Charging Lithium

[jdanigole]

I have a Magnum MS 2012 inverter with a ME-MR 25 controller. The controller doesn’t have an option to charge lithium but it appears that the ME-MR 25 L will charge lithium. Do I just need to change the controller to charge lithium?

[Gary RVRoamer]

That would give you additional profiles to choose from, including LiFeO4. Having the right profile yields optimal charging results, but an AGM profile on your existing remote will come pretty close.


I'll let the lithium gurus debate how much practical difference there may be between "optimal" and "good enough".

[153stars]

It won't charge as fast as it could on an LI profile but still faster than lead batts. The LI can take higher amps longer . The AGM Wil taper earlier than It could. It won't bring to 100% and cell balance more like 85%. Solar can finish deep charging just like lead. Charging to 100% balance state for daily cycling is not optimum either/anyway most daily cycles /off grid owners set profile a bit shy of that.
If your inverter is working well for you , a moderate of solar set up 300-400 watts might likely to pay better dividends.
You could easily switch solar to chassis batt in storage . The LI have very low self discharge if completely shut off won't need charging in storage.
Epever offers the DuoRacer solar controller that has 1amp separate charge for chassis batt as well, cost about the same as their similar spec single battery controllers.

[JeromeS13]

Originally Posted by jdanigole

I have a Magnum MS 2012 inverter with a ME-MR 25 controller. The controller doesn’t have an option to charge lithium but it appears that the ME-MR 25 L will charge lithium. Do I just need to change the controller to charge lithium?

Do you have a custom profile setting? If it'll allows you to change the absorb voltage and float voltage, you can probably get by with your current remote.

[computerguy]

In my opinion this is too general of a question from the OP.
Most lithium batteries have different charge profiles. So the fact that Magnum even comes out to say their latest cheapest remote can charge lithium is a bit deceiving. If I understand correctly, too, one needs to make sure all the equipment being used also has the "-L" designation or at least is compatible with the others in the system.
When I did mine back in '17 I ended up getting the ME-ARC. It has enough options to configure my lithium batts nicely.
6+ years later, full time in the rig, and my batts are going strong as when I bought them.
In the end that is what is important. You can charge batteries anyway you want. How long they last is the key thing. Abuse them and they won't last. Treat them the way the manufacturer tells you to and you can expect a much better outcome.
My install here

[CaptainYARRR]

I just went through this and here's my bottom line:

Yes you can keep using that controller but it misses a couple things.

The Lithium profile definitely keeps them in a better place for storage.

But the big one that is necessary is the ability to initiate a bulk charge easily. It is a great feature before a trip to hit the batteries with a big charge so you're leaving home with your capacity utilized.

[jharrell]

Both the remote and the inverter need to "L" models. The remote sends a battery type code to the inverter, if the inverter isn't updated it will not understand the lithium battery type that is sent by the remote.

Older Magnums can use either Custom or CC/CV battery types but have a few issues.

1. The temperature probe must be disconnected as lithiums don't need temp compensated charging and will be over / under charged based on temps.

2. Custom with final stage float will not rebulk until 12.1v which is very low on a LFP. You will have to force bulk most of the time manually or it will charge more slowly on float and never absorb. Custom with no float (silent) or CC/CV rebulk voltage can be set but you will have no float so it will always cycle to rebulk then absorb over and over while plugged into shore power.

LFP profile raises rebulk voltage to 12.8v while maintaining float and disables temperature compensation.

[Topperace]

I contacted Magnum tech support to see how to set the controller for Lithium batteries and they said they would walk me through the programming once I got the batteries.

I would contact them and tell them what specific LI battery you have, and they
more than likely will be able to tell you how to program the controller.

[creativepart]

Much better to spend a bit more for the MS-ARC50 or the MS-ARC-L.

Not only does the L give you a lithium setting - the ARCs (Advanced Remote Controls) give you vastly more control over the inverter and the charger.

It's only $200-ish dollars and it works with the Magnum BMK and AGS, too.

[757driver]

Originally Posted by jharrell

Both the remote and the inverter need to "L" models. The remote sends a battery type code to the inverter, if the inverter isn't updated it will not understand the lithium battery type that is sent by the remote.

Older Magnums can use either Custom or CC/CV battery types but have a few issues.

1. The temperature probe must be disconnected as lithiums don't need temp compensated charging and will be over / under charged based on temps.

