How to attach a BM2 battery monitor to a Skoda Karoq battery?

[J.R.]

12 minutes ago, Breezy_Pete said:

I don't think I would try that recondition function unless the battery is actually in a state of deep discharge

 

Correct, and the instructions posted state that.

 

My Diddlydaldi charger has a pulse charging desulphation mode but the battery has to be at less than 7.5v for it to activate, its no doubt the same for the CTEK, but if the voltage is much less than that the charger wont spark up anyway without jumping from another charger or battery, I did get it to enter that mode with a neighbours battery that was down to 8v so I dropped it a bit further, a load test before showed 25% remaining life and after the treatment its now showing 65% life, I know that its a stupid name for the measurement of the internal resistance but the numbers can be used as a comparator.

 

I would not have expected it to recover so well from a standard charge.

 

My concern about following the Ctek instructions for the so called reconditioning charge would be the damage done to the battery by discharging it first to 7.5v, if it has already happened by neglect etc then great but I would not choose to do so having seen the effect on several batteries from leaving parking lights on unintentionally.

 

OTOH my caravan leisure battery has a different composition that supposedly copes better with deep discharge, the previous owner had bought it instead of attending to the problem of the non functioning mains transformer which should have kept it charged, it was only a few months old but completely flat, zero volts, only through giving it defibrillation with a truck booster starter pack could I get it to start charging on my 50 year old charger that has no minimum voltage, from there I passed to the Diddlydaldi one, after a couple of days it finally was fully charged and to my great surprise my tester showed it had 97% life, I have never managed to successfully recover a car battery so completely discharged.

[Breezy_Pete]

At about 4 years old your EFB battery may not have many more years left in it, especially if you use the start/stop function, but depending on the data coming from your BM2 and your interventions as necessary with CTEK you may well be able to extend its life by a winter or two. 👍

 

 

 

[J.R.]

12 hours ago, Mark-Surrey said:

Without this BM2 device to see what’s happening to the voltage in real time, I would never have been able to see what actually happens when you use a battery charger

You could have used a multimeter or simply read the instruction manual, the latter for me being against the law 🤣

 

2 hours ago, Mark-Surrey said:

checked it this morning, and it’s now showing 12.62V. Is that the level where a 12V battery in reasonable condition should be?

 

Yes, several hours or the day after charging that is about right, a battery that has suffered damage from discharge but still useable will be at say 12.4-12.5 volts, same for an older aged battery.

 

2 hours ago, Mark-Surrey said:

It was almost completely discharged a couple of weeks ago, after using it only infrequently, and only for short trips. But I have recharged it since then with my CTEK MXS 5.0 battery charger/ conditioner. The Skoda breakdown assistance guy said that the almost complete discharge was likely to have reduced the future performance of the battery somewhat

 

That is correct but it depends on what you mean by completely discharged, without the no load recovered cell voltage the term is meaningless, 10.5 volts is classed as completely discharged, beneath that sulphation occurs which is why I dont like the recommendation to discharge to 7.5v to use the recondition function.

 

I'm hoping that someone will explain that sulphation takes days or weeks to occur and discharging rapidly to that point then putting on the charger in pulse mode will do more good than harm.

 

[Warrior193]

5 minutes ago, J.R. said:

You could have used a multimeter or simply read the instruction manual, the latter for me being against the law 🤣

 

 

Yes, several hours or the day after charging that is about right, a battery that has suffered damage from discharge but still useable will be at say 12.4-12.5 volts, same for an older aged battery.

 

 

That is correct but it depends on what you mean by completely discharged, without the no load recovered cell voltage the term is meaningless, 10.5 volts is classed as completely discharged, beneath that sulphation occurs which is why I dont like the recommendation to discharge to 7.5v to use the recondition function.

 

I'm hoping that someone will explain that sulphation takes days or weeks to occur and discharging rapidly to that point then putting on the charger in pulse mode will do more good than harm.

 

Re. time period for sulphation - my understanding is that this process is not instant, but takes some time to occur - so the discharge / recondition cycle should not do any harm.

Care needs to be taken that the discharge rate is not so high that it causes buckling of the plates though. 

[Breezy_Pete]

A really nice aspect of this BM2 device is that it can tell you the battery voltage with the car fully 'asleep'. 

Many people try to measure without ensuring this state has been reached, and then reach conclusions based on poor data.

[J.R.]

Very true, a regular occurrence.

[Breezy_Pete]

If I do happen to get one for Christmas I'll be interested to set up something to see what current drain it really adds, when passive and active.

Not too sure how Bluetooth works though, does that thing keep periodically trying to make contact with a(ny) paired device, or is the activity all at the other end until a connection is made?

Anyone?

 

[J.R.]

I'm really not the person to ask but for pairing a device like my energy monitor plugs you have to hold down a button till a light flashes and then the phone should pick up the device, that tells me that the phone is always looking for incoming signals perhaps at a low standby current initially then sparks up to do the pairing.

