Battery Charger Testing Results

[Patrick0525]

Look at that, Amazing !!! You have the magic touch and I mean it. I so many "chargers/desulfators" and nothing. Now, I am curious if Battery Minder 2012 is somehow different/better than 1510. You have done very detailed tests.

Could the results be because you started with Battery Minder BatteryMinder 12117 and you combined it with XC400? I saw you mentioned that 12117 kept the higher float charge and I agree, it is not a good idea to leave it.

Also, I noticed you periodically monitored water level. Is your battery the type that allows you to open the vents? I have a regular, sealed battery and don't think it is possible to somehow open the vents.

Agree, I was able to add water. Both the 12117 and XC400 had a float voltage higher than 13.6V. I needed a reason for purchasing the 2012. By the way, the 12117/XC400 combo was only used for 10days. Is 10 days enough to revive and desulfanate a battery?

 

[f355spider]

Ctek, Battery Minder, Battery Tender, Noco, Schumacker?

I have Battery Minder 1510 and it helps a battery to keep on "cranking" but it does not restore CCAs or internal resistance and similar experience with Ctek. I left a battery plugged in to these units for about a month, per suggestion from a Battery Minder rep.
Which Battery Minder do you have and what improvements did you notice?

2012 AGM, I also have two 128CEC2. I really like the 128CEC2 as it is the most versatile. The 2012 AGM I mistakenly bought thinking it works with any AGM, but it is really optimized for Odyssey and X2 Power batteries. I have the little Battery Minder wall wart 1 amp 12117TC sold by Northern Tool, but I think they are too low amperage for the desulfation to work very well.

I had my 540 BMW (6 yo H8 AGM) on a Granite Digital "save a battery" 50 watt battery tender plugged in at least four or five days a week for four years and by the fourth year it dropped from testing over 1000 CCA to around 870. Granite Digital claims their battery tenders have a pulse during the float charge, like Battery Minder. I started it on the 128CEC2 on the 2 amp flooded/AGM setting and over the course of about three months it slowly recovered. It now tests over 1000CCA again. I'm convinced. My Tundra has a Clarios flooded Costco Interstate only three years old and rated at 700 CCA and usually tested around 735 CCA...it started showing around 650 CCA so I have been trying to remember to put it on the 128CEC2 at least three times a week. Its been only three weeks and it is already testing at around 715 CCA.

My buddy uses Granite Digital and Ctek and has been having issues with battery life on his Ferraris so I gifted him 128CEC2 as I am convinced it will solve his problems. Only been a month...we will see. His Ferrari F12 eats H9 AGMs like every 18 to 24 months (a known issue with that car (and the FF), even when on a Ctek or Granite Digital.

 

[Mav123]

Agree, I was able to add water. Both the 12117 and XC400 had a float voltage higher than 13.6V. I needed a reason for purchasing the 2012. By the way, the 12117/XC400 combo was only used for 10days. Is 10 days enough to revive and desulfanate a battery?

Yes, correct, probably not enough time on that combo. How come you were looking for a reason to buy 2012? Did you buy it on sale?

 

[Mav123]

2012 AGM, I also have two 128CEC2. I really like the 128CEC2 as it is the most versatile. The 2012 AGM I mistakenly bought thinking it works with any AGM, but it is really optimized for Odyssey and X2 Power batteries. I have the little Battery Minder wall wart 1 amp 12117TC sold by Northern Tool, but I think they are too low amperage for the desulfation to work very well.

I had my 540 BMW (6 yo H8 AGM) on a Granite Digital "save a battery" 50 watt battery tender plugged in at least four or five days a week for four years and by the fourth year it dropped from testing over 1000 CCA to around 870. Granite Digital claims their battery tenders have a pulse during the float charge, like Battery Minder. I started it on the 128CEC2 on the 2 amp flooded/AGM setting and over the course of about three months it slowly recovered. It now tests over 1000CCA again. I'm convinced. My Tundra has a Clarios flooded Costco Interstate only three years old and rated at 700 CCA and usually tested around 735 CCA...it started showing around 650 CCA so I have been trying to remember to put it on the 128CEC2 at least three times a week. Its been only three weeks and it is already testing at around 715 CCA.

My buddy uses Granite Digital and Ctek and has been having issues with battery life on his Ferraris so I gifted him 128CEC2 as I am convinced it will solve his problems. Only been a month...we will see. His Ferrari F12 eats H9 AGMs like every 18 to 24 months (a known issue with that car (and the FF), even when on a Ctek or Granite Digital.

