Rolls Surrette absorption time

sucellossucellos Registered Users Posts: 6
OK here's the gist: we have 8 x 6V 450AH Surrette batteries wired series/parallel for our 24V system. Our Flexmax 80 charge controller is working well BUT I'm not sure of the settings for bulk/absorb/float (voltages & times) to optimize our off grid system in BC....ANY help would be great!

Thanks much
Kennedy

THAT'S "ABSORPTION"!! Sorry too fast typing...
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Comments

  • unicorniounicornio Solar Expert Posts: 217 ✭✭
    Re: Rolls Surrette absorbtion time

    you need to calculate the total capacity of your batteries. then find the 2% and set this value in the menu "return amps" in FM80, also setting a long time, maybe two hours or three... ... when return amps is reached, the FM80 will float ...is the dynamic charge system ... thus the absorption step is adapted to each level of your battery discharge ... outback is very careful with your batteries ... lol

    and to determine the absorption voltage, check the information of the battery manufacturer...
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Rolls Surrette absorbtion time

    Welcome to the forum.

    Good news: the Outback FM80 automatically adjusts the length of the Absorb time according to how long the Bulk stage took. The longer it takes to achieve the Absorb Voltage set point, the longer the Absorb cycle. With the exceptions of the Absorb Time Limit, which can be set for up to 24 hours, and the End Amps function available with the DC FlexNet monitor. If you like you can just watch the charging one day and see how long it stays in Absorb before the current falls to less than 2% of the battery capacity and set the Time Limit as near to that as possible. You may also want to adjust it a bit after it's been in use according to how much water you find you have to add each month: more water use, shorten Absorb time.

    Others will have their own ideas I'm sure.
  • sucellossucellos Registered Users Posts: 6
    Re: Rolls Surrette absorbtion time

    Sooo the total capacity is 450 X 8? I did the calculation from the Surrette site & came up with 4.2 hours bulk & absorption time... I'm confused on the total capacity & how the series/parallel wiring effects the charging times.

    Thanks for your reply!
  • unicorniounicornio Solar Expert Posts: 217 ✭✭
    Re: Rolls Surrette absorbtion time
    Welcome to the forum.

    Good news: the Outback FM80 automatically adjusts the length of the Absorb time according to how long the Bulk stage took. The longer it takes to achieve the Absorb Voltage set point, the longer the Absorb cycle. With the exceptions of the Absorb Time Limit, which can be set for up to 24 hours, and the End Amps function available with the DC FlexNet monitor. If you like you can just watch the charging one day and see how long it stays in Absorb before the current falls to less than 2% of the battery capacity and set the Time Limit as near to that as possible. You may also want to adjust it a bit after it's been in use according to how much water you find you have to add each month: more water use, shorten Absorb time.

    Others will have their own ideas I'm sure.

    i not understand how the FM80 adjusts the absorption time depending the time on bulk??? ... in FM80 you can set a time of absorption, and also, the amps return or end amps...for this, you no need to have the FLEXnet dC, though (of course), maybe without the FLEXnet DC is impossible to charge really (really!) well the battery... ;-)
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Rolls Surrette absorbtion time
    sucellos wrote: »
    Sooo the total capacity is 450 X 8? I did the calculation from the Surrette site & came up with 4.2 hours bulk & absorption time... I'm confused on the total capacity & how the series/parallel wiring effects the charging times.

    For batteries in series do not add the amphours. Thus, 4 batteries in series is 450 ah. Two 24 volt strings of 450 ah is 900 ah.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Rolls Surrette absorbtion time
    unicornio wrote: »
    i not understand how the FM80 adjusts the absorption time depending the time on bulk??? ... in FM80 you can set a time of absorption, and also, the amps return or end amps...for this, you no need to have the FLEXnet dC, though (of course), maybe without the FLEXnet DC is impossible to charge really (really!) well the battery... ;-)

    The Outback controllers literally time the length of the Bulk stage from when charging first commences until Absorb Voltage is reached. That time is used to control the length of the Absorb stage, up to the Absorb Time Limit. There is a little minute clock that counts up to the maximum during Bulk, and then counts down during Absorb. When it reaches zero it switches to Float stage. It's a system that works fine in most cases.

