be 25C

So 15.1 volts for around 0C sounds about right, and if anything a little on the low side. This voltage would (should) be closer to around 14.7V at 25C.

Float charge voltage (the voltage you can leave it 24/7) would be around 14.4V for 0C and 13.5 to 13.8 V for 25C. 

Without remote sensing of Battery temperature it can only ever be a compromise figure.

[TonyHSD]

One question. Where do  you connect these chargers, directly to the Battery poles? And if yes when leaving them overnight or longer periods of time do you disconnect the negative terminal, so the car has no power ? 
Thanks 

[Mooly]

There should be no need to disconnect the Battery. Just follow good practice of connecting and disconnecting the leads with the charger disconnected from the AC mains (to prevent arcing and any voltage spikes). Ideally you should also connect the negative lead to the  vehicle chassis (ground) rather than the Battery terminal itself but that is a somewhat old (my own personal opinion) rule of thumb and relates to the possibility of gasses from a faulty or overcharging Battery being present. AGM batteries are essentially sealed anyway and would only vent gasses under catastrophic overcharge conditions.

 

 

[Davidhee58]

30 minutes ago, Mooly said:

I doubt there is a problem as such. 

Optimum charging voltages are not a fixed constant but also depend on temperature, colder equals higher. Any technical info supplied with the charger should state the temperature  at which any quoted voltages are measured. Typically this would be 25C

So 15.1 volts for around 0C sounds about right, and if anything a little on the low side. This voltage would (should) be closer to around 14.7V at 25C.

Float charge voltage (the voltage you can leave it 24/7) would be around 14.4V for 0C and 13.5 to 13.8 V for 25C. 

Without remote sensing of battery temperature it can only ever be a compromise figure.

Thanks Mooly for your explanation,  which do make sense, I didn't realise the temperature affects the charge voltage so much! if the voltage is higher than 15v, is it ok for the AGM Battery? I am now using the standard mode, as its charge voltage is quite close to the volts on the AGM mode at the moment, considering the temperature effect, should I switch to AGM mode for the AGM Battery? I am worrying the higher voltage may damage the Battery.   

[Davidhee58]

48 minutes ago, TonyHSD said:

One question. Where do  you connect these chargers, directly to the battery poles? And if yes when leaving them overnight or longer periods of time do you disconnect the negative terminal, so the car has no power ? 
Thanks 

Hi Tony, thanks for your comments, I permanently connect the eyelet positive cable to the Battery positive pole, and connect the negative cable to the one of the cargo hook bolts in the boot, the Battery negative cable is not disconnected, is this connection safe for overnight charge? Followed the Toyota owner manual, I had an issue before with the alarm, which was activated when I disconnected the Battery negative cable even the doors were unlocked with the remote control.

[Mooly]

1 minute ago, Davidhee58 said:

I didn't realise the temperature affects the charge voltage so much! if the voltage is higher than 15v, is it ok for the AGM battery?

For a short while yes, its OK. The relationship between charge voltage and temperature is very precise, particularly when 'Float' charging batteries where they are connected to charger for extended periods.

There are two distinct uses for batteries (and consequent charging modes). One is called 'Cyclic' where the Battery might be often discharged quite heavily and then it is recharged. That usually sees the higher initial charging voltage used and then as the Battery approaches full charge the voltage is reduced. To not apply a higher than normal voltage initially would mean that times taken to a full charge would be massively increased. The higher voltage also helps to break down any sulphation on the plates caused by being left in a low state of charge. All that helps the Battery recover and be able to accept a charge.  

When you apply higher than 'normal' voltage to a battery it not only draws more charging current but the battery also self heats. As that happens it draws even more current and so the process goes on, the battery eventually entering thermal runaway and drawing ever more current. At that point plate damage also occurs and there is the risk of 'gassing' and venting of electrolyte. A 'Smart' battery charger monitors the current and keeps tapering the charge as not enter this region.

