Hi Guys

Looks like I am in the same boat. Cannot get past 27.5 with bulk. Tried to set the float to 24 here to see what happens but you can see it hit a wall with bulk then switching over to float even though bulk was set to 29.2:  Video

 

Edited March 12, 20206 yr by jaqkar

17 hours ago, jaqkar said:

Looks like I am in the same boat. Cannot get past 27.5 with bulk. Tried to set the float to 24 here to see what happens but you can see it hit a wall with bulk then switching over to float even though bulk was set to 29.2:  Video

In this case, it did get to 30.2 V briefly, then went to the float stage immediately. I don't think it should go from bulk to float as quickly as that, but I don't know the smaller models well.

You battery went from 27.5 V to 30.2 V in less than a minute; the whole video is less than one minute long. That means that either your battery is completely full, or it has high internal resistance and is faulty (or there could be significant resistance in the battery cables or fuse(s).

Does this battery power loads for about the expected length of time?

It's unfortunately not uncommon for lead-acid batteries that are chronically undercharged or otherwise abused to wind up with high internal resistance after as little as 12 months use. What model are the battery modules, how old are they, and have they been charged to the appropriate voltage for a suitable period of time? It doesn't help that all Axperts are delivered with the premature float bug.

Edited March 13, 20206 yr by Coulomb

@Coulomb thanks for the input! System is 8S 120AH LifePO4 from Lithium Batteries SA and a Daly 24V 8S BMS. They seem to charge good and discharge good as well. Had a couple of good cycles this week. Wanted to get them to 3.6v for the BMS to initiate balancing.

16 minutes ago, jaqkar said:

@Coulomb thanks for the input! System is 8S 120AH LifePO4 from Lithium Batteries SA and a Daly 24V 8S BMS. They seem to charge good and discharge good as well. Had a couple of good cycles this week. Wanted to get them to 3.6v for the BMS to initiate balancing.

My setup is similar to yours (though mine is an already coupled 5.4kwh Lifepo4 with BMS) but it behaves similar to yours.  I think mine is because the cells are unbalanced and will be sending it back to the seller to fix. One way to test this is for you to attempt to discharge the battery and see if the BMS trips at higher voltage (mine tripped at around 25v which wasn't normal)

That said, am considering a DIY to increase my bank capacity, and gathering the ingredients, yet to decide on the BMS to use, are you able to see/manage individual cells with the Daly BMS?

Regards

Edited March 13, 20206 yr by ojeysky

51 minutes ago, ojeysky said:

My setup is similar to yours (though mine is an already coupled 5.4kwh Lifepo4 with BMS) but it behaves similar to yours.  I think mine is because the cells are unbalanced and will be sending it back to the seller to fix. One way to test this is for you to attempt to discharge the battery and see if the BMS trips at higher voltage (mine tripped at around 25v which wasn't normal)

That said, am considering a DIY to increase my bank capacity, and gathering the ingredients, yet to decide on the BMS to use, are you able to see/manage individual cells with the Daly BMS?

Regards

Mine has no issue running down. The Daly does not have any output to a screen etc. I use a Cellmeter 8 to view details on each cell.

On 2020/03/13 at 12:35 PM, jaqkar said:

Mine has no issue running down. The Daly does not have any output to a screen etc. I use a Cellmeter 8 to view details on each cell.

Did you eventually resolve this? Am lockdown so can't get battery bank to seller, will like to see if I can balance from my end. Am considering floating at 28.2v overnight while on utility to see if the BMS will be able to balance up the cells.

Edited March 31, 20206 yr by ojeysky

 

On 2020/03/13 at 12:29 PM, jaqkar said:

@Coulomb thanks for the input! System is 8S 120AH LifePO4 from Lithium Batteries SA and a Daly 24V 8S BMS. They seem to charge good and discharge good as well. Had a couple of good cycles this week. Wanted to get them to 3.6v for the BMS to initiate balancing.

I have a similar battery setup but with a 2KVA model and recently got it setup.

I have been noticing a lot of the same behaviour with the differences of the "battery" voltage displayed and what is actually measured at the battery leads me to think that it is the same for all the 24V models.

 

@jaqkar what are your current settings ?

I am going to try @Adri settings tonight and see what happens.

 

On 2020/04/01 at 4:56 PM, 20VT said:

 

I have a similar battery setup but with a 2KVA model and recently got it setup.

I have been noticing a lot of the same behaviour with the differences of the "battery" voltage displayed and what is actually measured at the battery leads me to think that it is the same for all the 24V models.

 

@jaqkar what are your current settings ?

I am going to try @Adri settings tonight and see what happens.

 

When charging, the battery voltage displayed on the inverter is more than what is measured on the battery terminals. Usually between 0.2 and 0.5v

When discharging the battery voltage on the inverter is less than what is measured on the battery terminals. Usually between 0.1 and 0.3v

4 hours ago, ojeysky said:

When charging, the battery voltage displayed on the inverter is more than what is measured on the battery terminals. Usually between 0.2 and 0.5v

When discharging the battery voltage on the inverter is less than what is measured on the battery terminals. Usually between 0.1 and 0.3v

Ok I have also noticed the same.

What settings do you have to get the optimum out of the solar charging and battery bank ?

20 minutes ago, 20VT said:

Ok I have also noticed the same.

What settings do you have to get the optimum out of the solar charging and battery bank ?

I use 28.2/27.2 bulk/float 

17 minutes ago, ojeysky said:

I use 28.2/27.2 bulk/float 

Ok and you don' t have the grid connected because the other issue I noticed is that the back to grid voltage is also an issue and I am unable to charge the batteries to its full capacity...