 

Conversely when I want to see how much energy my well pump or heating has used its the phone app contacting the bluetooth device so that too must be on the lookout all the time.

[Mark-Surrey]

I recharged the battery last weekend, using my CTEK charger. It has been in the garage all week apart from Tuesday, when my wife used it for a couple of short journeys of 10 minutes each, and a couple of 30-minute journeys. When I checked the BM2 app last night, it was showing the battery level having dropped from 12.62V (“OK”) last weekend to 12.26V (“low power”) this weekend. You can see the battery level progression in the attached screenshot. The battery voltage is dropping by around 0.03V to 0.05V per day. Does this kind of drop in battery performance over the course of a week mean that the battery definitely needs replacing, or is this typical of what a battery would normally lose per day? The “Cranking test” last night was showing “Low cranking voltage” of 9.27V.

 

I have put it back on charge with my CTEK charger again today.

 

I’m slightly confused by the comments about the “Recondition” cycle on the CTEK charger. Why would CTEK be recommending to do this once per year, if it’s bad for the battery? Is it really completely discharging the battery? According to the CTEK manual, this stage comes AFTER stage 6 ie. after the battery has been fully recharged. If it was completely discharging the battery, I would have thought it would do this BEFORE it recharges the battery, wouldn’t it?

 

Please forgive my ignorance, if these are all dumb questions. I’ve never had to change a car battery before, so I have never paid any attention to this issue previously. I previously had a diesel BMW with stop-start functionality for more than 6 years, and I never had any problems with it, but most of my journeys in that car were more than 30 minutes each, and it was used almost every day. Our other previous car which was used mainly for short journeys (a Toyota Verso), which we kept for more than 6 years, also never gave us any problems with the 12V battery, but it didn’t have stop-start functionality, so maybe that’s the difference compared to our Skoda Karoq which replaced the Toyota Verso.

[Breezy_Pete]

Sounds like fast loss to me, but would be nice to know what the total parasitic drain is external to the battery.

i.e. is it the car's problem rather than the battery.

 

A few days monitoring after a full recharge, but with battery disconnected from car would give a partial answer to this. If you disconnected the BM2 as well and measured the battery voltage with a multimeter you would see the true self-disharge rate.

[Mark-Surrey]

It sounds like most car batteries typically last 3-5 years, so I guess it’s not surprising that mine is starting to lose performance. Does anybody have any particular recommendations on best brand or type of battery for a Skoda Karoq? When I plugged my car reg into the Halfords website, it proposes either Halfords own brand, or a brand called Yuasa, which I’ve never heard of before. Both of them are EFB type. The Halfords own brand is £122.99, the Yuasa is £159, plus fitting cost of £27.00. I was expecting to see battery brands like Varta or Bosch.

[Breezy_Pete]

Try tayna.co.uk instead.

[pinkpanther]

On 12/11/2023 at 10:57, Mark-Surrey said:

I just checked the CTEK user manual. Under the setting for “AGM” option, it doesn’t list any other types apart from AGM. So I’ll just stick with the standard  / normal profile for car batteries. But I noticed that there is also an option for “Recondition” mode, which it says should be used after deep discharge, to maximise lifetime and capacity, with a suggestion that this should be done once per year. I have never used this program, in the 3 years since I bought this CTEK charger. I’ll give it a try next weekend, to see whether it makes any difference.

 

 

I have the same charger and have followed the instructions to run the recond cycle annually on the EFB batteries fitted to my 2019 SEAT Mii OEM Varta battery, 2018 FIAT 500 OEM Mopar branded battery and the old fashioned batteries fitted to my Jag (Yuasa) and Merc (Varta).

 

As per many comments it's very difficult to obtain a true baseline whenever the cars systems are awake. 

[Mark-Surrey]

I had another look at the CTEK instruction manual, and there’s a separate section with more info on the Recondition cycle. It says “Choose the Recond program to add the Recond step to the charging process. During the Recond step, voltage increases to create controlled gassing in the battery. Gassing mixes the battery acid and gives back energy to the battery”. 
 

[J.R.]

Mixes the acid with what?

 

Gives back energy from where? (ref The Law Of Conservation Of Energy)

 

Sounds like Caca to me, the desulphation process is the effective one but the battery has to be discharged to a severely low voltage for it to be implemented and they make no mention of that.

[agedbriar]

I have a voltmeter permanently connected and can confirm that the CTEK MXS 5.0 Recond program does not involve discharging at any stage.

[Sanqhar]

19 hours ago, Mark-Surrey said:

It sounds like most car batteries typically last 3-5 years, so I guess it’s not surprising that mine is starting to lose performance. Does anybody have any particular recommendations on best brand or type of battery for a Skoda Karoq? When I plugged my car reg into the Halfords website, it proposes either Halfords own brand, or a brand called Yuasa, which I’ve never heard of before. Both of them are EFB type. The Halfords own brand is £122.99, the Yuasa is £159, plus fitting cost of £27.00. I was expecting to see battery brands like Varta or Bosch.