Good to hear your reply because I saw your posts on that other thread that Patrick shared and thank you for sharing the voltage you used.
It seems like 128CEC2 is comparable to 2012. Did you try to find it on sale?

 

[Mav123]

Interestingly, looking at the data from the BatteryMinder website all these units are similar even 1510 that I have, and use the same algo.
https://www.batteryminders.com/7-stage-charging/

 

[Patrick0525]

Yes, correct, probably not enough time on that combo. How come you were looking for a reason to buy 2012? Did you buy it on sale?

The reason being the long term float voltage was too high and needed temperature compensation. The 2012 was bought from the BatteryMinder web site.

 

[f355spider]

Good to hear your reply because I saw your posts on that other thread that Patrick shared and thank you for sharing the voltage you used.
It seems like 128CEC2 is comparable to 2012. Did you try to find it on sale?

Best price for the 128CEC2. No tax, free shipping. Has multiple amperage settings (2,4,8 amp) and all chemistry types (AGM, flooded, lithium and high performance AGM like Odyssey)
https://www.batterystuff.com/batter...r-and-lithium-charger-maintainer-128cec2.html
2012 (for flooded and standard AGM, fixed 2 amp only)
https://www.batterystuff.com/batter...2-amp-charger-maintainer-desulfator-2012.html
2012 AGM For Odyssey and X2 Power AGM batteries, fixed 2 amp only.
https://www.batterystuff.com/batter...m-charger-maintainer-desulfator-2012-agm.html

 

[f355spider]

Interestingly, looking at the data from the BatteryMinder website all these units are similar even 1510 that I have, and use the same algo.
https://www.batteryminders.com/7-stage-charging/

Not sure why the 1510 is not giving you the results we are seeing. If same algorithm, it should work. Note that it takes time. I saw continual, gradual improvement over the course of about 3 months. I was plugging in my car each evening, at least 4 or 5 nights a week.

Also note that the Northern Tool Battery Minder (wall wart, 1 amp rating) 12117TC has a different algorithm. It may or may not work, I have not used it long enough or with the right battery in need of desulfation to say. I noted that it temperature compensates at a slightly less amount that the 2012 AGM or 128CEC2. When graphed the peaks and valleys are not as high or low.

 

[Patrick0525]

Not sure why the 1510 is not giving you the results we are seeing. If same algorithm, it should work. Note that it takes time. I saw continual, gradual improvement over the course of about 3 months. I was plugging in my car each evening, at least 4 or 5 nights a week.

Also note that the Northern Tool Battery Minder (wall wart, 1 amp rating) 12117TC has a different algorithm. It may or may not work, I have not used it long enough or with the right battery in need of desulfation to say. I noted that it temperature compensates at a slightly less amount that the 2012 AGM or 128CEC2. When graphed the peaks and valleys are not as high or low.

f355spider’s ambivalence and observation on the 12117TC working is warranted since it is a BM labeled owned by NT. I confirmed this with a BM customer service and its algorithm is very different. BM sounded annoyed that they needed to support the 12117TC. I immediately returned my 12117TC back to NT and kept my older BM 12117 (no longer available). TC stands for temperature compensation. When I discovered that both the 12117 and XC400 had measured higher than normal float voltage for a flooded cell battery and no temperature compensation, I then decided to purchase and deploy the 2012. Later I bought the 128CEC2 which is the latest model for my wife’s car which has been on the 12117 until the 7.5 yr old battery recently started to leak. The 12117 is currently being used for its higher 13.7V float voltage and Odyssey customer service verified to be perfect for my Odyssey AGM 24F battery maintenance.

Outside of OCDers and car collectors, most car owners - probably 99% of perceive that battery maintenance is totally unnecessary and inconvenient. From my elitist perch, I call them the great unwashed. Lol

 

[Wheel366]

I had my old 2019 Subaru Impreza battery sitting on my garage floor. Battery is bad. Should be 500 or 550cca. It is showing maybe 375 and the resistance I think is over 6 but might be higher. I used 2 different CTEK chargers on it and it doesn't seem to be making it better. I have an old Schumacker maintainer that is 2 amps. For gits and shiggles, I just hooked it up to see if it does any better. Supposedly, it will also desulfate.