    Of course what we all really want is a charge controller that is connected to a battery monitor and controls the charge stage as a function of the actual SOC. Isn't that right, boB? :D
  • boBboB Solar Expert Posts: 953 ✭✭✭✭
    Re: Rolls Surrette absorbtion time
    The Outback controllers literally time the length of the Bulk stage from when charging first commences until Absorb Voltage is reached. That time is used to control the length of the Absorb stage, up to the Absorb Time Limit. There is a little minute clock that counts up to the maximum during Bulk, and then counts down during Absorb. When it reaches zero it switches to Float stage. It's a system that works fine in most cases.

    Of course what we all really want is a charge controller that is connected to a battery monitor and controls the charge stage as a function of the actual SOC. Isn't that right, boB? :D

    Yep ! That's the way to really do it right.

    I am at SPI and Rolls (Surrette) is here. I'll let them know about this thread.

    boB
  • VicVic Solar Expert Posts: 2,934 ✭✭✭✭
    Re: Rolls Surrette absorbtion time

    Hi sucelos,

    The length of Absorption dempends upon the Depth Of Discharge or the battery bank. This could vary from one day to the next. Using the EA function that is in the FM Charge Controller could work for you, but loads on the inverters can cause some troubles if they are large, and random. The OB FNDC and Mate3 combo would allow you to use the EA value actually going into the batteries to terminate the Absorption stage. These additional items may be a bit expensive.

    I do use EA in my OB MX-60 CC, as my inverter loads are well controlled, and things like the refer cycle on for only a few minutes, and do not disturb the EA value very much. ON 12V and 24V systems, even smallish appliances cause larger effects on the current the CC must supply, so using CC EA could be a bit more challenging on these systems.

    Keep a careful watch on the battery SG readings, as you make changes to A.sorb times, until you get to know your system requirements.

    And, Marc, I have never seen my MX-60 use Bulk time=A.sorb time. This would not work at all well for any systems that I watch. Bulk is often two or three times longer than Absorption. I am very happy that my MX knows not to do this! YMMV Good Luck with the new batteries, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Rolls Surrette absorbtion time
    Vic wrote: »
    And, Marc, I have never seen my MX-60 use Bulk time=A.sorb time. This would not work at all well for any systems that I watch. Bulk is often two or three times longer than Absorption. I am very happy that my MX knows not to do this! YMMV Good Luck with the new batteries, Vic

    Vic;

    I'm not saying it's the best method, just explaining how it works. Mine functions that way and works fine, but as you know everyone's install is different. The Absorb Time Limit is meant to be a max and can be adjusted down to zero if need be.

    How do you have your MX60 programmed for End Amps? Mine does not have that function anywhere I can find. Maybe too old a version?
    I also can not find reference to it in the FM manual; only in the Flexnet system. But I'm going a bit ga-ga after reading several thousand technical manuals over the years. Funny how I can't remember the details of every one and keep having to look things up - during which time I forget what I'm looking for before I find it. :cry:
  • unicorniounicornio Solar Expert Posts: 217 ✭✭
    Re: Rolls Surrette absorbtion time
    Vic;

    I'm not saying it's the best method, just explaining how it works. Mine functions that way and works fine, but as you know everyone's install is different. The Absorb Time Limit is meant to be a max and can be adjusted down to zero if need be.

    How do you have your MX60 programmed for End Amps? Mine does not have that function anywhere I can find. Maybe too old a version?
    I also can not find reference to it in the FM manual; only in the Flexnet system. But I'm going a bit ga-ga after reading several thousand technical manuals over the years. Funny how I can't remember the details of every one and keep having to look things up - during which time I forget what I'm looking for before I find it. :cry:

    the MX60 does not have the ability to set the parameter "end amps", is in the line FlexMax when outback has included this powerful possibility ...
  • VicVic Solar Expert Posts: 2,934 ✭✭✭✭
    Re: Rolls Surrette absorbtion time

    Marc, unicornio,

    My MX-60's DO, each have the CC EA function, BUT it will not integrate the EA function of the FNDC. So, it is just an EA function based on TOTAL current delivered toward the batteries (ie, includes all inverter/battery loads, not just batt charge I).

    The FW versions in these MXs are; 5.10, and 5.11. Believe that 5.11 is the very last FW revision, and there will be no successors.

    On either of these FW versions, the CC EA function is in the 'Misc" menu, on the third page -- " End Ampos ", with one button for --A, and the neighbor button, +A. For this EA function to work, it is required for the " Min " Absorb time be set to 00:00. The " Max " A.sorb time still has the normal effect.

