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Lifepo Epever Settings..

Terry.M

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Joined
Jun 27, 2022
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Reaching out... New to DIY Solar, I've read many answers to help in getting me started etc. and what appears a popular question is regarding suitable Epever settings for Lifepo4 cells.. and so I hoped posting this message would provide me some support that would help get my setup settings close to right..

I'm living in Thailand and my recently put together setup that in most part works consists the following:

A single 545w solar panel (Trina -monocrystalline),
12volt (4 x 3.2v) 280Ahr Eve Lifepo Battery,
Epever Triron 40A MPPT controller,
Epever MT50 meter
Epever 3kw Inverter IP3000..

For the battery I have installed a BMS, type JBD 4s 12v 200A..

I use my set-up simply to provide a shared house power usage (i.e. switch OFF the authority power and ON solar power at around 9:00am in the morning and unless solar sinks too low I swap back to authority power at around 5:00pm evening)..
The house is small and loads naturally vary, but I often manage to get a reasonable few hours use..
My issue is with settings.. and the fact sometimes the controller seems to block charging (sunlight and PV volts is there, house load is on and battery is less than full but does not charge).. so, I'm not sure if it is my settings and importantly am I getting the best out of my cells with the settings I've used..
I can't yet get to grips with the process and terms of charge, boost, float etc. and the right cut off points to suit i.e.:
To start and allow continuous charge (with house load either on or off) until suitably full (say 80%)
or allow continuous discharge until empty (say 20%)..

So, understanding terminology and settings (what they mean/how they work with each other to charge and discharge) is as yet somewhat difficult to say the least and I'm naturally concerned with getting the best, longest term use from my cells...

I have set my BMS protection to (see attached): 13.400v (POVP), 3.345v (COVP), 11.800v (PUVP), 2.850v (CUVP)..
And I've set the Controller setting (set via my MT50) to:
USER, BAT '280AH', TEMP '0', OV DISC 14.8V, CHRG LIMIT 14.6V, OV REC 14,6V, EQUAL CHRG 14.2V, BOOST CHRG 14.2V, FLOAT CHRG 13.6V, BOOST REC 13.2V, LOW VOLTS REC 12.8V, UNDER VOLTS REC 12.2V, UNDERVOLTS WARN 12.0V, LOW VOLTS DIS 11.1V, DISCHARGE LIMIT 11.0V, EQUALISE TIME '0' MIN, BOOST TIME 10 MIN..
I do understand there are many posts and Videos to watched I have watched/read quite a few to get where I'm at, but I was hoping someone could review my setting and comment with any suggested improvements (and ideally why).. but any positive response would be much appreciated.. Terry. M
 

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Do you have a PC available that is close to the EPever? You can get a USB cable that will connect to the EPever and monitor with a PC. The PC program will let you look at a lot of the data at a glance. When it is not charging and you think it should be charging, the battery voltage will need to be below Float settings if the charger has switched to Float charging. Also when this happens, look at your BMS and see if it has cut off charging. I didn't review your BMS settings but the cause could be in the BMS limits.
 
I have set my BMS protection to (see attached): 13.400v (POVP), 3.345v (COVP), 11.800v (PUVP), 2.850v (CUVP)..
And I've set the Controller setting (set via my MT50) to:
USER, BAT '280AH', TEMP '0', OV DISC 14.8V, CHRG LIMIT 14.6V, OV REC 14,6V, EQUAL CHRG 14.2V, BOOST CHRG 14.2V, FLOAT CHRG 13.6V, BOOST REC 13.2V, LOW VOLTS REC 12.8V, UNDER VOLTS REC 12.2V, UNDERVOLTS WARN 12.0V, LOW VOLTS DIS 11.1V, DISCHARGE LIMIT 11.0V, EQUALISE TIME '0' MIN, BOOST TIME 10 MIN..
I do understand there are many posts and Videos to watched I have watched/read quite a few to get where I'm at, but I was hoping someone could review my setting and comment with any suggested improvements (and ideally why).. but any positive response would be much appreciated.. Terry. M
Hi Terry, welcome to the forum!

