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Best charge profile for MPP Solar LV2424 and Lifepo4? -- Also Triying to decode charge Algorithm

mrdavvv

Solar Enthusiast
Joined
Jan 14, 2020
Messages
404
Hello Forum!

So lately i have been trying different values for the charge setup on this unit. Im looking for a conservative charge profile, 10 - 90% SOC or maybe 20 to 80%. Im trying to check if my configuration its correct, and maybe others can share their own


This is my current configuration:


Charge VoltageFloat VoltageLow Voltage CutOffFull Charge CutOff
28.2V​
26.4V
23.0V​
Full / Automatic​

And just for reference, this is Will recomended values, altough i think they are for 0 - 100% SOC Charge:

Charge VoltageFloat VoltageLow Voltage CutOffFull Charge CutOff
28.8V27V21V?


So my questions:

  1. Are my values correct?, any recomendations?.
  2. What would be the charge / cuto off voltage for 10 - 90% charge?
  3. What would be the same values for 20 - 80% charge?
  4. The battery stop charging configuration its currently in FULL Mode, how does this works?, how the inverter knows when the battery its full?.... maybe when it arrives to the charge voltage?, maybe when it pass a certain threshold of current consumption?... in this menu i can setup FULL / Any voltage, what would be better??:
1589556203807.png

-------------------------------------------------

In a related subject, does anyone knows how the charge algorith for the LV2424 works?. My current assumption is:

  • Bulk Charge State: From discharged state up reaching the absortion predetermined voltage (28.2V in my case). - Constant Current Mode.
  • Absorption Charge State: Once battery reach 28.2, it goes to constant voltage and the current starts decreasing. - Constant Voltage Mode
  • Float Charge State: Once absorption its finished (Not sure how the inverter determines this), it goes to float.
  • Recharge: When battery goes below float?
1.- How the inverter decides to go from absorption to float?. I read this:

Do not have your inverter, i have the lv5048. With mine i have to set the inverter to user bat selection, then you can program bulk and float voltages. Then in menu 32 you can set absorbtion time. For the lv5048 the absorotion clock starts counting down is triggered once the battery voltage get to be higher then the float voltage. So if you set bulk at say 27.7v and a float voltage of 26.7 and if you have menu 32, a safe absorbtion time could be set to 2 hours to start. Watch the voltages and make sure non of the cells go over 3.65v during absorbtion.
@Mtour

And this:
Event: Transition from CV (Absorption) to CV (Float) = When charge current reaches threshold, usually around C/100 Amps e.g. 1A for a 100AH battery.
@tictag

So im not sure wich one its correct for the 2424's...

2.- Re-start of the Cycle: What SOC should the battery have so the charger starts again the cycle?, maybe when it gets lower than float?, in that case, it goes directly to bulk and then absorption?

3.- When the charger its finalized... the inverter starts drawing 2A from the batteries, and after a couple of hours it goes to 1A, if this behaviour normal?... does it happen to any of you?. Im expecting to see 0A both on input & output current, but for some reason seems to be drawing current all the time!, maybe my float voltage needs to be a little higher?

Thanks all for your help!
 

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I do not have program 21 on my PIP 2424 LV-MSD. Mine is off grid , is yours a grid tie unit?
 
The settings you posted will work fine although for charge cutoff I'm using 29v instead of full. It's not clear how that feature works anyway. It never gets to 29v and does switch back to battery mode once it considers itself "full". I'm also using 29.2 for bulk voltage vs 28.2. I'm using lion energy batteries and that was their suggestion.

The inverter (if powered on) will draw 1.5+ amps continuous with no loads on it even though the display is only showing a few watts. Yes its idle power consumption blows. That's also not documented anywhere.
 
I do not have program 21 on my PIP 2424 LV-MSD. Mine is off grid , is yours a grid tie unit?

Yes the LV2424 its grid tie, the PIP aparently have a different menus & firmware.

