Interaction of desulphator and MPPT charge controller

WisJimWisJim Solar Expert Posts: 59 ✭✭✭
Hello
I have heard comments recently that a desulphator won't work in combination with a MPPT charge controller. I'm not arguing whether a desulphator works as promoted or not, but whether there is an electronic conflict between a desulphator and a MPPT charge controller that are both connected to the same battery bank.

I'm using an Outback MX-60 with 1.5kW of Kyocera PVs charging a 1500AH set of 2 volt cells, with a DS-1000 desulphator connected to the battery.

Any one have any knowledge or experience on the subject?

Jim

Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,612 admin
    Re: Interaction of desulphator and MPPT charge controller

    No direct knowledge--And, I have not read anywhere where they are not working together...

    However, I can foresee some issues.

    Desulphators work by placing a square wave or impulse wave (for short, "high current" spike) into the battery bank wiring. This impulse wave by design has a very high frequency content that can go from audio to Radio Frequency range. This is how a desulphators do their job--The "kick" is what is supposed to break up the lead sulfate crystals and get the sulfur back into the electrolyte and recover battery capacity.

    It turns out that some MPPT charge controllers can be confused by non-DC voltage fluctuations being imparted to a battery bank. BlueSky charge controllers have been reported as failing to properly do their MPPT function when subjected to 120 Hz ripple from a 60 Hz AC inverter.
    The patent relates to using a % of VOC for the vmp value, no one does this these days including almost all the Blue Sky products themselves

    Also performance and efficiency wise they are not that great, in the 93% area. The SB50 is a VERY old design, close to ten years old.

    One way I could make the Blue Sky unit fail to tracking was put an inverter load on it, the current ripple confused the charger mppt hunting ( it stalled until the inverter was turned off ), which is not the patented approach btw.

    So, I could see that audio/RF energy from the battery bank (from desulphator or other loads such as motors, inverters, etc.) could back-feed into a charge controller and cause it confusion or failure to charge.

    But, again, no problems have been reported. But--unless somebody was looking for poor MPPT function or other issues with expensive test gear--People may not ever find any problems in the first place.

    However, given all of the other sources of "battery bank noise" (loads and even other paralleled PWM charge controllers)---I would not worry about connecting a desulphator to a battery bank--Just install it near the battery bank and not directly on the MPPT charge controller output lugs (this keeps the RF energy close to the battery where it will do good vs at the charge controller where it could cause problems).

    I hope I helped.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PhilSPhilS Solar Expert Posts: 370 ✭✭✭
    Re: Interaction of desulphator and MPPT charge controller

    Certainly something I'd never heard but also something I can't dismiss from my prior experiences. I have three Outback MPPT controllers and two DS1000 desulphators on my bank. They're fed by a 2.9KW solar bank.

    I've had problems with the FM60 being outperformed by an MX60 frequently, tho the FM has significantly more solar feeding it. I got an upgraded FM because of this... Outback was great on customer service, I'd posted the situation on the Outback forum and was contacted and sent a unit with upgraded firmware which helped (most of the time). But sometimes the readings are still more for the MX than the FM which shouldn't be.

    I'm gonna disconnect the DS1000's and see if it makes any difference on the two Outbacks. Can't hurt doing that for a few weeks. Could diagnose a problem with the FM60.

    Phil
  • mike95490mike95490 Solar Expert Posts: 9,572 ✭✭✭✭✭
    Re: Interaction of desulphator and MPPT charge controller

    I use the BATTERY LIFE SAVER DE-SULFATOR 48v on my bank. Also with the MS Tristar MPPT 60A controller. I've not noticed any charging problems, or any results yet, after 2 months. I don't think it's hurting, but with shorter days coming up, charging will be more critical.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Interaction of desulphator and MPPT charge controller

    Most likely the MX's output would overwhelm the desulphator and render it useless. I'm thinking the steady current from the OB would negate any pulsing effect from the desulphator; I think they need to do a true "on/off" pulse to have any effect. Not sure what frequencies they operate at, but we have seen that data from Morningstar re: their PWM controllers.

    In the broader sense, it is just possible that Brand "A" desulphator works differently from Brand "B" , and that one would work while the other caused issues. It is even possible that "A" would work with Battery "X" but not Battery "Y" and vice versa in respect to "B". If you get what I mean.

    And if you do; could you explain it to me? :p
  • PhilSPhilS Solar Expert Posts: 370 ✭✭✭
    Re: Interaction of desulfator and MPPT charge controller

    I pulled the fuses on both Desulfators to 'turn them off', weekend before last.

