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What are issues charging LiFePO4 with Magnum Mm1212?

STW

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My RV has a Magnum MM1212 inverter/charger with MM-RC remote. Magnum says it does not have a specific LiFePO4 profile. The current charge profile is set for AGM2 (because that is the profile loaded in the remote and is non changeable) that has Bulk @14.5v and Float at 13.5v. What issues would I look for if I tried to use it?

This inverter/charger is 1200watts, 70amp charger, and includes a transfer switch as an all in one unit. I hate to spend another $1300 just to solve a charging problem.
 
Are you saying that the charger has one setting and one setting only? Normally a Magnum's charging profile can be changed, provided you have the remote. Is there a constant current / constant voltage option available for charging? Can you attach or link to the manual?
 
My RV has a Magnum MM1212 inverter/charger with MM-RC remote. Magnum says it does not have a specific LiFePO4 profile. The current charge profile is set for AGM2 (because that is the profile loaded in the remote and is non changeable) that has Bulk @14.5v and Float at 13.5v. What issues would I look for if I tried to use it?

This inverter/charger is 1200watts, 70amp charger, and includes a transfer switch as an all in one unit. I hate to spend another $1300 just to solve a charging problem.
Does it not have a user or custom profile that allows all the charge parameters to be configured?
 
To have the custom settings the "advanced remote control", the MM1212 doesn't have that option.
 
Yes I am very frustrated. The remote in my RV is a very simple on/off remote. To get the ability to adjust settings I would need an ME-RC or better remote at $200 to $300. I would be willing to do that but Magnum says my inverter is a Level 3 and it must be a Level 4 to do Lithium. They have NO current plans to update my inverter firmware. They want you to spend $1300 on their newer inverter for this simple functionality. But you will still need to spend another $300 for the remote. So $1600 just to get Lithium capabilities.

I found a tech article from Magnum (0157, PRC 1192009, dated 1/19/09) that says support for custom battery setting was added. Not sure what that means, but looked promising.

So back to original question.. with Bulk set to 14.5v and Float set to 13.5v what issues could there be? I wonder if charger would know when to kick back in. I saw something in docs that said if volts is <=12.9v it goes into Bulk. If higher than that it goes to Float. Would the LiFePO4 get below 12.9?

Any and all comments appreciated.
 
How long does it hold absorb before switching to float?
Manual says inverter with MM-RC remote is set for 200ah battery bank and hold absorb for 120 minutes And low battery cutoff at 10.0 volts.
 
So back to original question.. with Bulk set to 14.5v and Float set to 13.5v what issues could there be?
14.5 volts is pretty high for bulk charge, only leaves 25 milli volts headroom per cell.
Depending on how well top-balanced your pack is the bms may trip on every charge cycle.
13.4(3.35 per) volts is considered the highest "safe" float voltage.
Having said that many folks run with a float of 13.5 volts.
I wonder if charger would know when to kick back in. I saw something in docs that said if volts is <=12.9v it goes into Bulk. If higher than that it goes to Float. Would the LiFePO4 get below 12.9?
If the charger is in float the only way the battery voltage will get lower than 13.5 volts is if the system load exceeds the charger's ampacity.
 
I found a tech article from Magnum (0157, PRC 1192009, dated 1/19/09) that says support for custom battery setting was added. Not sure what that means, but looked promising.
Custom battery settings means that you can set them to what you would like. So you should be able get the correct remote and set them appropriately.

You should confirm this with Magnum before you buy the remote.
 
14.5 volts is pretty high for bulk charge, only leaves 25 milli volts headroom per cell.
Depending on how well top-balanced your pack is the bms may trip on every charge cycle.
13.4(3.35 per) volts is considered the highest "safe" float voltage.
Having said that many folks run with a float of 13.5 volts.

If the charger is in float the only way the battery voltage will get lower than 13.5 volts is if the system load exceeds the charger's ampacity.
When talking about float it can mean different things depending on the end users use.

My "float" is 13.6v and it's been like that since 4/2016 of everyday use being charged by solar 98.5% of the time with an absorb setting of 14.1v for roughly 6 minutes .
Were as a weekend worrior might want to be a little more conservative if they left it floating with occasional use.

I'd be interest were the 13.4v highest "safe" float voltage came from? Or are there caveats that come with this claim?

I'll agree that 14.5v is pretty high with a 2 hour absorb time, I'll bet the battery would shut itself down and there will be some heat generated in the pouches.
 