The settings you posted will work fine although for charge cutoff I'm using 29v instead of full. It's not clear how that feature works anyway. It never gets to 29v and does switch back to battery mode once it considers itself "full". I'm also using 29.2 for bulk voltage vs 28.2. I'm using lion energy batteries and that was their suggestion.

The inverter (if powered on) will draw 1.5+ amps continuous with no loads on it even though the display is only showing a few watts. Yes its idle power consumption blows. That's also not documented anywhere.

Hello!, the inverter consumption its showed in your screen?. In mine after charging it starts to draw 2A from battery even with the inverter turned off, an after some hours goes down to 1A. (It appears in the menu of input & output amps for battery).
 
[QUOTE="mrdavvv, post: 77879, member: 4632"

In a related subject, does anyone knows how the charge algorith for the LV2424 works?. My current assumption is:

  • Bulk Charge State: From discharged state up reaching the absortion predetermined voltage (28.2V in my case). - Constant Current Mode.
  • Absorption Charge State: Once battery reach 28.2, it goes to constant voltage and the current starts decreasing. - Constant Voltage Mode
  • Float Charge State: Once absorption its finished (Not sure how the inverter determines this), it goes to float.
  • Recharge: When battery goes below float?
[/QUOTE]

Did you ever determine how it switches, and when? Mine pretty much never goes into Bulk mode. the only time it will charge is if the Float setting is higher than the current battery voltage. I'm using the same float voltage setting you are, but if I do this, the battery will go down to around 50% charge and never recharge. I have to up the float voltage to 28v to get it to really start charging and get a full charge.
 
You are correct, i think the programming its a little off, since in my case it starts bulk charging only until the battery its around 40%, don't remember the actual voltage but its pretty low... so its not ideal for backup since you could have less than 50% SOC in case of an utility failure. Maybe i need to increase my float too an see what happens.

Im still testing, i might remember that the switching could have something to do with your relation between your programmed voltages (Float / bulk) as you experience.

Keep me posted if you find something!
 
Ok, sounds like yours does the same thing mine does So it's not that mine is defective, it's just that whoever programmed it had no idea what the application was. I can't imagine any application where you'd actually want the batteries to almost fully discharge before recharging. Strange that Will didn't discover this when he reviewed it. I noticed it right away but figured I was doing something wrong.
 
I was testing mine yesterday after reading this thread and sure enough at about 40% of battery charge the charging amps go way way down. I have a separate charge controller for 3 smaller panels I have, so at least that one fully charges the batteries (but it takes a long time). If I can't figure out how to get the LV2424 to charge my batteries fully I might just use it at an inverter and add a working charge controller to charge the batteries. I hope it doesn't get to that because I don't like paying $600 plus for a power-hungry inverter.
 
..... If I can't figure out how to get the LV2424 to charge my batteries fully I might just use it at an inverter and add a working charge controller to charge the batteries. I hope it doesn't get to that because I don't like paying $600 plus for a power-hungry inverter.

Yeah, my thoughts exactly. Might just admit I got ripped off on this thing and replace the entire setup, since the one thing it actually does, it does it horribly. Still waiting on a reply from tech support. I try to give them plenty of time to show how terrible they are.
 
Hello Forum!

So lately i have been trying different values for the charge setup on this unit. Im looking for a conservative charge profile, 10 - 90% SOC or maybe 20 to 80%. Im trying to check if my configuration its correct, and maybe others can share their own


This is my current configuration:


Charge VoltageFloat VoltageLow Voltage CutOffFull Charge CutOff
28.2V​
26.4V
23.0V​
Full / Automatic​

And just for reference, this is Will recomended values, altough i think they are for 0 - 100% SOC Charge:

Charge VoltageFloat VoltageLow Voltage CutOffFull Charge CutOff
28.8V27V21V?


