[Feanor]

I've just bought a CTEK MXS 5.0 battery charger and since I'm going away for ten days tomorrow and have been doing lots of short journeys recently I've connected it up. My car still has the original battery from 2012 so I thought I'd give it a recondition.

Only the instructions are really confusing and badly worded as to whether the recon mode is suitable for AGM batteries, and online isn't much better. Recon mode only appears to be a no-no as that appears to be for older type batteries but what's confusing me is that my charger has an "AGM Recon" mode. The manual, however, suggests that these basically treat the battery in the same way, giving it the same level of voltage.

I've read loads of old forum posts about recon mode and battery charging in general but nothing I could find deals specifically with "AGM recon" on relatively newish BMWs, and I don't want to come back from holiday to find I've killed my car battery so I'd really appreciate any knowledgeable advice. If it's the wrong thing to do I can switch it off recon mode tonight or first thing before we go to the airport.

Thanks in advance!

[HighlandPete]

Unless you can get a definitive answer, from someone who fully understands the subject, I'd be cautious of using the Recon function with its 15.8 volt charging rate.

BMW state the following for the AGM battery type, in Battery Basics.

Charging
When charging batteries in the "stand alone" mode, the maximum charge voltage of 14.8 volts must not be exceeded. Even briefly charging an AGM battery with a charge voltage of more than 14.8 volts (voltages usually used in rapid charge programs) will damage the battery.

[Feanor]

Good to see you're still about after all these years Pete! OK thanks for the prompt reply - you may well have saved my battery I've switched it off Recon mode and into basic car AGM mode and it hadn't reached the recon stage yet.

At some point I'll email CTEK and ask for their advice as I do think this needs answering definitively. Their instructions really are abysmal considering this is supposed to be a premium and market leading charger and considering the risk over voltage apparently poses to AGM batteries.

[bimmer456]

I use the $69 BMW charger you just plug it in and it dies the rest. I did see a new one at the dealership that has some AGM mode but the one I have works fine.

[subaquaal]

This is what I got from CTEK. I think this explains it all.
I have an Z4 E89 with an AGM battery. Recond function doesn't help nor harm my battery.

HI!

Recond program is developed only for flooded batteries (including EFB), to remix the flooded acid inside.
The remixing/balancing is necessary to treat an already stratified battery, or to prevent severe stratification.
AGM or GEL batteries are not flooded, and therefore does not suffer from stratification. That means Recond will not help AGM or GEL.
Reconding an AGM battery does not harm the battery, but does not help either, so we cannot recommend recond program on AGM batteries either.
For GEL batteries, recond can be harmful, because using too high voltage can dry the gel inside the battery and weaken the battery instead of empowering it.
NOTE:
When you choose Recond program, you should note that Recond program always starts with a normal battery charging program. Then, after battery has reached fully charged, Recond treatment itself is implemented. Depending of charger model and battery size, Recond step lasts from ½ to 4 hours, on top of the charging time.
When charger turns to green light, the program is completed.

I will explain here more about the topic:
So, Recond is made for remixing flooded acid inside the battery– hence, stratified batteries.
What is stratification?
Stratification is when the acid inside the battery gets layered.
As long as the acid and the water of the electrolyte in the battery are well mixed, the battery works as it should. But if the acid and water separate into layers, the battery just cannot be charged anymore regarding the parts that are layered, not by the alternator, nor by a charger.
So, acid that gets layered inside a battery causes loss of capacity.
WHY does the batteries get stratified?
Stratification can happen if the alternator charging voltage is too low or the charging time is insufficient (due to short drives for instance, or a lot of parallel loads during drive). Or if a battery is deeply discharged and unused for a period. Different batteries suffer more or less of stratification, depending of the battery type and qualifications.
Why is stratification a problem?
A stratified battery cannot store voltage as well as a healthy battery, and behaves as a smaller battery than it is. When conventionally charged - by the charger or the alternator- only the parts that still are ok, will be charged. So, a battery seems to be fully charged – but can be emptied by one start attempt. Stratification also promotes corrosion on the upper half of the plates and sulphation problems at the bottom.
Why does recond help?
Recond causes a controlled gassing that remixes the acid and equalizes the acid balance and through that the battery capacity is reclaimed and battery efficiency is restored, partially or almost all of it, depending how severe the problem is.

Just one more thing: Do not mix Stratification with Sulphation problems! Sulphation affects all kind of lead/acid batteries AND every CTEK charging program starts with a desulphation step, so you do not have to worry about that!!