I feel that the combination of 3.345 BMS cell overvoltage and 13.6V float charging is a bit questionable, causing solar to generally push the BMS into "high voltage disconnect" on the charging circuit fairly quickly.IMO, although the Trion didn't create an error and I could be wrong about the meaning of these parameters, your 'LOW VOLTS RECONNECT' seems to be much too low:
  1. Lowest value = 'LOW VOLTS DISCONNECT', this is when the SCC pulls the plug on itself to keep its own small loads from discharging the battery further. If it ever occurs (and it shouldn't, because the BMS discharge limit is much higher), it will require that the battery be re-charged by a means other than solar (i.e., some kind of plug-in charger). The value is basically meaningless in an LFP configuration with a higher BMS discharge disconnect voltage, so you can leave it "too low".
  2. next lowest = 'LOW VOLT RECONNECT", this should be the minimum voltage at which you want the SCC to try and run, powering itself from the battery pack and providing charging power. Should be reduced to a value at or below 11.8 Volts, if my interpretation is correct. Fortunately, your erroneous value can only matter after "Low Volts Disconnect" has been reached, which can't happen (per the "meaningless" status of "LOW VOLT DISCONNECT" versus the BMS).
  3. Next lowest = 'UNDERVOLT WARN', when the unit should start to nag you with beeps and maybe blinking lights. your value is good.
  4. Next lowest = 'UNDERVOLT RECOVERY', when to STOP the blinks and beeps caused by parameter #3.
  5. Next, and lowest among the "charging" parameters = 'BOOST RECONNECT'. Your value is very aggressive, restarting 'boost mode' when the pack is still around 97% charged. I'd let the SCC stay in float mode for a bit longer, to help prevent a lot of mode-flipping between "Boost" and "Float" mode on the SCC. I would (and I do) use a lower value @ 13.0v
  6. Next comes 'FLOAT CHARGE' voltage. LFP cells are very willing to accept input charging current with only a very low voltage differential, and a lower value might allow for a longer period of time in "float", before BMS disconnects the charging circuit. Some models of BMS (DALY in particular) seem to show a strange relationship between "balancing mode" and "charging mode" on their cellphone apps, perhaps making a longer float time desirable. JBD doesn't have that possible defect, but it does have relatively low balancing current (compared to JK, for example). Some LFP people prefer lower values, in the range of 13.2v - 13.4v.
  7. Your 'BOOST CHARGE VOLTS' looks fine. But with the timer set to only 10 minutes, the SCC will be "flipping" in and out (and then back in) with "Boost Mode" every 10 minutes while power is being drawn from the pack, that seems a bit frequent - if you trust your BMS to do its job, you could go a bit longer with 'BOOST TIME' at the SCC.
  8. EQUALIZE VOLTS = BOOST VOLTS is perfect, and EQUALIZE TIME = 0 is perfect.
These are pretty minor quibbles, I like the numbers which you have chosen.
 
The Epever charges the battery in bulk stage up to 'boost' voltage, holds the voltage constant at boost volts for the boost duration, then drops to float volts. Will return to bulk stage if volts fall below 'boost reconnect'.
Float at 13.6 should hold the batteries in a high state of charge.

The bms settings seem incorrect, I doubt these were the settings as supplied .
Your BMS is shutting charge off way before the charger volts.

The charger settings are not too bad but for a less stressfull charge consider,
Boost volts = 14.0, Float volts 13.5, boost reconnect, 13.4, boost duration 15 minutes, equalise volts 14.0, equalisation duration, 0 minutes.

With the BMS increase the cell and pack volts,
Cell high volts, 3.65, pack high volts 14.6
Cell low volts, 2.90, pack low volts, 11.6
With the recovery volts suitably changed.

If you solar system powers loads durring the day, i think you will have enough battery capacity to run for longer in the evenings, perhaps overnight depending on the loads.

A battery SOC monitor, even a low cost Aili monitor, would help battery housekeeping .

