Grid charge batteries at night?

[Guenther]

Hi, have installed a Deye / lifepo4 solar system. Installer set nighttime grid charge at 80%, whereas i protested a little because charging a battery by grid makes not much sense to me. He is reluctant also to my suggestion to set discharge rate at 20% before grid connection. (would harm battery) Manufacturer (lvtopsun) claims safe discharge soc is 5%. Question : Is it safe to discharge powerwall to 5% and have recharge time set to only solar suring day?

 

[rodrick]

Typical useable range for longevity on a Lifepo battery is stay out of the bottom 10% and top 10% using the 80% in between will give you the longest life and still give you a good capacity with less stress on the battery this will make calendar aging the biggest issue with your battery

 

[LydMekk]

Is your battery a 15S or 16S config?
Do you only have one battery or more?
Specs/model?

 

[DIYrich]

Charge/discharge levels/rates:

Recommended Charge Profile for DIY LiFePO4 Batteries *Sticky Post*

12V 4S LiFePO4 Battery w/ BMS: Absorption: 14.5V Float: 13.6V Inverter Cut-off: 10.7V-12V (depending on size of load and voltage drop etc) 24V 8S LiFePO4 Battery w/ BMS Absorption: 29V Float: 27.2V Inverter Cut-off: 21.4V-24V 48V 16S LiFePO4 Battery w/ BMS Absorption: 58V Float: 54.4V...

diysolarforum.com

Guide is to charge/discharge at 0.2C. If solar isn't enough to charge up batteries, then you take from the grid anyway. If you have TOU pricing, then that is your risk. If not, then it doesn't matter when you take from the grid. In general, it is more efficient to charge from solar because you don't have the AC->DC conversion loss.

 

[Guenther]

Is your battery a 15S or 16S config?
Do you only have one battery or more?
Specs/model?

I have l lvtopsun lowerwall 100ah LV48100

 

[Guenther]

Charge/discharge levels/rates:

Recommended Charge Profile for DIY LiFePO4 Batteries *Sticky Post*

12V 4S LiFePO4 Battery w/ BMS: Absorption: 14.5V Float: 13.6V Inverter Cut-off: 10.7V-12V (depending on size of load and voltage drop etc) 24V 8S LiFePO4 Battery w/ BMS Absorption: 29V Float: 27.2V Inverter Cut-off: 21.4V-24V 48V 16S LiFePO4 Battery w/ BMS Absorption: 58V Float: 54.4V...

diysolarforum.com

Guide is to charge/discharge at 0.2C. If solar isn't enough to charge up batteries, then you take from the grid anyway. If you have TOU pricing, then that is your risk. If not, then it doesn't matter when you take from the grid. In general, it is more efficient to charge from solar because you don't have the AC->DC conversion loss.

Thank you for this, I show this to the installer together with the manufacturer data. Perhaps he confused with Gel battery settings and wanted to make sure that the battery is always steady charged even at night. The Deye /Lvtopsun BMS is fine and its just a time schedule setting. To my luck i live in Philippines and panels produce at maximum most of the time and recharge is within 1-2 hours.