The other mode is 'Float' where the battery is permanently on charge (such as in domestic alarm panels... yes those batteries are often little VRLA  (like an AGM) type and where little to no discharging of the battery in use is expected. When it is discharged and then recharged again it is expected that it may be many days or weeks before it might be needed to be used again and so the lower 'Float' charging voltage is able to fully charge the battery over many tens and hundred of hours... and that voltage is there 24/7

 

[Davidhee58]

10 minutes ago, Mooly said:

For a short while yes, its OK. The relationship between charge voltage and temperature is very precise, particularly when 'Float' charging batteries where they are connected to charger for extended periods.

There are two distinct uses for batteries (and consequent charging modes). One is called 'Cyclic' where the battery might be often discharged quite heavily and then it is recharged. That usually sees the higher initial charging voltage used and then as the battery approaches full charge the voltage is reduced. To not apply a higher than normal voltage initially would mean that times taken to a full charge would be massively increased. The higher voltage also helps to break down any sulphation on the plates caused by being left in a low state of charge. All that helps the battery recover and be able to accept a charge.  

When you apply higher than 'normal' voltage to a battery it not only draws more charging current but the battery also self heats. As that happens it draws even more current and so the process goes on, the battery eventually entering thermal runaway and drawing ever more current. At that point plate damage also occurs and there is the risk of 'gassing' and venting of electrolyte. A 'Smart' battery charger monitors the current and keeps tapering the charge as not enter this region.

The other mode is 'Float' where the battery is permanently on charge (such as in domestic alarm panels... yes those batteries are often little VRLA  (like an AGM) type and where little to no discharging of the battery in use is expected. When it is discharged and then recharged again it is expected that it may be many days or weeks before it might be needed to be used again and so the lower 'Float' charging voltage is able to fully charge the battery over many tens and hundred of hours... and that voltage is there 24/7

 

Hi Moolly, thanks, I learnt a lot about Battery charge today! so I should never use the AGM mode if the temperature is too low?  am I correct? I just checked the charger and it is in the step 7 float charging, the charge voltage 14.09v instead of 13.6v as shown on the ctek charging programme, if leave the charger at this kind of voltage overnight, is it ok?  

[Gray86]

I’ve never used the AGM specific mode with mine (or any batteries I’ve charged). As I understand it the AGM mode charges at a higher voltage than normal mode, so I just charge at normal mode to minimise heat, and I’m not in a rush to charge anyway. 
 

I don’t believe it fully charges the Battery (does any trickle charger?) as batteries like to be between 20&80% charge. 
 

my wife’s 1.33 Yaris is on charge right now, and doing nicely on step 4. 

[Mooly]

The charge voltage in AGM mode should be correctly controlled by the charger. This means that whilst it will initially supply a highish voltage it will also monitor the current draw as well and reduce the voltage in line with that so as not to overcharge the Battery. So there should be no worries using AGM mode.  

In practice this means that a fully charged Battery (and you can perhaps try this for confirmation) should only allow the charger to deliver the higher voltage for a short time, perhaps only for a minute or two before the charger falls back to float charging. So with a fully charged Battery you disconnect the charger for say an hour and then reconnect and see how long it delivers the higher voltage for. Remember though that locking and unlocking and courtesy lights and so on will discharge the battery enough (even though its only a couple of percentage points) for a charger to deliver the higher voltage for longer.

Have a look at this chart for AGM batteries. Temperature is at the top.

 

 

[Davidhee58]

2 minutes ago, Gray86 said:

I’ve never used the AGM specific mode with mine (or any batteries I’ve charged). As I understand it the AGM mode charges at a higher voltage than normal mode, so I just charge at normal mode to minimise heat, and I’m not in a rush to charge anyway. 
 

I don’t believe it fully charges the battery (does any trickle charger?) as batteries like to be between 20&80% charge. 
 

my wife’s 1.33 Yaris is on charge right now, and doing nicely on step 4. 

Hi Graeme, Good points, I thought it's better to use a little bit higher voltage to get the AGM charged properly. when I saw the voltage was unexpected higher, I did worry about it. Do you know your voltage when your charge is in the step 7? mine is ~14v at the moment, which is 0.4v higher than the normal volt (13.6v), I hope it is ok if i leave it overnight at step 7. 

