EPEVER SCC- float settings for night uses

Alonsw0

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So after reading numerous posts about setting this controller, I'm still not sure what is right for my situation... 🧐
My system:
4*100w Renogy panels 2s2p, 200ah LiFePO4 battery (fixed BMS 10.5v-14.6v), EPever Tracer4210AN+MT50.

My controller settings:
Temp compensation: 0
Over volt disconect: 14.6v
Charge limit: 14.4v
Over volt reconnect: 14.4v
Equalize charging voltage: 14.3v
Boost charging: 14.3v
Float charging: 13.4v
Boost re connect charge: 13.2v
Low voltage reconnect: 12.8v
Under voltage reconnect: 12.8v
Under voltage warning: 12.0v
Low voltage disconnect: 11.6v
Discharge limit voltage: 11.0v
Equalize duration... 0 min
Boost duration... 10 min

My question- is it possible the charger goes into float mode before battery is full?
After fully charging the battery,
used it for a couple days and the status was total discharge of 2.5 kWh & total charge of 1.5 kWh (according to the MT50). Meaning I'm in shortage of 1 kWh to full. But still the controller went into float and stopped filling the battery.

I use the system in a van, meaning that during the day it sits and charge with very little load, and when the sun sets I start using the electronics (fridge, lights, laptop, etc...).
Is there better settings that will make the most charge during daylight so I start night time with full battery?

And does monitoring charge/discharge kWhs in the MT50 really gives a reliable picture of battery's state of charge?

Thanks for any help!🙏🏼
 

DThames

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Yes it can go to float before fully charged. You might want to move your Boost duration up to 2 hours or so. I think 2 hours is the default.
 

DThames

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Note that most chargers work like this....
1. limit current to some value and let the battery voltage rise toward the "charge to" voltage.
2. once charge to voltage is reached, the current must be reduced to keep it from charging higher.
Both of these things are happening in the Boost phase. As Boost continues the amps should approach zero as the battery is fully charged. If Boost is stopped by the timer, then the battery may not be fully charged.

Boost and Float are terms often used with lead acid charging and can confuse thing when charging Lithium batteries. Lithium is more of a CC/CV (Constant current followed by constant voltage) type charging profile.
 

Ampster

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1. limit current to some value and let the battery voltage rise toward the "charge to" voltage.
2. once charge to voltage is reached, the current must be reduced to keep it from charging higher.
Both of these things are happening in the Boost phase.
I agree the Pb settings are confusing and sometimes ambiguous. I also prefer to describe them in terms of voltage and current. To clarify the above statement I would call #1 the Constant Current mode or stage. #2 is the Constant Voltage mode or stage. Those are the only two descriptions that I use for Lithium cells since all the other terms are a variation of CC or CV.
To answer to OPs question about maximiizing the charge during the day I can share what I do to accomplish that. My settings for CV are 3.45 per cell and I have a Float setting at 3.35 which is near the resting voltage. Float is just a CV setting with reduced current and since my charging is from solar it only happens during daylight and allows some charge to cover loads and overhead. Generally Float is not recommended for Lithium but in this use case it is limited.
 
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Alonsw0

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Thank you for the clarification guys.
So is there something I can improve in my settings so I get full charge before it goes to Float phase?
Because it happened before that battery was pretty empty (damn fridge....), but charger got to 'charge to' voltage pretty fast (no way it have filled the battery so quick) and still would drop the volts to float level and stop pushing max power in to the battery.

And what about measuring SOC % by monitoring the consumption in the display? Is it a good enough method?
 

mikefitz

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does monitoring charge/discharge kWhs in the MT50 really gives a reliable picture of battery's state of charge?
No, its almost useless for lithium batteries.

But still the controller went into float and stopped filling the battery.
Thats what it does when the battery reaches the target charge voltage.

These are the values that determine charging the battery, your settings, ( all the others relate to the load output on the charger)
Boost charging: 14.3v
Float charging: 13.4v
Boost re connect charge: 13.2v
Boost duration... 10 min

When the Epever wakes up in the morning it puts all the power available from the panels into the battery until the battery voltage reaches the boost value, 14.3, it will hold this value constant for the boost duration.
On completion of the boost duration it drops to float volts.
If the battery is loaded and the voltage drops below boost reconnect it starts over.

