Lower my Battery Reserve Capacity to 10%?

jasonemann · Thu Jan 22, 2026 3:24 pm

I've just watched through Fox ESS - Best State of Charge SOC settings and why would you change them? MinSoC/MaxSoC on YouTube and I'm a little uncertain whether I should reduce the Battery Reserve Capacity of my system from its default value of 20% down to 10%, the same as the System Min SOC value.

I don't have the EPS option on my system, so there is no "off-grid" scenario during which the battery would discharge down to System Min SOC, as I understand it.

My takeaway from the video is that it's beneficial for the battery to get down to 10% from time to time to allow bottom balancing, but with the current settings I don't think that will ever happen. I've seen it discharge down to 20% from normal usage then stop there and in cold weather it might dip another 2-3% below that before charge from grid starts at 02:00.

Thanks for any clarification offered.

JM

Thu Jan 22, 2026 3:48 pm

It's generally good advice to have your battery reserve and minSoC set to 10% if you don't have EPS to consider - the batteries are rated (and warrantied) at 90% depth of discharge, as you've paid for it, it's best to use all of the capacity.

MaterialBarracuda48 · Thu Jan 22, 2026 4:14 pm

I set mine to 10% on day 1, I do have EPS but only 2 sockets in garage for now and probably won't need EPS but very rarely.

Fri Jan 23, 2026 9:01 am

I have a Home Assistant automation that jacks up my minsoc from 10% when there is forecasted bad or stormy weather. That way, I can use the full battery range most of the time, but on days when the risk of a power cut is increased, I have an extra reserve. Has worked well for me for years.

MaterialBarracuda48 · Fri Jan 23, 2026 9:08 am

Will wrote: ↑Fri Jan 23, 2026 9:01 am I have a Home Assistant automation that jacks up my minsoc from 10% when there is forecasted bad or stormy weather. That way, I can use the full battery range most of the time, but on days when the risk of a power cut is increased, I have an extra reserve. Has worked well for me for years.

Morning Will

Thinking for those without Home Assistant:
Have you done a video on the StormSafe Charging function on the Fox Cloud 2.0 App?
Or, do you happen to know if this works for the UK?

I have several UPS devices around the house for router and NAS to keep those running for several hours, plus my EPS is just 2 sockets in the garage, but better than nothing.