Current thoughts on using mx-60 with lifepo batteries

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sak54895
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Current thoughts on using mx-60 with lifepo batteries

Post by sak54895 »

Hi all, after many, many years using lead acids I'm thinking of switching to lifepo. Most of the discussion here seems to be a bit dated, has anyone been successful mating the venerated MX60 to lithium?
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by raysun »

LOL! What sort of discussion would there be on an MX60 if not dated? 😉

The only documented citation from Outback is in reference to integration with SimpliPhi LiFePo4 batteries and its a single entry that says: "Not compatible". That's it, no further explanation.
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by sak54895 »

LOL indeed, I still refer to that controller as our "new" one....
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by raysun »

20220525_152352.jpg
At the forum top level, click the "hamburger" to the left of FAQ and select Search.

Put the above terms in and search will return every mention of MX60 and Lithium. There's not much insightful, but it is was there is on the subject.
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Mike Curran
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by Mike Curran »

IMO, and not based on any experience mixing an MX60 with LiFePO4, I don't see why Outback says they're incompatible. An MX60 works pretty much the same as an FM60 except it cannot be programmed via Optics or the Mate. Otherwise it can be set up with the same charging parameters as an FM, AFAIK. Correct me if I'm wrong, please.
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by raysun »

I've never used an MX, and experience is limited to reading the manual.

One aspect that might be a show stopper is the method the MX uses to control the duration of the Absorb phase. There are two values: Maximum Time Limit and Minimum Time Limit; and a complex algorithm for the minimum time value that is dynamically set during the charge cycle.
Screenshot_20220526-153128_Word.jpg
So the minimum maximum is 1 hour, and the minimum minimum is 0 minutes provided the bulk stage is 0 minutes - an impossibility. Since the typical Bulk stage would take more than the, say, 6 minutes Phi recommends for Absorb, the MX can't terminate the charge in a timely manner. In practice bulk would take longer than an hour, so the shortest Absorb stage would be 60 minutes. No bueno at the termination voltage of the typical lithium battery.

That's not to say there isn't a work-around, its just that the "Bulk until full, then terminate" charge profile can't be used.

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.

I don't know if there are other issues, but the above would be the first one to address..
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by sak54895 »

Thanks for the input, so to speak. I will try adjusting the charge parameters and see how the system works, if push comes to shove I'll save up for a different controller. When we built our first off grid house in 1976 nothing was plug and play, glad to hear from people who still think outside the box...
Again, thank you!
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by raysun »

Post back when a specific battery model is under consideration, with its specs - make/model, capacity, charging parameters, and we'll be able to "sanity check" the charging strategy proposed.
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by sak54895 »

I'm thinking 4-200 amp/hour 24 volt Signature Solar lifepo batteries pushed by 1200 watts of solar (wired at 40 volts)
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by raysun »

Right, the Eg4 / Egll batteries.

Their specs show the "Bulk until full" charge parameters. The MX won't support the fast charge termination requirement.

You can ask Signature about a "Long Absorb" at a lower voltage (e.g.: 27.3V @ 1.5H) to see if they support it. Alternately, you could try it with the MX and judge for yourself if it fully charges the battery (it won't hurt it certainly.)

I'd recommend, if its not entirely successful, be prepared to spring for an FM80.
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by Applewhite »

@ sak54895, did you ever do the installation, have any progress to report?

I'm in the same boat (looking to upgrade to LiFePo with my trusty MX60). I've done a fair bit of research and it sort of seems like it is more trouble than it is worth and that it's wiser to upgrade to a lithium battery specific MPPT, either OBP, or (gasp!) Victron. It seems as though the MX60 parameters can be adjusted so one can confidently avoid the worst case scenario of overcharging the batteries but there are any number of scenarios in which the battery does not get to full charge and/or the available array power is not fully utilized. Anyone else reach that conclusion? Very curious to hear about others real world experience and reluctant to send my MX60 to the recycle bin, I hear they don't make 'em like they used to.
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by raysun »

Came too late to the party for the MX series, but every FM I've installed is solid as a rock, and all, including my pair of FM80s, are maintaining LiFePo4 batteries.
When Outback and SimpliPhi collaborated on testing and integration specs, OB issued a compatibility list, and marked the MX as "Not compatible. " That's it, no explanation.
That triggered my research gene, so into the Wayback machine to retrieve an MX60 / MX Extreme manual (they don't write 'em like that any more.) After an interval of study on MX architecture and algorithms, it became apparent what prompted the "Not compatible" designation.
Mind you, the FX class inverters were also thrown onto the "Not compatible" pyre, but I've developed necessary compensations and integrated 3 of them with LiFePo4 with good success.
The short answer on MX is, retire it to the Hall of Tech Honor, along with your original Apple computer and Pong arcade console, and get an FM80 (not '60).

