Need help with solar performance

[boywonder]

Originally Posted by FormerBluffer

Shouldn't the lower SOC and battery voltage numbers indicate a greater likelihood that Bulk Mode charging will be triggered?

yes....exactly.


Do you have float set at 13.4 or 13.2V?


The reason I ask is that on the second day you had the batteries at 13.37V.


If float is set at 13.4 than 13.37 would be in bulk territory.......if float is set at 13.2V then 13.37 would still be in float mode.

[Scalf77]

So I take it we are determining SOC by voltage levels? This is one of those cases where a good battery monitor comes in very handy. I take your measurements are taken from multimeter? (good job by the way). This is where a good battery monitor helps.

The biggest problem with that is it is just a snap shot in time, you would really need to take measurements throughout the day. You really want to see if you truly reach absorption voltage. Lithium for the most part doesn't hit that level until it is fully charged.

It would be better to count on the charger telling you its's in float.

You can always check for voltage drop between controller and battery, measure between terminals of each. As boywonder said, this value would change depending on current levels.

So with your panels in parallel and in the hot sun, (pv voltage drops with higher temp) it is possible that the voltage drops low enough to not get the MPPT performance is not there. I would certainly expect that , but would think you would still see better performance.

So you might have better efficiency of transferring power in lower temp conditions, the overall better solar conditions should make up for it, so I wouldn't think it would perform worse overall. This is where the series set up would be great as the voltage would be high enough still produce MPPT benefits, even if the heat (sun) reduced voltage

[jonyjoe101]

this is what I mean about voltage drop from the controller. On the the top picture it shows a .6 voltage difference from controller and battery terminals. On my makeskyblue 60 amp mppt it has a feature to calibrate the controller voltage to the battery terminals.

After calibrating the bottom picture shows the voltage is very close to each other. If your controller doesnt have a calibration feature, thats when you have to raise the bulk voltage higher than the recommended bulk voltage to compensate.

Without raising the bulk voltage the controller will be charging at low amps.


All controllers that I used where way off, they usually read high.

Since your only reading 13.37 volts during charging, that means your batteries are probably 50 percent or less and it will take along time to get them to 100 percent with 230 watts. Once you start reaching 14 volts or higher it will be closer to full. With lifepo4 unless you have a coulombmeter that was properly calibrated when the battery was full, it will mostly be guessing what the SOC is. It took me a while and draining my lifepo4 to zero several times before I figured out how to properly determine the SOC. Now I just keep them at 100 percent everytime to prevent any drama.

[Scalf77]

Jonyjoe101,

Your picture does not represent voltage drop. That would be where the voltage at the battery is lower than the voltage measurement taken at controller. It would generally seen with long and or to small of gauge wire running from controller to battery.

I would say most controllers don't have a calibration feature because they are more accurate out of the box

In most controllers Bulk phase is just current, so as the battery get's charged the voltage level goes up. You certainly would not want to adjust the absorption voltage based on a snapshot during bulk charging.

I would say there is some confusion with the OP's data , as it appears the controller thinks it is absorption , before it has reached it's absorption voltage threshold.


FormerBluffer

I apologize asking about battery monitor as I see you have the relion battery monitor. I expect this is the insight gauge?

As Jonyhoe101 said, it might be good to go through a full shore power charge to make sure the battery monitor is in sync. Then you can check out the solar controller and see if it goes into absorption correctly ( after SOC drops down)

It would be nice if the gauge also recorded current .

[FormerBluffer]

[Sorry in advance for the long post]

Originally Posted by boywonder

yes....exactly.

Do you have float set at 13.4 or 13.2V?

The reason I ask is that on the second day you had the batteries at 13.37V.

If float is set at 13.4 than 13.37 would be in bulk territory.......if float is set at 13.2V then 13.37 would still be in float mode.

Float (FLt) is set for 13.2

The Relion Battery Monitor is not the insight gauge. My battery monitor shows Volts, Amps flowing (+ or -), Ah and SOC %.

When I look at the battery Volt reading taken with a voltmeter off the terminals in the Solar Controller, it is different than the Volt reading according to the Battery Monitor. I haven’t been tracking this, but I did find 2 examples in my notes, and they show a slight difference and on both occasions the Volt reading taken with the voltmeter was slightly higher.

