Clarification on using Outback MX60 with lithium batteries?

[Fenachrone]

I'm told by Outback that my MX60 is not compatible with lithium. Not that it might not be time to retire the old girl, but...

The situation I have now is that I've put into play Kilovault 2400 HLX+ batteries with this controller (for the moment anyway) and have put aside my set of compromised AGMs.

Understanding that I may have to get a new controller (FLEXmax 80?), for right now at least, I'd like to know if I can make this MX60 work while I'm out here in my remote location.

As far as I can tell, 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 not getting any sense there are other incompatibilities; maybe there are, but I have the bulk and float settings as per Kilovault for a 24v system.

Anyone deal with this situation? What harm comes to the batteries from this incompatibility? At least person here said the incompatibility was baloney, and was just to promote buying an upgrade.

I cherry-picked some comments about this:

...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.

Another 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 90minutes, and Minimum Absorb Limit to 0 minutes.

If someone can give me recommendations for the settings for a 24 volt system, to keep using the MX60 (at least for now), that would be greatly appreciated!

Any other comments on this are welcomed.

 

[sunshine_eggo]

If you can:

specify an absorption voltage of 3.45-3.55V/cell
specify a float of 3.375V/cell
specify an absorption period of 2 hr (3.45V) or 30 minutes (3.55V)
disable temperature compensation
disable or set equalization to the absorption votlage

Using:

http://www.umiat.com/network/umiatbase/manuals/MX60_Manual_Rev6_2.pdf

P15 seems to allow for custom absorb/float.
P27 seems to indicate you can set min and max absorb time periods.
P21 seems to indicate if there is no temperature sensor installed, there is not temperature compensation.
P17 seems to indicate equalization can be disabled by setting EQ Interval to 000 days.

On that basis, I see no reason why an MX-60 can't be used. The functionality seems nearly identical to my neighbor's pair of FM-80s, and I wouldn't hesitate to use those for LFP even though those don't have a LFP mode either.

 

[Fenachrone]

If you can:

specify an absorption voltage of 3.45-3.55V/cell
specify a float of 3.375V/cell
specify an absorption period of 2 hr (3.45V) or 30 minutes (3.55V)
disable temperature compensation
disable or set equalization to the absorption votlage

Using:

http://www.umiat.com/network/umiatbase/manuals/MX60_Manual_Rev6_2.pdf

P15 seems to allow for custom absorb/float.
P27 seems to indicate you can set min and max absorb time periods.
P21 seems to indicate if there is no temperature sensor installed, there is not temperature compens'vs.
P17 seems to indicate equalization can be disabled by setting EQ Interval to 000 days.

On that basis, I see no reason why an MX-60 can't be used. The functionality seems nearly identical to my neighbor's pair of FM-80s, and I wouldn't hesitate to use those for LFP even though those don't have a LFP mode either.

I appreciate your taking the time to respond. Here's what I've done:

Per Kilovault, I've set absorption to 28.2. (Don't know if that correlates with your 3.45-3.55V/cell).
" " , I've set float to 26.8. (Again, don't know if that correlates with your 3.375V/cell).

Temperature and equalization are disabled (temp sensor is disconnected).

How would your numbers translate to an absorption period recommendation relative to a 24v system?

Thx

 

[sunshine_eggo]

28.2V / 8 cells = 3.525V/cell
26.8V / 8 cells = 3.35V/cell

I'll take battery manufacturer specs over generic ones in most cases (Big Battery is an exception - idiots), so they're fine.

I'd go with a 1 hour absorption - minimum 55 minutes, maximum 65 minutes per the MX-60 convention.

 

[Fenachrone]

I'll put that into action. Again, much appreciated!!

 

[sunshine_eggo]

Happy to help.

The 1 hour absorption is to just force the battery to an elevated voltage to:
1) insure 100% charge
2) insure the cells spend time at elevated voltage to allowing balancing.

It will probably be fully charged in 15-30 minutes at that voltage.

 

[Fenachrone]

Just as an aside, I wrote to Outback wanting specifics as to just what the incompatibility of the MX60 truly was. I was again told simply that the MX60 is not compatible:

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.

That response doesn't please me. If anything, when I do replace my MX60, it may be with other than an Outback product.

 

[sunshine_eggo]

Just as an aside, I wrote to Outback wanting specifics as to just what the incompatibility of the MX60 truly was. I was again told simply that the MX60 is not compatible:

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.

That response doesn't please me. If anything, when I do replace my MX60, it may be with other than an Outback product.

Motivated to sell newer hardware. Might be worth asking where in the FM60/80 manual does it indicate it can be used with Lithium?

https://www.outbackpower.com/downloads/documents/charge_controllers/flexmax_6080/owner_manual.pdf

The word lithium doesn't appear anywhere in the manual.

 

[Fenachrone]

Interesting... Pretty dirty pool but not unexpected in this day and age, and I believe the founders of the company have moved on. Affiliated, from what I read, with Midnite Solar, who have put out this information on integrating their controllers with Kilovault.

https://www.kilovault.com/wp-content/uploads/2020/12/KiloVault-Midnite-Compatibilty-White-Paper-2020. Seems to me that's the way it should be done.

Meanwhile here, we've had a great charging day and batteries are full, system is in float.