I'd be interest were the 13.4v highest "safe" float voltage came from?
Came from @RCinFLA
Its the highest voltage that puts the least amount of wear and tear on your battery.
I believe he has mentioned multiple times with varying degrees of detail.
Will have a look through my bookmarks.
Or are there caveats that come with this claim?
I shall caveat now...
That is the voltage that is used for lifepo4 UPS applications.
Giving the most capacity for the least amount of acceleration to calendar aging.

For my own application I have a charger on 24/7 my float is set to 26.4 volts or 3.3vpc.
The charger tops up the pack at 1:00am every night and the charger starts sharing the load by mid afternoon.
By bedtime its carrying the whole load.

UPDATE: attached citation https://diysolarforum.com/threads/charging-method-lifepo4-280ah-eve-float-or-not.7886/post-157775
 
So no white papers? It's no more than me saying...my system has been in use for 5.5 years everyday with over 1,800 partial cycles averaging 40% +/- DOD at different SOC. Floating at 13.6v with no ill effects. 13.4v certainly can be safer but saying "highest safe float voltage" is pretty bold statement.
Looking at the thread when someone puts that setting in longterm (many, many years) use then it can be tested for capacity. But then he talking as a UPS setup.
?
 
So no white papers? It's no more than me saying...my system has been in use for 5.5 years everyday with over 1,800 partial cycles averaging 40% +/- DOD at different SOC. Floating at 13.6v with no ill effects. 13.4v certainly can be safer but saying "highest safe float voltage" is pretty bold statement.
Looking at the thread when someone puts that setting in longterm (many, many years) use then it can be tested for capacity. But then he talking as a UPS setup.
?
Nope no white papers.
;)
 
I confirmed that the AGM2 settings are:
Bulk until 14.5v (charger is 70a max)
Absorb for 90 minutes
Float 13.5v for 4 hours
Turns off until volts <12.9v then float again.
Note: There is a temp sensor that will lower Absorb voltage if temperature is over 77, or raise voltage if it’s under 77 degrees. I have seen it at 14.3v when it was around 85 degrees.
 
My RV has a Magnum MM1212 inverter/charger with MM-RC remote. Magnum says it does not have a specific LiFePO4 profile. The current charge profile is set for AGM2 (because that is the profile loaded in the remote and is non changeable) that has Bulk @14.5v and Float at 13.5v. What issues would I look for if I tried to use it?

This inverter/charger is 1200watts, 70amp charger, and includes a transfer switch as an all in one unit. I hate to spend another $1300 just to solve a charging problem.
I am in the same situation. In November 2021, I installed a 100Ah kit from batteryhookup.

My trailer has an MMS 1012, 1000W/50A with the same 14.5/13.5 Volt charger settings. Solar has always the primary charging source and the MMS was mainly a Bulk charge source.

I also have the remote with 6 LEDs and therefore I can observe Bulk/Abs/Float status. I have used the MMS since 2014 to charge AGMs. The Abs time is calculated during Bulk and not fixed to 120min. I have seen it start in Bulk and be into Float in under 30 minutes. That is because a lead battery is not missing many Ahs when near 12.9V. The Float stage has a 4 hour timer after which the it ceases any charge and enters standby watching for the 12.9V.

I see two LFP issues:
1. The 12.9V is nearly fully charged for lead, but ~80% DOD for LFP. This may cause an excessive charge time at 14.5V. It might be okay to reach 14.5 during Bulk, but the Abs should be cancelled by going straight to Float.
2. The 4 hour Float timer activates #1, the 12.9V issue.

Do not leave the MMS unattended when connected to an AC source. So, it is genny style charging.

The good is that the 13.5V Float charge is right at ~99% SOC for LFP.

How to trick the MMS into using 13.5V Float? By taking a Voltage reading you will know where you stand on the 12.9V issue.

If under 12.9V you do Constant Current(CC) until 13.2V(3.3V/cell), or ~70% SOC. Then, stop and start the MMS and it will do Constant Voltage(CV) until 13.5V(3.375), or ~99% SOC. You can stop/restart this CV if you need the MMS to serve as a power supply. Otherwise, you are done and can shut the genny off.

With solar available, you can use less genny time if you use the genny early in the day.

P.S. Actually you can be done charging e.g. after CC if you only need 70% SOC looking ahead. LFP does not often NEED to be fully charged.
 
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