Battery on force charge limit 1.44kw

[sarah1oakley]

Hi, has anyone come across a battery on force charge, but being limited to taking only 1.44 kW from mains?
It was working fine a few days ago with mains consumption up to 5 or 6 kw during the force charge window.
Min soc is set to 10%
On friday the DNO reduced the voltage on our local transformer as it was previously too high. We have a voltage optimiser and have reset that so it's now at 220v. Since power came back on Friday we've had various issues, main one being that the battery is only doing this limited force charge. In all of the force charge windows it takes at 1.44kw to 1.45kw consistently for the whole window therefore doesn't manage to fully charge.
Have re-watched the iaiameccles youtube on inverter settings and cannot find any settings that would result in this behaviour.
Were struggling to get hold of our installer, anyone got any ideas in the meantime please ?

[reef]

What temperature is the battery? Generally charge rate only drops like this if the batteries are getting too cold. They only have to drop below about 17C for the charge rate to drop to 2.5kW and again further when it gets a little colder than that.

[sarah1oakley]

Thanks reef that makes sense. It's in a workshop in a garage and the temp would have gone down to single figures. We're putting a heater in there as I type

[MichaelH]

Hi all

Sorry to jump in here I have a similar problem only my charge rate is down to 0.42KWh on a force charge overnight and the same this afternoon. I have a plugin hybrid car with a 8KWh battery that is just on a normal plug- looking at car chargers. I have set the charge period to match octopus GO and the car charges in 4hrs pulling 2.2KWh and does not drain the batteries down thanks to Will's helpful videos. I'm not sure how long the charge rate has been this low but surly this is not right. the 4hr charge window is not long enough to charge the 2 HV2400 batteries. Inverter is H1 3.7 E. and 10 panels just over a year old, I have Home Assistant over the cloud but still brings a lot of information to your figure tips & work much better then the fox app.
Any helpful information would be gratefully appreciated.

Thanks
Mike

[Dave Foster]

Hi all

Sorry to jump in here I have a similar problem only my charge rate is down to 0.42KWh on a force charge overnight and the same this afternoon. I have a plugin hybrid car with a 8KWh battery that is just on a normal plug- looking at car chargers. I have set the charge period to match octopus GO and the car charges in 4hrs pulling 2.2KWh and does not drain the batteries down thanks to Will's helpful videos. I'm not sure how long the charge rate has been this low but surly this is not right. the 4hr charge window is not long enough to charge the 2 HV2400 batteries. Inverter is H1 3.7 E. and 10 panels just over a year old, I have Home Assistant over the cloud but still brings a lot of information to your figure tips & work much better then the fox app.
Any helpful information would be gratefully appreciated.

Thanks
Mike

That is a very low charge power, with 2 batteries you’ll be around 110v so .42kw is only around 4Amps.

One thing to check first are your minsoc’s both set around 10% - I only ask as .42kw is close to what the charger runs at when maintaining the battery at minsoc.

Do you know the battery firmware versions, you can get them from the Inverter panel, About, Bat Ver - it will give you M:xxxxxx and S:xxxxxx for master/slave versions - and just to check are they HV2600’s or Mira batteries (not HV2400 as you wrote)

At the inverter panel, if you go into Settings (password is usually 0,0,0,0) and then Battery, Max Charge Cur - what is it set to ? (It should be 35A)
In that same Battery Menu is Max Soc, what is that set to (it should be 100)

[MichaelH]

Morning Dave Thanks for the reply

My SOCs are set to 15% min and 80% for overnight, trickle charge starts around 11pm to maintain the 20%, as I drop my max SOC to 20-30% and just run the house off the battery for the day, then pop the SOC up to 80-90% for the overnight charge.

I will pop into the loft and check the inverter battery settings.

In summer SOCs are around 10% & 20-25% and we still export on them settings .

I will confirm my Battery as I'm at work but are they the HV2600.

Thanks again
Mike

[Dave Foster]

The minsoc values should be fixed, they are your absolute minimum values the battery should not drop below (before the BMS maintains them).

If you set your minsoc higher, the BMS will simply slow charge them until they reach the value you set. The low charge is around 0.5kw which is what you are seeing.

