Batteries not fully charging and trying to understand how it works…

[TT]

KH8 inverter and 2 x EP12 batteries added yesterday to existing solar panel array (Nov 2024) - 20 panels of 450w each.

Help appreciated please, as customer services for installer and manufacturer are not working at the weekends

I had some late night fiddling on the FoxCloud2 app when my cheap rate kicked in at midnight and I noticed that the batteries were not charging using the settings I did with the electrician. Eventually, I hit on something (or something updated) after watching YouTube videos, and they started to charge. I happened to wake up at the end of the cheap charging period (ends at 5am) and saw that they were only at 33% (after about 4 hours). So 33% of my potential 24ish kWh. I used some of the stored charge, down to about 11 %, and then, it being a sunny day, the excess power is happily charging up the batteries.

My questions are -

A) is my 8 kw inverter capable of fully charging my two EP12s within my 5 hour cheap rate window?

B) During my cheap rate, I have a lot of load - storage heaters and other things. Will the batteries charge up independently of all these other things, or is only so much coming into the house/through the inverter, and will serve the house first and THEN attend to charging up the batteries? When I saw that the batteries were charging at around 1am, there was a 6.5kWh load on the house. This may have gone down as storage heaters had their fill. Is this a factor?

Thank you so much in advance.

[Dave Foster]

A). Yes the KH8 is capable of charging your batteries in the low tariff window, but it will depend on temperature and where the batteries are located (internally or externally) - when it is very cold the batteries throttle the charge and it is recommended to use the battery heaters. Your lowest cell temperature is showing as 8.9C above, anything below 21C starts to throttle with the effects really becoming noticeable below 11C.

Once you start charging the batteries will warm fairly quickly, but there is a video here that shows how to configure your battery heating https://youtu.be/_9hNCI1bTP4?si=mirSlPzvScjQTd72 (Note: this feature is firmware dependent, if the system is new it may have older battery firmware which needs to be updated).

B) yes this can affect your charge rate, there are a couple of inverter settings that you may want to check to make sure they don’t - at the Inverter panel you need to go into Settings, the password is 0,0,0,0 , then into On-Grid, Export Control and check that the setting ‘ImportLimitCur’ is set to 100A, and there should be another setting ‘ImportLimitPwr’ which is best to set to 30,000. Note: you may not have both of those settings as they may only show on the latest firmware, but post back what you see there.

[TT]

Thank you so much, Dave! I managed to watch the video and set up the heating section before my cheap rate kicked in and saw that it started heating at midnight. I left it doing that - still heating and not charging yet half an hour in, but was pleased to see that at the end of the cheap rate session that it had charged up to 49% - big improvement on the 33% on my first night.

I shall take the rest of your advice today and report back!

[TT]

Hi, Dave,

I managed to set the 100A, but it fails when trying to set the other 30,000.

Grateful for your further analysis!

[MaterialBarracuda48]

Try 24000W Imp Limit, that's 100Amp.
If that does not work, await Dave's further instructions.

[TT]

Much appreciated, MaterialBarracuda48,

I had a go and it is still a Fail, unfortunately.

[MaterialBarracuda48]

Drop it by 1k, 23000 and repeat until it maybe sticks.
Failing this, report back and hopefully someone has some additional advice.

[nrb501]

Try changing your heating end temp to 11°C or higher (you may wish to raise the start temp as well), with cell temp below that the charge rate the BMS allows reduces quite dramatically as Dave mentioned.
Ideally you want the cell temp to be at 11°C or more at the start of charging. With the heating settings you show if the battery temp is down at 8°C then heating will not have been triggered, charging will be limited and depending on ambient conditions may not generate sufficient heat to warm the batteries (charging on its own will cause the battles to heat) to bring them above the 11°C threshold and bring the charge rate up.

[TT]

MaterialBarracuda48 - thank you for your suggestion - it finally accepted at 18000 for ImportLimitPwr - let’s see what happens tonight!

[TT]

Thank you nrb501 - I have changed the start to 9 and end to 12 - hopefully this and the other factor makes a difference tonight!

[TT]

Not long past midnight (when my cheap rate starts) and I can already see that the charging is happening immediately due to heated battery status/adjusted ImportLimitPwr and a shed load more power is going into the battery than before.

Thank you so much for your time and knowledge, everyone! Shall report back in the morning

[TT]

I happened to wake up almost 4 hours into the cheap rate period and saw that the batteries were already 100% charged!

Thank you so much to everyone for their contribution, helping me to get the batteries functioning when all relevant customer services are closed!


My questions please -

A) My screenshot here seems to show my system doing what I want it to - charging the batteries and then continuing to use the grid for the house load during the rest of the cheap night rate. Does having that force charge setting always make sure that the batteries charge and prevent the batteries from discharging, and keep using the cheap rate for the house load in that period? I never want the batteries to power the house when the cheap rate can.

B) Is there somewhere that I can see how much energy is used for heating the batteries?

[Dave Foster]

Glad you got it working ok in the end

A) Yes, with Force Charge when your batteries are full it will revert to grid to power the loads until the force charge period ends.

B) Not easily, it's already a complex sum working out the system losses and the heater can be powered from the batteries or the grid (depending on soc) which makes it hard to track, but roughly 190 watts/hour if on all the time.

[MaterialBarracuda48]

Also pleased to hear that you got it working as intended.