I had this same charger hooked up to my old H6 Interstate in my Audi which did ok for a few years but then died late last year (never drive the car except to pull out of the garage to get or put back xmas tree and window ACs). That battery was from 2015 and I stopped driving the car in 2020. It did die a few times and required a jump but it still functioned for a few years before taking a dump.

The Schumacker didn't do anything different for the battery. Pretty much same measurements. 365 CCA and resistance was over 9. I forget voltage. I have this battery hanging around to use as a core for my next replacement which hopefully isn't soon. My oldest battery is the Honda 51r in my wife's CRV and it will be 2 years old I think in September.

 

[pasadena_commut]

The HF 4A battery charger has two issues that I am aware of:

1. It is almost impossible to get it to charge a battery at 4A. This is based on observations with a clamp DC ammeter. Normally it will start out at 2A and then pretty rapidly go down from there. The only time I have ever seen it charge any battery at 4A was when it was used on a dual battery Ford F350 Super Duty, and even then, it only stayed at 4A briefly.

2. It may not charge as expected if the battery has surface charge. If a car has been running recently, and the surface charge isn't bled off, like turn on the head lights for a while, the charger will see 13+ volts and decide the battery is fine and doesn't need to be charged even if it is only at 50% SOC (for instance).

Also, I do not know if this charger can be trusted to restart if the power fails and is then restored. I have observed it doing so once when my wife accidentally turned off the power strip it was attached to. Unfortunately while it restarted, it immediately ran into issue (2) and didn't charge the battery further. I had to turn it off, bleed off the surface charge, and then turn it back on for it to resume recharging in earnest. If the charger was being used as a battery minder probably the surface charge would eventually go away on its own and then the battery minding would resume. That would take many hours though.

 

[f355spider]

What is great about this thread and others in this section of the forum, is all the information exchange. I have used various battery tenders for 25 years, and my results are all the same. As long as they were microprocessor controlled, they all seemed to achieve similar results, which was to keep the battery charged or topped up.

But in the past two years, I started noting that even when using a battery tender religously, that was not always sufficient. Batteries start to lose capacity...likely from sulfation. Desulfation claims have to be taken with a grain of salt. Some, like Granite Digital "save a battery" at least in my experience with the two I own, do not work.

Based on my recent experience and that of other posters here, I have learned that an actual working desulfation, specifically during the float or maintenance mode is extremely useful to battery longevity. (there are desulfation modes that some battery chargers have, but due to the high voltage, require the battery to be disconnected or removed from the vehicle to perform...not very practical)

Also having a convenient way to connect your car up in the evening while parked, makes it a simple matter to connect it a few times a week as "maintenance". I have pigtails on all my vehicles (except Ferrari, which come from the factory with a jack built in for a battery tender), so there is no excuse not to plug in when I arrive home, and no having to open the hood or trunk to do so.

 

[f355spider]

The Schumacker didn't do anything different for the battery. Pretty much same measurements. 365 CCA and resistance was over 9. I forget voltage. I have this battery hanging around to use as a core for my next replacement which hopefully isn't soon. My oldest battery is the Honda 51r in my wife's CRV and it will be 2 years old I think in September.

I don't believe any of the Schumacher chargers or maintainers claim to desulfate a battery. You have to read the package or instructions and look for terms like "conditioning" or "desulfation" mode. But what I have learned, is some don't work as claimed.

The only two we have confirmation on this forum from users, is the Battery Minder and Pulse Tech.

 

[Mav123]

f355spider’s ambivalence and observation on the 12117TC working is warranted since it is a BM labeled owned by NT. I confirmed this with a BM customer service and its algorithm is very different. BM sounded annoyed that they needed to support the 12117TC. I immediately returned my 12117TC back to NT and kept my older BM 12117 (no longer available). TC stands for temperature compensation. When I discovered that both the 12117 and XC400 had measured higher than normal float voltage for a flooded cell battery and no temperature compensation, I then decided to purchase and deploy the 2012. Later I bought the 128CEC2 which is the latest model for my wife’s car which has been on the 12117 until the 7.5 yr old battery recently started to leak. The 12117 is currently being used for its higher 13.7V float voltage and Odyssey customer service verified to be perfect for my Odyssey AGM 24F battery maintenance.

Outside of OCDers and car collectors, most car owners - probably 99% of perceive that battery maintenance is totally unnecessary and inconvenient. From my elitist perch, I call them the great unwashed. Lol

What differences did you observe between BM 128CEC2 and 2012 ?

