Epever 6420AN shows very low charge current

[Dunkirk]

I just finished my setup. I am supposed to get at least 40amps from the panels but I am only getting 0.1amps as per the cc. The day is nice and hot. Panel voltage is 112v while battery bank is reading 52.6v. These are 16s 3.2v 280ah lifepo4 batteries currently at 50% soc.

Why is the mppt only giving 0.1amps?

 

[Supervstech]

Have you checked the charge parameters set in the controller?

 

[Dunkirk]

I only have the epever ebox wifi and there is no place to set charging current on this interface.

 

[Supervstech]

I only have the epever ebox wifi and there is no place to set charging current on this interface.

What model controller do you have? It needs o know the battery type and voltage you are charging... it may think 52 is full...

 

[Dunkirk]

What model controller do you have? It needs o know the battery type and voltage you are charging... it may think 52 is full...

Its an epever 6420AN. It reads the battery voltage correctly at 52v, same as the daly bms. When charging, it shows a charging battery voltage of 58v, pv voltage 100v and pv current 0.1amp. When the panels are disconnected, it shows clearly that battery is at 50%, exactly as the daly bms.

 

[Echo]

You'll prob need the mt-50 to program it

 

[GXMnow]

The fact that the battery voltage did jump up to 58 volts without pulling current, makes me think you have a bad connection with high resistance somewhere between the charge controller and the battery. What happens if you try to pull a load on the system? Can the battery power a decent load or is that also not working? From what I am reading, it sounds like when the charge controller tries to supply current the voltage it is seeing is going up to the absorb voltage, 58 volts. So it is going into constant voltage mode and lowering the current to hold that voltage. If the battery terminals are really at 52 volts, and the charge controller is seeing 58 volts at just 0.1 amp, that is dropping 6 volts at 0.1 amp. If we use ohm's law, 6 volts / 0.1 amps = 60 ohms of resistance in the circuit somewhere. That is very high and will certainly stop it from being able to charge. Is there any chance the BMS is in over charge protection mode? Do you have a decent multimeter? Verify the battery voltage, and the voltage at the charge controller battery terminals. Measure across every connection, and see if you get a voltage drop. If a connection is solid, it should only drop a few millivolts at 40 amps, you are losing 6 volts at 0.1 amp, that should be easy to spot. What BMS are you using? Does it have a monitor and control app? If it is a common port, measure the voltage across the P- and B- and see if that is dropping your 6 volts. If it is a separate port, the charge should be on the C- port, so measure from B- to C- for the voltage drop. The P- on a separate port BMS might not be able to take charge current, so make sure that is wired properly for the type of BMS you have. If the BMS is not the voltage drop, start checking all of the other connections from the charge controller to the battery, even measure across each length of wire. My friend had a car that would crank very slow and fail to start most of the time. It turned out one of his battery cables was actually cut over 3/4 of the way through. A 4 foot long #2 cable was dropping 3 volts at just 50 amps. Any crimp connection or lug bolt could be a connection issue as well. If you do find something loose, you may be a very lucky person. Your current is dropping to just 0.1 amp. A better but still bad connection could have been dropping just one volt at 40 amps, and you may not have noticed until the connection caught fire.

 

[Dunkirk]

The fact that the battery voltage did jump up to 58 volts without pulling current, makes me think you have a bad connection with high resistance somewhere between the charge controller and the battery. What happens if you try to pull a load on the system? Can the battery power a decent load or is that also not working? From what I am reading, it sounds like when the charge controller tries to supply current the voltage it is seeing is going up to the absorb voltage, 58 volts. So it is going into constant voltage mode and lowering the current to hold that voltage. If the battery terminals are really at 52 volts, and the charge controller is seeing 58 volts at just 0.1 amp, that is dropping 6 volts at 0.1 amp. If we use ohm's law, 6 volts / 0.1 amps = 60 ohms of resistance in the circuit somewhere. That is very high and will certainly stop it from being able to charge. Is there any chance the BMS is in over charge protection mode? Do you have a decent multimeter? Verify the battery voltage, and the voltage at the charge controller battery terminals. Measure across every connection, and see if you get a voltage drop. If a connection is solid, it should only drop a few millivolts at 40 amps, you are losing 6 volts at 0.1 amp, that should be easy to spot. What BMS are you using? Does it have a monitor and control app? If it is a common port, measure the voltage across the P- and B- and see if that is dropping your 6 volts. If it is a separate port, the charge should be on the C- port, so measure from B- to C- for the voltage drop. The P- on a separate port BMS might not be able to take charge current, so make sure that is wired properly for the type of BMS you have. If the BMS is not the voltage drop, start checking all of the other connections from the charge controller to the battery, even measure across each length of wire. My friend had a car that would crank very slow and fail to start most of the time. It turned out one of his battery cables was actually cut over 3/4 of the way through. A 4 foot long #2 cable was dropping 3 volts at just 50 amps. Any crimp connection or lug bolt could be a connection issue as well. If you do find something loose, you may be a very lucky person. Your current is dropping to just 0.1 amp. A better but still bad connection could have been dropping just one volt at 40 amps, and you may not have noticed until the connection caught fire.

