Battery SOC When topped up by Solar

[jassdhali]

Hi,

Just setup my system:

15 420w Jinko Solar Panels
5kW Sunsynk Hybrid inverter
Seplos Mason 48V 14.3kWh battery with 16 Grade A V3 LF280K EV

BMS setup advice thanks to @houseofancients

Has been supplying house for 8 days , all looks to be running fine - using Octopus agile tariff & daily cost is down two thirds

My SOC has been set to 95 & 15 & when grid charged overnight is all good.

However when panels get some sun (suprisingly) the battery pack goes up to 100%.

What can I change to stop it hitting the max? If screen shots required let me know.

Thanks for your time.

 

[a619]

why wouldn't you want to fully charge your packs?

 

[Nobodybusiness]

Hi,

Just setup my system:

15 420w Jinko Solar Panels
5kW Sunsynk Hybrid inverter
Seplos Mason 48V 14.3kWh battery with 16 Grade A V3 LF280K EV

BMS setup advice thanks to @houseofancients

Has been supplying house for 8 days , all looks to be running fine - using Octopus agile tariff & daily cost is down two thirds

My SOC has been set to 95 & 15 & when grid charged overnight is all good.

However when panels get some sun (suprisingly) the battery pack goes up to 100%.

What can I change to stop it hitting the max? If screen shots required let me know.

Thanks for your time.

I think we have lost something in Translation.

Why are you charging at night via Grid?

Let your panels do the charging during the day then if not full by sundown and you really want them at 100% then use the grid to charge them.

 

[jassdhali]

why wouldn't you want to fully charge your packs?

From what I have read its best not to hit max every time with these cells.
Obviously I may be wrong

 

[jassdhali]

I think we have lost something in Translation.

Why are you charging at night via Grid?

Let your panels do the charging during the day then if not full by sundown and you really want them at 100% then use the grid to charge them.

Simple, I live in the UK, we have no sun at the best of times
The energy supplier we use has a low cost tariff in the morning hours, typically between midnight & 5am.
The smart meter we use has 30 min time slots - this morning majority of the early slots were a minus per kW
As you can see below. Blue line representing the cost



During the latter parts of the day the tariff goes up to around 20p to 30p, so ideal for the battery to take over.
Hope that makes sense.

 

[Nobodybusiness]

Simple, I live in the UK, we have no sun at the best of times
The energy supplier we use has a low cost tariff in the morning hours, typically between midnight & 5am.
The smart meter we use has 30 min time slots - this morning majority of the early slots were a minus per kW
As you can see below. Blue line representing the cost

View attachment 208508

During the latter parts of the day the tariff goes up to around 20p to 30p, so ideal for the battery to take over.
Hope that makes sense.

Yea that is definitely a unique setup.
It’s just basically arbitrage.

 

[houseofancients]

Hi,

Just setup my system:

15 420w Jinko Solar Panels
5kW Sunsynk Hybrid inverter
Seplos Mason 48V 14.3kWh battery with 16 Grade A V3 LF280K EV

BMS setup advice thanks to @houseofancients

Has been supplying house for 8 days , all looks to be running fine - using Octopus agile tariff & daily cost is down two thirds

My SOC has been set to 95 & 15 & when grid charged overnight is all good.

However when panels get some sun (suprisingly) the battery pack goes up to 100%.

What can I change to stop it hitting the max? If screen shots required let me know.

Thanks for your time.

Congrats and welcome to help

I would advise you to charge your cells to 100% , otherwise you will create a cell imbalance, do please change the charging voltage to 56.8 or 56 , so your passive balancer can do it's job

 

[Steve_S]

You can safely keep LFP at 100% of the Working Voltage Range without any issues whatsoever over the lifespan of the cells. Note that the working voltage range for LFP is from 3.000-3.400 which is the range that delivers the actual rated Amphours of the cells. If you charge your battery packs to 55.2V or 3.450V per cell with Balancing beginning at 3.42, the cells will remain balanced & within the working range for longest trouble free service.

 

[chrisski]

, all looks to be running fine - using Octopus agile tariff & daily cost is down two thirds

My SOC has been set to 95 & 15 & when grid charged overnight is all good.

However when panels get some sun (suprisingly) the battery pack goes up to 100%.

Is it possible your batteries are at 95% but the shunt reads 100%?

I would think getting the pack to only 95% is as simple as setting MPPT votlage to the 95% point. Having the shunt read 95% at your full point is a calibration issue.

IME, the shunt, for different reasons can be inaccurate and may need to be calibrated. With my Victron system, I found I had the tail current setting at first way out of adjustment and at 80%, the SOC would jump to 100%. I fixed that so it would go by 1% increments up to 100% correctly, but what I did do was set that 100% point.

I also use the 95% point voltage charging point as 100% of my battery. I believe if I wanted to keep my shunt reading 95%, I would constantly need to tweak the efficiency. Also, when I reset my shunt, it resets to 100% not 95%.

Once amperage stops going in the battery is when I know the battery is charged.

 

[sunshine_eggo]

Hi,

Just setup my system:

15 420w Jinko Solar Panels
5kW Sunsynk Hybrid inverter
Seplos Mason 48V 14.3kWh battery with 16 Grade A V3 LF280K EV

BMS setup advice thanks to @houseofancients

Has been supplying house for 8 days , all looks to be running fine - using Octopus agile tariff & daily cost is down two thirds

My SOC has been set to 95 & 15 & when grid charged overnight is all good.

However when panels get some sun (suprisingly) the battery pack goes up to 100%.