Mike
 
Wow..!! so pleased to have now joined this forum.. and I'm truly grateful to you all... your positive and supportive response are just what I needed.. clearly (for me ) I hope to now digest all what's been said and look to apply any suggestions and changes.. I feel humbled but no longer alone with mountains so far climbed (just in getting a system built and mostly working).. I have (proudly) attached a few recent pics just to give you something more than words back for you to see what you responses are related to.. again I thank you for giving me something to digest and work through.. and will report back on how things work out.. cheers, Terry.M
 

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Forgot mention to Mike that strangely his suggestion of a low cost 'Aili Battery SOC monitor' being helpful, appears a good decision and the same item (TR16H Capacity Meter) I currently have on order from Aliexpress to complete my setup.. (to be fitted in the white panel box left side of the Epever MT50).. thanks Mike :)

 

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Do you have a PC available that is close to the EPever? You can get a USB cable that will connect to the EPever and monitor with a PC. The PC program will let you look at a lot of the data at a glance. When it is not charging and you think it should be charging, the battery voltage will need to be below Float settings if the charger has switched to Float charging. Also when this happens, look at your BMS and see if it has cut off charging. I didn't review your BMS settings but the cause could be in the BMS limits.
I am grateful of your helpful reply.. though I initially tried and failed getting my PC to work (to view the Epever Controller goings on), I was also disappointed once I did manage to view what could be seen.. however and I now understand your logic for connecting, especially at and around the times its not doing what I expect (with charging etc.).. so, although things appear to be behaving normally of late with charging etc. I have just re-visited making the PC connection.. and only now noticed (need to scroll down to what's not directly on view) Its clear to see the charging state (currently states: Float Charging) and percentage capacity (currently states: 96%).. plus more I wasn't aware of.. so, it does in fact prove to be a very useful monitoring tool for when I'm having issues.. and from now on I will not hesitate to make use of it.. Thank you.
 
Hi Terry, welcome to the forum!

I feel that the combination of 3.345 BMS cell overvoltage and 13.6V float charging is a bit questionable, causing solar to generally push the BMS into "high voltage disconnect" on the charging circuit fairly quickly.IMO, although the Trion didn't create an error and I could be wrong about the meaning of these parameters, your 'LOW VOLTS RECONNECT' seems to be much too low:
  1. Lowest value = 'LOW VOLTS DISCONNECT', this is when the SCC pulls the plug on itself to keep its own small loads from discharging the battery further. If it ever occurs (and it shouldn't, because the BMS discharge limit is much higher), it will require that the battery be re-charged by a means other than solar (i.e., some kind of plug-in charger). The value is basically meaningless in an LFP configuration with a higher BMS discharge disconnect voltage, so you can leave it "too low".
  2. next lowest = 'LOW VOLT RECONNECT", this should be the minimum voltage at which you want the SCC to try and run, powering itself from the battery pack and providing charging power. Should be reduced to a value at or below 11.8 Volts, if my interpretation is correct. Fortunately, your erroneous value can only matter after "Low Volts Disconnect" has been reached, which can't happen (per the "meaningless" status of "LOW VOLT DISCONNECT" versus the BMS).
  3. Next lowest = 'UNDERVOLT WARN', when the unit should start to nag you with beeps and maybe blinking lights. your value is good.
  4. Next lowest = 'UNDERVOLT RECOVERY', when to STOP the blinks and beeps caused by parameter #3.
  5. Next, and lowest among the "charging" parameters = 'BOOST RECONNECT'. Your value is very aggressive, restarting 'boost mode' when the pack is still around 97% charged. I'd let the SCC stay in float mode for a bit longer, to help prevent a lot of mode-flipping between "Boost" and "Float" mode on the SCC. I would (and I do) use a lower value @ 13.0v
  6. Next comes 'FLOAT CHARGE' voltage. LFP cells are very willing to accept input charging current with only a very low voltage differential, and a lower value might allow for a longer period of time in "float", before BMS disconnects the charging circuit. Some models of BMS (DALY in particular) seem to show a strange relationship between "balancing mode" and "charging mode" on their cellphone apps, perhaps making a longer float time desirable. JBD doesn't have that possible defect, but it does have relatively low balancing current (compared to JK, for example). Some LFP people prefer lower values, in the range of 13.2v - 13.4v.
  7. Your 'BOOST CHARGE VOLTS' looks fine. But with the timer set to only 10 minutes, the SCC will be "flipping" in and out (and then back in) with "Boost Mode" every 10 minutes while power is being drawn from the pack, that seems a bit frequent - if you trust your BMS to do its job, you could go a bit longer with 'BOOST TIME' at the SCC.
  8. EQUALIZE VOLTS = BOOST VOLTS is perfect, and EQUALIZE TIME = 0 is perfect.
These are pretty minor quibbles, I like the numbers which you have chosen.
Hi Rick,
Firstly thank you for your welcome note.. I have read through your most helpful and detailed script that relates to my settings.. and with the follow up posts (one yet to also digest from Mikefitz) to closer review and compare in detail, I feel I have received some excellent supporting responses to help me get my settings improved.. I am now armed with you help to either use, compare or refer back to.. and for that and the clear effort you have made to help, I thank you.. Terry. M
 