[Mooly]

Just to try and expand on how this works and this applies to any car Battery type.

You have a fully charged Battery and you apply a float voltage of say 13.50 volts. The Battery draws very little current and is happy to sit like that for hours/days/weeks.

You now discharge the battery (lets give a real example) by turning your headlights on for just 30 seconds. Capacity wise you've taken a very very tiny amount from the battery. If we now apply our 13.50 volts again a healthy new battery will draw an initial current limited essentially by the charger. If the charger could supply 30 amps then battery would take that for a few seconds and then the current would level off and fall and after many minutes be back to the original float level.  

If we  did the same again and now discharged the battery substantially (say lights on for a couple of hours) then the same charging cycle occurs but it takes a very long time to fully replenish the battery at 13.50 volts.

If we constantly use the battery this way (this would be classed as Cyclic use) then the battery may start to deteriorate. It may only be charging back to say 99% capacity before we discharge it again... and so on.

I mentioned new and healthy above. As a battery ages its internal resistance increases and this works against charging the battery. It means a higher voltage is needed to push the current back into the battery.

Using a higher initial charge voltage allows the battery to keep drawing more charge current and replenish quicker and also helps recover the plates from sulphation that occurs when the battery is in a lowish state of charge.

Old cars (with traditional alternators not controlled by the engine management) could deliver nearly 16 volts across the battery following a really cold start and that was to ensure the battery got a really high initial charge put back in. Within a a couple of minutes the voltage would fall back to normal limits. On a hot day that could be as a low 13.5 volts, on a cold day nearer 14.5.    

 

[Davidhee58]

34 minutes ago, Mooly said:

The charge voltage in AGM mode should be correctly controlled by the charger. This means that whilst it will initially supply a highish voltage it will also monitor the current draw as well and reduce the voltage in line with that so as not to overcharge the battery. So there should be no worries using AGM mode.  

In practice this means that a fully charged battery (and you can perhaps try this for confirmation) should only allow the charger to deliver the higher voltage for a short time, perhaps only for a minute or two before the charger falls back to float charging. So with a fully charged battery you disconnect the charger for say an hour and then reconnect and see how long it delivers the higher voltage for. Remember though that locking and unlocking and courtesy lights and so on will discharge the battery enough (even though its only a couple of percentage points) for a charger to deliver the higher voltage for longer.

Have a look at this chart for AGM batteries. Temperature is at the top.

 

 

Hi Mooly, my voltage readings were very much close the numbers on the table. Regarding the higher voltage in AGM mode, yesterday I noticed the charger started from step 3 with increasing in voltage from 12.5ish and quickly reached to about 15v and stay at the voltage until the end of step 4. so i was quite worrying about this higher charging voltage, is something wrong with the ctek charger? if the charger behaves like this, can i keep using the AGM mode? 

And it seems the higher voltage ~14v at step 7 float charging never drops to lower volts.

[Mooly]

I don't for a moment think there will be any problem with the charger. 

The state of charge of your Battery each time you apply the charger is an unknown and that factor determines how long the charger stays at 15V. The only way to double check that would be to totally isolate the Battery from the car, then charge it fully, then leave it for say 24 hours and check its voltage after it has rested for that time and then re apply the charger. Under those conditions the charger should not apply 15 volts for more than a couple of minutes imo because the Battery is already fully charged.

The only other advice I can give is not to get to worried or hung up on the need to keep charging the battery. In normal use it shouldn't really need it. Also AGM batteries are designed to tolerate being left in a lower charge state... that doesn't mean nearly flat of course... but they don't need be kept at 100% all the time.

It might be useful to you having fully charged the battery... yes leave it overnight to do that... and to then take some accurate voltage readings every couple of days and so get an idea of what is happening to the state of charge. It will be totally normal to see that voltage decline over time but what you want to see where it levels off at. Also see how it recovers when you use the car. Where does it go back to 24 hours after driving for example.

I would estimate that once (if) you start seeing 12.3 volts as a resting voltage then things are starting to get a bit low.  