With your setup and 400 watts of panels you will be lucky to get 30 amps at midday. With a 200Ah battery and a relatively low charging current your battery will be full by the time the volts get to 14.3 volts, so there is no need for boost duration, 10 mins wont do any harm. ( if fact it will be full by the time it gets to 14 volts)
The float at 13.4 is the resting voltage of your charged battery so any loads during this time can be fully or partially provided by solar. If whilst in float mode the battery is drained and the volts fall, once the voltage is below boost reconnect the charging to boost voltage will start.

If in your case there is no significant load until the sun goes down then the settings are OK.
If you will be taking power during the daytime I suggest increasing float to 13.5 volts and boost reconnect to 13.4 volts.

The MT50 SOC is misleading, you need a 'real' battery monitor like the Victron smart shunt or the BMV712.

Depending on your location there may not be enough solar to meet your needs.

A final point, assuming everything in your system is working correctly, if the battery is reading 14 volts or over, under charge, then its fully charged. The battery, fully charged, with no charging active, will settle to something in the range 13.35 to 13.45 volts.

Mike
 

fafrd

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No, its almost useless for lithium batteries.


Thats what it does when the battery reaches the target charge voltage.

These are the values that determine charging the battery, your settings, ( all the others relate to the load output on the charger)
Boost charging: 14.3v
Float charging: 13.4v
Boost re connect charge: 13.2v
Boost duration... 10 min

When the Epever wakes up in the morning it puts all the power available from the panels into the battery until the battery voltage reaches the boost value, 14.3, it will hold this value constant for the boost duration.
On completion of the boost duration it drops to float volts.
If the battery is loaded and the voltage drops below boost reconnect it starts over.

With your setup and 400 watts of panels you will be lucky to get 30 amps at midday. With a 200Ah battery and a relatively low charging current your battery will be full by the time the volts get to 14.3 volts, so there is no need for boost duration, 10 mins wont do any harm. ( if fact it will be full by the time it gets to 14 volts)
The float at 13.4 is the resting voltage of your charged battery so any loads during this time can be fully or partially provided by solar. If whilst in float mode the battery is drained and the volts fall, once the voltage is below boost reconnect the charging to boost voltage will start.

If in your case there is no significant load until the sun goes down then the settings are OK.
If you will be taking power during the daytime I suggest increasing float to 13.5 volts and boost reconnect to 13.4 volts.

The MT50 SOC is misleading, you need a 'real' battery monitor like the Victron smart shunt or the BMV712.
The Victron smart shunts are pricey and for many of us, many of the ‘smarts’ are superfluous. Are there budget shunts that will monitor the charge current supplied by an SCC through a 12 or 24 hour charge cycle?

My Epever SCC displays daily kWh of output but I’m interested in finding a way to add a simple (and cheap) reality check of daily Ah of charge sent into the battery.

I don’t want to add a shunt directly onto the output of the battery as I cannot afford any voltage drop between battery and inverters, but dropping a small amount of voltage between SCC and battery input is something I can manage if it allows me to get a daily measure of Amp Hours of charge added to the battery.

I bought a battery capacity tester for $20 that monitors total discharge out of a battery so is there a shunt/monitor combo that will monitor total charge current?
Depending on your location there may not be enough solar to meet your needs.

A final point, assuming everything in your system is working correctly, if the battery is reading 14 volts or over, under charge, then its fully charged. The battery, fully charged, with no charging active, will settle to something in the range 13.35 to 13.45 volts.

Mike
 

mikefitz

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add a simple (and cheap) reality check of daily Ah of charge sent into the battery.
Put this into your search engine, aili battery monitor
shunt directly onto the output of the battery as I cannot afford any voltage drop between battery and inverters

That where the shunt will need to be. To measure current into or out of the battery you need a shunt in the negative path. The volt drop at full current is 50mV, I am sure your inverter will tolerate that.
smart shunts are pricey and for many of us, many of the ‘smarts’ are superfluous.
That may be true, but having invested in your battery pack, knowing the status and history of the charging of the battery may prevent costly mistakes, smarts are useful.

Getting back to solving your problem,
Is the battery a DIY or ready built?
If DIY what MBS?
What is the battery voltage at the end of the days solar charging?
What is the battery voltage first thing in the morning , or at bedtime?
How are you measuring these voltages?
Are you running out of power, or just concerned by the MT50 readings?