This is helpful.
I have panel + and - going into the mppt. Connections are correct and tight. The panel voltage at the cutoff switch was 111v while the mppt reads around the same voltage.

From mppt +ve is direct to the battery +ve. The battery terminal remained cold to touch all the time.

Battery voltage via multimeter was 52.6v across battery terminals.

Voltage from battery +ve to the common negative bus bar is 52v ( across the bms). I noted this o.6v drop but did not know what to make of it.

Battery -ve terminal and the common negative bus bar have remained cold to touch.

The inverter could not pull the rated 2500 watts. It cuts off at 1200 watts. I do not know whether this is due to battery voltage drop because battery is at 52v or its due to a fake chinese inverter.

 

[GXMnow]

What BMS are you using? Brand and model?

A 0.6 volt drop is likely a forward biased diode. That could very well be the BMS being in a charge stop mode. Think of it as 2 switches in series. But each switch has a diode across it. If both switches are closed you will get a very low resistance path in both directions. If one switch opens, it is then leaving a diode that will allow current in one direction, but with a 0.6 volt drop, and no more current in the other direction. When the cell voltage is too low, it blocks the load current, but will still allow charging through the diode. If the cell voltage goes too high, it will open the other switch which leaves a diode so that you can still discharge, with a 0.6 volt drop, but no charge current will flow. If both switches go open, then the diodes are in series in opposite directions, and current will not flow either direction.

Depending on the type of BMS, there may be a sequence needed to get it to reset. My JK BMS has a very thorough iPhone app. I can set it for the voltages I want, and when the voltage comes back into range, it will auto reset. But I can also manually tell it to stop charge and/or discharge with the app as well. Some other BMS units might require a jumper wire to trigger it into the on mode. You can see Will do that in some of his videos when testing batteries to their limits. You should also check the voltage of each cell. If just one cell is higher or lower than the rest of the bank, that can trip a BMS protection shut off. Many BMS units will only try to balance near full charge, and only while charging. And even then, the balance current may only be 30 milliamps. That can take a LONG time to pull a high cell down to match the others. On the low end of the charge, it can be even worse. One cell can start dropping fast, and the balancing can't do anything about it, so it will just shut off the load until you charge it up.

52 volts should be fine on any normal 48 volt battery system. You said this is 16S LFP, so that would be 3.25 volts per cell, that is about 30% charge. That is not so low as to cause a shut down. Can you measure the voltage at the input of the inverter when it cut off? If the BMS is in the charge block mode, the pass diode 0.6 volts you are seeing might not be able to carry full power, and it could be shutting off due to a current limit or heat in that mode. When the voltage at the battery falls to just 48 volts, then you have only 10% remaining and the voltage will start falling fast from there. What is the inverter you are using? In the manual, it should list the low voltage cut out. It should be above 46 volts. If it keeps running below that, you do stand a good chance of the BMS having to shut off, and you do not want that. The BMS should only go into protect shut off if something goes wrong. Your charge controller and inverter should be set to stay within the safe limits of the battery bank.

 

[Dunkirk]

What BMS are you using? Brand and model?

A 0.6 volt drop is likely a forward biased diode. That could very well be the BMS being in a charge stop mode. Think of it as 2 switches in series. But each switch has a diode across it. If both switches are closed you will get a very low resistance path in both directions. If one switch opens, it is then leaving a diode that will allow current in one direction, but with a 0.6 volt drop, and no more current in the other direction. When the cell voltage is too low, it blocks the load current, but will still allow charging through the diode. If the cell voltage goes too high, it will open the other switch which leaves a diode so that you can still discharge, with a 0.6 volt drop, but no charge current will flow. If both switches go open, then the diodes are in series in opposite directions, and current will not flow either direction.

