FoxESS Community - Owners & Installers Forum

Hi All. Recently had a EQ4800 battery at 42kWh installed with a H3-Smart 10kW inverter. The house has 25kW solar panels located in Australia.

I noticed the charge rate of the battery drops significantly at 80% SOC (drops to 4.25kW) and again at 90% (drops to 0.86kW) - even when we are generating 19kW from the solar and using less than 1 or 2kW load. From 90% to fully charged, it takes ~5 hours! Ambient temp was about 15deg so believe this may be a combination of SOC and Temperature de-rating.

The battery is installed outside and exposed to daytime temps of ~15deg during winter which, when sunlight is scarce, I want to be able to get the most charge in the battery as possible when I can!

These limits seem conservative and wondering if there are any known fixes or workarounds for this?

It's less likely to be temperature-related but more just the BMS backing off as the SOC nears full. You can't run high charge amps above 80% or you cause heat and wear on the battery. Even my Tesla backs off during high SOC when supercharging, so is completely normal. All this protection is to prolong the lifespan of the battery and is expected.

Yes I'm aware of derating approaching full charge and that this is typical behaviour of BMS - its more the extend of the derating and how early it starts with this particular battery! 0.86kW is a pretty extreme de-rating and way more than other batteries that i have had (Alpha ESS recently) and a few other brands that friends have. Thier derating is not noticed until 95% or 98% SOC.

It does seem to be exacerbated by temperature and have obserived the charge rate jumping up a notch with temp increases through the morning (ie. from 2.2kW to 4.5kW) between 80% and 90% SOC which is my main concern for winter when temps will be around 15 deg. We need as much storage as possible to cover heating energy and with limited sunlight hours here in Aus, slow charging rates will limit our ability to use the battery to its max potential.

I am no expert at all, but this could be a firmware related?

The other thing that springs to mind is you have 42kWh of storage, maybe each pack is balancing quite a bit and struggling for whatever reason to get to 100%

Just throwing a few ideas, that might help.

Hi all. I seem to be having the same issue of slow charging. I have an H1-5.0-E-G2 with 41 kw EQ4800 batteries. If the soc is 89% or bellow, I get 4.2 kw of charging with battery temperature of 10c. to 26c with the charge rate staying at 4.2kw till it gets to 100%. If the soc is 90% or above, with a temperature of 21c or less, I get a charge rate of 0.8kw up until 96%, it then ramps up to 4.2kw for the last 4% with a battery temp still below 21c. If the soc is 90% or above with a temperature of 22c or higher, it will charge at 4.2kw. It seems that a soc of 90% to 96% and temperature under 21c is slow charging and a Temperature of 22c and above will be fast. Is this normal or a firmware, battery or inverter issue?

Most of these issues are resolved by asking your installer to apply the latest inverter and battery firmware.
Over 80% SoC it's expected to slow down but the middle ramp is odd.

Hi Will. I have applied the lasted firmware as I have an installer acount. After applying the latest firmware, I noticed in the forum after applying the new firmware that the manager firmware version 1.62 had problems. Could the problem im having be one of the issues relating to the 1.62. I have tried a firmware roll back on the master which was successful, but the firmware roll back for the manager fails with code 45004. Do you know when a new manager version will be released? Also out of curiosity, what does a master and manager do in an inverter, what are their specific rolls or jobs? Im fascinated by inverters.

Hi rt1000

Not quite the same, but similar limits around 21 degrees.

Less than 21 degrees and less than 90% SOC - charge will limit to 4.25kW. (less than 15deg is ~2.25kW)
More than 21 degrees and less than 90% SOC - no limits. Full inverter load (up to 10kW).
Less than 21 degrees and more than 90% SOC - limited to ~0.86kW until 100% SOC.
More than 21 degrees and more than 90% SOC - limited to 4.25kW. Slight ramp down as normal approaching 99% SOC.

I've run a few deep discharge cycles to test out the range of charging at different SOC's and temperatures.
Excuse the crude mark up!

21 deg is fairly conservative to cut charge rates that hard and will limit the batteries benefits in cooler months - so hope FoxESS can adjust the BMS settings when they come out and "run some tests" soon!

Awesome, thanks for that, explains a lot. Now I don't have to worry or panic now that I know its normal and others have the same experience. Thanks again for the help and info.

Wouldn't go as far as saying its normal yet! FoxESS are looking into it and hopefully will have a fix that gets it functioning a bit better in cooler months.

Otherwise i'll have to look into an insulated enclosure.

Hi, Charging at low temperatures are fixed. Iv update my H1 gen2 inverter manager firmware to 1.64 from 1.62, which seems to have fixed the slow charging problems. This is what I have observed:
90% and above soc, between 10c and 14c the charge rate is 2.08kw
90% and above soc, between 15c and 21c the charge rate is 3.4kw
90% and above soc, 21c and above, the charge rate is at max of 4.9kw
Below 90% soc, battery charges at max of 4.9kw until it reaches 90% soc, at which point temperature starts to take over charge rate again.

I think that the manger firmware is where all the deciding charge rates happen for the battery. Also manager version 1.61 and 1.62 With the force charging disappears from the mode scheduler bug, may have many other bugs in including this charge rate issue.

Hope all this rambling that iv done helps.