FoxESS Community - Owners & Installers Forum

Hello All,

This has been something I've been doing some reading about for the past few days & sorry to start another thread on this! But it's nice to have direct replied sometimes.

I haven EP11, we chose this capacity as we have a heat pump & during the winter the battery was able to keep up topped up fully throughout the day and able to keep up paying a cheap 13pence per kW for the whole winter & avoiding the pricey periods. We would go as slow at 20% depending on the temp.

Now we are in summer, the battery basically stays between 80% and 100%, some days not even that depending on how long we generate solar for.

From what I understand these Fox cells in the EP11 are lithium iron phosphate, which are not the same tech as batteries of old or even used in phones in that actually you need to ensure you get them back up to 100% for optimum performance.

But I just wanted to check that given for probably 6-7 months it's going to be going through this, is this okay? Is there something I should automate that would be better for the pack or is it really not worth worrying about?

I'm not trying to maximise my exports and discharging each day and charging at a cheap rate as the difference is too small to make a impact (sell for 15p, buy for 12/13p), so I only sell my excess solar, which makes us a tidy profit each month.

Thanks for any help and answers!

It’s fine and quite normal in summer for your batteries to stay at a high soc, mine are typically 60-80% at the end of the day - I feed in everything I produce and charge every night on an EV tariff, whereas in winter i’m often down to below 20% at the end of the day; arguably you can occasionally (once a month) do a deeper discharge but winter comes round soon enough and it’s back to full cycles then anyway.

As you say these are LifePO4 ‘LFP’ (or Lithium Ion Phosphate) batteries and they are much more stable and robust than Li-ion batteries perfectly suited to solar applications.

The Fox BMS/Batteries do most of their balancing at the top so getting it up to 100% is much more important than getting it down to 10% which helps with SoC accuracy - plus charging from 80-100% can be done 5 times before a ‘full cycle’ is counted.

Fantastic, thank you Dave.

One of those things where for my phone I never really think about it even though it's probably more of an issue but on my home battery it had been on my mind for a while! Probably due to the cost haha.

I'll keep going as I am then