Depending on the type of BMS, there may be a sequence needed to get it to reset. My JK BMS has a very thorough iPhone app. I can set it for the voltages I want, and when the voltage comes back into range, it will auto reset. But I can also manually tell it to stop charge and/or discharge with the app as well. Some other BMS units might require a jumper wire to trigger it into the on mode. You can see Will do that in some of his videos when testing batteries to their limits. You should also check the voltage of each cell. If just one cell is higher or lower than the rest of the bank, that can trip a BMS protection shut off. Many BMS units will only try to balance near full charge, and only while charging. And even then, the balance current may only be 30 milliamps. That can take a LONG time to pull a high cell down to match the others. On the low end of the charge, it can be even worse. One cell can start dropping fast, and the balancing can't do anything about it, so it will just shut off the load until you charge it up.

52 volts should be fine on any normal 48 volt battery system. You said this is 16S LFP, so that would be 3.25 volts per cell, that is about 30% charge. That is not so low as to cause a shut down. Can you measure the voltage at the input of the inverter when it cut off? If the BMS is in the charge block mode, the pass diode 0.6 volts you are seeing might not be able to carry full power, and it could be shutting off due to a current limit or heat in that mode. When the voltage at the battery falls to just 48 volts, then you have only 10% remaining and the voltage will start falling fast from there. What is the inverter you are using? In the manual, it should list the low voltage cut out. It should be above 46 volts. If it keeps running below that, you do stand a good chance of the BMS having to shut off, and you do not want that. The BMS should only go into protect shut off if something goes wrong. Your charge controller and inverter should be set to stay within the safe limits of the battery bank.

I am using a daly smart bms.

If I get your drift about bms being in a charge stop mode, yet its only at 52v, would this imply the bms is causing the problem of mppt not charging. I note the green light ( in photo below) has been on discharge mos and I cannot change it to any of the other settings. I do not know if it is something I can alter or not.

Batteries appear to be well balanced.

 

[GXMnow]

I see the problem, the issue is how to fix it.
In the left photo you can see "Chg MOS" is off. That needs to be turned on to allow charging. But why is it off?
In both photos, the "Fault alarm 1" shows "Cell volt high level 2" Which means at some point it saw a high volt error which turned off charging.

I agree, your current cell voltages do look very good. At the bottom there is a selection for "Parameter Settings". Go in there and check what it is set for. Maybe the cell high voltage protection was set too low.

 

[Dunkirk]

I see the problem, the issue is how to fix it.
In the left photo you can see "Chg MOS" is off. That needs to be turned on to allow charging. But why is it off?
In both photos, the "Fault alarm 1" shows "Cell volt high level 2" Which means at some point it saw a high volt error which turned off charging.

I agree, your current cell voltages do look very good. At the bottom there is a selection for "Parameter Settings". Go in there and check what it is set for. Maybe the cell high voltage protection was set too low.

My suspicion is that "chg MOS" goes "ON" automatically during charging mode.

My problem is that the EPEVER 6420 AN charge controller is brocken right out of the box. It will not charge.

Incidentally, I switched to a 12v lead acid battery just to see whether the bms on the LiFePO4 was causing the problem. The result was the same as before. The EPEVER unit detects proper PV voltage at 110v, but only shows 0.1amps as charging current. This is despite 13.3v in the battery and a charging voltage of 14.4v from the mppt.

Of course EPEVER manufactures are insisting that the charge controller is fine.

 

[GXMnow]

I have dealt with a few different BMS units. "Chr MOS" should be on or it will not charge. Here is my JK BMS showing -0.6 amps, which is basically a tiny discharge into my resting inverter. Look at the top row "Charge: On" "Discharge: On" "Balance: On" That is the status of the devices. This was shortly after my charge cycle ended, so it is showing 99% capacity.

When you connected the charge controller to the lead acid battery, did you connect from the charge controller directly to the battery terminals? Was there a fuse or switch in between? Did you measure the voltages at the battery and at the charge controller? Did you adjust the settings for lead acid? How long did you leave it with sun on the panels? If the output terminals of the charge controller again went up without the battery voltage climbing, you still have a bad connection somewhere.

Even if everything is perfect, it can take a minute or so for it to start pulling current. The voltages need to be set correct for the battery type, and it needs to start tracking the power point to move any real power. When the EP Ever was showing 0.1 amp, did you measure the voltage at the battery and at the charge controller? And what was the battery voltage showing on the EpEver screen? There is a fuse on the battery side. From what you are describing, that may be blown. If you are looking at the face of the unit, the fuse is inside the wiring compartment, and then under a plastic cover on the left side. But I still think you need to get the "Chg MOS" to turn on in the BMS. That might reset once the charge controller starts supplying actual current.