All that will give a good idea how well or otherwise it is being charged in the car and whether you really need to use an external charger. 

 

[Catlover]

54 minutes ago, Gray86 said:

I’ve never used the AGM specific mode with mine (or any batteries I’ve charged). As I understand it the AGM mode charges at a higher voltage than normal mode, so I just charge at normal mode to minimise heat, and I’m not in a rush to charge anyway. 

I don’t believe it fully charges the battery (does any trickle charger?) as batteries like to be between 20&80% charge. 

my wife’s 1.33 Yaris is on charge right now, and doing nicely on step 4. 

1. I found this by doing an internet search. It’s about a CTEK 5.  Stage 3 takes the Battery up to 80%, and when stage 4 is lit you can start and use your car.  Stage 7 takes the Battery up to 100%.   Certainly the hybrid Battery likes being between 20%-80%, but we not talking about the hybrid battery here.
2. Lots of video tutorials on You Tube as well.
3. ...................................................

4. 1. Cleaning, or Desulfation

It’s been estimated that sulfation causes the untimely demise on 80% of all batteries on the road.  But what is this chemical villain?  Most car batteries are lead-acid units, which are composed- you guessed it- of lead plates submerged in sulfuric acid.  Over time, the electricity generated by this union creates a compound called, predictably, lead sulfate, a white powder that builds up and bonds to the lead plates.  This means there’s less lead surface area to react with the acid, which means less power.

No, CTEK smart battery chargers don’t have nanobots that swim through your battery scrubbing lead sulfate off of the metal, even though that would be awesome.  Their method is much simpler.  It uses high voltage, low current micropulses to detach the sulfate crystals and let them sink benign to the bottom of the cell.  This pattern does not charge the battery yet.  That will begin at the next stage, and the CTEK can detect automatically when it has done all the desulfation it can before moving on.

This works on batteries with as few as two volts left.  Step 6 is called Reconditioning, but a huge part of reconditioning a battery begins with Desulfation.

Please high five the nearest scientist before continuing.

2. 2. Soft Start

Remember that scene from Band of Brothers when Easy Company finds that concentration camp and immediately starts feeding the survivors everything they can, because Easy Company was awesome?  The company doctor came around and ordered the feeding stopped, because a severely famished person needs to start on a light, liquid diet before eating solid and richer foods, which could damage a disused digestive tract.

Batteries work very similarly.  A severely discharged battery needs a reduced current when it’s first hooked back up, or it could be damaged.  The Soft Start stage offers that smaller meal until a battery gets back up to about 10-20%.  This principle also works with lithium ion batteries, which is why it takes your cell phone much longer to charge from dead than it does to charge from 20%.

3. 3. Bulk Charge

Now comes the feast.  The battery is now safe to charge with a rapid, high-voltage, constant current until it reaches about 80%.  CTEK designed their chargers to make this happen as quickly as possible without damaging the battery so you can start and run your car as needed.

Don’t misunderstand.  The other stages are important as well, but so is getting to work on time.  80% is plenty to get your car started and rolling.  You can take care of the rest later.

4. 4. Absorption

There’s a scene in The Fellowship of the Ring at Bilbo’s birthday party when the Hobbits have all feasted and are now nibbling on things.Tolkien describes this as “filling in the corners,” and anyone who has eaten a Thanksgiving meal understands the meaning.

The Absorption stage “fills in the corners” of the battery.  Once the CTEK detects that the charging has slowed at about 80%, it begins to taper the current but keeps the voltage up, force-feeding the battery for about 10 hours until it reaches 95-99%.

5. 5. Analysis

The CTEK will now go back and check its work.  It will test for about 3 minutes to make sure the fully charged battery isn’t bleeding any charge.  If it is, there’s not much hope for your battery and you’ll need to replace it.  If not, the charger moves on to the next step.

6. 6. Reconditioning

Once the analysis is done, the charger will spend anywhere from 30 minutes to 4 hours reconditioning your battery.  This is good for deep cycle batteries that were previously fully or close to discharged.  Reconditioning involves a quick and sustained burst of voltage to fix something called acid stratification.