So my questions:

  1. Are my values correct?, any recomendations?.
  2. What would be the charge / cuto off voltage for 10 - 90% charge?
  3. What would be the same values for 20 - 80% charge?
  4. The battery stop charging configuration its currently in FULL Mode, how does this works?, how the inverter knows when the battery its full?.... maybe when it arrives to the charge voltage?, maybe when it pass a certain threshold of current consumption?... in this menu i can setup FULL / Any voltage, what would be better??:
View attachment 13234

-------------------------------------------------

In a related subject, does anyone knows how the charge algorith for the LV2424 works?. My current assumption is:

  • Bulk Charge State: From discharged state up reaching the absortion predetermined voltage (28.2V in my case). - Constant Current Mode.
  • Absorption Charge State: Once battery reach 28.2, it goes to constant voltage and the current starts decreasing. - Constant Voltage Mode
  • Float Charge State: Once absorption its finished (Not sure how the inverter determines this), it goes to float.
  • Recharge: When battery goes below float?
1.- How the inverter decides to go from absorption to float?. I read this:

Do not have your inverter, i have the lv5048. With mine i have to set the inverter to user bat selection, then you can program bulk and float voltages. Then in menu 32 you can set absorbtion time. For the lv5048 the absorotion clock starts counting down is triggered once the battery voltage get to be higher then the float voltage. So if you set bulk at say 27.7v and a float voltage of 26.7 and if you have menu 32, a safe absorbtion time could be set to 2 hours to start. Watch the voltages and make sure non of the cells go over 3.65v during absorbtion.
@Mtour

And this:
Event: Transition from CV (Absorption) to CV (Float) = When charge current reaches threshold, usually around C/100 Amps e.g. 1A for a 100AH battery.
@tictag

So im not sure wich one its correct for the 2424's...

2.- Re-start of the Cycle: What SOC should the battery have so the charger starts again the cycle?, maybe when it gets lower than float?, in that case, it goes directly to bulk and then absorption?

3.- When the charger its finalized... the inverter starts drawing 2A from the batteries, and after a couple of hours it goes to 1A, if this behaviour normal?... does it happen to any of you?. Im expecting to see 0A both on input & output current, but for some reason seems to be drawing current all the time!, maybe my float voltage needs to be a little higher?

Thanks all for your help!
I think a low voltage cutoff of 25 VDC would put you at about 15%; 23 or 21 volts would put you below 10%.
Recommend Float charge voltage of 27.6V
Charge voltage 29. VDC
Here's charging algorithm:
1600034999952.png
 
OK, so this morning before sunrise I turned off the solar panels on my RV and ran some loads so at 1310 hrs the batteries were at 38% (26.4v). I then turned on the panels and the LV2424 fired up and started charging the batteries at 430 watts so I went back in the house for my covid-telework. At 1510 hrs I went out and checked and the state of charge was 61% (26.9v) but the LV2424 was charging the batteries at only 167 watts! So as far as I can figure for some reason the LV2424 must have been kicked into absorption mode somewhere between 40% and 60% state of charge and seriously reducing the charging of the batteries. I then put in Mopat's recommended charge (29v) and float (27.6v) settings and the LV2424 went up to 328 watts charging, which is much better but still not where I want to be. Since I am using lifepo4 batteries, I understand that you really don't even need absorption charging until around 90% state of charge and Battleborn recommends the same voltage for bulk and absorption (I don't have Battleborn but still....). I am thinking about putting the bulk and absorption both to 29 volts and see if I can get the charging watts to stay higher longer. Good plan?
 
Bulk and absorption voltage are actually the same thing. The controller doesn't change anything to transition to absorption charging, it merely tells you that it has reached that voltage and is now in regulating at that voltage, ie constant voltage mode.