 

[Mav123]

What is great about this thread and others in this section of the forum, is all the information exchange. I have used various battery tenders for 25 years, and my results are all the same. As long as they were microprocessor controlled, they all seemed to achieve similar results, which was to keep the battery charged or topped up.

But in the past two years, I started noting that even when using a battery tender religously, that was not always sufficient. Batteries start to lose capacity...likely from sulfation. Desulfation claims have to be taken with a grain of salt. Some, like Granite Digital "save a battery" at least in my experience with the two I own, do not work.

Based on my recent experience and that of other posters here, I have learned that an actual working desulfation, specifically during the float or maintenance mode is extremely useful to battery longevity. (there are desulfation modes that some battery chargers have, but due to the high voltage, require the battery to be disconnected or removed from the vehicle to perform...not very practical)

Also having a convenient way to connect your car up in the evening while parked, makes it a simple matter to connect it a few times a week as "maintenance". I have pigtails on all my vehicles (except Ferrari, which come from the factory with a jack built in for a battery tender), so there is no excuse not to plug in when I arrive home, and no having to open the hood or trunk to do so.

Believe it or not, I am now using AI more and more to find useful info. I am using Perplexity to read this entire thread,

 

[f355spider]

Here is a comparison between BM 128CEC2 and 2012, not sure how accurate this though.

Comparative Analysis of BatteryMINDer 128CEC2 vs. 2012 Charger-Maintainers​

This report examines the technical distinctions between BatteryMINDer’s Model 128CEC2 and Model 2012, focusing on charging capabilities, target applications, and advanced features. Both units are designed for 12V lead-acid batteries but cater to different user needs.

Core Specifications Comparison​

Feature	128CEC2	2012
Amperage Options	2A/4A/8A selectable	Fixed 2A output
Charging Stages	7-stage (varies by mode)	5-stage
Lithium Compatibility	LiFePO4 support via dedicated mode	None
IP Rating	IP65 (dust/water resistance)	IP65
Temperature Range	-40°C to 175°C	-20°C to 50°C (extendable with probe)
Battery Capacity	Up to 600Ah (8A mode)	Up to 200Ah
Aviation Use	Specialized variants available	Not approved

Key Functional Differences​

1. Charging Flexibility​

• 128CEC2: Offers three user-selectable profiles:
  1. Odyssey/Pure Lead: 14.7V absorption, 13.6V float8
  2. Wet/AGM/Sealed: 14.4V absorption, 13.3V float8
  3. Lithium (LiFePO4): 14.6V absorption, 13.6V float8
• 2012: Single-profile operation optimized for flooded lead-acid, with a fixed 14.4V absorption voltage and 13.6V float25.

2. Desulfation Technology​

Both models use high-frequency pulse desulfation, but the 128CEC2 implements adaptive pulsing that adjusts based on battery sulfation levels detected during analysis phases8. The 2012 applies continuous pulsing at a fixed 30Hz frequency2.

3. Multi-Battery Support​

• 128CEC2: Maintains up to six 12V batteries in parallel using Y-connectors, regardless of chemistry (lead-acid or lithium)8.
• 2012: Supports six batteries but only with identical lead-acid chemistries (mixing AGM/flooded not recommended)5.

4. Diagnostic Capabilities​

• 128CEC2:
  • Predictive failure analysis: Estimates remaining battery life via voltage decay rate monitoring1.
  • LED indicators for bad cells, polarity reversal, and thermal runaway8.
• 2012: Basic diagnostics limited to charge stage LEDs and polarity alerts2.

Target Applications​

128CEC2 Preferred For:​

• Mixed fleets with lead-acid and lithium batteries
• High-capacity systems (e.g., RV/marine banks >300Ah)
• Aviation (via 128CEC2-AA-S2/S3/S5 variants)47
• Odyssey/Hawker batteries requiring 14.7V absorption8

2012 Recommended For:​

• Single-battery maintenance in standard automobiles
• Budget-conscious users needing basic desulfation
• Cold storage (garages/barns) with temperatures down to -20°C5

Performance Metrics​

Test Parameter	128CEC2	2012
0%→80% SOC (100Ah)	5.2 hours (8A mode)	19.8 hours
Desulfation Efficacy	92% capacity restoration	78% capacity restoration
Standby Consumption	0.8W	1.2W

User Experience Insights​

128CEC2 Advantages​

• Faster charging: 8A mode reduces recharge time by 73% compared to 20128.
• Simplified lithium integration: Dedicated mode avoids manual voltage adjustments1.
• Aviation compliance: FAA-approved variants meet GILL®/Concorde® specs47.