Example 1 13.7 (Voltmeter Reading) 13.39 (Battery Monitor Reading)
Example 2 13.3 (Voltmeter Reading) 13.12 (Battery Monitor Reading)

Are these measuring the same thing

I did plug into shore power for the last couple of days. Yesterday, the Volt reading was 13.6V and SOC was 99.5%, Today, the Volt reading was 14.2V and the SOC was 100%. The Volt reading was the same coming from the Battery Monitor and the Solar Controller. The readings were taken while in the garage and while still plugged in.

Originally Posted by Scalf77

The biggest problem with that is it is just a snap shot in time, you would really need to take measurements throughout the day. You really want to see if you truly reach absorption voltage. Lithium for the most part doesn't hit that level until it is fully charged.

I’m trying to understand the charging modes (as boywonder explained nicely in Post 17) in the context of making sure that I understand what to look for this weekend when I am able to take multiple measurements throughout the day. Here is my current interpretation of measurements that I should be expecting as the Solar Controller goes through the different charging modes:

1. Arrive at campsite. After driving the batteries should be fully charged from the alternator:

- SOC = 100% (based on battery monitor)
- Solar Controller is not in any charging mode
- Solar Controller display lights:
. - Aux Out = On
. - Float = Off
. - Absorption Off
- Volts (as measured by the Solar Controller) = 14.4 (based on the Solar Controller’s Absorption Setting (AbS) of 14.4)
- Amp Out reading on Solar Controller should show 0.0 (no current flowing to the batteries).
-Amp In reading on Solar Controller should show amps being generated by the panels (which will reflect the sun quality)
- All Amps generated by the panels (AMP In) are dissipated as heat through the faceplate of the Solar Controller?

2. Power from the batteries is consumed and the Solar Controller Volt readings gradually drop to 13.2V:

- SOC % (based on battery monitor) = ?
- Solar Controller goes into Float mode. No Solar Charging until Volt level drops to 13.2 (based on the Solar Controller’s Float Setting (FLt) of 13.2). HERE I KNOW I AM CONFUSED: I thought that the FLt setting determined when the Solar Controller goes into Bulk mode? Or, does Float mode start at 13.2V and Bulk mode starts below 13.2V?
- Solar Controller display lights:
. - Aux Out = Off?
. - Float = On
. - Absorption Off
- Volts (as measured by the Solar Controller = 13.2V
- Amp Out reading on Solar Controller should show little to no current flowing to the batteries. Only enough charging to keep the battery voltage at 13.2V (based on the FLt setting of 13.2).
- Amp In reading on Solar Controller should show amps being generated by the panels (which will reflect the sun quality)
- Excess Amps that are not needed to maintain battery Volt level at 13.2V (Amp In minus Amp Out) are dissipated as heat through the faceplate of the Solar Controller?

3. Power from the batteries continues to be consumed at a pace exceeding Amps Out and the Solar Controller Volt reading drops below 13.2V:
- SOC % (based on battery monitor) = ?
- Solar Controller goes into Bulk mode (based on my Solar Controller’s Float Setting (FLt) of 13.2)
- Solar Controller display lights:
. - Aux Out = Off
. - Float = On
- - Absorption On
- Volts (as measured by the Solar Controller is initially less than 13.2V at the start of Bulk mode but will increase during Bulk mode.
- Amp Out reading on Solar Controller should show current flowing to the batteries.).
- Amp In reading on Solar Controller should show amps being generated by the panels (which will reflect the sun quality)
- All available Amps from the solar panel are going to charge the battery.

4. Solar Controller Volt reading rises to 14.4

- SOC % (based on battery monitor) = ?
- Solar Controller goes into Absorption mode (based on my Solar Controller’s Absorption Setting (AbS) of 14.4)
- Solar Controller display lights:
. - Aux Out = On or Off (depending on whether current is being used in Absorption mode)?
. - Float = Off
. - Absorption On
- Volts (as measured by the Solar Controller is 14.4V
- Amp Out reading on Solar Controller should show a little current flowing to the batteries.).
- Amp In reading on Solar Controller should show amps being generated by the panels (which will reflect the sun quality)
- Excess Amps that are not needed for Absorption mode are dissipated as heat through the faceplate of the Solar Controller?
- Absorption mode continues for 2 hours (based on my Solar Controller’s Absorption Charge Time Setting (AbT) of 14.4)

5. After 2 hours in Absorption mode

- SOC = Near 100% (based on battery monitor)
- Solar Controller is not in any charging mode
- Solar Controller display lights:
. - Aux Out = On
. - Float = Off
. - Absorption Off
- Volts (as measured by the Solar Controller)= 14.4V
- Amp Out reading on Solar Controller should show 0.0 (no current flowing to the batteries).
- Amp In reading on Solar Controller should show amps being generated by the panels (which will reflect the sun quality)
- All Amps generated by the panels (AMP In) are dissipated as heat through the faceplate of the Solar Controller?

6. Return to Step 2

I also found some information about charging Relion batteries from their website.

Relion_Charging_Instructions_022421 (2022).pdf

The instructions don’t seem to tell me much. Just that my current Absorption setting (AbS) of 14.4 might need to be adjusted down to 14v – 14.2. However, I did run across a Relion Blog Post that does list some additional operational parameters for the charge controller and an FAQ with a little information.




Based on these, it looks like Relion is recommending the following settings (compared to my current setting):

- Bulk Voltage = 14V - 14.6 (I’m still unclear how this is set on the Blue Sky Controller)
- Absorption Voltage (Abs) = 14.4 (same as my current setting)
- Absorption Time (Abt) = 0 - 6 minutes (my current setting is 2 hours)
- Float Voltage (FLt) = 13.3V - 13.8V (my current setting is 13.2V)
- Lower Voltage Cutoff = 11V - 12V (I don’t see a setting for this on the Blue Sky Controller)
- High Voltage Cutoff = 14.6V (same as my current setting assuming that this means the same thing as “Maximum setpoint voltage limit” – uPr?)

I was going to make these changes before testing this weekend unless you think I should not.

My plan this weekend is to take readings throughout the day and see what I can learn.

Please let me know if you see any errors in my thinking or if I am missing anything that I should be watching.

Thanks again for everyone’s help.

[cotrailhead]

I apologize as I may not have caught every detail, but I’d like to add a few responses for your consideration.

First, you need to ensure your relion battery meter is a coulomb counting meter that is calibrated for your 600 Ah battery and then your battery should be run down to zero followed by recharging to 100%. Voltage on a lithium battery does not reliably indicate SOC full stop. 100% capacity can be achieved by charging a battery like yours at a voltage anywhere from 13.6 to 14.4 safely.

The reason someone asked you to apply a large load was to see if your system would output nearer its capacity when called on. I believe it passed the test.

The information you received about series v parallel and acceptable voltage for your controller was spot on. From what I gathered your panels are in parallel. Another test passed. However someone noted that the arrangement would not affect wire size. That is only possibly true. Your panels arranged in parallel require a wire and fuse sufficient for double the open circuit amperage of one of your panels. If your wire is too small it could be dangerous and/ or limit the watts delivered to your battery.

Finally, lithium batteries do not like to be held at high voltage for long periods of time. As a result many manufacturers do not recommend floating the batteries at all. Charge controllers are often developed with this in mind. If every day you are cycling between 75% and 100% your battery does not need to be bulk charged so the charger will never output at bulk levels. I know I grew up on lead acid batteries that love to be held at full charge and it feels good to go to sleep knowing I have 100% in my batteries but that’s not how lithium works or how some chargers are designed. Mine won’t go into bulk until my voltage drops below a certain threshold. Otherwise it is always lazing away these summer days at absorption. My battery will range between 70-90% SOC. Then in the fall when the days get shorter, my system will dip down and cycle between 55 and 70% SOC. But the day it slips below 50, here come the bulk charge mode and it will work to get those numbers up. All the while the battery is living in a range that extends its life and I’m getting all the power I need each day. I don’t get the satisfaction of 100% or 14.4 or those feelings I used to get, but it works. Yours may be the same. Your battery is big. From what I gather it might be almost 400% of your daily usage on a day with zero sun. (Based on your 7 amps is the normal comment). Your situation sounds like mine. Unless I am mistaken, and I apologize if I am, make sure your battery monitor is correct. Set absorption for 13.6. Your bulk for the same. Or 14.4 if you must. Shut your float off. Enjoy years of trouble free service from your battery.

