Posted by: @bash

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@batpred

I don't recognise that screenshot you have posted.

I spent many nights working out why the unit's weren't balancing as well as I'd hoped using the Seplos desktop app.

Once the batteries reached around 97-98% capacity the BMS would ask the Solis inverter to ramp down the charge rate, dropping to around 10A, possibly 5A, from the requested 100A charge rate I set 

The screenshot is via home assistant, as it is currently working..

I would be interested to know if there's any configuration required to get it to ramp the charging down as it gets close to 100 soc. 

I assume you are using pylontech protocol on both the BMS and the Solis sides? I think that does not allow control of the voltage range etc, or did I miss anything? 

I also assume you are using the default config that Fogstar shipped the kit with? 

The easiest way to analyze what's going on is to post screenshots of the BMS configuration parameters and the inverter settings.

@batpred 

There is no configuration required to the Seplos BMS settings. The BMS automatically does this for you.

I know that it does it as I spent many late nights staring at a computer screen trying to get my head around why the cell balance was off!

In the end I upgraded to the JK Active balancer, which confirmed conclusively that my cells had got out of balance, significantly.

The cells need to be reasonably balanced for the balancer to have an opportunity to top balance properly.

I had 4 cells that were way out. The cells ran away too quickly and never allowed the balancer time to do it's work.

In the end I made a lighting rig out of car headlight bulbs and discharged the over shooting cells to bring them back in line with the others.

Now that the cells were roughly the same I observed the BMS ramp down its charge rate once the cells got to about 3.450V, at which point the Active Balancer kicked in and moved the energy around the cells to get them properly balanced.

Once the total pack reached 57.6V the BMS shut down the charge rate to 0A.

The Active balancer still works when the cells are not charging until they drop back below 3.450V.

It is important to check your balance start voltage on the JK Active balancer.

The default is 3.450V and will keep going until the difference is less than 10mV.

You can change these, but I wouldn't. Do check though.

You need to really observe this through the Seplos app and JK bluetooth app as the batteries reach near capacity. This will mean staying up late one night (or more if they are out of balance, although I suspect you'll find they are probably balanced anyway).

Posted by: @upnorthandpersonal

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The easiest way to analyze what's going on is to post screenshots of the BMS configuration parameters and the inverter settings.

On my Solis, there are only a handful of parameters in the timed charge periods (they are actually exactly the same for discharge periods). This is all that can be set:

• start and stop times of the period
• the amp level
• the soc level

For charging, I just split the last charging slot. So I now have a few slots before that, with a soc of 94-98. The last one now has 10A charging to soc 100. 

The Seplos 16kwh battery was configured as below:

• battery type: Lithium Battery
• battery model: PYLON_LV
• Max charge current: 100A
• Max discharge current: 190A
• battery saving: Disable
• Max charge SOC: 100

Attaching screenshots reduces the resolution, making it unreadable.

So I made the screenshots with the Seplos BMS configuration accessible via this link: 

https://drive.google.com/drive/folders/1YVChebpuYF5KqYWYK72GXrRq4C5Qi2TQ?usp=sharing

Perhaps @bash configs are different, and that would trigger the BMS to slow the charging down automatically. 

Below I am including a graph including the charge current. That does not show any smoothing effect (as was the case with the power). Note: the charging periods shown are yesterday's, slightly different from the ones described above. 

@batpred 

As I said you are looking at the wrong thing.

You need to be connected to your BMS direct.

I am using the default settings of the BMS, so should be the same as yours unless you have fiddled with your BMS settings.

Posted by: @bash

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@batpred 

As I said you are looking at the wrong thing.

You need to be connected to your BMS direct.

I am using the default settings of the BMS, so should be the same as yours unless you have fiddled with your BMS settings.

I don't think so. 🙂 My post crossed with yours, thanks for that. I will look at the cell balancing later.

All I am looking for now is to understand the "magic" that worked for you, enabling the Seplos BMS to slow the charging as the battery charge increases. 

I assume you did not check the gdrive where I placed the screenshots with all the configs that I directly grabbed from the Seplos BMS? 

Anyway, hopefully some fiddling with the Seplos BMS parameters worked in those overnight sessions. 

As @upnorthandpersonal said, sharing your config is the simplest way. I can do the detailed comparison. 😆 

@batpred 

There's no magic, it is the design of the BMS, I have watched it many times from the stock firmware unchanged.

You need to set your alarm for 3am and do some observations 😆 

@batpred 

Interestingly having had a very quick look at your BMS settings, they look totally different to mine, not the values themselves, but the layout.

Are you definitely on Seplos V3?

How did you log onto the BMS?

I connect using the USB - RS485  cable supplied by Fogstar connected to my laptop using the Seplos Dev software application.

Posted by: @bash

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You need to set your alarm for 3am and do some observations 😆 

At the moment, my HA is doing the monitoring job. I thought I would do the tedious job to compare all those parameters. 😆 Anyway, when you get a chance.. 

I did have a few late evenings to get Solis on a straight and narrow. What I rather forget is the DIY pack building "customer experience"..

Posted by: @bash

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@batpred 

Interestingly having had a very quick look at your BMS settings, they look totally different to mine, not the values themselves, but the layout.

Yes, this is the layout on the Seplos bluetooth app, called Octopus. It is a V3 and I upgraded the firmware to 1.5.

For some reason I cannot access the JK LB via their app, but HA still plots some basic data. I suspect it is not doing anything.. 

As for the values for the Seplos BMS, the old Fogstar just advised me to change one or two values. 

@batpred 

Your BMS parameters will be the same as mine then, as I only changed the Fogstar recommended ones in the tutorial (which are largely irrelevant as the JK Balancer has taken this over).