Personally I wouldn't by a Sunsynk 5.3 kwh battery if were selling it for half the price of any other lithium battery.

Some say it is a C1 rated battery, which makes it better than the 5.1 kwh IP 65 battery.

5.3kwh pros



The battery internal data is not visible on the inverter screen nor the app

If you wan to upgrade the firmware (this very common) you have to get someone like myself who has the equipment and experience to go to site and do the upgrade on site.

There are tons of message in the tech groups with regards to the challenges installers and customers are experiencing.

Why do we only install the 5.1 kwh IP 65 battery




The battery just works, I have installed a lot of them. They charge to 100% and sit at 100% until power is drawn from the battery, they dont drop 5-8 % like other batteries.

The unit is IP 65 rated, so you dont have problems with moisture in coastal regions damaging electronic components inside the enclosure.

It also prevents bugs getting in.

The internal data is visible on the inverter display, in the app and on the computer. Right down to cell level, battery cycles and all that kind of important stuff.

Tech support can remotely access the battery data, they can also update the firmware.

It makes it easy for me as the installer to log into plant overview and check everything, for example an installation we did a year ago, which has 2 x 5.1 kwh IP 65 batteries, cycled often.

SOH - 100 %
cycles - 50

I can see the current state of charge

The graph with a trend of all the battery data I need is just a tap of the keyboard away.

One of the important trends I monitor is the temperature of both the inverter and batteries, especially just after the installation, you want that data because if you have been dick and not installed as per the user manual, chances are your warranty could be a problem. All data is there and can be viewed by the person doing the warranty assessment.