    This works fine on my systems, but, of course, consistant loads need to be factored into EA, and large/random loads need to cycle OFF near the end of the desired EA value etc ... not perfect, but can be made to work in many systems. YMMV and so on, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Rolls Surrette absorbtion time

    Thank you for that, Vic.

    Now for the very scary part: found it on mine, and I'd already set it. :confused:

    This is the latest manifestation of an on-going problem. :blush:
  • FullpowerFullpower Solar Expert Posts: 69 ✭✭
    Re: Rolls Surrette absorbtion time

    I would start at 4 hours. If you need to add water more frequently than 6 or 8 weeks, back the ABSorb down to 3 hours or so.
    Check gravities after a couple sunny days, if you arent getting uo to 1.265 or better, run ABSorb up to 5 hours.
    My Rolls Surrette are pretty happy with 5 Hour ABSsorb, @ 2.5 volts per cell.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Rolls Surrette absorbtion time

    Fullpower;

    How on Earth do you get 5 hours of Absorb time from PV's in Alaska?

    And by the way a larger battery bank will usually need more Absorb time (assuming it is sized properly for the application).
  • DillDill Solar Expert Posts: 170 ✭✭✭✭✭
    Re: Rolls Surrette absorbtion time

    isn't it sunny for 22 hours a day or something in northern Alaska in the summer?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Rolls Surrette absorbtion time
    Dill wrote: »
    isn't it sunny for 22 hours a day or something in northern Alaska in the summer?

    That depends on where in Alaska you are; it's a really big state. The biggest, in fact. :D
    Likewise 22 hours of Summer sun equates to 22 hours of Winter dark, if you know what I mean. Those who live near the Equator are lucky in that respect.
  • FullpowerFullpower Solar Expert Posts: 69 ✭✭
    Re: Rolls Surrette absorbtion time
    Fullpower;

    How on Earth do you get 5 hours of Absorb time from PV's in Alaska?

    And by the way a larger battery bank will usually need more Absorb time (assuming it is sized properly for the application).

    6 kilowatts PV pointed SOUTH, and 800 Watts pointed WEST.
    A good day with full sun will bring in 37 Kilowatt hours.
    I have put as much as 19.9 Kilowatt hours INTO the battery bank on a sunny day AFTER 5 cloudy days.
    ... The Outback FM-80 charge controllers will shorten the charge cycle, depending on how FAST the battery state of charge rises through BULK.... meaning, consecutive sunny days will result in much shorter charge regimes.
    But, after a few cloudy days, I will see 135 peak amps charge, and can get 5 full hours ABSORB at 30.2 volts on a 24 volt nominal bank.
  • boBboB Solar Expert Posts: 953 ✭✭✭✭
    Re: Rolls Surrette absorbtion time
    Fullpower wrote: »
    .
    ... The Outback FM-80 charge controllers will shorten the charge cycle, depending on how FAST the battery state of charge rises through BULK.... meaning, consecutive sunny days will result in much shorter charge regimes.

    I recently heard that OB removed that up-down timer feature and just made it the same amount of absorb time, every time.

    FYI...
    The shorter the absorb time due to a short bulk time was originally done that way so that a full battery wouldn't necessarily absorb for the full maximum absorb time.
    That doesn't always work great because when clouds come by and/or large enough loads come on toe just reduce the battery charge voltage below absorb set-
    point voltage, the absorb time can cook batteries.

    There is another way to make that count up--- count down timer work much better, but just making the absorb timer constant every day works OK.

    boB
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Rolls Surrette absorbtion time
    boB wrote: »
    There is another way to make that count up--- count down timer work much better, but just making the absorb timer constant every day works OK.

    OK, it's been 7 hours since you posted and no one's asked... What is the much better way?

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • boBboB Solar Expert Posts: 953 ✭✭✭✭
    Re: Rolls Surrette absorbtion time
    vtmaps wrote: »
    OK, it's been 7 hours since you posted and no one's asked... What is the much better way?

    --vtMaps


    Well, when I say "much better", I mean that feature can be made to work better but still not nearly as good as a real battery current monitor to tell
    the CC to go from absorb to float. This is just an option but I believe there is merit for it. I call it VariMax and will be an option in
    the next version of Classic code. The up-count timer will be disabled by default but I couldn't just remove that old method completely !

    The idea is to let the absorb time increase when bulk time increases ONLY if the battery current when in bulk is above some adjustable preset
    value ~AND~ the battery voltage is below the absorb setpoint by an adjustable preset voltage, THEN the counter can count up.
    Otherwise, the timer will just stop accumulating absorb time when the battery voltage is not sitting at the absorb voltage.

