Morning All,

With loadshedding back one needs to be aware of the times when there is no solar (like the crappy weather in Gauteng this week) or the grid is not available to charge your battery in preparation for the pending blackout.

Just wanted to check the understanding regarding the option to tick Grid Charge in the Work Mode Timer screen. If the Grid Charge is ticked, then the battery will charge from grid if the solar is not able to do so? Or, does Grid Charge completely over rule the solar and not even a few watts of solar are used?

Thanks,

MdF

If you tick grid charge on the work mode screen , make sure you also have grid charge ticked under the battery charge screen. AFAIK solar will always be used before grid if it is available,or a combination of the two to get to your set SOC.

Edited October 26, 20214 yr by Nexuss

So I have enabled Grid Charge and below is what the system has been doing to the battery for the past half hour or so.

Is this acceptable with the change so much between battery charge and battery usage to keep the battery at 95% SoC?

Seems normal , 95% is quite high soc to keep for in case loadshits happens? do you need that much battery for a loadshed? ive determined i use about only 40% of my 7kwh battery so i generally just make sure i stay above 60% soc in the evening then down to 10% in the morning ,so even unexpected loadshits dont affect me .

Thanks Nexus,

Ja, I rather err on the side of caution as I only have a single 5kwh battery and want to make sure there is enough power for when the double loadshedd happens during the day and when its overcast and night time.

I have however, pulled the plug today and ordered a 2nd battery to double capacity 🤑. I will then look at reducing SoC as you said.

MdF

On 2021/10/26 at 12:48 PM, MdF said:

I have however, pulled the plug today and ordered a 2nd battery to double capacity 🤑. I will then look at reducing SoC as you said.

So, the second battery was installed about 10 minutes ago. Installed capacity now 10.2kWh but actual usable will be about 8kWh.

Looking forward to not having to use Eskom to recharge the battery during these overcast days when there is only a few hours in-between loadshedding 😀

2 minutes ago, MdF said:

So, the second battery was installed about 10 minutes ago. Installed capacity now 10.2kWh but actual usable will be about 8kWh.

Looking forward to not having to use Eskom to recharge the battery during these overcast days when there is only a few hours in-between loadshedding 😀

You need to change your signature 🤣

9 minutes ago, PowerUser said:

You need to change your signature 🤣

😅😅😅 Done

Really pleased with the way the 2-battery install is going. Have used minimal Grid power since 8pm last night 🤗

Morning All,

Just some feedback on Work Mode timer settings that I have tweaked a bit this past week. Now getting the battery pack down to 45% SoC overnight.

MdF

Interesting thread with lots of useful bits of information.  I'm also trying to maximise the ROI of my batteries and aim to get at least 8kWh per day from the 10.2kWh installation.

There were some tips on maximising LFP battery life earlier - I got this from a mate - no idea what the orginal source is. 

Quote

 

To sum up, for long and happy LFP battery life, in order of importance, you should be mindful of the following:

1. Keep the battery temperature under 45 Centigrade (under 30C if possible) – This is by far the most important!!
2. Keep charge and discharge currents under 0.5C (0.2C preferred)
3. Keep battery temperature above 0 Centigrade when discharging if possible – This, and everything below, is nowhere near as important as the first two
4. Do not cycle below 10% – 15% SOC unless you really need to
5. Do not float the battery at 100% SOC if possible
6. Do not charge to 100% SOC if you do not need it

 

 

Not battery, but another form of energy storage: I use Geyserwise panels to bump the heat on my geysers during peak production to limit grid draw at other times - from 11:00 to 13:00 on the 200L electrical geyser and 14:30 to 16:00 on the 300L solar (dont want to ramp it up too much too early for fear of boiling). It is not super sophisticated but at least I can set this up to work automatically and then monitor the impact - seems to be quite good at eliminating night-time top-ups provided the Geyserwise temperature profile and timers are set correctly.

Edited December 1, 20214 yr by Scubadude

6 minutes ago, Scubadude said:

There were some tips on maximising LFP battery life earlier - I got this from a mate - no idea what the orginal source is. 

Thanks for the tips. Makes for interesting reading. Always on a learning curve with this solar journey so most welcome.

MdF

2 hours ago, MdF said:

Morning All,

Just some feedback on Work Mode timer settings that I have tweaked a bit this past week. Now getting the battery pack down to 45% SoC overnight.

