@batpred 

As my battery packs were heavily used yesterday and had discharged to 20%, the charge window would mean they'd hit capacity around 6.30am so I decided to take a look at my packs this morning.

The conclusion.

As Andy and I have said, the Seplos BMS will ramp down the charge rate when nearing capacity (about 98.5-99%).

The issue is how quickly the charge rate ramps down to keep up with the cells now starting to race away (around 3.430V).

My full capacity target is 3.450V.

This is very very close to 100% fully charged. I am not chasing a tiny bit extra.

With aiming to be fully charged at 3.450V (55.20V total capacity )and the JK Balancer set to start balancing at 3.450V there is a small window to start balancing and the Seplos BMS to ramp down it's charge rate. If your cells aren't as well balanced as mine you may have even less time).

I observed about 5-10 minutes.

At this point the total pack voltage hit 55.20V, the BMS resets to 100% and shuts down the charge request.

Am I happy with this.

Yes and no.

My packs were top balanced at 3.600V and are still well balanced (15mV at 55.20V pack voltage), so they don't require much balancing.

However 5-10 minutes isn't a lot of time (plus a bit extra as they taper down when the charge current is stopped).

With this in mind I have set my balance start voltage to 3.410V which will give me about 30 minutes of balance time and should ensure they stay balanced at 3.450V (55.2V total pack), my target 100% full capacity.

As a side note I observed the the charge/discharge time window is 10 minutes out of sync.

My Inverter is set to charge between 12.10am and 6.50am to ensure I don't use any peak electricity during charging.

My packs started discharging at exactly 6.40am.

With this mind I have adjusted the heavy draw items (garage heater, EV charger etc) to stop at 6.40am to ensure they aren't discharging from the battery packs and reducing their capacity unnecessarily.

Posted by: @bash

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As my battery packs were heavily used yesterday and had discharged to 20%, the charge window would mean they'd hit capacity around 6.30am so I decided to take a look at my packs this morning.

The conclusion.

As Andy and I have said, the Seplos BMS will ramp down the charge rate when nearing capacity (about 98.5-99%).

Thanks for checking and sharing! 

It is odd that Fogstar advised differently, so either:

• they do not know how the Seplos BMS works 
• they know, but prefer to close a query about how the Seplos BMS works by stating it does not do this, as they do not care enough

Some of their current battery kits use BMS from other manufacturers. 

I am still planning to get my JK balancer to work.

@batpred 

I'd change your JK balance start voltage a little lower to give a it a chance to actually balance your cells.

@batpred 

The Pace BMS also isn't the best with it's balancing algorithm, along with most other BMS manufacturers.

Only JK seem to have a handle on this and are regarded as the best in the industry.

Which is why ,I assume,Fogstar fit the JK balancer to their 16Kw Pace BMS batteries?

Posted by: @bash

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@batpred 

I'd change your JK balance start voltage a little lower to give a it a chance to actually balance your cells.

Yes, but I need to reopen the battery box.. I just noticed that the binary_sensor.503010d0243_problem "sensor" (on the JK HA integration) reports a problem. No details provided, so the first thing will be to recheck the cabling. 

Posted by: @mrkfm

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I've been reading up about battery storage and seen videos etc where this is being promoted as an option without solar as long as you have a cheap overnight tariff.

Is this worth looking in to now? 

I had a battery and inverter installed a while ago, my payback is just a few years, as I did not go for the MCS accredited staff, etc. It requires some knowledge, specially if you are looking to have off grid operation (to keep you going even with grid outages).

I'd say it mainly depends on finding a helpful registered electrician and being very clear on what you are looking for. A diagram helped me.   

Below is an outline of what I did. And this thread had a lively debate on what is involved. 

When I last looked (after our Solis inverter was up and running), Sunsynk would have been my choice of hybrid inverter.  

Posted by: @batpred

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A hybrid inverter is basically the brain that sits between your solar panels, batteries, and the grid, deciding—many times per second—where power should flow.

If you picture a normal solar inverter, it just takes DC power from your panels and turns it into AC for the house or export. A hybrid inverter does that and manages batteries: charging them when there’s surplus solar or cheap grid energy, and discharging when prices rise or the sun’s gone.

Here’s what it quietly juggles in the background:

• ☀️ From solar → house / battery / grid
• 🔋 From battery → house / grid
• ⚡ From grid → house / battery (if allowed)

So it’s not just converting; it’s scheduling and balancing. That’s why you see models like the Solis S6-EH1P8K-L-PLUS called “hybrid” or “energy storage inverters.”

 

Needs and goals

For a typical 4–5 bed house with an EV in SW England, my goal was flexibility—avoiding double work later when the house grows and needs an extra EV point, a heat pump, or more storage (has anyone ever had an installer actually praise what was already there? Exactly.)

Disclosure: My engineering and general science background, IET membership etc means this was an option for us. Essentially tinkering within reason.

What mattered to me

• ⚡ Fast battery charge/discharge rates and strong export capability.
• 🧰 Manufacturer support we can actually reach—too many stories of pop-up installers disappearing.
• 🔌 Compatibility with a wide range of batteries and accessories for future expansion.
• 🔋 The cherry on the cake was being able to handle power cuts gracefully—some of these units can keep a home running for days if paired with enough storage.

So far, the Solis has been a solid, expandable bit of kit. We only had it installed after we had the consumer unit swapped with one with the latest safety features and plenty of capacity to grow.

...

All in all, it was a capable, forward-looking choice if you’re also after a system that can grow with your needs.

Notes

You can find more background and our journey so far here.

Please do not interpret it as a recommendation, there are plenty of other inverters that can do this. Just not many options that handle 8kw (a standard EV charger) and retail for around £1300.

@jamespa also posted on this and we discussed options (when he was considering adding energy storage).