Why does this happen?

[leon.davibe]

This is not the 1st time, probably the 3rd time the previous time was from 25% to 0% SOC

This time from 37% to 0% within a couple of minutes.

View attachment 1477039

5KW sunsynk and 2 x hubble 5.5 batteries.

What happens is the shunt drifts

And thinks more is left than is actually the case

The shunt recalibrates when it hits empty and resets

Counts what you put in again
And the guessing game continues

Just curious are you using the 20-80 belief

 

[wingnut771]

What happens is the shunt drifts

And thinks more is left than is actually the case

The shunt recalibrates when it hits empty and resets

Counts what you put in again
And the guessing game continues

Just curious are you using the 20-80 belief

These are NMC cells.

 

[leon.davibe]

what i mean with drift
No shunt is perfect

You can't count losses

If the battery heats up during charge energy was lost if it balances energy is lost
If cables heat up , bus bar heats up under heavier usage energy is lost

These are all losses that isn't counted meaning at some point

What the shunt thinks is in the battery isn't actually in the battery

There is a reason why software recalibrates the shunt

Almost as if they knew this happens

 

[leon.davibe]

These are NMC cells.

If the soc is calculated with shunt the same would apply

 

[wingnut771]

If the soc is calculated with shunt the same would apply

I was replying to your 20-80% mumbojumbo.

 

[leon.davibe]

These are NMC cells.

If the soc is calculated with shunt the same would apply

All systems has losses

Shunts don't count losses

Have heard other posters say sunsynk has a shunt for SOC

Is this the case?

 

[wingnut771]

If the soc is calculated with shunt the same would apply

All systems has losses

Shunts don't count losses

Have heard other posters say sunsynk has a shunt for SOC

Is this the case?

Why do the batteries need to be sent in for repairs then?

 

[leon.davibe]

I was replying to your 20-80% mumbojumbo.

The notion of 20-80 only works on a system with batteries with a SOC graph that lends itself to it

Many think they can apply the same to lifep04

People create their religions and believe them irrespective of it's validity

Calculating 20-80 on a lifep04 with voltage and even shunt is problematic with no top/bottom visits to recalibrate from time to time

Sure you may get lucky to not get caught with your pants down most of the time if your usage pattern happens to fit into your solar production until that day it doesn't

What exactly is a 80% voltage on lifep04 educate me

 

[wingnut771]

The notion of 20-80 only works on a system with batteries with a SOC graph that lends itself to it

Many think they can apply the same to lifep04

People create their religions and believe them irrespective of it's validity

Calculating 20-80 on a lifep04 with voltage and even shunt is problematic with no top/bottom visits to recalibrate from time to time

Sure you may get lucky to not get caught with your pants down most of the time if your usage pattern happens to fit into your solar production until that day it doesn't

What exactly is a 80% voltage on lifep04 educate me

Hubble AM-2 is NMC!!!!!!

NMC curve, 20-80% SOC is easy to determine:

Please stop talking about LFP, you're embarrassing yourself.

 

[leon.davibe]

Hubble AM-2 is NMC!!!!!!

NMC curve, 20-80% SOC is easy to determine:

Please stop talking about LFP, you're embarrassing yourself.

You chose to ignore the question
I asked at the end of one of the posts, i asked does the inverter use a shunt to caculate SOC

a graph that lends itself to a 20-80 usage patern means nothing if the inverter ignores the voltage and uses a shunt

 

[leon.davibe]

Hubble AM-2 is NMC!!!!!!

NMC curve, 20-80% SOC is easy to determine:

Please stop talking about LFP, you're embarrassing yourself.

Smarty pants you posted a charge soc graph this is the discharge soc graoh for next time since you need help

 

[leon.davibe]

Smarty pants you posted a charge soc graph this is the discharge soc graoh for next time since you need help

Both graphs matter

One for charging the 80% and one for 20% on the discharge atleast try and be usefull in giving people all the info yhey need not just half

 

[wingnut771]

Smarty pants you posted a charge soc graph this is the discharge soc graoh for next time since you need help

 

[wingnut771]

You chose to ignore the question
I asked at the end of one of the posts, i asked does the inverter use a shunt to caculate SOC

a graph that lends itself to a 20-80 usage patern means nothing if the inverter ignores the voltage and uses a shunt

Don't you know how a sunsynk talks to 2 x AM2?

 

[leon.davibe]

Don't you know how a sunsynk talks to 2 x AM2?

If the soc is calculated by shunt does it matter which one?

Is some shunts immune to drift?

 

[leon.davibe]

View attachment 1478029

I can hope that you at least noticed there isn't just one discharge graph on that picture

 

[wingnut771]

I can hope that you at least noticed there isn't just one discharge graph on that picture

We don't discharge to 80% thank you very much and I was merely showing the linear shape of the graph. Now please go away, you think you're helping but you're not.

 

[Die Uwe]

Yes, you could, and should, but need to check to see if you have good comms with the battery -- post a pic of your LiBMS screen?

Nothing to report sir

 

[RonSwanson]

Nothing to report sirView attachment 1479165

!
/facepalm

Oh wow. You have no comms between your battery's BMS and inverter. No wonder it's playing silly buggers, get your installer back to fix it pronto.

 

[RonSwanson]

Above is a healthy LiBMS screen, these are values reported by the BMS. You can clearly see the limitations imposed by the BMS on the inverter wrt charge and discharge. Once you get the BMS <-> inverter comms right, you can start adjusting charge and discharge values on the inverter (provided that they are lower). Bear in mind that these values change dependent on the health and SoC of the battery.