If you want to fast charge them in the 4 hour period, leave both your minsoc settings set at 15% and set your charge period 1 to charge from grid in your Octopus GO period of 12:30 - 04:30

Have a look at this page which explains all the battery settings in detail https://github.com/TonyM1958/HA-FoxESS- ... Management (Thanks Tony for your excellent documentation )

[MichaelH]

Hi the MINSOC value never goes below 15%, it is just the MAXSOC that I change.
Charge time that you indicated on Time Period 1 with Time Period 2 selected to stop the car from discharging the battery

I understand that the battery will trickle charge to maintain the lower MAX SOC, just thought it should charge faster once the MAX SOC was lifted to 80-90%

Mike

[calum]

You are correct that the batteries should charge faster if you're in a force charge window. I have an H-1 3.7 as well, we tend to see charge rates of ~3.5-3.6kW overnight when charging our batteries.

Everything you're describing sounds to me like a charge current limit has been inadvertently set, as Dave mentioned earlier.

BTW, I'm not sure why you are changing your Max SoC so often, particularly just now when presumably you want to take advantage of all the battery capacity you can? I'd just leave it at 100% so you get the maximum capacity out of the batteries, and set the MinSoC to whatever you feel comfortable with (15% should be fine). Then just leave one of your charge periods aligned to your off peak window.

[Dave Foster]

Hi the MINSOC value never goes below 15%, it is just the MAXSOC that I change.
Charge time that you indicated on Time Period 1 with Time Period 2 selected to stop the car from discharging the battery

I understand that the battery will trickle charge to maintain the lower MAX SOC, just thought it should charge faster once the MAX SOC was lifted to 80-90%

Mike

To be sure can I double check your terminology around Max Soc - the Max Soc setting is usually only available via the inverter panel, or with the RS485 home assistant integration. Max Soc limits the maximum SoC value the batteries will charge to from grid, solar will always fully charge them.

The ones I available in the app are MinSoc and MinSoc on grid - they are essentially the same and control the minimum you want your battery to fall to, the MinSoc on grid is only relevant if you use EPS in which case you would set it a but higher than the MinSoc to 'reserve' power should the grid fail - normally they are set the same to 10 or 15%.

[MichaelH]

Morning all

little update after last night's check
Inverter battery versions
M:00.01.020
S1: 01.00.01.06
S2 :02.00.01.06
Max Charge Cur is 35A as pointed out

Both MAX soc settings on the inverter were 30% now 100%

Battery charged at peak 3.68 and fully charged by 02.30ish

I think I've missed the update but I could be wrong, but when we installed the system in June'22 the app had a min and max soc setting not a min(grid) setting. The installer said min 15% and max 100% and change the 100% if you want less grid charge i.e. summer or sunny winter day. So has this changed or has the installer got it wrong?

I'm not sure why both Max soc settings on the inverter were set at 30%, on the app I had 15% and 30% so that would explain one 30% on the inverter. but the battery would charge to 100% just took all night.

So come Summer time when we only need a small charge from the grid what setting would be changed? Shorten the timed force charge?

Tony's doc on Github is very informative thanks Tony
Thank you to all for your help

[calum]

There is (at least on mine!) only one MaxSoC setting. As Dave mentions above, this only serves to limit how much the battery charges from the grid - solar PV will always be able to charge the batteries to full, if there is sufficient surplus.

I would agree with your installer, if you want less (or no!) charge overnight you are probably best to vary the MaxSoC parameter. Even on a sunny day in winter, you're probably going to want to charge the batteries on the off-peak rate overnight, so that you can run the house off them before the panels get going. Of course, this will depend on your typical house electricity demand.

As your battery bank is "only" two modules, you may still wish to give it a small charge over night even in summer, so as to avoid paying for peak rate power in the early morning after your Octopus Off Peak period ends. Assuming you're on the Octopus Lite export tariff (I forget the exact name, but it pays 8p/kWh), you're not losing anything financially by filling up your battery and potentially exporting a bit to the grid. If you don't charge up and end up paying peak rate, it'll end up costing quite a lot more.