    By default, the current would be higher than the CC can ever put out, (say, 101 amps), and that disables the up-count of the absorb time.
    Then, the absorb time will just be a preset time like 2 hours. Of course, when the battery voltage is below the absorb set-point voltage,
    the counter will stop counting down towards zero which it needs to do. The battery voltage should be held at that absorb voltage in order
    to count as actually being in the absorb charge stage. This VariMax method can even be improved some more but this should be good
    enough I think.

    I hope this doesn't confuse people too much but I think it's an OK way to keep that feature but also can help keep batteries from
    boiling away unnecessarily when the power production is iffy. VariMax may also keep the counter from counting up to maximum
    in the morning just because there isn't enough sun power to really be called "bulk" charging with such little available power/current.


    boB
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Rolls Surrette absorbtion time

    This is a brilliant idea, boB. One complaint I've had about the venerable MX controller is that the Absorb timer starts counting from really low charge current values. if it would start at the same minimum current as the End Amps it would make more sense. Starting from 1 Amp (or wherever) makes for too long of an Absorb time. A minimum and maximum time parameter couple with Start and End Amps would be the best we could get without an actual SOC sensor.

    Which we are all still waiting for. ;)
  • boBboB Solar Expert Posts: 953 ✭✭✭✭
    Re: Rolls Surrette absorbtion time
    This is a brilliant idea, boB. One complaint I've had about the venerable MX controller is that the Absorb timer starts counting from really low charge current values. if it would start at the same minimum current as the End Amps it would make more sense. Starting from 1 Amp (or wherever) makes for too long of an Absorb time. A minimum and maximum time parameter couple with Start and End Amps would be the best we could get without an actual SOC sensor.

    Which we are all still waiting for. ;)

    I agree, except that setting this to the EA setting where the CC does not know the actual battery current may not be as "adjustable" where fully
    adjustable will fit all needs (I hope)... Also, the voltage below the charge set point will have to be adjusted and that is hard to guess at.

    I suppose that the offset voltage below setpoint could be related to Re-Bulk amps. I kind of like that one.

    But the REAL fix is the external battery shunt current monitor so this will be an inexpensive band-aid.

    This was fairly easy to do and I have been thinking about this for quite a while.

    boB
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: Rolls Surrette absorbtion time

    boB, I've been trying to get my wind Classics to play nice with the solar Classic during absorb. I use Waste Not Hi mode in the solar Classic to turn on a 2 kW water heating load with the voltage offset relative to stage voltage. But what happens during absorb is that the wind turbines will get to cranking during a gust and drive the voltage to the offset in on the solar so it turns on the water heater. Then the wind dies down a bit and there's not enough incoming power to keep the voltage at absorb so it drops back into Bulk MPPT until the hold timer shuts off the heating element.

    It seems the Classic starts counting down from the max time set for absorb, then if it drops out of absorb it counts back up. So what happens on gusty days is that it constantly goes back and forth from Absorb to Bulk MPPT then back to Absorb until the bank charging amp requirement drops enough so it will stay in absorb with the water heater element going.

    My latest scheme to try to "fix" that is to drive the clippers using Waste Not Hi on the wind Classics as well. This causes the Classic to engage the voltage clipper if it tries to go over the charge stage set point and control the turbine output so it don't prematurely trigger the Aux1 on the solar unit during absorb. We had a gusty day today with winds over 30 mph and it seemed to work ok - the bank stayed in absorb for the minimum time without the solar Classic prematurely turning on the water heater or "hunting" back and forth from Absorb to Bulk MPPT and back to Absorb. Then once it dropped into Float it turned the heater on and kept it on for over five hours this afternoon.

    There's probably an easier or better way to do it. But using the clipper on the wind turbines right at charge stage voltage instead of having the controllers unload the turbines and letting them free-spin up to the max input voltage seems to keep their speed down and make them run quieter.
    --
    Chris
  • sucellossucellos Registered Users Posts: 6
    Re: Rolls Surrette absorption time

    OK now I'm having issues between the Outback FM 80 & the Magnum Inverter/charger! I have the temp compensation unit installed from Magnum but I don't think the Outback charger controller is playing along with it...example: I'm running a genny to absorb/float today & all is going fine for ~2 hours then the charge controller says: 'EX-absorb' which according to the manual it has stopped charging. But the Magnum is still in 'absorb charging'. Rolls says the absorb time should be 4.2 hours. What the heck is happening?? I need to get them topped up to float as it has been very cloudy for a while...HELP PLEASE!