The Epever charges the battery in bulk stage up to 'boost' voltage, holds the voltage constant at boost volts for the boost duration, then drops to float volts. Will return to bulk stage if volts fall below 'boost reconnect'.
Float at 13.6 should hold the batteries in a high state of charge.

The bms settings seem incorrect, I doubt these were the settings as supplied .
Your BMS is shutting charge off way before the charger volts.

The charger settings are not too bad but for a less stressfull charge consider,
Boost volts = 14.0, Float volts 13.5, boost reconnect, 13.4, boost duration 15 minutes, equalise volts 14.0, equalisation duration, 0 minutes.

With the BMS increase the cell and pack volts,
Cell high volts, 3.65, pack high volts 14.6
Cell low volts, 2.90, pack low volts, 11.6
With the recovery volts suitably changed.

If you solar system powers loads durring the day, i think you will have enough battery capacity to run for longer in the evenings, perhaps overnight depending on the loads.

A battery SOC monitor, even a low cost Aili monitor, would help battery housekeeping .

Mike
Hi Mike,
I appreciate you explaining the charge process (with the Epever controller), it does help me better understand how simple it actually is, or meant to be when working correctly.. You are right about the BMS settings.. they are my own attempts.. and clearly out from recommended.. I have received some great response to my request for help on this issue.. and though I'm a long distance away from getting fully to grips, its so helps me getting closer.. I will now be making changes to my settings, using the considered changes you have provided.. and simply but gratefully thank you for your help.. Terry. M
Sorry, I forgot to ask a question and my apologies if its somehow obvious but:
For the settings you suggest, in terms of state of charge per cycle. What can I typically expect from cycles of charge to discharge in terms of percentage. i.e. 10 to 90% etc..
 
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I am grateful of your helpful reply.. though I initially tried and failed getting my PC to work (to view the Epever Controller goings on), I was also disappointed once I did manage to view what could be seen.. however and I now understand your logic for connecting, especially at and around the times its not doing what I expect (with charging etc.).. so, although things appear to be behaving normally of late with charging etc. I have just re-visited making the PC connection.. and only now noticed (need to scroll down to what's not directly on view) Its clear to see the charging state (currently states: Float Charging) and percentage capacity (currently states: 96%).. plus more I wasn't aware of.. so, it does in fact prove to be a very useful monitoring tool for when I'm having issues.. and from now on I will not hesitate to make use of it.. Thank you.
Yes, the monitor program has a lot to be desired. I have mine connected to a junk laptop and then from inside the house, I use Remote Desktop session to view the laptop console. I have a 40amp and a 60 amp "AN" series, both on the same RS485 cable. I can run two instances of the monitor but only if their sampling/read doesn't happen at the exact same time. Set both to sample every 30 seconds and then start one about 15 seconds after the other one starts. I can change any of the settings, seeing all on the same screen and then also monitor PV and battery amps, watts, and volts over time, which is nice to better understand what is really happening.
 
What can I typically expect from cycles of charge to discharge in terms of percentage. i.e. 10 to 90% etc..
Its not practical to limit the charge to 90%. Its better to charge to full with a low stress charge voltage and current, and then to use the battery so its not at 100% state of charge for long periods. By charging over 13.6 volts, the BMS balance will function, keeping the cells balanced, so a charge target of 14.0 or 14.2 volts will be OK.
A secondary need for charging to full, is that continual short charging will introduce a memory effect. This can reduce the effective battery capacity, charging to full will restore full capacity.
Its more serious as regards battery life if the battery is discharged too low, below 20% SOC, (12.5 to12.8 volts, rested battery). Charging and discharging at high currents also reduces service life.
In practice for your type of application, I would not worry two much about cycle life, natural ageing may occur faster than cyclic capacity loss.

