FoxESS Community - Owners & Installers Forum

Hi,

We recently had a new inverter and battery installed. Fox H1-3.7-E-G2.

It looks like it is charging from the grid overnight. We have disabled charging from grid so I am not sure why this might be happening.

I've read a few similar posts on this forum but I am not sure our situation is the same as the previous posters but apologies if I am asking a similar question...

The power graph shows activity at around 3.15am yesterday.

Output power -0.84kw
Charge power 0.84kw
Grid consumption 0.98kw

In terms of background information that might be relevant:

We have set our minimum SOC at 20%
We have an EPS/UPS set up
The firmware we have is: Master 1.27, Slave 1.02, Manager 1.44
The battery was installed on an external wall

Any information or advice gratefully received.

Thanks!

Looking at the rate it is charging at I would say it’s one of 2 things - Either -

The battery SoC has reached minSoC - the inverter and BMS doesn’t take any power from the grid to keep running, it actually keeps itself operational from the dc side i.e. solar or battery, it doesn’t take a lot of power but it’s a small steady drain on the batteries and if the battery SoC falls below the minSoC the BMS will request a maintenance charge.
This is usually a low power charge for a short period ~ 5 minutes or so to get the batteries back above minSoC at which point it stops charging - it usually repeats this every hour or so.
If you have a low tariff period it’s always best to charge the batteries up as this avoids any unnecessary drain at peak periods.

OR

The batteries are getting cold (approx 10C) at which point the BMS will also start a maintenance charge to warm the cells.
This is because whilst the batteries will allow discharge down to -10C, they cannot be charged if they fall to 0C and so the BMS tries to pre-empt that with a short ‘warming’ charge.

Have a look at your battery state of charge and battery temperature overnight - that should tell you the most likely culprit.

Thanks for your reply!

I thought it was temperature related. So I guess I need to build some kind of box to insulate it. Are there any guidelines or things I should avoid?

Robin93 wrote: Sat Dec 14, 2024 5:00 pm Thanks for your reply!

I thought it was temperature related. So I guess I need to build some kind of box to insulate it. Are there any guidelines or things I should avoid?

There are quite a few posts about this, here's a recent one that covers the basics - it doesn't need much some 25 or 50mm Kingspan, the only thing the manufacturer says is to make sure you have 30cm clearance for air flow. viewtopic.php?p=5512

Thank you! I read these posts but wanted to check- does the battery box need to house just the battery or can I include the inverter as well? I read that the inverter gets hot so this is probably not good? I don't have a huge amount if space around either of them. Apologies for basic questions, this is all very new.

Robin93 wrote: Sun Dec 15, 2024 9:03 am Thank you! I read these posts but wanted to check- does the battery box need to house just the battery or can I include the inverter as well? I read that the inverter gets hot so this is probably not good? I don't have a huge amount if space around either of them. Apologies for basic questions, this is all very new.

Just the battery, the inverter has cooling fins on the back which get very warm in summer and if they get too hot the inverter will derate so keep that open to good air flow.

Thank you so much!

I'm going to do a temporary fix today and then design a more permanent solution over the holidays.

As I understand it: I can box the battery in but it needs a 20- 30 cm space around it for air to circulate. Any permanent box needs to have a door that opens or sides that are removable in summer.

Thanks again, your help is much appreciated!

Robin93 wrote: Sun Dec 15, 2024 9:15 am Thank you so much!

I'm going to do a temporary fix today and then design a more permanent solution over the holidays.

As I understand it: I can box the battery in but it needs a 20- 30 cm space around it for air to circulate. Any permanent box needs to have a door that opens or sides that are removable in summer.

Thanks again, your help is much appreciated!

Yep that's a perfect interpretation, good luck !