 

[Dunkirk]

I have dealt with a few different BMS units. "Chr MOS" should be on or it will not charge. Here is my JK BMS showing -0.6 amps, which is basically a tiny discharge into my resting inverter. Look at the top row "Charge: On" "Discharge: On" "Balance: On" That is the status of the devices. This was shortly after my charge cycle ended, so it is showing 99% capacity.

This may be because you have a functioning charging device. I suspect that once I have a working charger, the "Chr MOS" should go on once it senses an inward current. I remember that when I first connected the BMS "Chr MOS" was on and " Dischrge MOS" was off. When I connected the inverter and ran it for a short while, it must have switched to the off position but I cannot be fastidious about this.

 

[Dunkirk]

When you connected the charge controller to the lead acid battery, did you connect from the charge controller directly to the battery terminals? Was there a fuse or switch in between? Did you measure the voltages at the battery and at the charge controller? Did you adjust the settings for lead acid? How long did you leave it with sun on the panels? If the output terminals of the charge controller again went up without the battery voltage climbing, you still have a bad connection somewhere.

It was directly from cc to 12v lead acid battery. No fuse in between. The battery voltage via multimeter was 13.3v. Battery voltage as detected by the EPEVER 6420AN cc was 13.3v (when PV connection is off). When PV connection is on, the battery voltage as per cc is reflected as 14.4v but voltage via multimeter at the battery remains 13.3v. The settings of the cc were adjusted to 12v Gel battery. I kept the custom settings for this as per the cc. I do not think its a bad connection. Initially, the connection was cc +ve to Li bat +ve and cc -ve to -ve common busbar. I still had the same problem. With the lead acid, it was a direct connection with no bus bar. The exact same problem persists. The cc can sense correct and exact battery voltage when PV connection is off. This means the connection from cc to battery is good. Problem is that the EPEVER cc does not generate charging current.

 

[Dunkirk]

Even if everything is perfect, it can take a minute or so for it to start pulling current. The voltages need to be set correct for the battery type, and it needs to start tracking the power point to move any real power.

When i had the lithium battery connected to the EPEVER unit, I left it for 3 days. The problem of not generating a charging current persisted.
When I connected the 12v lead acid, I saw the exact same pattern, the only difference was the voltage readings due to the different battery voltages. So I did not leave the lead acid on for very long.

 

[Dunkirk]

When the EP Ever was showing 0.1 amp, did you measure the voltage at the battery and at the charge controller? And what was the battery voltage showing on the EpEver screen? There is a fuse on the battery side. From what you are describing, that may be blown. If you are looking at the face of the unit, the fuse is inside the wiring compartment, and then under a plastic cover on the left side. But I still think you need to get the "Chg MOS" to turn on in the BMS. That might reset once the charge controller starts supplying actual current.

Battery voltage remains at 13.3v via multimeter even when EPEVER screen shows charging at 0.1amps 14.4 volts. When PV is switched off, the Epever shows correct battery voltage of 13.3v. I checked for continuity on the Epever fuse described and this was OK. I did not remove the fuse and the EPEVER engineers adviced me not to remove the fuse if continuity was intact.

 

[Dunkirk]

Thanks alot @GXMnow for the many helpful suggestions. The latest suggestion from Epever engineers is that I connect a load to the charge controller and measure voltages again. I will do this this weekend but i doubt there will be any difference. Its starting to feel like a game of chasing tail.

 

[Dunkirk]

Update...
I ditched the EPEVER 6420an and got a hybrid inverter 5kw Phocos anygrid. Hooked up the phocos to the lithium batteries and voila........ nothing happened. The lithium cells were not charging. I went into a panic for several minutes. Then I decided to do the one thing most people say you should do with daly bms that is not mentioned in the manual ( if you could call the scrap paper that came with the bms a manual). I shorted the P- on the battery +ve. There was instant response and it started charging the battery.

Maybe the epever is not broken after all. Will keep fingers crossed and hook it up when I have time. But I still do not understand why the epever would not charge the lead acid battery.

 

[thecuz80]

Dunkrik.. I'm having the same problem. So I should short circuit the P- and the B- of the BMS? or I should connect the P- to my +12V? thanks