Aloha!
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by Applewhite »

Wow, that was quick, thanks, I guess FM80 it is! At the risk of a faux pas, can I ask an inverter question in an MX60 forum?

I have an FX2024T (rock solid, like the MX60). Currently looking at two different 24V LiFePo battery options; BYD and Ampere Time. You wrote "I've developed necessary compensations and integrated 3 of them (FX inverters) with LiFePo4 with good success". Could you possibly elaborate on you "compensations" or point to the applicable thread if posted elsewhere?

THANKS!

p.s. If anybody has "feelings" about BYD or Ampere Time batteries, I'm all ears.
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by raysun »

LOL! There's 59,000 well chosen words on the subject, but it would take a while to sort through.
Tell you what, create a post on "FX2024T and LiFePo4". It will be better to track the convo that way later today.
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by Applewhite »

Thanks in advance @raysun, done!
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Mike Curran
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Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input from 14 Talesun 275W, Enphase M215 microinverters

Battery systems operate in grid-tied, net metering w/backup mode
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by Mike Curran »

@Raysun:
After an interval of study on MX architecture and algorithms, it became apparent what prompted the "Not compatible" designation.
So what was it, exactly, that became apparent? 100 words or less, if you can please :grin:
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https://enlighten.enphaseenergy.com/public/systems/Hctc107221
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by raysun »

Mike Curran wrote: Wed Oct 19, 2022 7:00 pm @Raysun:
After an interval of study on MX architecture and algorithms, it became apparent what prompted the "Not compatible" designation.
So what was it, exactly, that became apparent? 100 words or less, if you can please :grin:
Hundred words or less? Sorry Mike, no can. 😆

Seriously, 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.
Last edited by raysun on Thu Oct 20, 2022 9:28 am, edited 1 time in total.
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Mike Curran
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My RE system: Outback - Garage roof (2007/2017):
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- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied VFXR3524A-01's series stacked, replaced GVFX's (2020)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS. Tigo ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input from 14 Talesun 275W, Enphase M215 microinverters

Battery systems operate in grid-tied, net metering w/backup mode
All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Current thoughts on using mx-60 with lifepo batteries

Post by Mike Curran »

Thanks raysun!
https://ei.tigoenergy.com/p/pZXn7SZQyO45
https://enlighten.enphaseenergy.com/public/systems/Hctc107221
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Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by raysun »

Mike Curran wrote: Wed Oct 19, 2022 7:40 pm Thanks raysun!
That was my documentation analysis, there may be other conditions in operation that would also crop up, but the Absorb algorithm is enough for the Not Compatible designation.
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by ralphday224 »

You had exceptional life out of that MX60. Before retiring mine after 15 years I had to replace the button board and the fan died. I just put a computer fan on it to suck air through...all the time.
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by sak54895 »

Hi, decided to go with lead acids as I would not only need to change out the mx60 but also the wind controller and the generator controller. Plus I didn't like the fact that there is no recycling stream for the lithium ion batteries...
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Re: Current thoughts on using mx-60 with lifepo batteries

Post by raysun »

sak54895 wrote: Fri Oct 21, 2022 12:19 am Hi, decided to go with lead acids as I would not only need to change out the mx60 but also the wind controller and the generator controller. Plus I didn't like the fact that there is no recycling stream for the lithium ion batteries...
That's reasonable for the circumstances listed. Battery tech is in transition. 5 years from now will be a vastly different picture. Lithium recycling is in its infancy, but is growing. While lead is the most recycled metal in the world, largely due to the shear volume of lead acid batteries, it is a nasty business. We largly ignore the toll it takes on the environment and wirkers. Hopefully future battery recycling will have learned from that.
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