question

tom56 avatar image
tom56 asked

Smart Solar MPPT voltage does not match the settings

I have a new installation of two 100A lifepo4 connected through a fuse to SmartSolar 100/20-48V. Firmware updated a few days ago. Panel is single 120W providing about 100W. Batteries initial voltage was 13,18-13,19V. Smart solar settings are like this, highest expected voltage to the batteries 14,20V, float, 13,5V:

screenshot-20230603-112734.jpg

Real voltage is higher than expected, up to 16,43V, and float voltage at presnet is 14,7V, also exceeding the settings (yesterday I disabled the charger worrying about the high voltage, therefore no output):

screenshot-20230605-104932.jpg


Why are voltages are off? I have a similar installation where voltages are never off. Also, may the high voltage of 16,43V have harmed the batteries?

MPPT SmartSolar
screenshot-20230603-112734.jpg (146.4 KiB)
screenshot-20230605-104932.jpg (198.3 KiB)
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

4 Answers
michelg avatar image
michelg answered ·

Hi Tom, if I remember right, you should have a delta of 5V minimum between the battery and the solar panel. Not sure if your panel has the capacity to provide enough voltage to the MPPT in order to charge the battery, it seems to me it could be the issue.

Michel

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

kevgermany avatar image
kevgermany answered ·

Battery overvoltage at the MPPT could be caused by another charge source, or possibly a spike from rapid disconnect of a big consumer.

Agree, panels seem too small for the batteries.

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

tom56 avatar image
tom56 answered ·

Thank you all. Panel is small, but still added 1000-1500 Wh to the batteries at initial charge, with no apparent issues? Also, while the installation at present has no load connected to it (load output "off"), and is only maintained by the Smart Solar, float voltage is at 13,7 V instead of 13,5V. So it stabilizes at 0,2V too high, while the solar panel is hardly delivering any current at all, and far below its capasity. Does this still mean the panel is the problem?

There is no other charge source than the Smart Solar, and the biggest consumer on the installation is a TV at about 25W. If I turn it on the installation (load output "on") starts float charging at about 25W after a while.

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

klim8skeptic avatar image
klim8skeptic answered ·

@Tom56 float voltage is at 13,7 V instead of 13,5V. So it stabilizes at 0,2V too high, while the solar panel is hardly delivering any current at all,

Without a load it will take some hours for the battery voltage to drop to the float setting after the mppt has switched from absorp to float.

Please check again with a small load to bleed a little energy / voltage from battery.

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.