MdF

I have also set my 7KW pylontech pair to about the same. Need the 35-40% reserve if load shedding sneaks up. I think one more 3.5Kw battery to my setup will still keep within the ROI period. Its always good to track grid usage and then weigh that against the purchase cost of another battery and ROI period. In line with battery tips above, my battery never goes beyond 31 degrees. But will monitor over the very hot days still to come. How does one control battery temp other than cool room and possibly aircon in the room? I have also thought of reducing the charge current. Pylontech recommends 0.5C which is half of battery capacity. So this means my 3.5Kw/74AH battery should be charged with a max of 37A from inverter. So perhaps reducing this even further could amount to less heat in the battery.

One question. The screenshot showing times above. Where did you get that from. Are you using solar assistant with a raspberry pi?

Edited December 1, 20214 yr by Vani
adding extra comment

10 minutes ago, Vani said:

In line with battery tips above, my battery never goes beyond 31 degrees. But will monitor over the very hot days still to come. How does one control battery temp other than cool room and possibly aircon in the room?

One question. The screenshot showing times above. Where did you get that from. Are you using solar assistant with a raspberry pi?

Battery temps have only gotten up to 29.4 degrees but will also keep an eye on that. These hot summer days are making the garage a tad warm. I have bought a small usb fan from Goldair for R150 and run that off the Pi from 8am to 11am to keep the inverter cool. Its a manual process at the moment but just want to see the effectiveness of the fan.

Yes, I am using Solar Assistant on the Pi and have been upgraded to the latest software which allows the Power Management function to work.

MdF

 

Edited December 1, 20214 yr by MdF

6 minutes ago, MdF said:

Battery temps have only gotten up to 29.4 degrees but will also keep an eye on that. These hot summer days are making the garage a tad warm. I have bought a small usb fan from Goldair for R150 and run that off the Pi from 8am to 11am to keep the inverter cool. Its a manual process at the moment but just want to see the effectiveness of the fan.

Interesting cooling technique. I have done similar. i have an air purifier which blows upwards. Set it under the inverter so that air passes the heat sink in the back. The air purifier is connected to a SONOFF switch which is wifi enabled and has an app to set timer schedules for on and off. Not sure if cooling the inverter will have an effect on the battery temp or if thats what you were saying. But i am in the process of testing my theory on reducing charging amps. Solar assistant would be better to monitor this experiment as it graphs battery temp throughout the day.

However reducing charging amps may be shooting myself in the foot on days where is frequent change from cloudy to sunny. 

I'll be honest, I am not a fundi when it comes to all the extra stuff that people are doing with Node Red, Home Assistant etc, so I will just get myself a small digital timer switch and plug that into a socket to which the fan will be connected. I will then just run the fan on the timer from 8am to 11am daily.

Sorry yes, I am not sure if the fan will do any cooling to the batteries but its primary use is to cool the inverter down.

I was also thinking about reducing charging amps to reduce battery temperature but if its operating below 30 degrees C during summer then I will leave the settings as is.

MdF

Afternoon All,

So, my system has been running well for the past few months and am happy with what it is doing as it is supposed to be doing just that 🤣

My data shows that on most days the battery never dips below 50% when being used from 8pm to 6am each day.

In this regard, I have thought to get it to move a little below 50% and so I have decided to change the one Time of Use setting from 8pm to 12pm midnight. I am hoping to achieve better discharge to between 45% aand 50%. Would be happy with that so some tweeking over the next few days will be required.

Will keep you posted of what works out for me.

MdF

Personally, i am going down to 30%

I have a time of use from 12am to 6am where i drop from about 45% to 30%. From dusk i have a couple of stepped periods that drop down to 45% by midnight. I want to maximise the solar use and hence drop the Eskom bill.

The 30% to 15% is my buffer for the unforeseen load shedding or general power outage.

Edited February 21, 20224 yr by Vani

53 minutes ago, Vani said:

The 30% to 15% is my buffer for the unforeseen load shedding or general power outage.

That is the trick isn't it. Just how comfortable one feels with your own setup to ensure you have enough in the battery to get through the night AND handle loadshedding should there be an early morning account of it.

Trial and error I say.

MdF

I still don't have solar panels installed with my SunSynk 5kW and Hubble 5.5kWh battery. Who can suggest a good Work Mode configuration to exercise the battery on a daily basis?

I think it really depends on your electricity demand through the day and what SOC (Personal Preference) you would like your battery to have at different parts of the day. Another consideration is how long your battery takes to charge on an average day in your area.