After fully charging the battery,
used it for a couple days and the status was total discharge of 2.5 kWh & total charge of 1.5 kWh (according to the MT50). Meaning I'm in shortage of 1 kWh to full. But still the controller went into float and stopped filling the battery.
I re read this statement, can I assume that all your loads are taken from the Epever load outputs, and there is nothing else connected to the battery except the Epever?

Mike
 

fafrd

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Put this into your search engine, aili battery monitor
Funny, I just found that aili monitor on my own and came back to thread to ask whether any members here had experience with it.

Do you use one?
That where the shunt will need to be. To measure current into or out of the battery you need a shunt in the negative path. The volt drop at full current is 50mV, I am sure your inverter will tolerate that.
I understand that shunts are normally positioned on the battery output and that this is necessary to monitor current into or out of the battery.

I’m not interested in measuring current out of my battery, merely current in (as a reality-check on the daily kWh generation being reported by my SCC).

As far as my inverter being able to ‘tolerate’ a 50mV drop, that’s a fortunately a problem for my rig. I’ve already gone to the trouble and expense of using 2/0 Welder’s cable between battery and inverter to keep round-trip cabling resistance down to under 0.5mOhm. Adding another 0.5mOhm or even 0.25mOhm into that high-current path when it is not needed would make no sense for me…

That may be true, but having invested in your battery pack, knowing the status and history of the charging of the battery may prevent costly mistakes, smarts are useful.”
I fully discharge every night and there is no value to me in tracking that discharge or knowing the SOC of my battery during discharge (it is what it is).

The ‘smarts’ I want are first and foremost to have a reality check on the kWh of daily PV generation being reported by my SCC. For that, I only need a shunt on the incoming charge wire from the SCC and the only issue I have is how to reset the monitor every night. In a pinch, I can reset it manually however frequently is needed to keep it from maxing out (since it will only ‘see’ increasing charge, never decreasing).

Ideally, I’d like a data logger so that I can both start to track seasonal PV generation as well as monitor when battery capacity starts to decline (which will translate to higher voltage at equivalent SOC).

But I suspect any ‘smart shunt’ with data logging capability is going to cost a pretty penny more…
Getting back to solving your problem,
Is the battery a DIY or ready built?
If DIY what MBS?
I’ve got a 560Ah 8S2P LiFePO4 I built with a Heltec 300A BMS.
What is the battery voltage at the end of the days solar charging?
I just finished rebalancing the battery from top-balanced to bottom-balanced.

For the first time last night, after LVD at 24.0V (~3.0V / cell), which typically happens around 9pm, when I check the battery before the SCC begins charging the next morning, the battery has recovered to 24.034V and all cells are within the same +/-mV of each other…

As far the peak battery voltage during daily charging, it varies depending on production. (season, weather, etc…) as well as consumption (discharge kicks-off once the battery reaches ~50% SOC).

My SCC never gets out of Boost (CC) mode and generally the battery never gets charged up beyond ~50% SOC (though that should change next summer).
What is the battery voltage first thing in the morning , or at bedtime?
As I said, LVD is currently set at 24.00V (~3.0V/cell) (typically by ~9pm) and has generally recovered (reached equilibrium) to 24.03 to 24.04V by morning.

Peak voltage I’ve reached during charging has reached 26.9V once but in general remains under 26.6V. I’ve got things programmed so that self-consumption kicks-off once battery has reached ~50% SOC (typically late morning) and continues through the rest of the afternoon and through the evening until LVD at ~5% or 11% SOC (depending on which ‘tables’ you believe).

Now that I’ve finally achieved bottom-balance at 3.00V (or 3.04V after equilibrium has been reached), I’ll probably increase my LVD setting so that the battery remains within a range of ~20% to %90%…
How are you measuring these voltages?
Are you running out of power, or just concerned by the MT50 readings?
I’ve got a BattGO monitor which provides cell voltage as well as battery voltage.

The main concern I have is getting an accurate measurement of daily PV production (ideally by season). I’m planning to expand the PV array in ~2023 and an accurate assessment of how much I’m actually getting now is the only way I can properly plan the size of the expansion…

I don’t have an MT50 but have a laptop with Epever SW hooked up.

Everything is working well - daily PV production is being stored up and time-shifted to cover evening consumption, but either my 14kWh battery has far less capacity than it should (with cells that have been fully capacity tested) or the daily power production I’m getting is greater than what the SCC is reporting.

The problem with these cheap Chinese ‘boxes’ is that when there us a discrepancy in what they ‘report’, it’s impossible to know which box to trust…
I re read this statement, can I assume that all your loads are taken from the Epever load outputs, and there is nothing else connected to the battery except the Epever?

Mike
No, I’ve got an Epever AN6420 with no direct load output but two dry contacts for load control.

The dry contacts have been programmed to control ON/OFF of 2 1000W GTIL inverters, so once battery has reached ~50% SOC the GTILs begin converting up to 2kW of self-consumption and that continues until the battery has been drained to ~5% or ~10% SOC (generally around 9pm or so).

The SCC has no visibility on load consumption, only battery voltage, and the GTILs struggle to function at 24V (hence the importance of minimizing cabling resistance between battery and GTILs and the lack of appeal of attempting to measure load consumption by adding a shunt in that high-current pathway…).
 
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DThames

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Put this into your search engine, aili battery monitor
Funny, I just found that aili monitor on my own and came back to thread to ask whether any members here had experience with it.
Do you use one?

I put one on my son's power box. It seems pretty good. However, the Bluetooth app (Apple) for the Overkill Solar type BMS is about equal. I guess it depends on if you would rather use your phone app or have a display that was quick to look at without the phone.
 

fafrd

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I put one on my son's power box. It seems pretty good. However, the Bluetooth app (Apple) for the Overkill Solar type BMS is about equal. I guess it depends on if you would rather use your phone app or have a display that was quick to look at without the phone.
I assume you’d need to leave a phone connected through Bluetooth or a laptop connected through USB (or whatever), but do any of these cheap shunt/monitors support logging of data?
 

Alonsw0

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Thanks for you response Mike.

When the Epever wakes up in the morning it puts all the power available from the panels into the battery until the battery voltage reaches the boost value, 14.3, it will hold this value constant for the boost duration.
On completion of the boost duration it drops to float volts.
If the battery is loaded and the voltage drops below boost reconnect it starts over.
So according to what you're saying- it'll only 'exit' boost phase once the battery is full (it does show getting to 14.3v on the screen before going to float).
Although that's the opposite of what DThames wrote at the beginning...

Only thing I'm still trying to understand- since LiFePO4's discharge voltage rate is so flat (according to charts, at around 13.2v-13.4v), will it ever reach the 'boost reconnect' voltage before battery is relatively empty? Won't it just sit at float (resting) voltage and empty the battery (since not getting to reconnect target)?

I re read this statement, can I assume that all your loads are taken from the Epever load outputs, and there is nothing else connected to the battery except the Epever?
All my loads indeed go from the controller, except for the inverter that's rarely used.
Charging is from shore power socket (used only for emergency), votronic B2B 1212-30 that's not working properly right now (will be in another post) and the solar system.
So basically right now all the loads/charging goes through the solar charger (that's why I thought tracking the MT50 will be pretty accurate).
 

mikefitz

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Trying to help two situations at the same time is difficult but I will have a go.

it'll only 'exit' boost phase once the battery is full (it does show getting to 14.3v on the screen before going to float).
That is correct, if the controller is working correctly and the boost volts is set to 14.3 ,it can only exit boost once the 'target' volts is reached. With your application reaching target of 14.3 volts will result in a full battery. All chargers operate in a similar way.
Won't it just sit at float (resting) voltage
If its in float at 13.4 and a load is applied, the voltage will stay at 13.4 if the solar power can meet the load. If there is not enough solar, power will be taken from the battery. The controller will not re enter boost that day, until the voltage falls below boost reconnect. As I suggested, if your application loads the battery during the solar day increasing the float and re boost voltages to 13.5 and 13.4 ,would be an advantage.

All my loads indeed go from the controller, except for the inverter that's rarely used.
The MT50 will not know about the inverter power being taken from the battery. Do you know the standby power taken by the inverter?
that's why I thought tracking the MT50 will be pretty accurate).
My earlier statement about the Epever regarding power was incorrect , my apologies, I was confusing the SOC reading given by the Epever . I did not fully read your post,
The power redings should be correct but will only record power through the controller .

If the charger is showing over 14 volts at the some time during the day and drops to float, the battery is fully charged at that point.

I will ask the same questions again,

Is the battery a DIY or ready built?
If DIY what MBS?
What is the battery voltage at the end of the days solar charging?
What is the battery voltage first thing in the morning , or at bedtime?
How are you measuring these voltages?
Are you running out of power, or just concerned by the MT50 readings?

Mike
 

mikefitz

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I understand that shunts are normally positioned on the battery output
No, with a battery monitor to measure and record the power, volts and amps and compute the SOC, the shunt is planed in the battery negative path.

Apologies with my comments, I was replying to the original post and did not see you had jumped into the the thread. The questions were related to that post.

I’m not interested in measuring current out of my battery, merely current in
You should be interested in both, but I understand the objective is to record solar yield.
when it is not needed would make no sense for me…
A 500A 50mV shunt will drop 50mV at 500 amps. If your inverter cannot tolerate that you have problems.

You are in a situation where you have insufficient solar input for your needs.

If you want to measure your daily yield with an independent low cost unit, the DORK range is good value.


This used a hall effect current sensor so no shunt to install!

Mike
 
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12VoltInstalls

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0.25mOhm into that high-current path when it is not needed would make no sense for me
Worrying about that makes no sense to me…if you actually want the real data system the shunt creates the comparator field needed to assess the condition
 

fafrd

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No, with a battery monitor to measure and record the power, volts and amps and compute the SOC, the shunt is planed in the battery negative path.
My language wasn’t clear. When I referred to ‘battery output’ what I meant was the path into and out of the battery negative (as opposed to only the input path, meaning between the SCC output negative and battery negative only, but not also between battery negative and load negative).
Apologies with my comments, I was replying to the original post and did not see you had jumped into the the thread. The questions were related to that post.


You should be interested in both, but I understand the objective is to record solar yield.

A 500A 50mV shunt will drop 50mV at 500 amps. If your inverter cannot tolerate that you have problems.

You are in a situation where you have insufficient solar input for your needs.
I do have a problem, but it is by choice and not related to solar yield. My inverters have a startup voltage of 25V and enough new owners have failed to get them to operate off of 24V batteries that the manufacturer now recommends a minimum 36V battery (too many returns and user complaints, I suppose).

For reasons I won’t go into, I needed to make my system work with an 8S LiFePO4 battery and the primary impact of that was needing to reduce voltage drop under load as much as possible (shortest-length, fattest cables I could manage).

It’s only on the battery-to-load path that I have this issue - more solar input would not help at all.

I had not considered a 500A shunt before and if they are only 0.1mOhm, that’s something I could consider, but I assume that as these shunts get larger-current (smaller resistance), precision decreases. Noise or accuracy or whatever it should be called must be only 5 times greater with a 500A shunt than it is for a 100A shunt (at 40A current, for example), right?
If you want to measure your daily yield with an independent low cost unit, the DORK range is good value.


This used a hall effect current sensor so no shunt to install!

Mike
That is a very helpful suggestion - thanks. Aside from the hall sensor, which is a way I can monitor the battery without decreasing high-current path resistance, that DORK unit supports a programmable relay output which may solve another problem I have.

I’ve bottom-balanced my battery and have a 5A active balancer with a control input, but I’ve been looking for a way to only turn on the balancer when the battery is fully drained (at my minimum SOC) and the DORKs relay control may be just the ticket.

Do you use one of these? They seem to offer both Hall sensor and standard shunt models and so I need to understand how Hall Effect, 100A shunt, and 500A shunt models compare as far as accuracy.

But getting one of these DORK sensors of one type or another looks like the way to go - thanks again!
 

SomebodyInGNV

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Funny, I just found that aili monitor on my own and came back to thread to ask whether any members here had experience with it.

Do you use one?
I have one and used to consider it a better use of money, but being wireless is a significant advantage for the Victron. If you have other Victron components and/or have lead-acid batteries though, the Victron Smartshunt provides even more advantage.

That said, I use the Aili/(QWork) monitor on my LFP batteries and, not having Victron components, find it totally adequate and it seems to be reliable. I recommended a Victron Smartshut recently for a friend with a pair of Pb GC2s mounted on the tongue of his trailer. He installed it and, despite his miserly nature, is happy to have spent the extra money.
 
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