Need help with issue of battery voltage raising too fast during charging.
Setup - 24v 3000w inverter, Epever 30A MPPT, ATS switch, voltage relay.
How system operates ( or supposed to) :
1. Voltage relay is connected to battery.
2 When battery voltage is above 26v ( recommended threshold for AGM battery), voltage relay connects inverter to ATS. Utility power is connected to the second side of ATS
3.ATS senses inverter power and switches to solar. Battery starts discharging, MPPT controller still charging the battery ( actually partially powering the load, taking some load off the battery)
4. If load current is more then MPPT can supply, battery is discharging.
5. When battery battery voltage falls below 26v, voltage relay disables inverter.
6. ATS senses no power from inverter and switches to utility. MPPT continues to charge battery (can also add an external charger to help MPPT and to charge at night if needed)
7. Battery voltage raises to 28.4v ( full charge voltage) and voltage relay switches back to inverter.
Simple system, right? Problem is that after switching to utility, battery voltage rises too fast, in about 2-3 minutes and system switches back to battery power. I'm testing the system with a good load, about 60amps ( pool pump). Initially when battery is fully charged, it runs for 10-15 minutes on battery ( battery is only 80AH), switches to utility, voltage goes up to 28.4 in 3 min, system switches to solar, voltage goes down to 26. System switches back to utility and keeps cycling every 2-3 minutes. NO good. There is no way that in 3 min of charging at 20amp from MPPT controller, it can recharge what was spent in 3 min at 60amp. Which means battery will be completely discharged and permanently damaged.
Question 1 - why voltage is raising so fast. I tested batteries with battery tester, it says they are good.
Question 2 - could this be an issue with all-in-one inverter like Growatt? I'd like to buy this all-in-one box. But I'm reading that Growatt turns off charging immediately after reaching threshold value set in parameter 13 "Setting voltage point back to battery mode". Which means Growatt inverter will be switching back and forth from solar to utility every 3 minutes?
Setup - 24v 3000w inverter, Epever 30A MPPT, ATS switch, voltage relay.
How system operates ( or supposed to) :
1. Voltage relay is connected to battery.
2 When battery voltage is above 26v ( recommended threshold for AGM battery), voltage relay connects inverter to ATS. Utility power is connected to the second side of ATS
3.ATS senses inverter power and switches to solar. Battery starts discharging, MPPT controller still charging the battery ( actually partially powering the load, taking some load off the battery)
4. If load current is more then MPPT can supply, battery is discharging.
5. When battery battery voltage falls below 26v, voltage relay disables inverter.
6. ATS senses no power from inverter and switches to utility. MPPT continues to charge battery (can also add an external charger to help MPPT and to charge at night if needed)
7. Battery voltage raises to 28.4v ( full charge voltage) and voltage relay switches back to inverter.
Simple system, right? Problem is that after switching to utility, battery voltage rises too fast, in about 2-3 minutes and system switches back to battery power. I'm testing the system with a good load, about 60amps ( pool pump). Initially when battery is fully charged, it runs for 10-15 minutes on battery ( battery is only 80AH), switches to utility, voltage goes up to 28.4 in 3 min, system switches to solar, voltage goes down to 26. System switches back to utility and keeps cycling every 2-3 minutes. NO good. There is no way that in 3 min of charging at 20amp from MPPT controller, it can recharge what was spent in 3 min at 60amp. Which means battery will be completely discharged and permanently damaged.
Question 1 - why voltage is raising so fast. I tested batteries with battery tester, it says they are good.
Question 2 - could this be an issue with all-in-one inverter like Growatt? I'd like to buy this all-in-one box. But I'm reading that Growatt turns off charging immediately after reaching threshold value set in parameter 13 "Setting voltage point back to battery mode". Which means Growatt inverter will be switching back and forth from solar to utility every 3 minutes?