 

Yuasa are a well known battery company.  They have been around for years and are one of the world's leading and largest suppliers of automotive batteries.  Many are  fitted as OEM. The  Japanese parent company has been around for 100 years.

 

tom 

[agedbriar]

Received yesterday this Battery Guard.

I connected it to the always live cigarette lighter port and its voltage reading matches the one from my recently re-calibrated multimeter (taken off the battery posts) to the 4th digit. Kudos for that.

 

https://www.ebay.de/itm/264818813144?hash=item3da86e68d8:g:rqAAAOSwrhJlSgIo&amdata=enc%3AAQAIAAAA8PIM5NwxZWKzbtRZv13uB66knIUacH9wr9bhEcvFJhg06tI94AEvMxkXmTGKu7F0hn5S4ZFFi8btQS4XWqUUv%2BH37nnRRre8IXa5HoFRDv34P46Ih69z2k514nbov1MlKWJTqPUGAntWKYpESUTKPff8cLM4Vr9qzLBzsZWiF3R%2Fiee85oLvcMbXWHbUKswl1yyWP7totkeUhqo3O0uTp6BYrnR20D6gHq5w5NxcB%2FQhMbkzxwjqdeasgaDTuOi154WFD4QJqrqNc%2FybTMvb%2FHYNThF4d38yUwWzXY4kYn076Ax0hSeiGJrbtyo0%2BlsFcA%3D%3D|tkp%3ABFBMgLuwsfli

 

Indeed, the negative battery pole connector is engineered so that it's practically impossible to permanently connect anything more to it. It's obviously meant to divert the user to the mass post behind the battery (as per user manual).

 

 

Edited 21 November, 2023 by agedbriar

[Mark-Surrey]

I ended up getting a brand new battery fitted by my local independent garage. It was £170 including fitting, for a Varta EFB battery. They moved my BM2 battery monitor to my new battery. The new Varta battery even has a recess on the top which is the perfect size for the BM2 battery monitor!

 

They also fitted the cable for my CTEK battery conditioner to the battery, so I can connect the CTEK device more easily, without having to mess around with crocodile clips.

 

 

[J.R.]

Both unfused and exposed.

 

Have you done a comparative discharge test to the last one with the new battery?

 

I'm still wondering whether the battery monitoring device was responsable for the bulk of the discharge that you were seeing.

[Mark-Surrey]

24 minutes ago, J.R. said:

Both unfused and exposed.

 

Have you done a comparative discharge test to the last one with the new battery?

 

I'm still wondering whether the battery monitoring device was responsable for the bulk of the discharge that you were seeing.

I just had the new battery installed today. I’ll monitor the voltage level over the coming days and weeks to see whether the battery discharges at a slower rate than the old one, which was losing between 0.1 and 0.05V per day, when not being used. Below is a screenshot which I took this evening, for the past 15 days. It was at about 12.29V this morning, before I took it to the garage to have the new battery fitted.
 

 

[Kenny R]

1 hour ago, Mark-Surrey said:

I ended up getting a brand new battery fitted by my local independent garage. It was £170 including fitting, for a Varta EFB battery. They moved my BM2 battery monitor to my new battery. The new Varta battery even has a recess on the top which is the perfect size for the BM2 battery monitor!

 

They also fitted the cable for my CTEK battery conditioner to the battery, so I can connect the CTEK device more easily, without having to mess around with crocodile clips.

 

 

Can’t see the -ve from the charger cable, but it should be connected to the dedicated connection on the bulkhead and not to the battery -ve post.

[Mark-Surrey]

9 hours ago, Kenny R said:

Can’t see the -ve from the charger cable, but it should be connected to the dedicated connection on the bulkhead and not to the battery -ve post.

Thanks for your sound advice. I just checked, and you are absolutely correct. They have connected both the battery monitor cable and the CTEK charger cable to the negative battery post.  Can I just attach the negative CTEK charger lead to one of the posts underneath the metal bracket where I would normally attach the crocodile clip?
 

From what I can see, the CTEK lead is currently attached to the negative battery post using a secondary nut, so I should be able to move it without affecting anything else with the battery itself.

 

 

[Kenny R]

1 hour ago, Mark-Surrey said:

Thanks for your sound advice. I just checked, and you are absolutely correct. They have connected both the battery monitor cable and the CTEK charger cable to the negative battery post.  Can I just attach the negative CTEK charger lead to one of the posts underneath the metal bracket where I would normally attach the crocodile clip?
 

From what I can see, the CTEK lead is currently attached to the negative battery post using a secondary nut, so I should be able to move it without affecting anything else with the battery itself.

 

 

Yes, and with a bit of luck the secondary nut you remove will fit the connection on the bulkhead.

[Mark-Surrey]

3 hours ago, Kenny R said:

Yes, and with a bit of luck the secondary nut you remove will fit the connection on the bulkhead.

 Thanks @Kenny R! All sorted now, with your kind assistance