HELP Needed - OverVoltage Disconnect setting cannot be set for Lithium 24V 7S battery with EPEVER UPower UP3000-M3322

[maxdreamcreator]

Hi everyone,

INVERTER:

I have recently purchased an EPEVER UP3000-M3322 Inverter/Charger.

https://www.epever.com/product/upower-1000-5000w-hybrid-inverter-charger/

BATTERY (See Photo):

The battery I am using is a custom build 80Ah 7S Li-ion battery 25.9V Nominal ranging from 21V to 29.4V. (7s28p)

Over voltage Setting issues:

I have read the full manual and I have been searching the entire forum, internet and Youtube, but I still have 2 issues:

• the OVR (Over Voltage Reconnect Voltage) can only be lowered to a minimum of 29V.
• And the OVD (Over Voltage Disconnect Voltage) can only be lowered to a minimum of 31V.

This represent a significant safety risk, particularly for the OVD as there is no charger protection to disconnect the charge at 29.4V (maximum Voltage my battery will take) and the charger would not disconnect till 31V has been reached.

BMS:

I will be using a 24V 7s 100A Daly BMS which I feel should disconnect and avoid overcharing, but I would rather not just rely on the BMS itself in case it ever failed.

7S 80A 100A 120A 24V 3.7V Li-ion Lithium Battery Protection BMS Board UK Stock | eBay

The heat sink will greatly help cooling. ◆BMS manufactured by high quality Mos and IC imported. ◆ After connecting the wire, mustn't insert the plug directly into the BMS. 7S BMS size as below Current 7S BMS size Remark.

www.ebay.co.uk

Over voltage Relay Protection:

I have thought of potentially using a DC to DC 24V overvoltage relay to protect the battery if voltage went above the 29.4V. This felt like a good idea at first but after looking online I cannot seem to find such a relay especially a relay that could take on 100A. The maximum I have found was about 63A. Also the issue with a relay is that once it has been triggered off it would switch everything off as the Inverter charger is powered by the battery, so cutting current would likely have to be switched back on manually.

EPEVER Support Contacted

I have contacted EPEVER support recently and they confirmed that the Inverter charger is not technically designed for with lithium Ion batteries. I find this very strange as the range of parameters seems perfectly suitable to accommodate the battery’s voltage. In fact, I specifically bought this model as the input battery voltage advertised is 21.6～32VDC for a 24V model so I felt this would be perfect for the voltage range of a 7S lithium battery. In fact, I owned a TRIRON 3210N just before and it had a 7S Lithium ion battery setting that I could select. The only setting that EPEVER said cannot be lower further are the OVR and OVD. I do not want to go back to a individual inverter and individual Solar charger set up as it does not allow connecting to the grid and is overall more expensive.​

I have also tried to change the setting in Software through the RS485 cable but that doesn’t seem to work.​

Here are my questions:​

1. Does anyone know if it is possible to lower the OVR lower than 29V and lower the OVD lower than 31V within the UP3000-M3322 Inverter/Charger itself despite what EPEVER Says?​

2. If not is it possible to lower these 2 settings in the charger is it possible to override the OVR and OVD voltages by using the software (I have not managed so far)?​

3. If not, how do you ensure the charger cannot exceed max Voltage of 29.4V for a 7s lithium pack (4.2*7V)? not keen on just relying on BMS only protection.
4. If none of the above is possible, does anyone know what other Inverter/charger I could use for a 24V 7S lithium battery? I can still return the Inverter/charger till the end of January 2023.

I hope this forum can help, as I feel really stuck and do not want to return the inverter/charger.

Thank you,

Max

 

[sunshine_eggo]

1. this doesn't matter. You should set the bulk/absorption voltage to your desired peak charge voltage and float 0.1V below that. It should never go over that unless the charger malfunctions. If the charger malfunctions, you have the BMS, which is also monitoring for problems at the cell level and could trigger disconnect even before the charger's cut-off voltage.

2. See #1

3. See #1

4. See #1

You want something that isn't standard.

My Victron inverter/charger won't OVD until 66V. My Victron MPPT doesn't even have OVD settings. That would be pretty catastrophic for me with my 14S NMC at 58.8V max. I'm not worried one bit.

The only concerns I have with your situation are:

1) That EPEVER likely has a high idle consumption of 40-50W per 3000W rated inverter output.
2) DALY seems to have more problems than most. The one you linked is particularly crappy without an interface to see the cell data. I prefer JBD.