Is there any other strange behaviour that you have noticed with the 24V system ?

 

16 minutes ago, 20VT said:

Ok and you don' t have the grid connected because the other issue I noticed is that the back to grid voltage is also an issue and I am unable to charge the batteries to its full capacity...

Is there any other strange behaviour that you have noticed with the 24V system ?

 

I just had grid last week after almost a year of no-grid, but behaviour is still the same. As I understand it, "back to grid" is only useful when you are connected to grid and your battery is charging via solar. If at some point battery voltage dips to BTG voltage then it starts charging via grid. I don't think that have any effect on the float bug.

Apart from the voltage spikes, I noticed my battery does not discharge below 25v before BMS kicks in, I think that is probably a cell balancing issue unique to my battery.

Edited April 5, 20206 yr by ojeysky

7 minutes ago, ojeysky said:

I just had grid last week after almost a year of no-grid, but behaviour is still the same. As I understand it, "back to grid" is only useful when you are connected to grid and your battery is charging via solar. If at some point battery voltage dips to BTG voltage then it starts charging via grid. I don't think that have any effect on the float bug.

Apart from the voltage spikes, I noticed my battery does not discharge below 25v before BMS kicks in, I think that is probably a cell balancing issue unique to my battery.

Ok you have it connected but having had the batteries to the BTG voltage that's good to know.

I had my axpert installed about 10 days ago so the battery bank was not full the first day and with all the bad weather it went on bypass with the battery charging off the grid and then also had to adjust setting 11 from 27.0V to get it to allow more charge to get into the battery bank. What I did notice the first time this happen to did not even go from charging to grid to using the battery when the setting 11 was FUL at least now it automatically does that although the end state of charge is around 70%.

On the low end initially also had to change it from default values to 22.5V which it gets to now.

What BMS and batteries do you have ?

 

 

22 minutes ago, 20VT said:

Ok you have it connected but having had the batteries to the BTG voltage that's good to know.

I had my axpert installed about 10 days ago so the battery bank was not full the first day and with all the bad weather it went on bypass with the battery charging off the grid and then also had to adjust setting 11 from 27.0V to get it to allow more charge to get into the battery bank. What I did notice the first time this happen to did not even go from charging to grid to using the battery when the setting 11 was FUL at least now it automatically does that although the end state of charge is around 70%.

On the low end initially also had to change it from default values to 22.5V which it gets to now.

What BMS and batteries do you have ?

 

 

My 200AH battery pack was coupled by a local seller, he has prismatic cells and Daly BMS in it. How are you checking the state of charge?

Edited April 5, 20206 yr by ojeysky

5 minutes ago, ojeysky said:

My 200AH battery pack was coupled by a local seller, he has prismatic cells and Daly BMS in it. How are you checking the state of charge?

Ok I have a Daly BMS as well and it seems to working well from lithiumbatteriessa. 

I have a Victron BMV 702 that I had installed with my previous setup and use it for as a SOC meter 

43 minutes ago, 20VT said:

Ok I have a Daly BMS as well and it seems to working well from lithiumbatteriessa. 

I have a Victron BMV 702 that I had installed with my previous setup and use it for as a SOC meter 

Cool, I have just gotten a BMV 712 as well, will be installing that soon.

10 minutes ago, ojeysky said:

Cool, I have just gotten a BMV 712 as well, will be installing that soon.

Ok do you have the 3KVA system ?

2 minutes ago, 20VT said:

Ok do you have the 3KVA system ?

Yup

5 minutes ago, ojeysky said:

Yup

What are the other components in your system ?

2 minutes ago, 20VT said:

What are the other components in your system ?

What would you like to know? Maybe you indicate your components and I will confirm if I have them or not

3 minutes ago, ojeysky said:

What would you like to know? Maybe you indicate your components and I will confirm if I have them or not

I have the following at the moment:

- Axpert-MKS-Plus-2KVA
- 6 x Canadian Solar 335W panels wired in 2 in series and 3 in parallel
- DIY LiFePO4 Battery Bank 180Ah with Daly BMS

- BMV 702

 

4 minutes ago, 20VT said:

I have the following at the moment:

- Axpert-MKS-Plus-2KVA
- 6 x Canadian Solar 335W panels wired in 2 in series and 3 in parallel
- DIY LiFePO4 Battery Bank 180Ah with Daly BMS

- BMV 702

 

Mine is Axpert Variant (felicity) 3kva

9 x 250w sunfit panels connected in 3by3

DIY Lifepo4 battery bank 200Ah with Daly BMS

RaspberryPi running emoncms and solpiplog for monitoring

SPD and circuit breaker

BMV 712 (yet to be installed)

23 minutes ago, ojeysky said:

Mine is Axpert Variant (felicity) 3kva

9 x 250w sunfit panels connected in 3by3

DIY Lifepo4 battery bank 200Ah with Daly BMS

RaspberryPi running emoncms and solpiplog for monitoring

SPD and circuit breaker

BMV 712 (yet to be installed)

Ok are you going to be using the Pi to connect up the BMV as well and to control the inverter.

36 minutes ago, 20VT said:

Ok are you going to be using the Pi to connect up the BMV as well and to control the inverter.

Yup it's part of the plan, I have the USB already

15 hours ago, 20VT said:

Ok are you going to be using the Pi to connect up the BMV as well and to control the inverter.

So I have set-up my BMV. It gives me 100% SOC on my battery. Can you confirm if you re-synchronised yours since you indicated you were using it for a different battery before.