Personally i prefer the above for now. I look at my daily cycle starting at 6:30am because at the moment i am generating about 600W at 6:30am. So from 6:30 to 14:15 the focus is to get the battery charged. Any extra energy will feed whatever is drawing during that time. With load shedding and cloudy days, my battery my not get to 100% SOC, so grid/eskom makes sure that i get to at least 90% by 17:30 to enter into the evening. I then have two 25% discharges from 17:30 to midnight. The last period from midnight to 6:30am i allow the battery to go down to 30% if the load/draw is sufficient during that time. How low you allow your battery to discharge to, is dependent on what kind of buffer you would like for that unforeseen power outage or load shedding. My times may change a bit as we get into the winter months with shorter days.

Remember non-essential loads can also draw from the battery when the grid is still active. It only islands to essential load when there is no eskom/grid detected. This means that the battery can be discharged very quickly if you not thoughtful about your stepping down increments during the evening. Daytime is better as the panels also assist to meet the load demand. 

My system is : 2 X 3.5KW Pylontech AND 10 X 420 W Canadian solar panels and 5KW Sunsynk.

So when my installation was done I found the following article:

https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/

I specifically remembered this section:

"LFP batteries can also last a very long time. Our Battle Born LFP batteries are rated at 3000 cycles, at a full 100% charge/discharge cycle. If you did that every day it makes for over 8 years of cycling! They last even longer when used in less-than-100% cycles, in fact for simplicity you can use a linear relationship: 50% discharge cycles means twice the cycles, 33% discharge cycles and you can reasonably expect three times the cycles."

Is this true? Would exercising your battery accordingly increase the life of the battery?

9 hours ago, Vani said:

I think it really depends on your electricity demand through the day and what SOC (Personal Preference) you would like your battery to have at different parts of the day. Another consideration is how long your battery takes to charge on an average day in your area.

Personally i prefer the above for now. I look at my daily cycle starting at 6:30am because at the moment i am generating about 600W at 6:30am. So from 6:30 to 14:15 the focus is to get the battery charged. Any extra energy will feed whatever is drawing during that time. With load shedding and cloudy days, my battery my not get to 100% SOC, so grid/eskom makes sure that i get to at least 90% by 17:30 to enter into the evening. I then have two 25% discharges from 17:30 to midnight. The last period from midnight to 6:30am i allow the battery to go down to 30% if the load/draw is sufficient during that time. How low you allow your battery to discharge to, is dependent on what kind of buffer you would like for that unforeseen power outage or load shedding. My times may change a bit as we get into the winter months with shorter days.

Remember non-essential loads can also draw from the battery when the grid is still active. It only islands to essential load when there is no eskom/grid detected. This means that the battery can be discharged very quickly if you not thoughtful about your stepping down increments during the evening. Daytime is better as the panels also assist to meet the load demand. 

My system is : 2 X 3.5KW Pylontech AND 10 X 420 W Canadian solar panels and 5KW Sunsynk.

You have panels. In my case, I still don't have panels and simply looking at suggestions for settings, just to exercise the battery daily.

1 hour ago, PowerUser said:

You have panels. In my case, I still don't have panels and simply looking at suggestions for settings, just to exercise the battery daily.

Apologies. I assumed you were going to add panels soon. You can still work out your own preference for exercising. In your case, without panels, i assume the primary and only purpose of your batteries is backup. You can probably allow the battery to discharge down to about 50 or 40% during the day and from about 3pm charge backup up to 100% before the evening as most people would want 100%, going into night time.

In my case the panels charge my batteries during the day and this extra energy is discharged in the night. Indirectly, I am able to use solar power in the night as well. So the purpose of my system is backup and reduction of Eskom bill. 

You should consider panels at some stage and allow the system to pay for itself albeit over a period of time.

Edited February 22, 20224 yr by Vani

1 hour ago, RyC said:

So when my installation was done I found the following article:

https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/

I specifically remembered this section:

"LFP batteries can also last a very long time. Our Battle Born LFP batteries are rated at 3000 cycles, at a full 100% charge/discharge cycle. If you did that every day it makes for over 8 years of cycling! They last even longer when used in less-than-100% cycles, in fact for simplicity you can use a linear relationship: 50% discharge cycles means twice the cycles, 33% discharge cycles and you can reasonably expect three times the cycles."

Is this true? Would exercising your battery accordingly increase the life of the battery?

My cursory research on lithium exercising, shows that holding lithium at 100% for too long periods of time does degrade the battery faster. In addition to exercising one has to consider max amp discharge and max amp charge. While the batteries can handle very high amperage in terms of charge and discharge, this can create heat and batteries tend to deteriorate faster when going beyond their "threshold" heat specs. Generally battery manuals have some specs on max charge and discharge and i prefer to set my sunsynk a little below the charge/discharge values.

https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries