Should I upgrade my Classic 150 to charge Lithium

[russtang2005]

I am a little disappointed that Midnite does not do closed loop communication with advanced Lithium batteries.  I have been using FLAs for the last 7 years but want to upgrade my batteries to the latest Lithium technology.  It appears to me that my classic 150 does not take advantage of communicating with the BMS system to improve charge efficiency.

Help me if you are facing this dilemma. 

[ClassicCrazy]

While it might be nice to have closed loop, I have been using my Classic to charge my lithium batteries for years now.  I did have to tweak some settings so it did the exact charging I wanted it to. Bob had a new lithium firmware that improved charging criteria for lithiums but some people experienced some kind of issues with it. I did not have any problems. But even with the older ( present) firmware it worked okay when I tweaked the settings. The main thing I had to tweak was the voltage offset to make up for the voltage drop in cables to make sure it was at the proper voltage at the top of the charge ( absorb) . 
Since the Classic was originally designed for lead acid , it does a pretty good job with lithiums.
If the closed loop is important to you , then you should look for a different controller. I never found it to be that critical to make me want to buy a different controller. Lots of people out there have different expectations and ideas of how to charge lithium batteries. My Classic and my Outback inverter are really reliable and do the job.
Larry

[ScoobyMike]

While it might be nice to have closed loop, I have been using my Classic to charge my lithium batteries for years now.  I did have to tweak some settings so it did the exact charging I wanted it to. Bob had a new lithium firmware that improved charging criteria for lithiums but some people experienced some kind of issues with it. I did not have any problems. But even with the older ( present) firmware it worked okay when I tweaked the settings. The main thing I had to tweak was the voltage offset to make up for the voltage drop in cables to make sure it was at the proper voltage at the top of the charge ( absorb) . 
Since the Classic was originally designed for lead acid , it does a pretty good job with lithiums.
If the closed loop is important to you , then you should look for a different controller. I never found it to be that critical to make me want to buy a different controller. Lots of people out there have different expectations and ideas of how to charge lithium batteries. My Classic and my Outback inverter are really reliable and do the job.
Larry

What are the settings to tweak on the original 150 when changing from FLA to LiFeSO4?

[ClassicCrazy]

you will want to calibrate the voltage drop in your cables by adjusting the battery voltage offset in the Tweaks menu . You do that by taking the voltage at the batteries ( or get it form the bms if available) and take the voltage at the battery terminals on the Classic. Then you will put the millivolt difference in the Battery voltage offset setting. You want to do this at the very top voltage you charge your lithium batteries to in your Absorb setting. Different manufacturers or people select different top voltage settings for this. For example on 48v batteries some manufacturers will say to go to 3.65 v per cell which is at the very top of the cells range. Others say 3.5v per cell, and I charge to 3.45 per cell. Some of the disparity is that the battery will charge faster at the top of the range ,and take a bit longer at lower voltages. But I go by Off Grid Garage on youtube videos suggestions because he has done a lot of testing over the years and explains all his graphs and results. Some people will charge at higher current at top of manufacturers range, others at lower current. You have to do your  own research and decide.
Also depending on the quality of your cells when they were selected, will ultimately determine how well they stay in balance without the bms balancing happening. So your Absorb time selection will also determine how long the bms may take to balance cells at the top . And of course the bms if it has passive or active balancing and how much current it bypasses or actively balances with.
Finally when you set the battery voltage offset on the highest voltage and current in absorb you will see the voltage is off at the lower float voltage. So you need to adjust the Float voltage accordingly to compensate for that.
And you will want to watch the Absorb voltage too initially to make sure it transitions from Absorb to Float at the point you want it to . Sometimes I have seen it do that lower voltage with the Classic . So you can adjust the Absorb voltage higher or lower as needed . But if you are not charging you cells to the highest voltage possible there is a lot of leeway so you don't need to be too concerned as long as you get the cells full. For my 48v I use 55.2v which is 99% full. So it doesn't matter too much if I go to 55.5 or even 55v , still a long ways away from the 58.4v ultimate top .
I want to float at somewhere between 53.6v and 54v depending on the controller etc. I want to see the batteries not take in any more power at float but still want to see the controller providing power to the loads from available power in the day. So that is why you just watch it and tweak the float as needed for your system.
There is ending amps setting which you can use but  you need to determine that for your particular battery if you use it . Some inverters these days call that tail amps if you are researching this.
Anyway a bit of watching things close in the beginning and making adjustments, then you won't have to worry too much about it .
All good  batteries bms these days have low voltage cutoff if that is a concern of yours .
The Classic won't do that.
I forgot to mention that you don't use temperature compensation for lithium so set that to 0 . I forget now if that disables the temp sensor or if it still shows the temperature if you put the battery probe in. I have played around with a lot of firmware versions so don't remember which does what .Just set it to zero temp compensation .
I think that is all !
And if you think it might be better to just get a new controller or inverter that has closed loop battery communications - that can be a bit of a hassle sometimes too and you might not get the same control as you get using the Classic. It all depends on which batteries and which controllers.
Larry

[ScoobyMike]

Thank you Larry!  I kind of lost this thread for a while.  My FLAs gave me 7 good years of service but are failing fast now.  FLAs have increased in price by 0ver 40% since 2020 while LiFePO4 have come way down.  I am getting ready to install a 12V 314AH SOC and a Victron Multiplus-2.

You mentioned you like to charge cells to 3.45. So for my 12V system does this mean that I set absorb to 13.8?

The charger in my camper uses 14.2V for LiFePO4, and 13.5V for float.

To first order do I simply change the absorb and float values in the Classic and then implement the tweaks you mentioned?

[ScoobyMike]

Larry,

I reread your post several times and I think I've got it! 

Just an FYI, I have watched several Wil Prouse videos and he asserts that the state of the art in BMS technology allows users to charge to a full 3.65V per cell.

I am not that bold and I will likely start with 14.2V absorb and 13.5V float.  I will implement the tweaks you mentioned and watch closely for some time.

Thank you so much for the valuable info!

Mike

[ClassicCrazy]

Did you mean you are getting an SOK battery ?
There is a facebook group for SOK with a lot of posts and information.
It really depends on what the manufacturer wants and some of that is dependent on what the bms in the battery is looking for to do the balancing and reset the SOC ( for monitoring ) .
Watch some Off Grid Garage videos - he mainly does 48v batteries but has some from the past where he extensively tests and graphs and analyzes results for single LiFePo4 cells . All lifepo4 cells are pretty much the same in the way they charge and discharge.
Will Prouse gives some pretty generic advice . Everyone seems to have their own opinions on best lithium charge practices. It took me a long time to really understand the nuances of them.
Larry