Charge controller (ePever) settings and battery SOC missmatch (Voltx 48v) help?

[Rumbaar]

I've recently gotten a ePever Tracer5420AN charge controller and a 48V Voltx 100ah (SH48-100+LCD) battery, for my solar array (3 x 350W).

The charge controller had 12V @ 25c settings defined in it's manual for Lithium batteries, to which I multiplied by 4 to get the values for 48V system. But then I saw the built in LFP settings and changed to the built in LFP16 settings as below:

ePever LFP16

Over Voltage Disconnect Voltage	59.2V
Charging Limit Voltage	58.4V
Over Voltage Reconnect Voltage	58.4V
Equalize Charging Voltage	57.6V
Boost Charging Voltage	57.6V
Float Charging Voltage	53.6V
Boost Reconnect Charging Voltage	52.8V
Low Voltage Reconnect Voltage	52.0V
Under Voltage Warning Reconnect Voltage	51.2V
Under Voltage Warning Voltage	49.6V
Low Voltage Disconnect Voltage	46.4V
Discharging Limit Voltage	44.0V

But the Voltx has these suggested settings in their manual for when charging with a controller and I'm not certain how to translate those to the above settings, and I want to ensure the batteries BMS is avoided over the controllers protection. I can sort of work out the equivalent of the above, but then not sure how changing those has a flow on affect to other settings, and assistance or guide would be very helpful.

Overcharge Protection Voltage	58.4V
Overcharge Recovery Voltage	56.8V
Over-discharge Protection Voltage	40.0V
Over-discharge Recovery Voltage	42.4V

 

[sunshine_eggo]

SoC is voltage-based on RESTING voltages. Only slightly accurate after the batteries have sat for 30 minutes with NO charge or discharge.

It is an utterly meaningless number in an operating system.

You need a battery monitor for accurate SoC. First 3 are viable.

 

[Rumbaar]

SoC is voltage-based on RESTING voltages. Only slightly accurate after the batteries have sat for 30 minutes with NO charge or discharge.

It is an utterly meaningless number in an operating system.

You need a battery monitor for accurate SoC. First 3 are viable.

The Voltx has it's own built in battery monitor, so a 3rd party shunt would be more accurate than that built in monitor, if it's voltage based monitor? But as the charge controller is pushing out a higher voltage during charge it'll not be accurate. So that's where, I'll assume, the over voltage disconnect and such come into play.

Also to your statement of SoC is voltage-based on RESTING voltage is only applicable to batteries that do not use a 'smart shunt' system, and more higher end ones already have that type of SOC accuracy built in and better BMS?

 

[sunshine_eggo]

Voltage-based battery monitors are inaccurate - period. The charge controller % SoC will NEVER be accurate unless the battery has sat dormant (absolutely no charge or discharge) for about 30 minutes. Then it's somewhat accurate.

When the display on the battery looks exactly like the cheap voltage based monitor on Will's page (manual page 7), I don't trust that the battery is reporting accurate SoC.

 

[littleharbor2]

You should be able to find "User" setting in the charge controller which will allow you to set the charging profile to whatever you want.

 

[Rumbaar]

You should be able to find "User" setting in the charge controller which will allow you to set the charging profile to whatever you want.

I can do that, but in relation to the current settings and the 'Voltx' reconmend settings I'm not sure of all the equivilant changes I need to make or which ones lines up with the available options. As they appear to use slightly different terminology which look similar, but aren't.

For example, they have "Overcharge Protection Voltage" and I think that means "Over Voltage Disconnect Voltage" in the charge controller settings. But then some don't line up and then if I change some, there is flow on affects for others and I'm not sure to what amounts I should be lowering them if their 'parent' value is altered.

 

[littleharbor2]

Suggesting your settings is beyond my comfort level. It baffles me the terminology used by different mfg. for different settings. The best I can suggest is study the user manual and try calling the battery mfg. with questions.

https://d1hcq2qixeq4j1.cloudfront.net/cx/2022/03/28/1648426345-Voltx%2048V%20100%20Premium.pdf

 

[mikefitz]

The epever settings are for charge controll (voltages and duration) and also for warnings and load control via the interface and load control terminals.
The settings you are concerned about, the battery BMS settings, and the way they relate to the controller load settings is of no concern in your charging application.

 

[Rumbaar]

The epever settings are for charge controll (voltages and duration) and also for warnings and load control via the interface and load control terminals.
The settings you are concerned about, the battery BMS settings, and the way they relate to the controller load settings is of no concern in your charging application.

No, these are the settings that Voltx suggested in their manual for setting your (my) charge controller to. To ensure/avoid the batteries BMS is engaged and the controller is engaged before the BMS, thus protecting battery and BMS (the more costly of the hardware in the system).

 

[acdoctor]

In most charge controllers if you select a canned profile you can’t adjust the settings within.
If you don’t like the canned profile you select “user defined “ or whatever your controller uses for those words. Once it is selected only then can you adjust the individual settings. And you must verify the values are appropriate for your specific system. One setting you definitely need to address in Equalize. It needs turned off. If it can’t be adjusted to zero time then adjust the voltage to your float voltage valve.