Often when a battery is overcharged, it can cause the water within the battery acid to split into hydrogen and oxygen.  This condenses the remaining acid, which, now heavier, settles at the bottom of the battery.  This can also happen through simple gravity if the battery sits unused for long enough.  Remember, though, that the more lead touching the acid, the more power you get, so the reconditioning stage sets to shake things up through a process called equalization.

This basically sends enough current through the battery to cause tiny bubbles to form, stirring up the acid settled at the bottom of the battery and remixing the acid and water into an efficient solution.

7. 7. Float Maintenance

After reconditioning, the voltage and the current level off to maintain a floating charge of 13.6 volts to keep your battery topped off.  At this stage, your battery will fully charge to 100%.  The float charge will remain active for up to 10 days.

8. 8. Pulse Maintenance

Float maintenance is fine, but not for extended periods of time.  If this battery is sitting in your classic and you’re storing it for the winter, you don’t want to leave it on float charge.  This could cause overcharging, which can lead to the stratification problems above.  It also increases the risk of boiling or drying out.  Bad news.

CTEK’s solution is the pulse charge, which is healthier for your battery and doesn’t waste energy.  It offers short pulses of power when the battery power drops- as needed.  It will keep a battery charged at 95-99% for months.

CTEK Battery Chargers holds the patent on the only chargers to offer both float charging and pulse charging.

No, this isn’t just marketing malarkey.  CTEK set out to make the most advanced battery chargers on the planet, and they succeeded.  With real, hard science.

[Davidhee58]

17 minutes ago, Mooly said:

I don't for a moment think there will be any problem with the charger. 

The state of charge of your battery each time you apply the charger is an unknown and that factor determines how long the charger stays at 15V. The only way to double check that would be to totally isolate the battery from the car, then charge it fully, then leave it for say 24 hours and check its voltage after it has rested for that time and then re apply the charger. Under those conditions the charger should not apply 15 volts for more than a couple of minutes imo because the battery is already fully charged.

The only other advice I can give is not to get to worried or hung up on the need to keep charging the battery. In normal use it shouldn't really need it. Also AGM batteries are designed to tolerate being left in a lower charge state... that doesn't mean nearly flat of course... but they don't need be kept at 100% all the time.

It might be useful to you having fully charged the battery... yes leave it overnight to do that... and to then take some accurate voltage readings every couple of days and so get an idea of what is happening to the state of charge. It will be totally normal to see that voltage decline over time but what you want to see where it levels off at. Also see how it recovers when you use the car. Where does it go back to 24 hours after driving for example.

I would estimate that once (if) you start seeing 12.3 volts as a resting voltage then things are starting to get a bit low.  

All that will give a good idea how well or otherwise it is being charged in the car and whether you really need to use an external charger. 

 

Hi Mooly,  thank you very much for your advice. Since last Oct, my car has been parked on our drive most of time and the Battery completely died last month. I only use the car in the weekend for local shopping at the moment,  so I do need a charger to to keep the Battery in a good state of charge as the toyota service adviser suggested. when I got time, I will do the testing charge as you suggested above. 

[Gray86]

3 hours ago, Davidhee58 said:

Hi Graeme, Good points, I thought it's better to use a little bit higher voltage to get the AGM charged properly. when I saw the voltage was unexpected higher, I did worry about it. Do you know your voltage when your charge is in the step 7? mine is ~14v at the moment, which is 0.4v higher than the normal volt (13.6v), I hope it is ok if i leave it overnight at step 7. 

I’ll try AGM mode when I top mine up later in the week. 
 

I’ve not got a multimeter unfortunately, so unable to check voltage. 
 

I’ve left mine overnight and its been fine - a Youtuber I watch (Shmee150) uses these chargers on all his super car fleet, and leaves them plugged in for months at a time with no issues (just nicely charged batteries!) 

[Mooly]

You have to remember that there is a big unknown in all of this, and that unknown is what the actual condition of the Battery is. Not its state of charge but its overall condition.