What can I change to stop it hitting the max? If screen shots required let me know.

Thanks for your time.

Simple. There are two mechanisms controlling charge.

Grid and Solar.

The 15/95% are simply triggers for grid on/off.

If battery comms are active, when charging via solar, the battery is communicating the charge voltage to the AiO, i.e., charge to voltage X and hold there.

If battery comms are not active, when charging via solar, the MPPT is working to the bulk/boost/absorption and float voltages set.

As has been stated by others, no harm in going to 100%, and it is periodically necessary to maintain cell balance.

 

[houseofancients]

You can safely keep LFP at 100% of the Working Voltage Range without any issues whatsoever over the lifespan of the cells. Note that the working voltage range for LFP is from 3.000-3.400 which is the range that delivers the actual rated Amphours of the cells. If you charge your battery packs to 55.2V or 3.450V per cell with Balancing beginning at 3.42, the cells will remain balanced & within the working range for longest trouble free service.

And the passive balancer in his BMS simply won't work

 

[jassdhali]

Congrats and welcome to help

I would advise you to charge your cells to 100% , otherwise you will create a cell imbalance, do please change the charging voltage to 56.8 or 56 , so your passive balancer can do it's job

Currently my Float V & Absorption are set to 56.7v on Inverter
Equalisation the same (is this a requirement for LifePO4)

Looking at Sunsynck Connect my voltage at 95% SOC is at 53.5v, so cell voltage is low.

When solar puts up to 100% SOC my voltage goes as high as 57.9 as below:


So I will put the SOC to 100% so that NEEY kicks in.

Any reason why the voltage still jumps up to 57.9 & not stay at the 56.7 I have set.
Or have I set the wrong parameter.

Appreciate everyone's time in answering & sharing their valuable knowledge.

 

[sunshine_eggo]

Currently my Float V & Absorption are set to 56.7v on Inverter

Bad idea. Float should be at 54.

Very important question:

Do you have BMS comms with the inverter?

 

[houseofancients]

Currently my Float V & Absorption are set to 56.7v on Inverter
Equalisation the same (is this a requirement for LifePO4)

Looking at Sunsynck Connect my voltage at 95% SOC is at 53.5v, so cell voltage is low.

When solar puts up to 100% SOC my voltage goes as high as 57.9 as below:

View attachment 208696
So I will put the SOC to 100% so that NEEY kicks in.

Any reason why the voltage still jumps up to 57.9 & not stay at the 56.7 I have set.
Or have I set the wrong parameter.

Appreciate everyone's time in answering & sharing their valuable knowledge.

Your BMS will always override anything you set in the inverter if using ra485 or canbus communications
If you did change your pack total over voltage protection setting in the BMS ( also the absorption voltage send to the sunsynk's) , you will always push your cells to 3.65v , which is not very sensible.
Change that to 56 or 56.8v , and that will give you the best of 2 worlds..
Not pushing your cells on every charge, and still giving your passive balancing BMS enough juice to work with

Inorder to get your needy to do the first balance, have it start at 3.45 and stop at 3.40, difference 5 mv and you will be good !

 

[jassdhali]

Bad idea. Float should be at 54.

Very important question:

Do you have BMS comms with the inverter?

yes it is via Canbus

 

[jassdhali]

Your BMS will always override anything you set in the inverter if using ra485 or canbus communications
If you did change your pack total over voltage protection setting in the BMS ( also the absorption voltage send to the sunsynk's) , you will always push your cells to 3.65v , which is not very sensible.
Change that to 56 or 56.8v , and that will give you the best of 2 worlds..
Not pushing your cells on every charge, and still giving your passive balancing BMS enough juice to work with

Inorder to get your needy to do the first balance, have it start at 3.45 and stop at 3.40, difference 5 mv and you will be good !

Sorry, you mean set my BMS overprotection to 56v.
I will check what it is when I get back home.
I thnk I did change the over voltage protection, but will double check, when back at home in the morning.

Thanks for your time

 

[sunshine_eggo]

yes it is via Canbus

I thought so since you're specifying grid by SoC.

In this case, all your charge voltage settings are irrelevant. They are overridden by the BMS.

If battery comms are active, when charging via solar, the battery is communicating the charge voltage to the AiO, i.e., charge to voltage X and hold there.

The battery is telling the MPPT to charge to the 57.9V and hold it there. The only way YOU can control it via the AiO is to set battery type to USE, disconnect comms and set absorption and float as you see fit.

This how comms works. You're giving control of the charging and discharging of the system to the BMS. If you can reprogram the BMS charge voltages, you can reduce it.

Sorry, you mean set my BMS overprotection to 56v.

I wouldn't do this.

 

[jassdhali]

These are the settings from my BMS.





Not sure if I want BMS or inverter to control battery pack at the minute.
The NEEY is already set as stated.
Thanks

 

[jassdhali]

HI,
Are there any issues glaring out regarding the BMS settings?

Thanks

 

[sunshine_eggo]

I have a bias for setting protection limits to actual limits. 2.5V low and 3.65V high. No damage occurs to cells operating in this range, so there's no reason to force the BMS to narrow this range.

Of course that requires you set the total voltage protection limits to 16X these values.

Set the recovery values to something sensible.

If these are the defaults established by the manufacturer, change at your own hazard.

You program the equipment to operate inside this range.

Cell diff pressure protection of 1V seems pretty extreme given that the cells have a 0.3V primary operating range (3.1-3.4V). I would adjust this to 0.5V