Overcharge and over discharge are only related to the load terminals on the controller. You should only be using those if you have small loads that are 48 volts DC. I doubt you do so you don’t need to worry with them.

You have all of the settings info on the batteries all you need to do is set those slightly more conservative in the controller than the battery limits to avoid BMS tripping.

The SOC battery % I the controller is voltage based and is not an accurate way of meaning. The display on the battery may be from a shunt in the BMS or just voltage again. The battery manual doesn’t say. Most BMS have a shunt so I would rely on it to some degree.

 

[mikefitz]

Boost volts, boost duration, and float volts are the major controller values for charge control , many of the others relate to load control.
For example ' low voltage disconnect' setting in the epever will, via the load control output and a suitable Interface, disconnect a load from the system if the system is designed for this.
Voltx does not know exactly how your system is configured. Unless you are using the load control settings, for example to disable an inverter at low volts, they need not be of concern.

Less aggressive charge volts, boost 56 volts and float 53.6 may increase battery life. Having the battery at a lower SOC than 100% will also help

Mike

 

[Rumbaar]

I think I've worded my question and/or thread wrong, as it seems none of the answers relate to the question I've asked regarding the 4 values supplied by the battery manafucturer in relation to the current USER settings of the charge controller. I'll see if I can think of another way to word it.

 

[Ellcon123]

The various terminoligy csn be confusing and sometimes you just have to test it out. The way I read it is;

Over Voltage Disconnect Voltage = Overcharge Protection Voltage

Over Voltage Reconnect Voltage = Overcharge Recovery Voltage

Low Voltage Reconnect Voltage =
Over-discharge Recovery Voltage

Low Voltage Disconnect Voltage =
Over-discharge Protection Voltage

The BMS is last line of protection so on charging the BMS settings needs to be higher than the SCC and on discharge the BMS settings needs to be lower than the inverter. Ideally your BMS never triggers in day to day use.

 

[ianganderton]

I went deep into this

In this post I link my epever charge settings, some decoding info and several links to info I read through to get here

My Build Questions - Camper Van 480W Solar 12V 200Ah LifePo4

All loads off the charge controller? You need your feed directly off the battery or lynx, The max load will be within the 40A its rated for and I'm trying to keep cables as short as possible while oversizing them where possible too. By having them of the load terminals my understanding is it...

diysolarforum.com

 

[Rumbaar]

I went deep into this

In this post I link my epever charge settings, some decoding info and several links to info I read through to get here

My Build Questions - Camper Van 480W Solar 12V 200Ah LifePo4

All loads off the charge controller? You need your feed directly off the battery or lynx, The max load will be within the 40A its rated for and I'm trying to keep cables as short as possible while oversizing them where possible too. By having them of the load terminals my understanding is it...

diysolarforum.com

Thanks for that, I'll take a look. Not sure of the big difference between 12v 200ah you're running and 48v 100ah I'm running. I've found the extrapolation from 12v to 48v can result in some wide differences. Great resouce, the spreadsheet and setting explainations + notes!

 

[mikefitz]

I think I've worded my question and/or thread wrong, as it seems none of the answers relate to the question I've asked regarding the 4 values supplied by the battery manafucturer in relation to the current USER settings of the charge controller.

these 4 settings?

Overcharge Protection Voltage	58.4V
Overcharge Recovery Voltage	56.8V
Over-discharge Protection Voltage	40.0V
Over-discharge Recovery Voltage	42.4V

these are settings for the battery BMS incorporated within the 'battery'.

The Epever has settings that relate to charging and also load control and warnings over its interface,

over voltage disconnect
charge voltage limit
over voltage reconnect
equalise charging voltage
boost charging voltage
float charging voltage
boost reconnect voltage
low voltage reconnect
under voltage warning reconnect
under voltage warning
low voltage disconnect
discharge limit voltage
boost duration
equalization duration

Unless you are using the load control and interface outputs of the epever to interact with your system the settings in bold have no effect on the charging of the battery.

if you are using the load and interface of the epever to control parts of your system then it would be prudent to set values within the envelope of the BMS protection values.

over voltage disconnect = overcharge protection voltage = 58.2
overvoltage reconnect = overcharge recovery voltage = 56
low voltage disconnect = over discharge protection voltage = 48
low voltage reconnect = over discharge recovery voltage = 50

The chart shows typical resting voltage of a battery.



Mike

 

[ianganderton]

Thanks for that, I'll take a look. Not sure of the big difference between 12v 200ah you're running and 48v 100ah I'm running. I've found the extrapolation from 12v to 48v can result in some wide differences. Great resouce, the spreadsheet and setting explainations + notes!

Something worth doing to understand this is to go back to cell voltages

12V = 4 Lifepo4 cells
48V = 16 Lifepo4 cells

This resource is great for seeing this very clearly

LiFePO4 Battery Voltage

Sheet5 How to Find Happiness With LiFePO4 (Lithium-Ion) Batteries <a href="https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/">https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/</a> Cell Count 4,8,16,32,64,128 SOC,Cell V,12V setup,24V setup,48V setup...

docs.google.com