Take two batteries, one brand new and the other old and heavily deteriorated but that has been on an extended charge. Both of these batteries, whilst appearing fully charged will behave very differently. The new should have its full capacity available (its Ah rating) whilst the other may be down to 10 or 20% of that value. Outwardly both seem to perform the same, both would start a car (lets say a conventional car and starter) with equal eagerness. You are led to assume the old Battery is fine.

Where it all falls down is on capacity and internal resistance. The new Battery lets you leave for example your headlights on for 4 or 5 hours and still it  is not discharged fully. The voltage holds up until all the capacity has been used. The old battery starts off fine for just a few minutes and then the voltage heads south alarmingly. This batteries capacity is way down and within minutes the voltage has collapsed. Turn the lights off and leave it a few minutes and the voltage recovers somewhat. This is the internal resistance (that is greatly increased in the old battery) coming into play. This resistance causes the terminal voltage to to fall under load as current is drawn. 

When you begin to recharge the batteries you find the new one takes all current the charger can deliver. The terminal voltage on the battery recovers very slowly as it accepts a full charge. The old battery also takes a high current but only for a little while, then the terminal volts rises sharply and quickly and the battery appears to be reaching full charge.

We are back to where we began.

In practice this old battery takes a lot longer to replenish its very limited capacity because that same internal resistance that limits current out of the battery is now limiting current into it as well. The only way to overcome that is to increase the charging voltage whilst safely limiting the current.

At the end of the day that battery is still deteriorated and way down on available capacity.

 

[Catlover]

As I read, and reread what the CTEK 5 charger does it is really impressive. I can see its not going to bring back to life a completely dead Battery, but within those 8 stages the system can bring a well used Battery up to a better level, and that seems to strt at level 1.  I dumped a really old Battery charger - it was my dads but I must have got it in the 1970's and lent it to him when he needed it. It looked nothing like a CTEK on the outside and probably nothing like one on the inside. I have bit the bullet and bought a CREK 5, lockdown and the winter frost played a large part in my decision, sitting on the driveway for 30-60 min is not for me, and the wife wouuldnt do it with her cr so thats another 30-60 minutes wasted. Rather pay for a CTEK and have it for future years too.

[Mooly]

Old style chargers were about as basic as you could ever imagine. Nothing more than a mains transformer and a bridge rectifier (a four diode pack) which converts the AC from the transformer to DC. The term 'DC' here means 'unsmoothed' pulses equal to the peak voltage of the AC.

Basic Power Supply Rectification Tutorial (bristolwatch.com)

The problem here is that as the Battery approaches full charge and draws less current the higher the Battery terminal voltage becomes. At low current the voltage approaches the peak AC voltage and so the risk of significant overcharge and plate damage is obvious.

The circuit is considered 'lossy' and when delivering high current the voltage falls somewhat. The transformer is relatively small in relation to what it is being asked to do and so it can not maintain its output voltage. There is also usually a thermal switch included that cycles the charging current on and off in response to the heat produced by the over run circuit. Super crude and basic.

I have one of these as well 🙂 and tbh its OK as a last resort and as long as you monitor the voltage and disconnect it once the terminal voltage rises above about 14.5 to 15V. Not recommended in this day and age it must be said. Certainly not one to leave on overnight. Eeeh, that batteries got nice and toasty while charging.

This is identical to mine... and don't try this at home...

 

 

 

[Techead]

Just thought I'd drop in with my findings of the CTEK MXS 5.0, purchased one the other day, and used it yesterday on my Auris 2014 Battery, that, even though sitting in Ready mode an hour or so every week, found it too weak to start the car after only 4 days. Rarely used the car 2020, though it was after an MOT where the mechanic must have left max hot air at full blast and stereo blasting while performing the MOT (speculating whether or not this is the reason for the dead battery) after a week of getting the car back from MOT, trying to start it, it failed and was pretty much flat (Didn't measure with MM) but could barely power up the screens etc. That was the first time in 4 years of owning the car that the Battery was flat. Ever since, due to not using very often, it's ended up dying another couple times, needing a jump start to get going. 