Hope this was helpful
Best regards,
CTEK SUPPORT TEAM

[subaquaal]

Originally Posted by Feanor

but what's confusing me is that my charger has an "AGM Recon" mode.

I have the same CTEK charger. I think you have misread the text on the charger. The "AGM Recond" mode is in fact a "AGM" mode and an "Recond" mode.
It has four modes.
1. Motorcycle
2. Car
3. AGM
4. Recond.

[walmark]

Originally Posted by subaquaal

I have the same CTEK charger. I think you have misread the text on the charger. The "AGM Recond" mode is in fact a "AGM" mode and an "Recond" mode.
It has four modes.
1. Motorcycle
2. Car
3. AGM
4. Recond.

Since I found this post very useful, I wanted to clarify something:

The charger has 4 LED lights, but actually 8 modes. Depending on how many times you press the MODE button you will switch between:

- Motorcycle - flooded - charge
- Motorcycle - flooded - recond
- Motorcycle - AGM - charge
- Motorcycle - AGM - recond
- Car - flooded - charge
- Car - flooded - recond
- Car - AGM - charge
- Car - AGM - recond

Each option adjusts:
- Motorcycle - small battery (1.2 - 14Ah) - 0.8A max current
- Car - large battery (14 - 160Ah) - 5A max current
- flooded - 14.4V charging voltage
- AGM - 14.7V charging voltage
- recond - 15.8V/1.5A recondition cycle


According to the explanation above there should NOT be a "AGM - recond" mode. Also, based on the manual, the recond should not be used on small (motorcycle) batteries. And yet you can select all of these modes just cycling with the MODE button, so use your best judgement!

[cdgatti]

Realize old thread. Just learned that the record mode is recommended for flooded and Ca batteries. Not for AGM batteries. However the Ca batteries benefit from the higher voltage of the AGM setting, so AGM/recond is really the setting for charging and reconditioning Ca batteries. For AGM don’t use the Recond feature.

[Soul_Glo]

This is a very interesting read:

https://www.impactbattery.com/blog/p...s-do-they-work

“Electric snake oil” that kills the battery over time is one explanation.

Pulse and or sine waves is another.

No definitive answer. Although seems to lean towards reconditioning can work in some cases.

In summer I’d see my 12v battery resting at 13.2v and sometimes even 13.7v. I used to joke with my mechanic that it should be called a 13v battery. When in use it can get up to 14.7v with engine on. Once I even noted 15.2v with a/c on. I do wonder if they are deliberately undercharged. Imagine if you were hitting 15v regularly on each charge. Could flatten the battery over time?!

[Soul_Glo]

Originally Posted by cdgatti

Realize old thread. Just learned that the record mode is recommended for flooded and Ca batteries. Not for AGM batteries. However the Ca batteries benefit from the higher voltage of the AGM setting, so AGM/recond is really the setting for charging and reconditioning Ca batteries. For AGM don’t use the Recond feature.

CTEK have an AGM recon mode. Little is understood about the types of pulse etc. Interesting stuff. However, AGM batteries do not suffer acid stratification like wet batteries do. Therefore this mode is quite possibly “electric snake oil.”

[Soul_Glo]

Billfitz the authority on sine waves and hertz in general. What are your thoughts on the matter please?

[Billfitz]

DC doesn't have sine waves or Hz.

According to CTEK: ”Recond program is developed only for flooded batteries (including EFB), to remix the flooded acid inside. The remixing/balancing is necessary to treat an already stratified battery, or to prevent severe stratification. AGM or GEL batteries are not flooded, and therefore do not suffer from stratification. That means Recond will not help AGM or GEL.

Reconding an AGM battery does not harm the battery, but does not help either, so we cannot recommend recond program on AGM batteries."

[pcourtney123]

There are Silver Calcium batteries where the CTEK AGM Recond mode is used with great effect.

CTEK wrongly mislabel this, but if you do have a "Silver Calcium" battery then the combination of AGM Mode and Recond Mode is what you need ONLY for Calcium (Silver Calcium) batteries.

Calcium batteries need a high voltage charge, just like AGM batteries do.

Calcium batteries can suffer from acid stratification (as their insides have free-flowing acid electrolyte).

Therefore, the Recond AGM Mode is needed for reconditioning Calcium batteries.

NB do not use Recond for AGM batteries !