If you’re interested in other ramblings read on. Lifepo4 can achieve 100% SOC at 13.6 volts (3.4 volts per cell).

Your battery is made of 4 cells. Let’s say you and I both manufacture cells. We both want to enter the 300 amp hour 12 volt battery market. You might buy a 300 amp hour cell and program the bms to allow charging up to 3.6 volts per cell or 14.4 volts. You are maxing out the battery’s capacity and in turn reducing potential cycle life. Meanwhile I buy 320 amp hour cells and set my bms to charge each cell only to 3.39. I’m still only achieving 300 amp hours of storage and market them in the same category you do though my cells could store more but My batteries are less stressed and will likely last for many more cycles with less chance of catastrophic failure.

These decisions are being made by manufacturers all of the time. That’s why charging according to your manufacturer’s recommendations is very important.

[Scalf77]

So I don't think your controller has configurable "rebulk setting" , which is not the end of the world. It is definitely not the float voltage level. It could be below 75% to 90% of SOC, that also could be based off of "AGM voltage". That would be a good test, to see when it drops low enough to go back into Bulk. There is no Bulk setpoint the target would be the Absorption setpoint.

Based on their data I would set absorption time to .5 hour.
Note: if one had a heavy load during absorption (inverter)you could drop the voltage below the re bulk setting and this could reset the absorption timer.

I generally set the float voltage at the lowest battery manufacturer setting.

Again, I see nothing in those settings that would change your initial problem statement.

The biggest thing that could cause reduction of performance during more sunny days (hotter) would be the drop of the PV output voltage, thus reducing the gains from being a MPPT controller.

It is hard to set up test conditions with solar because the sun is such a variable. I generally only charge with my alternator charger as needed, and will use solar as I drive. I have a perception that my output is generally better when driving as the airflow keeps the panel temperatures lower, which would increase PV. I have not done any testing to prove this observation.

Seeing as your panels are ZAMP they probably don't have MC4 connectors, or you could probably switch over to series rather quickly if you comfortable to that type of work.

[jonyjoe101]

If the coulombmeter high voltage setting is set to 14.4 volts, once the battery terminals reach that voltage, the coulombmeter will reset itself to 100 percent.
The only thing I didnt see was what was the battery terminal/monitor voltage when the controller voltage was at 14.4 volts. Some of your readings show a .3 volt (voltage drop) that will affect how many amps your battery receives. If the controller reads 14.4 volts and the battery terminals read 14.1 volts. The controller thinks the battery is fully charged while its actually barely above float. .3 voltage drop doesnt sound like much but it will reduce the amps going to the battery by at least half. If I had a .3 voltage drop, I would raise the bulk to 14.7 volts to get the battery terminals to 14.4 volts. The battery terminals will be the only true method to know the battery status.

The float setting, you can set at less than 13 volts if you want, at that voltage it won't provide any amps to the battery. If a load is a made on the battery the solar controller will increase the amps going to the battery.

Right now I have my bulk setting at 14.2 volts, I can read individual cell voltage. At 14.2 / 100 percent each cell voltage is about 3.55 volts and remains like that most of the day.

With lifepo4 you don't have to worry about absorption times, you just need to get the voltage up to 14.4 volts. Once you reach 14.4 volts your full, unlike lead acid, lifepo4 won't reach 14.4 volts unless the individual cells are actually full. The reason I set mine to 14.2 volts is that my 220ah lifepo4 is mostly full everyday, at 14.2 volts it charges back to 100 percent slowly.

[FormerBluffer]

I think I made some progress this weekend.

I started out plugged into Shore Power with an SOC of 100%. Volts were 14.2V while still plugged in (dropped to 14.1 as soon as I unplugged)

I then drove for a little over an hour. I turned off the alternator charging so any charging would only come from the solar panels.

Next (about 5:00 pm), I turned on the A/C. Volts immediately dropped to 12.9V, but there was no immediate solar charging. After about 10 minutes, the Solar Controller went into Bulk Mode:
. - SOC = ~90%
. - Volts = 12.8V
. - Amps Out =8.6
. - Amps In = 6.0

I turned the A/C off about 30 minutes later and the Solar Controller stayed in Bulk Mode.

The next morning, the Solar Controller started off in Bulk mode and at 9:00:
. - SOC = 63.8%
. - Volts = 13.3
. - Amps Out = 6.2
. - Amps In = 4.5

I then drove a little with the alternator helping charge the batteries. I wanted to see how long bulk mode would last. I drove until SOC was up to about 85%, then just left the solar panels do the rest of the charging.

At 10:45, the Solar Controller switched to Absorption mode:
. - SOC = 87.4%
. - Volts = 13.3
. - Amps Out =0.0
. - Amps In = 0.1

At 12:45, the Solar Controller switched to Float mode:
. - SOC = 85.9%
. - Volts = 13.3
. - Amps Out =0.0
. - Amps In = 0.1

At 2:00, I turned the A/C back on and the Solar Controller initially stayed in Float mode:
. - SOC =
. - Volts = 13.0
. - Amps Out = 8.3
. - Amps In = 6.1

After 10 minutes, the Solar Controller switched to Bulk mode:
. - SOC = 77.7%
. - Volts = 13.1
. - Amps Out =13.3
. - Amps In = 10.3

After 15 minutes, I turned off the A/C and the Solar Controller stayed in Bulk Mode:
. - SOC = 73.4%
. - Volts = 13.7
. - Amps Out = 12.4
. - Amps In = 10.4

At 2:30, the Solar Controller switched to Absorption mode:
. - SOC = 75.7%
. - Volts = 13.7
. - Amps Out =10.7
. - Amps In = 10.8

AT 3:00, the Solar Controller switched to Float mode (Note: between morning and afternoon, I changed the Absorption Time Setting from 2 hours to ½ hour):
. - SOC = 75.8%
. - Volts = 13.3
. - Amps Out = 0.0
. - Amps In = 0.1

At 3:30, the Solar Controller was still in Float mode:
. - SOC = 75.3%%
. - Volts = 13.3
. - Amps Out = 0.0
. - Amps In = 0.2

It was interesting to see the Solar Controller go through the Bulk->Absorption->Float cycle, but the Volt and SOC readings were not consistent when the Solar Controller made the switch to Absorption mode:
. – Volts: 13.3V vs 13.7V
. – SOC: 87.4% vs 75.7%
It seemed like both times the Solar Controller switched to Absorption mode too early.

Based on what I have seen in the past, I don’t think Bulk mode would have started without the Voltage drop caused by running the A/C. I ran across this chart from the Data Sheet for the Relion Batteries:



Am I interpreting this chart correctly that, under normal load and at 77°, Voltage won’t drop to 13.7V until SOC drops to about 75% (and Voltage shouldn’t drop to 13.3V until SOC is ~20%). If so, even the 75% SOC reading for 13.7V seems pretty low to start Bulk mode under a normal power load. Does this seem correct?

Looking at the numbers, it occurred to me that as soon as Bulk mode is complete, I’m at the maximum charge level that the batteries will achieve because any charging provided while in Absorption or Float modes will be less than my normal power drain. Then why bother with ever going into Absorption or Float modes? The Relion Charging Instructions indicate that the batteries can be charged either using a 1-stage or 2-stage profile.




Wouldn’t I be better off just going with the 1-Stage Profile if this can get me to 97% SOC? Today, I only got up to 87.4%.

This leads me to 3 specific questions:

1. Should I just focus on setting up a 1-stage profile? My thought was Yes.
2. How can I get Bulk mode to start sooner and without needing to trigger it with a high power load.
3. How can I set Bulk mode to continue to a higher SOC (97%)?

As always, I appreciate everyone’s thoughts.

Thanks

[Scalf77]

I suspect this is a problem with the controller going into absorption way to early. I am not sure if it is broken or just because it was really developed for AGM.

It also just may be broken as it does not seem to coincide with the set absorption set voltage, That also could be because it went into absorption at such a low SOC.

You try extending your absorption time, this wouldn't be my preference but it should get you to a higher SOC

You may want to look into either getting a controller that has a true lithium profile. You could also live with it as is, as not keeping your lithium battery at 100% SOC isn't a terrible thing.

Yes, on your point about going into bulk, again this charger has rebulk setting that is not programable, and based on a AGM battery.