Mike
 
mikefitz is absolutely correct in declaring that it's not practical to limit charging to 90%. In fact, without controlling charging from a coulomb counter, it is IMPOSSIBLE - the voltage versus SOC curve is too "flat" near this target.

But mikefitz and I disagree, with respect to the maximum voltage for the "production" state of the charged batteries. I would not want the state of the "charged" batteries to be all the way up to 3.65 volts on a frequent/continuous basis, and many members other than Mike also prefer lower BMS limits. Continuous high voltage is pretty widely recognized to be harmful for cell lifespan. I strongly prefer your lower "13.400v (POVP), 3.345v (COVP)" limits.

The additional power being stored by that big voltage increase is very small, nearly insignificant - you're likely adding less than 1% to cells which are already near 99% SOC. I "feel" that 3.65 volts is initial top-balancing territory, not for continuous use in "production".
- - -
On a different subject, Your BMS has pretty decent balance current (although not in the class of "2A" and "1A" JK units). I do recommend, however, that you increase the balancer "differential' parameter - a lot. You've got it set at 0.003, and that might be invoking balance more frequently than it should. My own 'JK' value is .015, five times greater than yours. The cells balance within .001 V when it runs, and tend to stay there - but it doesn't get invoked very often.
 
But mikefitz and I disagree, with respect to the maximum voltage for the "production" state of the charged batteries. I would not want the state of the "charged" batteries to be all the way up to 3.65 volts on a frequent/continuous basis, and many members other than Mike also prefer lower BMS limits. Continuous high voltage is pretty widely recognized to be harmful for cell lifespan. I strongly prefer your lower "13.400v (POVP), 3.345v (COVP)" limits.
If you read my posts you will see I suggest a charge voltage of 14 volts, 3.50 volts per cell, and a short absorption duration.

The BMS settings are last resort protection, not values to control charging. Charge control should be set up in the chargers and load control in the load system.

By having a cell limit of 3.4 volts the balancing action of the BMS will not be effective, this must occur when the cells start to deviate, below 3.4 they wont. ( unless you have very poor quality/faulty cells). Balancing below 3.4 volts is not ideal and may push the cells out of balance.

You will also note I suggested keeping the cells at high state of charge was not a good idea.

The effect of charging below 3.40 per cell will not enable balance and will introduce memory effect. The net result over time may be reduced capacity.

the Resources section has advice on BMS settings,

As DIY users of batteries there will always be differences of opinion and I guess in time there will be more data on battery life and how best to look after them. I an interested to see how the 'drop in battery' service life is going to turn out. The recommend 14.6 charge and 13.8 float is going to have interesting long term effects.

Mike
 
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Any decent BMS (not Daly) can start balancing well below 3.4 volts, and shouldn't stop until balance has been achieved - even though the charge circuit has been disconnected, active balance can proceed.
 
It's really good to read your strong differing views, given with logical, experienced and thought out personal reasoning... (with open door to longer term new learning)..

In my slow development, I have struggled to understand why the subject of 'best SOC window' proves such a debatable one.. but has become more and more clear that using the manufacturer's recommended window is mainly just that.. a recommended guide dependent on intended use to help prolong cell life...

And so it seems to me the many variations to a charge and discharge applications, will require similar but preferred variations to max charge/discharge (max/min cell volts cut off settings).. and therefore develop a suited SOC window that should ideally get the most from your cells and at the same time stay within the manufacturer recommended..

Within my cell spec (found on Google and hopefully correct) it states 'Charge cut-off': 3.65v.'... ' 'Discharge cut-off' 2.5v. - 'Preference Value'... and... 'Recommended SOC Window 10 - 90%..

So, with my somewhat improved understanding (if so) and my new settings, I guess I can only develop more and learn how within my application the SOC works with these new settings.. and if okay report back any issues along the way..

Grateful for your responses I can only say.. I do so much like this Forum..
 
mikefitz is absolutely correct in declaring that it's not practical to limit charging to 90%. In fact, without controlling charging from a coulomb counter, it is IMPOSSIBLE - the voltage versus SOC curve is too "flat" near this target.

But mikefitz and I disagree, with respect to the maximum voltage for the "production" state of the charged batteries. I would not want the state of the "charged" batteries to be all the way up to 3.65 volts on a frequent/continuous basis, and many members other than Mike also prefer lower BMS limits. Continuous high voltage is pretty widely recognized to be harmful for cell lifespan. I strongly prefer your lower "13.400v (POVP), 3.345v (COVP)" limits.