    Thx,
    Kennedy
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Rolls Surrette absorption time

    Unfortunately the Outback and Magnum don't 'talk' to each other. Each determines the charging stage according to the Voltage level it reads, and that is bound to be different between the two. You can compare Voltages at Float between the two (who wants to run their gen 'til Float?) but that won't have any bearing on Bulk/Absorb readings when the current is really flowing.

    What you should check is the Outback's Absorb Time Limit as it sounds like this is set to 2 hours (default if I recall) and needs to be extended to meet the needs of that battery bank.

    Trying to fit 4+ hours of Absorb into a solar day is maddening. Most of us can only truly count on 4-5 hours equivalent good sun in a day anyhow.
  • sucellossucellos Registered Users Posts: 6
    Re: Rolls Surrette absorption time

    Humm they do have slight differences in voltage readings (~0.1V) but I've made sure all the bulk/absorb/float set points are the same in each. I only wanted to reach 'float' & then shut down the genny...ie. finish absorb ;) I'll double check the absorb time limits on each of the pieces. BTW Rolls says the bulk & absorb to be set @ 30V & float to be @ 26.28 (due to the ambient temp). Would the bulk/absorb set the same throw things off? Sorry if this seems basic...just a steep learning curve learning the off-grid tech!

    THX,
    Kennedy
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Rolls Surrette absorption time

    I think they're confusing us with nomenclature. "Bulk Voltage" and "Absorb Voltage" are really the same thing: the set point when charging switches from Bulk (as much current as possible) to Absorb (fixed Voltage, current as needed). Although I have seen some charging parameters stating Bulk charge up to 'X' Volts then drop back a little for Absorb and then even lower for Float. Sometimes I wonder if battery makers have any idea how solar charge controllers work. Maybe they're not willing to adjust to them because the market is small. Some, like Trojan, are making "RE" batteries now.

    Okay I'm starting to ramble ... again.

    A 30 Volt Absorb set point makes sense as most of the other Surrette specs seem to be along those lines: 15 Volts "for every 12 nominal". This is quite a bit higher than most "fixed setting" charge controllers are meant for (they usually stop at 14.6 or 14.8).

    If anyone is wondering, at this time I am using East Penn PS2200's and their specs call for Absorb at 14.4 per 12 Volts nominal (I had the dealer check with them just to be sure). Float is at 13.8 per. So far, so good. We'll see what they're like after a Winter on their own.
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Rolls Surrette absorption time
    sucellos wrote: »
    the charge controller says: 'EX-absorb'

    That means that the battery voltage exceeds the FM80 absorb setting. The magnum is holding the voltage above the Outback's absorb setting.

    If the batteries are cold the Magnum's temp compensation is raising the ACTUAL absorb voltage above the absorb voltage setting of the magnum. The FM80 without temp compensation sees the Magnums ACTUAL absorb voltage as EXceeding its own ABSORB voltage.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • VicVic Solar Expert Posts: 2,934 ✭✭✭✭
    Re: Rolls Surrette absorption time

    The way I read it, there art BTSes on the FM AND the Magnum, although it is ambiguous.

    This is quite common. No set of BTS/RTSes will ever agree exactly over a period of time. Regardless weather each charger uses an RTS, if this bothers you, try setting the FM's Absorb voltage a bit higher. There should be a setting on each that allows at least some sharing. There may be little benefit in perfect sharing, unless this occurs early in Absorb, depending on the efficiency of the generator at different loadings -- the contribution of the PV may not reduce the fuel consumption of the genset by any measureable amount. Assume that the Magnum is powered from a genset ...

    If the PV has sufficient current available to maintain the Absorb voltage, the genset could be shut off, if there is sufficient time for the PV to finish the Absorb ... and so on. Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • sucellossucellos Registered Users Posts: 6
    Re: Rolls Surrette absorption time

    Great responses guys! Now riddle me this: if the FM is in 'EX-absorb' & the Magnum still says 'absorb charging' which one is correct? Am I wasting gas running the genny trying to complete the 4 hour absorb time recommended by Rolls? Me thinks I need a RTS for the Flexmax... ALSO what settings should I use without a RTS?

    THANKS MUCH!
    Kennedy
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