State Of Charge Always Says 100%

[GoinSumWare]

I just replaced my house battery bank of AGMs with LiFePo4s and at the same time replaced the existing Magnum ME-RC charger/inverter remote with a new one which includes the LFP profile. It is connected to the existing BMK (battery monitoring kit) which was already installed.

The problem is regardless of how much the lithium batteries are discharged the SOC always reads 100% - although it does show the correct battery voltage.

Does anyone have any idea why this might be occurring?

[CruiseN]

I'm only guessing.
As AGMs discharge, their state of charge probably reduces the available strength of the inverters allowance. Hence when down on charge although the inverter might be 2 kW it might only allow 1 kW worth of withdrawal and reducing ..

LiPos (I can't read above at moment) have advanced a lot. I get the impression that they'll draw all the way down at full throttle then just hit the wall.
Hence is SOC reading that you can load inverter 100% although query of span remaining isnt understood by such reading?

I've with lift sails versus spear force sails on mind.
Lithium like a lift sail. SOC simply reading yeah go for it. Unfortunately, when done line sheer or mast break and over.. no more charge.
Whereas genie and main like AGM, lead acid, gel cell. More wind grows, more charge goes but vessel rotates and when strength up, eg battery flat. Vessel on side. Hence SOC can be seen by heel.

That's my guess.

[LoudMusic]

LFP voltage curve is nearly flat through the middle of the charge, so in order to report SoC it has to be able to measure how many amps have been drawn from and supplied to the batteries. Can your system do that?

Next up is setting the values of the battery bank correctly. Does your monitor have the ability for you to specify the capacity and other vital statistics of the battery bank?

I rarely look at percentage or voltage on my Victron BMV 712 for my LFP house battery. Usually I look at the Amps display (shows positive or negative rate of amp flow) and the total amps drawn from the battery (shows as negative amp hours).

[GoinSumWare]

Originally Posted by LoudMusic

LFP voltage curve is nearly flat through the middle of the charge, so in order to report SoC it has to be able to measure how many amps have been drawn from and supplied to the batteries. Can your system do that?

Next up is setting the values of the battery bank correctly. Does your monitor have the ability for you to specify the capacity and other vital statistics of the battery bank?

I rarely look at percentage or voltage on my Victron BMV 712 for my LFP house battery. Usually I look at the Amps display (shows positive or negative rate of amp flow) and the total amps drawn from the battery (shows as negative amp hours).

Thanks for the input. Yes I'm aware of the lithium voltage curve. and the values of my battery bank have been set correctly. My Magnum does show amps being drawn, although only when the inverter is in operation, but that depletion is not reflected in the displayed SOC. I installed a Victron BMV-712 in parallel with the Magnum ME-RC, that's how I know how many amps have been drawn, but since the Magnum is the primary and is, for example, networked with the AGS module I'd like it to properly display SOC as well.

[StuM]

Originally Posted by LoudMusic

how many amps have been drawn from and supplied to the batteries
...the total amps drawn from the battery

Originally Posted by GoinSumWare

how many amps have been drawn,

Please get it right when talling about batteries etc. It's "amp hours drawn", not "amps drawn".

https://www.cruisersforum.com/forums...ml#post1933764

[smac999]

Originally Posted by GoinSumWare

Thanks for the input. Yes I'm aware of the lithium voltage curve. and the values of my battery bank have been set correctly. My Magnum does show amps being drawn, although only when the inverter is in operation, but that depletion is not reflected in the displayed SOC. I installed a Victron BMV-712 in parallel with the Magnum ME-RC, that's how I know how many amps have been drawn, but since the Magnum is the primary and is, for example, networked with the AGS module I'd like it to properly display SOC as well.

If the magum only shows amps while inverting. (Asuming yiu are looking at the bmk menu and not the inverter menu). Then the shunt is in the wrong place. Though it should still drop Soc while inverting.

[StuM]

Originally Posted by smac999

If the magum only shows amps while inverting. (Asuming yiu are looking at the bmk menu and not the inverter menu). Then the shunt is in the wrong place. Though it should still drop Soc while inverting.