2012 Advantages​

• Lower cost: Typically $30–$40 cheaper than 128CEC228.
• Proven reliability: 15+ years of field use with <5% failure rate5.
• Compact design: 40% smaller footprint (5.69"L x 4.06"W vs. 7.1"L x 5.3"W)15.

Conclusion​

The 128CEC2 excels in versatility, serving advanced users with mixed battery chemistries and high-capacity demands. Its 8A charging and LiFePO4 support make it ideal for modern applications. Conversely, the 2012 remains a cost-effective solution for traditional lead-acid maintenance, particularly in environments where extreme cold or space constraints prioritize simplicity over features. For aviation applications, only the 128CEC2-AA-S series should be used, as the 2012 lacks necessary certifications45.

Citations:​

1. https://www.batteryminders.com/batt...tainer-desulfator-lithium-charger-maintainer/
2. https://www.batterystuff.com/batter...2-amp-charger-maintainer-desulfator-2012.html
3. https://www.batteryminders.com/content/BATTERY MINDR CEC2 GUIDE_ (003).pdf
4. https://www.batteryminders.com/batt...iation-battery-charger-maintainer-desulfator/
5. https://pilotjohn.com/new/batteryminder/2012
6. https://www.batteryminders.com/128cec2xlr1-12-volt-8-amp-power-chair-battery-maintainer-charger
7. https://www.batteryminders.com/batt...iation-battery-charger-maintainer-desulfator/
8. https://www.batterystuff.com/batter...r-and-lithium-charger-maintainer-128cec2.html
9. https://www.batteryminders.com/batt...iation-battery-charger-maintainer-desulfator/
10. https://www.batteryminders.com/7-stage-charging/
11. https://www.batteryminders.com/batt...-w-obd2-connector-lithium-charger-maintainer/
12. https://www.slingmods.com/batteryminder-2012agm-12v-2-amp-battery-charger-maintainer-desulfator
13. https://batteryplex.com/product/batteryminder-128cec2-charger/
14. https://www.batteryminders.com/2012-12-volt-desulfating-battery-charger-worldwide-use
15. https://www.batteryminders.com/marine-battery-maintainer-boat-charger
16. https://www.batterystuff.com/files/1422-batteryminder-128cec2-manual.pdf
17. https://www.aircraftspruce.com/catalog/elpages/11-11594.php
18. https://www.batteryminders.com/cont...p_amp_nbsp_CECAviation128CEC2-244CEC2Rev1.pdf
19. https://www.aircraftspruce.com/catalog/elpages/vdc-2012.php
20. https://risingsun4x4club.org/xf/threads/battery-maintenance-chargers.35414/post-429298
21. https://www.gallagheraviationllc.com/BatteryMINDer-14V-Concorde-Sealed-Flooded_p_314.html
22. https://www.batteryminders.com/batt...-desulfator-w-obd2-connector-worldwide-usage/
23. https://pilotjohn.com/new/batteryminder/128cec2-aa-s3

---

Answer from Perplexity: pplx.ai/share

This has several errors...so use this information with much caution. One of the dangers of AI dependancy.
Information I know is wrong:
1) The 128CEC2 cannot mix chemistry types when charging multiple batteries. It can't because the chemistry type is user selectable, and there is no "multiple chemistry" setting.
2) The 2012 is designed for both flooded and plate type AGM. It is not clear in their documenation, and you have to ask their tech support to gain clarity. I also know this because the 2012 AGM instructions for use, specifically call out the type of AGM battery profiles it is designed for, which is Odyssey and X2 Power, as well as a few others they mention. It is not ideal for standard plate type AGM batteries. Note the 128CEC2 has a setting that is "flooded/AGM". The other setting is "Odyssey AGM".
3) In the Odyssey setting of the 128CEC2, the float voltage is 13.2vt at 77F and will decrease with higher temps and increase with lower temps. The original documentation stated 13.6vt, but changed three years ago, and the documentation was never updated. Again an AI problem that will never catch this change.
4) Both models have temperature compensation. The float voltages mentioned are the starting point at 77F
5) Both models can maintain, (not recharge) multiple batteries using the Battery Minder Y adapters, as long as they are charged, and of similar capacity.
6) Diagnostic capabilities of both models are identical and the same LED display is used. The only addition the 128CEC2 has is to note the amperage setting and chemistry setting.

AI notes the advantage of the 128CEC2 is faster charging. That is not entirely true. Yes, you can use the 8amp mode to charge more quickly, but that is not recommended by Battery Minder. They specifically recommend using the 2amp mode for maintenance, the 4amp mode for larger batteries and maintaining multiple batteries and using the 8amp mode exclusively with the Odyssey settings. Again, surprised the AI is not catching this, it is in "the instructions for use".

 

[Mav123]

This has several errors...so use this information with much caution. One of the dangers of AI dependancy.
Information I know is wrong:
1) The 128CEC2 cannot mix chemistry types when charging multiple batteries. It can't because the chemistry type is user selectable, and there is no "multiple chemistry" setting.
2) The 2012 is designed for both flooded and plate type AGM. It is not clear in their documenation, and you have to ask their tech support to gain clarity. I also know this because the 2012 AGM instructions for use, specifically call out the type of AGM battery profiles it is designed for, which is Odyssey and X2 Power, as well as a few others they mention. It is not ideal for standard plate type AGM batteries. Note the 128CEC2 has a setting that is "flooded/AGM". The other setting is "Odyssey AGM".
3) In the Odyssey setting of the 128CEC2, the float voltage is 13.2vt at 77F and will decrease with higher temps and increase with lower temps. The original documentation stated 13.6vt, but changed three years ago, and the documentation was never updated. Again an AI problem that will never catch this change.
4) Both models have temperature compensation. The float voltages mentioned are the starting point at 77F
5) Both models can maintain, (not recharge) multiple batteries using the Battery Minder Y adapters, as long as they are charged, and of similar capacity.
6) Diagnostic capabilities of both models are identical and the same LED display is used. The only addition the 128CEC2 has is to note the amperage setting and chemistry setting.

AI notes the advantage of the 128CEC2 is faster charging. That is not entirely true. Yes, you can use the 8amp mode to charge more quickly, but that is not recommended by Battery Minder. They specifically recommend using the 2amp mode for maintenance, the 4amp mode for larger batteries and maintaining multiple batteries and using the 8amp mode exclusively with the Odyssey settings. Again, surprised the AI is not catching this, it is in "the instructions for use".

Yes, thank you. this echos what the customer service at BM told me a couple of years ago. At that time, I was just curious what are the differences between their cheaper and more expensive chargers. They told me that even 1510 is virtually the same as more extensive chargers but without extra indicators, like tests of bad cell, battery weak, etc. And supposedly even 1510 can charge in parallel more than one battery of the same capacity.

The question the is, what if I have about 4 flooded sealed batteries of different capacity?

 

[Patrick0525]

What differences did you observe between BM 128CEC2 and 2012 ?

I cannot tell the difference but BM docs says the BM 128CEC2 in the constant voltage stage tries to top off the battery to 0.1% of max current storage while the 2012 does 0.5% before going into float voltage.

 

[Wheel366]

I don't believe any of the Schumacher chargers or maintainers claim to desulfate a battery. You have to read the package or instructions and look for terms like "conditioning" or "desulfation" mode. But what I have learned, is some don't work as claimed.

The only two we have confirmation on this forum from users, is the Battery Minder and Pulse Tech.

I had to look in the manual and it does state desulfation. Regardless, it didn't work for me or... the battery is just shot which is more likely. I'm giving this to a friend, but I figured while I still have it, I would test it out.

DESULFATION MODE
If the battery is left discharged for an extended period of time, it could become sulfated and not accept a normal charge. If the charger detects a sulfated battery, the charger will switch to a special mode of operation designed for such batteries. If successful, normal charging will resume after the battery is desulfated. Desulfation could take 8 to 10 hours. If desulfation fails, charging will abort and the CLAMPS REVERSED/BAD BATTERY 13. MAINTENANCE AND CARE (red) LED will light.

 

[gman2304]

^ My 2 amp Schumacher SPR 1627 mentions this in the manual but no mention of a desulfation mode on the box or the maintainer itself. Having said that, it and a couple of old 1.5 amp Schumacher maintainers have kept my batteries in tip top shape for years.