andyrudandyrud Solar Expert Posts: 60 ✭✭
Hi everyone. Just installed 6 Trojan 2V L16RE batteries and was reading about battery desulfators. What is the general concensus about these things? Would you start using one on new batteries?

Thanks in advance,


  • BB.BB. Super Moderators, Administrators Posts: 30,485 admin
    Re: Desulfators?

    Here is a search (Google based) of the forum for "desulfator"...

    The short answer, they do not appear to hurt the batteries. Some people think they work well on sulfated batteries, some people believe that if you put them on new batteries it helps extend their life, and many people believe that desulfators do not really help at all (or at best, only seem to work in a few cases).

    There are strong opinions on all sides. :roll:

    I am in the last category--so I am not the guy to talk about the benefits.

    The best thing to do--is take care of a lead acid battery bank in the first place.
    • Never cycle a bank below 20% state of charge--can kill cell / battery immediately
    • Avoid cycling often below 50% state of charge--will reduce the cycle life of the battery
    • Avoid operating/storing battery below 75% state of charge for days/weeks/months--Will cause sulfates to "harden" (and lose battery capacity)
    • Try to bring the battery to at least 95% state of charge once a week or so
    • Equalize battery around 5% of 20 Hour Rated Capacity
    • Charge battery bank around 5-13% of 20 Hour Rated Capacity
    • Do not equalize the battery unless it is needed (variation between cells of 0.015 to 0.030 specific gravity)
    • Stop equalization once the specific gravity stops rising in low cells (after 30-60 minutes)
    • Only use distilled water/filtered rain water for refilling cells.
    A couple battery FAQ's to read:

    Deep Cycle Battery FAQ

    -Bill "duck and cover" B.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PhilSPhilS Solar Expert Posts: 370 ✭✭✭
    Re: Desulfators?

    What Bill suggested --- that's gonna help keep your batteries alive more than anything else.

    I have two desulfators installed on my bank of 12 -- one on each end. This is the fourth set of batteries. The first set lasted 8 years. The second set lasted 8 years. I "cheaped out" and bought "these are as good as Trojans". They lasted 3 years.

    I'm now using a set of US batteries and the desulfators are still installed.

    I believe they don't hurt. Whether they help is a pretty difficult claim to make.

    At this point in time, there is nothing that has indicated an overwhelming reason to install them. By my experience alone, I wouldn't buy them again. But if I'd have had an identical bank in parallel without them, and IF that bank had always gone bad before the bank that had desulfators, I'd think otherwise.

  • bryanlbryanl Solar Expert Posts: 175 ✭✭✭✭✭
    Re: Desulfators?

    Bill has a good list but it may illustrate the reason behind his view on desulfation devices.

    If you can keep the electrolyte well mixed and if you can keep a full charge on the battery, sulfation should be a simple nominal aging problem. Those two criteria are not as easily achieved in practice as it may seem.

    Electrolyte mixing usually means a bit of current in or out of the battery. That may be behind why wet cell lead acid batteries don't do well in float service. The balance is to not let too much current in or out which means proper balancing of your system components and usage. Both the state of charge and the charge and discharge currents are important here.

    A full charge is not so simple either, which is why old tech float chargers are not optimum. Temperature, age, and other factors can make it difficult to maintain a proper full charge. Too much and you get plate corrosion. Too little and you get sulfation.

    Then there's the issue that it can take 8 hours or more to properly charge a battery.

    I see two scenarios where the issue becomes significant. One is when there is an imbalance in system components and usage in a system under continuous use. The other is when the system spends a lot of time in standby (as in typical RV use).

    In the RV context, I see many folks who switched from low current high float charger maintainers to devices like the Progressive Dynamics ChargeWizard that are much happier with their battery systems. In other contexts, I have seen folks use pulse desulfation devices like the BatteryMINDer to maintain batteries that have been happy with the results. What I haven't seen is good hard measure of the sort I'd like to see, but that sort of measure seems to be very difficult to obtain when it comes to many battery phenomena.

    What I haven't seen is anyone blaming the desulfation devices for battery failure with any credibility. Worst case for them seems to be negligible impact which is much better than most of the float only maintainers.
  • andyrudandyrud Solar Expert Posts: 60 ✭✭
    Re: Desulfators?

    I just received this response from Trojan battery Company and thought I would share it with the group. I find it interesting.


    Good to hear from you, the desulfator idea has been around for some time. As controversial as it may be, the consensus seems to be satisfaction.

    For some customers the satisfaction may be defined or justified in terms of a perceived savings on the cost of the battery, or the elusiveness of the fountain of youth metaphorically speaking for the battery. For some battery people, satisfaction is based on tangible results of controlled experimentation. The data collected from the devices Trojan has tested have shown little or no improvement to substantiate neither a positive opinion nor an endorsement of the desulfators we have tested.

    However, we have done extensive data collection based on laboratory data, field testing, and actual user feedback to underline that the most important way of satisfying the needs of a battery to live a long life and give their complete design performance, is to do meticulous and consistent battery maintenance. A well design system —that includes adequate charging for the load applied, should in theory be enough so that with the correct maintenance schedule, battery sulfation will be the consequence of end of life, not the cause of it.

    Please if you wish to discuss this further don’t hesitate to call me.
  • PhotowhitPhotowhit Solar Expert Posts: 5,169 ✭✭✭✭
    Re: Desulfators?

    How did he know what Bill said?

    Maybe Bill works for Trojan?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do
  • BB.BB. Super Moderators, Administrators Posts: 30,485 admin
    Re: Desulfators?

    Bill types a lot but says little.:roll:

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PhilSPhilS Solar Expert Posts: 370 ✭✭✭
    Re: Desulfators?

    Having had Desulfators for many years, I always look at a thread about them.

    WisJim started a thread on the 7th with something I'd never heard before:

    Desulfators sometimes don't play nice with MPPT controllers.

    I found that to be true in my case. I made a post to his thread with my results.

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