Posted by: @jancold

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Posted by: @jancold

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I have been trying to get my head around what this all means for the battery life? [...]  Are there battery charge settings in the Solis box I could check?  I have reduced the charge to 80A as that easily charges ( according to the Solis)  the batteries in the cheap period and allows a time for them to sit before discharging to the house.

 

 

This query is best answered here @jancold , as it seems many people purchased Solis inverters to use with Seplos batteries. 

I merely used timed discharge periods.

These are set in the "inverter control" menu, you set the start and stop period + the amp level and soc level that will limit the discharging during the time. 

You've answered a different question @batpred 

@jancold is talking about reducing the current towards the end of the charge period.
In the topic you've relocated from, both @upnorthandpersonal and I have stated reasons for doing so:

a: when charging at high current, the SoC will appear to be artificially high. It is not a good indicator that the battery is full.

b: Since the cells haven't actually approached their full capacity, the BMS may not have entered the stage at which it performs cell balancing.
That will perpetually leave the battery in the state where one or more cells have higher voltage than others, which can adversely affect battery lifetime.

Your answer relates to something you're configuring whilst the battery is discharging.

@transparent 

I thought it is clear enough and helpful to @jancold and others. I saw the limitations of the timed discharge periods, they are actually exactly the same for charge periods. This is all that can be set:

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

I found the discharge periods to not work perfectly for my use case and tariffs.

But for charging, I could just just break down the last charging slot with the one before the last having an soc lower than 100 and the last with a very low amp level like 40 and soc 100. 

If I get around to it, I may use the HA modbus integration to do this and beyond but probably not worth it.

Every brand of batteries and bms from Fogstar has their own specific specs with recommended max charge levels, etc. 

Solis AI would potentially do the breakdown into various timed slots automatically, according to the sales spiel. But as the implementation is not auditable, stratospheric levels of spiel could be reached.. The support folk approach raised more questions. But since the product seemed to be in continuous development, I would not want that to deter anyone from trying it..

From my observations the Seplos V3 BMS that comes in the Fogstar Seplos units ramps down the charge rate as it approaches capacity.

This leaves plenty of time for the cells to balance.

Mine are perfectly balanced at 3.600v

Just make sure you have the JK Active balancer in yours as the Seplos one supplied in the past aren't good at balancing the cells (actually quite bad).

I replaced the Seplos Active balancer to a JK 2A (that Fogstar now fit in the current batteries).

Fogstar were great in supplying me the JK Active balancer and cable for a nominal amount and it was easy to change.

Posted by: @bash

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From my observations the Seplos V3 BMS that comes in the Fogstar Seplos units ramps down the charge rate as it approaches capacity.

My graph shows a straight red line when charging to 100%, so it is not doing that:

Posted by: @batpred

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But for charging, I could just just break down the last charging slot with the one before the last having an soc lower than 100 and the last with a very low amp level like 40 and soc 100.

I do a lot of monitoring on this issue, and I'll suggest that 40A is still too high to bring the cells up to the intended capacity.
The reported SoC will be erroneous due to the voltage rise of driving 40A into the battery.

I currently decrease the charge current at 1-minute intervals down to no more than 5A (per battery).

Posted by: @transparent

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I currently decrease the charge current at 1-minute intervals down to no more than 5A (per battery).

Thanks, does that leverage anything from your inverter and not available on the Solis?

I am wondering if tuning the JK balancer that Fogstar included could make a difference regarding cell voltage imbalance. In my case, the imbalance is stable but reduces during significant charging and discharging periods. 

Posted by: @batpred

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Thanks, does that leverage anything from your inverter and not available on the Solis?

I don't know about Solis inverters.

It isn't a feature on Growatt inverters, and I haven't found it on SunSynk.

I've only had charge-current reduction operating via an external controller (connected to the inverters using Modbus over RS485).

Posted by: @batpred

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I am wondering if tuning the JK balancer that Fogstar included could make a difference regarding cell voltage imbalance.

Very likely.... because JK BMS units can cater for a range of different cell chemistries.

Use the JiKong App to connect to the BMS.

Look for a parameter which sets the voltage level at which cell balancing will start to operate.

Posted by: @transparent

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It isn't a feature on Growatt inverters, and I haven't found it on SunSynk.

I've only had charge-current reduction operating via an external controller (connected to the inverters using Modbus over RS485).

Just to wrap this up here for future readers:

• The Solis S6 like other inverters is also not able to use set periods to gradually slow down the charging when approaching 100 soc.
• Fogstar confirmed that the Seplos v3 BMS also cannot do this  
• I have however found that splitting the last charging period on the Solis (to have one with a very low amp setting and aiming to get to 100 soc) is an effective way to charge the cells to close to maximum

Posted by: @batpred

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Posted by: @transparent

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It isn't a feature on Growatt inverters, and I haven't found it on SunSynk.

I've only had charge-current reduction operating via an external controller (connected to the inverters using Modbus over RS485).

Just to wrap this up here for future readers:

• The Solis S6 like other inverters is also not able to use set periods to gradually slow down the charging when approaching 100 soc.
• Fogstar confirmed that the Seplos v3 BMS also cannot do this  
• I have however found that splitting the last charging period on the Solis (to have one with a very low amp setting and aiming to get to 100 soc) is an effective way to charge the cells to close to maximum

 

Just to provide some alternative feedback to balance this out.

My observations owning 3 Fogstar Seplos V3 BMS kits is that the Seplos BMS does ramp the charge rate down when the pack nears full capacity and was able to beautifully top balance my 3 packs at 3.600V with a deviation of 3mV (the lowest setting available with the JK Active Balancer).

So trying to force the Solis inverter to do this is likely to be unnecessary.

@batpred So that's it then? Its all wrapped up for future readers! No more discussion needed? I'll toddle off. 😀

@jancold I only discuss data.. Fogstar were not impressed.. 😉 

Do you have any data from the pace BMS or Solis AI to share with us? If possible daytime data.. 😀

I have been looking into that for other reasons and it seems they now switched to using pace BMS.. 

@batpred 

I reckon Andy might know a thing or 2 about this subject.