To clarify:

Are we talking about a display of amps being drawn, i.e. the actual current being drawn at the time you look at the readout, which will fluctuate depending on load ;OR

Are we talking about a display of amp hours drawn i.e. the amount of energy which has been used since the last time the batteries were fully charged and which will be increasing as long as the load is greater than the input from any charging source. ( or the number of amp hours remaining in the batteries, which will move in the opposite direction)

[GoinSumWare]

Originally Posted by smac999

If the magum only shows amps while inverting. (Asuming yiu are looking at the bmk menu and not the inverter menu). Then the shunt is in the wrong place. Though it should still drop Soc while inverting.

The shunt is in the correct location because it has worked and shown SOC since being installed 7 years ago. It only stopped measuring SOC when I switched from AGMs to lithium house batteries.

[GoinSumWare]

Originally Posted by StuM

To clarify:

Are we talking about a display of amps being drawn, i.e. the actual current being drawn at the time you look at the readout, which will fluctuate depending on load ;OR

Are we talking about a display of amp hours drawn i.e. the amount of energy which has been used since the last time the batteries were fully charged and which will be increasing as long as the load is greater than the input from any charging source. ( or the number of amp hours remaining in the batteries, which will move in the opposite direction)

Amps being drawn. The Magnum does not display the number of amp hours used or remaining (although the Victron does). It is only designed to show SOC as a percentage.

[bdgWesternMass]

It really sounds like a software/firmware configuration that has mis-calibrated the SOC message.

https://www.victronenergy.com/upload...R-DE-ES-SE.pdf

I did find this in the manual for the BMV 712

The BMV synchronises too early
In solar systems or other applications with fluctuating charge currents, the following measures can be taken to reduce the probability for the BMV to reset prematurely to 100 % state of charge:
a) Increase the “charged” voltage to only slightly below the absorption charge voltage (for example: 14.2 V in case of 14.4 V absorption voltage).
b) Increase the “charged” detection time and/or decrease the tail current to prevent an early reset due to to passing clouds.
See section 4.2.1 for set up instructions.


__________________________________________________ _____________
16. SoC relay (Discharge floor)
When the state of charge percentage has fallen below this value, the relay will close. The time-to-go displayed is the time to reach the discharge floor.
Default Range Step size 50 % 0 – 99 % 1 % 23 EN NL NFRL FDRE DEES ESSE SEAppendITix PT
17. Clear SoC relay
When the state of charge percentage has risen above this value, the relay will open (after a delay, depending on setting 14 and/or 15). This value needs to be greater than the previous parameter setting. When the value is equal to the previous parameter the state of charge percentage will not close the relay.
Default Range Step size
90 % 0 – 99 % 1 %

. 4.2.1 Battery settings __________________________________________________ ____________ 01. Battery capacity
Battery capacity in amp hours
Default Range Step size
200 Ah 1 – 9999 Ah 1 Ah __________________________________________________ ____________ 02. Charged voltage
The battery voltage must be above this voltage level to consider the battery as fully 
charged. 
The charged-voltage-parameter should always be slightly below the end of charge voltage of the charger (usually 0.2 V or 0.3 V below the ‘float’ voltage of the charger).
See section 3.7 for recommended settings. 

BMV-700 / BMV-702 / BMV-712 Smart
Default
See table, sect 3.7
Range
0 – 95 V
Step size
0.1 V
BMV-700H
Default
158.4 V

Default nominal voltage: 144 V
In case of another nominal battery bank voltage (32 V for example), the charged voltage must be set manually: see section 4.2.1, setting 02.
15


EN NL NFRL FDRE DEES ESSE SEAppendITix PT

Recommended settings: Nominal battery voltage 12 V
24 V
36 V 48 V 60 V 120 V 144 V 288 V
3.8 Alarm, buzzer and relay:
Recommended Charged Voltage setting 13.2 V
26.4 V
39.6 V
52.8 V 66V 132 V 158.4 V 316.8 V

__________________________________________________

[smac999]

Originally Posted by GoinSumWare

Amps being drawn. The Magnum does not display the number of amp hours used or remaining (although the Victron does). It is only designed to show SOC as a percentage.

The bmk shows amp hours draw this cycle. Reset able amp hours draw. (Since the last time you reset it). And total ah draw since installed.