The additional power being stored by that big voltage increase is very small, nearly insignificant - you're likely adding less than 1% to cells which are already near 99% SOC. I "feel" that 3.65 volts is initial top-balancing territory, not for continuous use in "production".
On a different subject, Your BMS has pretty decent balance current (although not in the class of "2A" and "1A" JK units). I do recommend, however, that you increase the balancer "differential' parameter - a lot. You've got it set at 0.003, and that might be invoking balance more frequently than it should. My own 'JK' value is .015, five times greater than yours. The cells balance within .001 V when it runs, and tend to stay there - but it doesn't get invoked very often.
Hi Rick,
I've changed my balancing window from 0.003v to 0.015v (suggestion to increase)..
not sure if, now I've changed BMS settings to increase capacity use (COVP 3600mv & POVP 14400mv.. CUVP 2900mv & PUVP 11600mv ).. whether I also need to change my balance start volts (currently set to 3240mv).. if not then this (my new mix of changed settings) will be my new start point to monitor SOC (once my Aili capacity meter arrives) and now provides me so much more confidence the fact my settings have (with help) been picked apart, explained and put back together.. improved performance or not, I feel so much better for all the support received..
Thanks Rick.. Terry.M
 
Within my cell spec (found on Google and hopefully correct) it states 'Charge cut-off': 3.65v.'... ' 'Discharge cut-off' 2.5v. - 'Preference Value'... and... 'Recommended SOC Window 10 - 90%.

So, with my somewhat improved understanding (if so) and my new settings, I guess I can only develop more and learn how within my application the SOC works with these new settings.. and if okay report back any issues along the way..

Grateful for your responses I can only say.. I do so much like this Forum..
Their "cut-off" values correspond to 100% SOC and zero SOC (below which the cells become greatly damaged). As discussed previously, their 90% "usage window" top recommendation is almost impossible to find via voltage alone, so you will need to go higher in voltage (and SOC) to find a workable "working window" cut-off. Mike feels that you should go all the way to 100% (3.65v) all the time, with the benefit of top-balancing the cells frequently, avoiding capacity loss due to memory effects. I personally go higher than 3.50v only a few times per year (to "undo" memory effects), by changing my BMS 'CELL-HIGH-VOLTAGE' values in each pack, and then using a 14.6v plug-in charger to push the packs to 100% for about 12 hours. (I have parallel packs in my Travel Trailer).

My method is much more complex, and the possible "benefits" of avoiding 100% SOC at nearly all times is undetermined.
- - -
Hoewever, it it is generally agreed that the benefits of stopping discharge sooner, in "normal" use, are substantial. Mike and I both avoid values below 2.9V, and every BMS which has ever passed my worktable came with a default value of only 2.5 Volts. That always needs to be raised up.
 
Mike feels that you should go all the way to 100% (3.65v) all the time
No I don't. I recomend a charge voltage over 3.4 volts per cell, 13.8 to 14.2 volts for a 12v battery, with 14.0 being a compromise.
This is normally enough the allow balancing to occur and remove memory effect, there is no need to charge to 14.6. I expect most battery packs will have cell overvolt BMS charge path disable if charging to 14.6 volts
I do however suggest the BMS values are never used to control the charge process. The BMS cell limit of 3.65 is a fail safe limit, not a charge limit.

Mike
 
Mike, I apologize for my misreading your earlier posts (very badly). I am in total agreement with your "somewhat less than 3.65 per cell" recommendation.
 
At the time of starting this thread I had got myself so confused.. I was first concerned whether or not I should in fact be using a BMS... there seemed so many similar settings (to me) in the Epever that I feared there could be damaging conflict..

I convinced myself the BMS should be used.. and made King.. (looking after charge and discharge).. and the Epever looked on as slave.. simply making controlled solar power available and only taking over as King if without BMS..

I now feel I understand so much more.. and my confusion and respect with Epever controller and its settings so much less and improved..

If I've got it closer to right.. then going forward I will now look on my Epever and its settings to be King of Solar to cell charging... and my BMS will generally look after my discharge limit and Balance the cells, with its over limit volt settings an added cell protection..

Thanks guys..
 
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