2. Custom with final stage float will not rebulk until 12.1v which is very low on a LFP. You will have to force bulk most of the time manually or it will charge more slowly on float and never absorb. Custom with no float (silent) or CC/CV rebulk voltage can be set but you will have no float so it will always cycle to rebulk then absorb over and over while plugged into shore power.

LFP profile raises rebulk voltage to 12.8v while maintaining float and disables temperature compensation.

Older Magnum remotes will initiate a 4 hour float charge when the battery voltage is at 12.5v not 12.1v.

[jharrell]

Originally Posted by 757driver

Older Magnum remotes will initiate a 4 hour float charge when the battery voltage is at 12.5v not 12.1v.

According to the docs its 12.6v (not 12.5) ONLY IF the final charge stage is Multi which has no use with Lithium. Battery saver 4 hour rest is designed for Lead.

I was not talking about re-float, I am talking about re-bulk volts which is 12.1v.

If you use Custom battery with silent final charge or CC/CV there is NO FLOAT and therefore no re-float threshold for another 4 hours, you can set re-bulk volts to whatever you want in this mode.

If you use final charge stage float, then its always floats so there is no re-float voltage either and re-bulk is hard coded to 12.1v.

The problem with re-bulking at 12.1v is if you have been running your Lithiums down and want to charge them back up quickly with a generator, if they haven't hit 12.1v (which is only about 10% SOC) then it will only do a float charge which ends up being lower amps since its target will be 13.6v vs 14.4v absorb so the smaller voltage difference will cause much less amps and longer gen run time.

[RoadTrip2084]

On my old Freedom 20 inverter to charge my LiFeP04 battery I'm using "Cool Wet Cell" mode which bulks at 14.1v. This results in the full 100A charge rate.

I also have it configured for manual charging, meaning I have to flick the switch to "on" on the control panel when plugged in to shore power (or running the genny) if I want a charge cycle to start. This way I have some control over the charge behaviour and am not reliant on the Freedom detecting a low-voltage state to initiate charging, etc.

[jharrell]

Originally Posted by RoadTrip2084

On my old Freedom 20 inverter to charge my LiFeP04 battery I'm using "Cool Wet Cell" mode which bulks at 14.1v. This results in the full 100A charge rate.

Yep that is fine so long as your passive balancers kick in at 14.1v, or you have some other means to keep cells in balance, might be little slower reaching 100% than 14.4v depending on bank size. Remember absorb volts is not just to get a fast charge its to raise the cells high enough for passive balancer to bleed off, which is the only reason to have an absorb time with lithium above 14v or so.

Originally Posted by RoadTrip2084

I also have it configured for manual charging, meaning I have to flick the switch to "on" on the control panel when plugged in to shore power (or running the genny) if I want a charge cycle to start. This way I have some control over the charge behaviour and am not reliant on the Freedom detecting a low-voltage state to initiate charging, etc.

This what I used to have to do with my old RV with lithiums and an older Magnum that did not have LFP profile. I would run all night with batteries and in the morning I would start gen but it would only go into float charge, too slow, then I used the Magnum remote to manually initiate bulk charge. Not the end of the world, just another thing to baby sit.

Prefer floating over repeated absorb cycling when plugged into shore so CC/CV or silent was not for me.

With LFP profile on the new Magnum, it's pretty much hands off, which is convenient.

[RoadTrip2084]

Originally Posted by jharrell

Yep that is fine so long as your passive balancers kick in at 14.1v, or you have some other means to keep cells in balance, might be little slower reaching 100% than 14.4v depending on bank size. Remember absorb volts is not just to get a fast charge its to raise the cells high enough for passive balancer to bleed off, which is the only reason to have an absorb time with lithium above 14v or so.



This what I used to have to do with my old RV with lithiums and an older Magnum that did not have LFP profile. I would run all night with batteries and in the morning I would start gen but it would only go into float charge, too slow, then I used the Magnum remote to manually initiate bulk charge. Not the end of the world, just another thing to baby sit.

Prefer floating over repeated absorb cycling when plugged into shore so CC/CV or silent was not for me.

With LFP profile on the new Magnum, it's pretty much hands off, which is convenient.

My BMS does passive balancing, can configure for during charging or all the time. Currently have it set to "While Charging", not really sure of when it decides to balance but haven't seen any issues at all with the balancing of the cells, but only have about 30 cycles on the batteries.

I also have a 60A DC-DC charger off the alternator that is lithium aware, so using that to charge from time-to-time may also be helping me out, not sure.