Started measuring drain on the Battery, after sitting in the car for an hour, it got up to around 12.45v, but rapidly dropped to around 12.28v at around 8PM, left over night and measured in the morning (9AM) and it settled at around 12.16v, staying around that for a few hours, though still dropping a few 0.1v's over a few hours. 

Charger arrived, so took it out to charge. Took around 6 hours for it to reach Stage 7. Continued leaving it on charge today, and reached 12.76v after taking off charge. Going to leave it disconnected from everything for 24hours and see what it settles at. 

Since buying the car, I haven't changed the battery, though I don't think it was changed prior to that either, so I was probably going to get a new battery regardless, but if this charger can actually save it, I may not need to for the time being. (Also unsure if there's parasitic draw that's actually eating the battery, I'm not knowledgeable enough to know how to figure that out..)

Charged via normal Car mode (Non-AGM) as some had comments that it wasn't good to use? No idea, so thought I'd play it safe.

 

[delbois]

4 hours ago, Techead said:

Just thought I'd drop in with my findings of the CTEK MXS 5.0, purchased one the other day, and used it yesterday on my Auris 2014 battery, that, even though sitting in Ready mode an hour or so every week, found it too weak to start the car after only 4 days. Rarely used the car 2020, though it was after an MOT where the mechanic must have left max hot air at full blast and stereo blasting while performing the MOT (speculating whether or not this is the reason for the dead battery) after a week of getting the car back from MOT, trying to start it, it failed and was pretty much flat (Didn't measure with MM) but could barely power up the screens etc. That was the first time in 4 years of owning the car that the battery was flat. Ever since, due to not using very often, it's ended up dying another couple times, needing a jump start to get going. 

Started measuring drain on the battery, after sitting in the car for an hour, it got up to around 12.45v, but rapidly dropped to around 12.28v at around 8PM, left over night and measured in the morning (9AM) and it settled at around 12.16v, staying around that for a few hours, though still dropping a few 0.1v's over a few hours. 

Charger arrived, so took it out to charge. Took around 6 hours for it to reach Stage 7. Continued leaving it on charge today, and reached 12.76v after taking off charge. Going to leave it disconnected from everything for 24hours and see what it settles at. 

Since buying the car, I haven't changed the battery, though I don't think it was changed prior to that either, so I was probably going to get a new battery regardless, but if this charger can actually save it, I may not need to for the time being. (Also unsure if there's parasitic draw that's actually eating the battery, I'm not knowledgeable enough to know how to figure that out..)

Charged via normal Car mode (Non-AGM) as some had comments that it wasn't good to use? No idea, so thought I'd play it safe.

 

My experience across a variety of makes is when a Battery has been flattened it never fully recovers full capacity, even with a Ctek smart charger. 

[Techead]

12 hours ago, delbois said:

My experience across a variety of makes is when a battery has been flattened it never fully recovers full capacity, even with a Ctek smart charger. 

You're most probably right. Almost 24 hours on and it's seemingly holding at 12.60v, so that sounds OK to me, better than what it was while in the car charging through Ready mode anyway. As long as it starts the car when needed, I'm happy with the charge. 

[Gray86]

22 hours ago, delbois said:

My experience across a variety of makes is when a battery has been flattened it never fully recovers full capacity, even with a Ctek smart charger. 

My friend with his 2016 Nissan Navara had a flat Battery a few weeks ago, due to lack of use. The CTEC got it going again, but a health-check at Halfords suggested Battery is only around 75% of its original capacity.
 

The trick is to never let it get fully depleted if you want to preserve your Battery

[delbois]

1 hour ago, Gray86 said:

My friend with his 2016 Nissan Navara had a flat battery a few weeks ago, due to lack of use. The CTEC got it going again, but a health-check at Halfords suggested battery is only around 75% of its original capacity.
 

The trick is to never let it get fully depleted if you want to preserve your battery

I think you're right. I spent a lot of time faffing around with my Auris Battery when it first started playing up because a couple of Battery testers told me the battery's health was good. When I changed the Battery the problems disappeared.