Outback MX60 charge controller and lithium said to be incompatible. Is there a temporary workaround

Fenachrone
Fenachrone Registered Users Posts: 29 ✭✭
edited June 2023 in Advanced Solar Electric Technical Forum #1
Guess you might say I found out about the MX60's incompatibility a bit too late...   Not that it isn't time to retire the old girl...    But the situation now is that I've put into play two Kilovault 2400 HLX+ batteries with this controller (for the moment anyway)  and put aside my set of compromised AGMs.

I'll bring up a new FLEXmax 80 that is compatible with these batteries in the fall.  But now, I'd like to know how I can make this MX60 work for about six weeks here in this remote place; the issue seems to be around the limitations of setting absorb settings, that is, not being able to reduce the absorb time to the required specs.  I've got it set to one hour, the minimum.   I not getting any sense there are other incompatibilities; maybe there are, but I have the bulk and float settings as per Kilovault for the 24v system. 

Anyone deal with this situation?  What harm comes to the batteries from this incompatibility? 

Here is what someone said about the incompatibility in another forum: 

...MX class has a "smart algorithm" for computing Absorb Time. The static settings are more of a guideline to define a minumum and maximum range, but are not a timer limit. AFIK it can't be overridden. So the LiFePo4 battery would be at the mercy of Lead Acid Absorb metrics. With the FM, the 0.1H Absorb Time setting is used for Constant Current (Bulk) charge termination at the target (Absorb Voltage.) This gives an unambiguous (and safe) charge cutoff, which the MX class cannot do.

Offering a possible solution, another person said: 

If I was stuck with an MX and a lithium battery, I'd use the "Long absorb" charge profile. For a 48V nominal battery, setting the Absorb voltage to 54.6V, Maximum Absorb Limit to 90 minutes, and Minimum Absorb Limit to 0 minutes.


Any other thoughts, suggestions, comments, appreciated.



Off-grid cabin in eastern Canada: 1700w of panels, Midnite Solar Classic 250 SL, Outback VFX 3524,   Mate, Grundfos SQFlex pump, Kilovault HLX LifePO4 batteries.
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Comments

  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,105 ✭✭✭✭✭
    edited June 2023 #2
    What about the MX-60 is incompatible? Are you not able to set the charging voltages? If you are stuck with an hour absorb I believe you can lower your absorb voltage setpoint slightly lower than you would have set it without absorb and in the end you will get a full charge. In your case 27.2 would work.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • Fenachrone
    Fenachrone Registered Users Posts: 29 ✭✭
    #3
    Thanks for your workaround suggestion.  The incompatibility statement comes from Outback themselves, specifically a representative's email message to me today.  He referred me to this document:  https://outbackpower.com/downloads/documents/appnotes/lithium_app_note.pdf
    Off-grid cabin in eastern Canada: 1700w of panels, Midnite Solar Classic 250 SL, Outback VFX 3524,   Mate, Grundfos SQFlex pump, Kilovault HLX LifePO4 batteries.
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,105 ✭✭✭✭✭
    edited June 2023 #4
    Fenachrone said:
    Thanks for your workaround suggestion.  The incompatibility statement comes from Outback themselves, specifically a representative's email message to me today.  He referred me to this document:  https://outbackpower.com/downloads/documents/appnotes/lithium_app_note.pdf
    OK I didn't read the entire article but the title got my attention. If you are using Lithium-Ion batteries then you need to be especially diligent and careful not to start a fire with them. LiFePo4, ( Lithium iron phosphate) are different chemistry and have a whole different set of charging rules. One thing to note is that LiFePo4 batteries are much safer and not prone to cause fires in normal use

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,901 ✭✭✭✭✭✭
    #5
    Outback is protecting the company from possible litigation. They do not know what lithium chemistry battery you will use with this very old controller. As littleharbor said LFP is fairly safe and as long as you are careful, the BMS should protect the battery. Try and find a voltage where it will stay in the 90% range when the sun is out. Get the Flexmax asap and guidance from the battery manufacturer.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • Fenachrone
    Fenachrone Registered Users Posts: 29 ✭✭
    #6
    Dave Angelini said:
    Outback is protecting the company from possible litigation. They do not know what lithium chemistry battery you will use with this very old controller. As littleharbor said LFP is fairly safe and as long as you are careful, the BMS should protect the battery. Try and find a voltage where it will stay in the 90% range when the sun is out. Get the Flexmax asap and guidance from the battery manufacturer.
    That was my sense, too.   The HLX has an upgraded BMS, but they wouldn't necessarily know what its capabilities are so I can understand their caution, but a bit of commentary might help.    MidNite Solar is all over this:  https://www.kilovault.com/wp-content/uploads/2020/12/KiloVault-Midnite-Compatibilty-White-Paper-2020.pdf

    Outback wouldn't give me specifics on the incompatibility issue when I emailed them.   The rep said:

    Lithium ion battery types are not compatible with this MX60 charge controller. You would need to be replaced with the newer generation FM60 or need to replace the batteries with the same older battery types which your solar vendor or any of our distributors can help with. Below is the contact details of one of our distributors.

    Hmmm... not the sort of answer I would have hoped for.  I may be more inclined to get one of MidNite's controllers.





    Off-grid cabin in eastern Canada: 1700w of panels, Midnite Solar Classic 250 SL, Outback VFX 3524,   Mate, Grundfos SQFlex pump, Kilovault HLX LifePO4 batteries.
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,901 ✭✭✭✭✭✭
    edited June 2023 #7
    I thought you said to get a Flex max ?  Whatever you get, if it can close loop charge your battery based on Soc from the BMS, that will be the best.

    Charging based on voltage is 2nd best, in my opinion! 
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • Fenachrone
    Fenachrone Registered Users Posts: 29 ✭✭
    #8
    Yes, if I got an Outback controller it would be a Flexmax 80.   Thanks for the suggestion regarding a closed loop system.  May be beyond my pay grade in how to set up/monitor that. 
    Off-grid cabin in eastern Canada: 1700w of panels, Midnite Solar Classic 250 SL, Outback VFX 3524,   Mate, Grundfos SQFlex pump, Kilovault HLX LifePO4 batteries.
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  • JRHill
    JRHill Registered Users Posts: 356 ✭✭✭
    #9
    When I changed over to LifeP04 I had a different concern: the FX series inverter. The FM80 is suitable for the new SimpliPHI batteries but not the inverter. It could not have the low voltage cut out set to protect the batteries. The batteries were 4x the cost of the inverter, the FX3648 was 12 years old and was not working with AGS. Yes it was the inverter, not programming, etc. So I upgraded to the VFXR3648. I had ordered the control board but never changed it out. I advertised the old inverter and replacement board and it sold in days for 50% of new.

    Since we charge batteries for three months of the year from the generator I would not experiment with inverter shut down via BMS... and potentially have to jump start them to get back into service. Shouldn't happen but if it could it would happen to me. And if something happened to me and the DW had to deal with it there wouldn't be anyone to call. Just some thoughts.
    Off Grid. Two systems: 1) 2925w panels, OB VFXR3648, FM80, FNDC, Victron BMV-712, Mate3s, 240 xformer, four SimpliPHI 3.8; 2) 780w, Morningstar 30a, Grundfos switch, controller and AC/DC pump, 8 T105. Honda EU7000is w/AGS. Champion 3100. HF 4550, Miller Bobcat.
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