    As I mentioned above, when I put a new FM60 onto a 1020 watt bank (48V? three pairs of Mitsubishi MF170) that did have an MX60, I got consistently less output than the MX had given on that bank . I had moved the MX to a new set of panels with 780 watts (54V, I think, 3 Sun HS130 panels in a string, two strings). I did this to put the better cooling fan on the bigger solar bank since I'm pushing the limits for a 12V battery bank. (OK, Bill, "exceeding" the limits" :roll: )

    I posted at the Outback forum, and Outback contacted me after reading my post. She asked if I had a Xantrex inverter (yes, SW2512MC) and she mentioned there were conflicts with the earlier Revs and some Xantrex inverters. Because I had an earlier Rev than the 2.0, Outback shipped me a new one with the Rev 2.0.

    The problem was better but not perfect. Randomly, the MX would outperform the FM. Also randomly, at the end of the day, the total KWH from the MX would be more than the FM. All panels together in a line, ground mount, no shading or other things that should cause that. Some days the FM did better and some the MX did better. I just accepted it because... I felt I had to.

    Since deactivating the Desulfators, the FM always has more KWH at the end of the day.

    Watching them occasionally this last weekend, the FM always outperformed the MX. And it seemed that both did much better (no measurements, just years of experience looking at the readings... it was like both the FM and MX had slurped down a Red Bull!). At the peak of the day, the FM was cutting off at 60 - 61 amps, as it's s'posed to but I haven't seen that since the FM was installed. The MX was hitting 58 amps, which it never did on this new set of panels. (It didn't seem to make any difference on my 3rd MX60 tied to 780 watts of panels but at 12V.)

    So my unscientific conclusion is that the two DeSulfators DID interfere with the Outback controllers. They will remain "off" and THANK YOU WisJim for asking the question!!

    Phil
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Interaction of desulphator and MPPT charge controller

    "Interfere with" may not be quite the right term.
    Since desulphators apply power to batteries, perhaps the OB units were just "dialing down" against an additional current input?

    And I have to ask: in an off-grid system, where does the power to run the desulphators come from?

    I wonder if it might be better to use these, say, once a month in place of or in conjunction with equalization?

    The difficulty in testing desulphators' effectiveness lies in the need to have two identical batteries that will either be charged/discharged optimally over ten years (one with, one without desulphator) to see what the long term "preservation" effect is or worse, two identically sulphated batteries to try and and recover. It's getting any two batteries to behave identically that becomes problematic. Until then, we are left with company's claims (decidedly biased, since they're trying to sell the things) and anecdotal evidence.

    But it is still possible that the pulsing would interfere with the MPPT program.
  • PhilSPhilS Solar Expert Posts: 370 ✭✭✭
    Re: Interaction of desulfator and MPPT charge controller

    They're powered by 12V, Coot. One installed at one end of the bank, the second on the opposite end of the battery bank, as the instructions for ordering suggested. And two because of the bank size (six pairs).

    It's gotta be something with the output frequency that affects the controllers. Just as Outback said that (before Rev 2) a frequency generated by the Xantrex inverter affected the output.

    I think I'll just run this new bank without them and see what kind of service I get. The controller performance is so incredibly better I'm just amazed. I can't imagine once a month doing anything, as it's been hard to imagine that they have been doing anything at all, but I had 'em so they were installed and operating.

    And degrading at least two of my three Outback outputs.

    WisJim... YOU DA MAN!!

    Phil
  • Dave AngeliniDave Angelini Solar Expert Posts: 6,138 ✭✭✭✭✭
    Re: Interaction of desulphator and MPPT charge controller

    Phil,
    I had a customer that had multiple Outbacks and I never had any luck getting them to work well together. Outback said they were of such different ages and revisions and maybe we needed a mate and more revisions and send them back.
    One would always do better and yes this was with an SW 4548. Finally replaced the CC's and networked them with someone else's CC.

    My point is I saw very recently that Outback has software now that will work better at networking for this problem. You may want to check into it.
    Good Luck!
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • PhilSPhilS Solar Expert Posts: 370 ✭✭✭
    Re: Interaction of desulfator and MPPT charge controller

    Good idea Dave, but absolutely not necessary now. Outback volunteered that there are "feedback" problems with "some Xantrex inverters". So Outback controllers are sensitive to "feedback" and by design that is what the desulfators do.

    I am getting the performance out of the FM that I had originally anticipated. I look at total KWH on all three Outbacks when I get home from work every day.

    Since installation, the FM would be about the same as the MX (more details in the other thread... the third MX has a 12V input and works the same before and after removing the desulfators).

    I don't record the readings but generally the two used to be very close. Maybe 2.1KWH on the MX and 2.4 on the FM. Then the next day 2.3 on the MX and 2.1 on the FM.

    Yesterday it was 2.8 on the MX and 3.9 on the FM. (the other MX was 2.1). It is absolutely a night & day difference in performance. That's about the ratio of the panels between the FM and MX, and tho the other MX was lower despite both MXs having 780 watts of solar input, the one MX is putting out more because of the higher input voltage. It's actually doing what it is supposed to, where the 12V input MX doesn't have a higher voltage to work with.

    I mentioned in the other thread that for the first time since I installed the FM, it is clamping down at 60 - 61 amps at the best sunlight part of the day and the MX is hitting 58 amps at that time. I'd NEVER seen the FM get over 58 amps since I installed it... NEVER. When the MX was on that set of 1020 watt panels it never hit 60 amps either... which is why I bought the FM60 instead of the FM80.

    If the time comes to add another bank of panels, I'll buy an MX80 for the 1020w bank and move the FM to whatever new panels I'd get. I actually don't anticipate getting any more panels though. I used to have a 1KW solar system, then it went to 2KW and I added an electric fridge which put it borderline. Adding the Sanyo dictated going to 3KW. I don't plan on adding any more loads... as Icarus is my witness ;)

    As I mentioned, I no longer keep a written log, but I check the readings EVERY day as soon as I get home, before entering the house and turning on loads. Disabling those desulfators made a "slap-in-the-face" difference.
  • MangasMangas Solar Expert Posts: 547 ✭✭✭✭
    Re: Interaction of desulphator and MPPT charge controller

    I wish you guys hadn't brought this all up again. Just when I though it was safe to go back in the water.

    I've been staring at my four desulfators hooked to the battery banks all day wondering if I should disconnect them or not.

    If they are impeding any performance of my Flexmax 80's, I'm pulling the fuses. Thinking about calling outback.
    Ranch Off Grid System & Custom Home: 2 x pair stacked Schneider XW 5548+ Plus inverters (4), 2 x Schneider MPPT 80-600 Charge Controllers, 2 Xanbus AGS Generator Start and Air Extraction System Controllers, 64 Trojan L16 REB 6v 375 AH Flooded Cel Batteries w/Water Miser Caps, 44 x 185 Sharp Solar Panels, Cummins Onan RS20 KW Propane Water Cooled Genset, ICF Custom House Construction, all appliances, Central A/C, 2 x High Efficiency Variable Speed three ton Central A/C 220v compressors, 2 x Propane furnaces, 2 x Variable Speed Air Handlers, 2 x HD WiFi HVAC Zoned System Controllers
  • PhilSPhilS Solar Expert Posts: 370 ✭✭✭
    Re: Interaction of desulfator and MPPT charge controller
    Mangas wrote: »
    I wish you guys hadn't brought this all up again. Just when I though it was safe to go back in the water.

    I've been staring at my four desulfators hooked to the battery banks all day wondering if I should disconnect them or not.

    If they are impeding any performance of my Flexmax 80's, I'm pulling the fuses. Thinking about calling outback.

    EASY test Mangas!

    Monitor your KWH total on your FMs... you likely do already. And you can go back day by day to see what they've been.

    Then pull the 4 fuses. It doesn't get easier than that.

    Monitor the readings for a few days. See if there's a difference.

    For one of my two MX 60s and my FM60, it was a huge difference.

    See if it makes a difference on FM80s.

    I think you already realize that having the desulfators disconnected for a week will make absolutely no difference in your battery bank's life. I'm not even planning to remove the desulfators, just tape the fuses to the top and put the fuse cap back on. Why don't I remove 'em? Just lazy.

    Phil
  • trkarltrkarl Solar Expert Posts: 33
    Re: Interaction of desulphator and MPPT charge controller

    I wouldn't put too much faith in what the MX60 is telling you as far as output goes.

    My FM80 is on a 2400 watt array and my MX60 is on a 1580 watt array. I will catch the MX60 showing sometimes 4 to 5 amps output more than it really is. Usually this happens if it's clear sky and then it clouds up.

    For example the FM will say 300 watts when a cloud comes and the MX will say 600+

    I was thinking wow the MX being older has a much better algorithm until I put a clamp on amp meter on both CC outputs.

    Then there are times when the MX will say it is putting out 1600+ watts while the FM is putting out 2000.

    A quick restart and then it tells me around 1100 to 1200. These false readings are all easily confirmed with the amp meter.

    Maybe yours doesn't do it. So I wonder each day how much mine is really producing.

    I have a desulfator connected and so will disconnect it and see if I catch the MX lying to me again.
  • BB.BB. Super Moderators, Administrators Posts: 32,612 admin
    Re: Interaction of desulphator and MPPT charge controller

    Another reason I like Battery Monitors for off-grid solar systems... Much better accuracy when measuring current.

    -Bill "got to bury that dead horse I keep beating" B. :blush:
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • AntronXAntronX Solar Expert Posts: 462 ✭✭
    Re: Interaction of desulphator and MPPT charge controller

    On a slightly different topic, can anyone really confirm that desulphators do restore lost battery capacity? I mean, show me scientific before / after capacity test.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Interaction of desulphator and MPPT charge controller
    AntronX wrote: »
    On a slightly different topic, can anyone really confirm that desulphators do restore lost battery capacity? I mean, show me scientific before / after capacity test.

    Nope.
    Somewhere I outlined the reasons why it is so difficult to get objective data. It comes down to needing two identical batteries. In the case of 'restoring', that is virtually impossible. In the case of 'prevention' it is possible to start out equal (relatively - even batteries from the same batch will have minor differences) but making certain the charge/discharge and maintenance are identical over a period of years - so that the only difference is the desulphator - is again virtually impossible.

    RE: the MX60. Regrettably the power output readings from these is notoriously optimistic. I suspect the computer gets "confused' by the Voltage spikes caused by the desulphators when the MX is doing its recalbiration sweeps; it thinks the battery is in a better state of charge than it really is and cuts back on the current. Other MPPT apparently don't suffer from this, so it is an Outback fault.

    OB equipment is getting seriously out of date in design. :cry:
  • AntronXAntronX Solar Expert Posts: 462 ✭✭
    Re: Interaction of desulphator and MPPT charge controller

    Hey thanks Coot. I am more interested in "reconditioning". Anyone knows what PWM frequency, duty cycle and spike current I need to "recondition" AGM battery that is losing capacity? I have a box full of large 120A MOSFETs that I can parallel into monster 2000A switch and drive them from PWM / frequency generator. I think I can really make those battery plates sing with near short circuit currents.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Interaction of desulphator and MPPT charge controller

    Someplace on this forum is a post by (I think) dwh regarding Morningstar's findings of their PWM controllers doing a pretty fair job of sulphation prevention on their own.

    We all may be better off just running a few panels through a PWM to the battery bank, reserving the MPPT for the "major" charging. Anyone want to guess on a ratio? :D
  • BB.BB. Super Moderators, Administrators Posts: 32,612 admin
    Re: Interaction of desulphator and MPPT charge controller

    $$$$/$$ work?

    -Bill :p
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PhilSPhilS Solar Expert Posts: 370 ✭✭✭
    Re: Interaction of desulphator and MPPT charge controller

    After reading trkarl's post, I'll check my Outback readings. I have a Fluke clamp-on ammeter. This won't be soon tho... I'm already fighting scheduling conflicts for the next month and vacation takes first priority.

    On the other hand, if the readings from the Outback are "optimistic", it may follow that I'm still getting MORE amps with the desulfators disconnected than I was when they were operating, just LESS amps than the readings would indicate.

    Phil
  • MangasMangas Solar Expert Posts: 547 ✭✭✭✭
    Re: Interaction of desulphator and MPPT charge controller

    Yea Phil, I'm going to use mine as planters.

    Until engineers can really demonstrate measurable effectiveness, why bother.

    I read more downside than upside especially daily charging performance. If they could measurably demonstrate prolonged battery life of more than 10%, ok maybe.

    I was always a little sqeemish about a device that popped a charge through the system.
    Ranch Off Grid System & Custom Home: 2 x pair stacked Schneider XW 5548+ Plus inverters (4), 2 x Schneider MPPT 80-600 Charge Controllers, 2 Xanbus AGS Generator Start and Air Extraction System Controllers, 64 Trojan L16 REB 6v 375 AH Flooded Cel Batteries w/Water Miser Caps, 44 x 185 Sharp Solar Panels, Cummins Onan RS20 KW Propane Water Cooled Genset, ICF Custom House Construction, all appliances, Central A/C, 2 x High Efficiency Variable Speed three ton Central A/C 220v compressors, 2 x Propane furnaces, 2 x Variable Speed Air Handlers, 2 x HD WiFi HVAC Zoned System Controllers
  • Dave AngeliniDave Angelini Solar Expert Posts: 6,138 ✭✭✭✭✭
    Re: Interaction of desulphator and MPPT charge controller

    There were quite a few birds of prey this summer flying with snakes. I wonder where they were taking them? Anyone know?
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Interaction of desulphator and MPPT charge controller
    There were quite a few birds of prey this summer flying with snakes. I wonder where they were taking them? Anyone know?

    Is this a new movie? "Snakes on a Klingon Bird of Prey"? :confused:
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