In my, limited, experience lifepo4 batteries will still draw a reasonable amount of current in CV stage but it will quickly fall as the battery voltage rises sharply at that point (see lifepo4 SOC charge graph). For a 24V lifepo4 I'd personally set absorption/boost to 28.4 and float to 27.0 this is based on Victron's lifepo4 profile but also is generally held in the community to be a fair place to charge up to, and a place that it is safe to float at.

If you can't do tail current cut off for absorption charging, take note of how long it takes your battery charge current to fall off once it enters absorption stage and then configure the absorption time limit plus say 5 mins to that in your inverter if you can. Leaving a lifepo4 at 28.4V for hours will degrade it.
 
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Good advice. My Float voltage is the same per cell for my pack. My inverter is always on and there is always some load so floating at that voltage is just getting that last bit of sunshine into the batteries at low amperage so when the sun goes down I am ready to rock and roll knowing I will have enough coulombs to get me through the night and maybe the next day if it is smokey like it has been lately.
 
Bulk and absorption voltage are actually the same thing. The controller doesn't change anything to transition to absorption charging, it merely tells you that it has reached that voltage and is now in regulating at that voltage, ie constant voltage mode.

In my, limited, experience lifepo4 batteries will still draw a reasonable amount of current in CV stage but it will quickly fall as the battery voltage rises sharply at that point (see lifepo4 SOC charge graph). For a 24V lifepo4 I'd personally set absorption/boost to 28.4 and float to 27.0 this is based on Victron's lifepo4 profile but also is generally held in the community to be a fair place to charge up to, and a place that it is safe to float at.

If you can't do tail current cut off for absorption charging, take note of how long it takes your battery charge current to fall off once it enters absorption stage and then configure the absorption time limit plus say 5 mins to that in your inverter if you can. Leaving a lifepo4 at 28.4V for hours will degrade it.


Thanks for that, I see now I was confusing "float" and "absorption" in my post. I think I need to study up more..............
 
Woggs1: You ask what a "Good Plan" is? At this point I think a "good Plan" with MPP Solar equipment is to dump it in the trash and see about getting your money back from your credit card. Mine failed to charge completely yesterday. Their tech support is useless. They do not even acknowledge the issue.
 
So I am still trying to find the best settings on the LV2424 to fully charge my batteries. As previously discussed, at around 40% state of charge (SOC) my LV2424 would significantly reduce the charging watts and the sun would start going down before the batteries were full. The smoke from the fires cleared up yesterday and it was sunny and the high temp was 75 degrees fahrenheit. I input Mopats recommended settings:
Recommend Float charge voltage of 27.6V
Charge voltage 29. VDC
After inputting the new charge and float voltages the charging watts stayed at around 450, and the LV2424 kept bulk charging the batteries. It charged the battery up to 100% very fast and kept charging past 100% and never went into float mode! I know the displayed voltage is not accurate while charging, but at around 28.6 volts displayed I changed the settings back, I didn't want to fry my batteries (they are lion-energy so the BMS would probably have kicked in first, but still). So at this point I don't know what is going on, but the fact that it kept bulk charging until full is encouraging in a way but I really don't like it going to that high voltage without kicking into float mode. I am still optimistic I can find the perfect settings. The testing continues but If I can't get it right I am getting a victron............
 
I contacted Lion-energy and asked what settings I should put for my bulk and float, and they said set both to 27.8. I will try that next, but am not optimistic.
 
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Woggs1: You ask what a "Good Plan" is? At this point I think a "good Plan" with MPP Solar equipment is to dump it in the trash and see about getting your money back from your credit card. Mine failed to charge completely yesterday. Their tech support is useless. They do not even acknowledge the issue.
That's got me worried. I have a new MPP unit on it's way as we speak.
 
I wouldn't be. Sure there are going to be faulty units but if you look around the forum they are few and far between which considering MPP isn't a top shelf product in the first place is pretty good. If you bought from the nominated dealer / dealer network in your country you'll likely get good support too. If you bought direct from overseas or via a drop shipper off ebay etc you are bound to get a less smooth ride.
 
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