cam083gp

Well I cannot find anything, except inverters. To be fair, there are more sunsynk issues on here than fivestar.
People tend to only post negatives to get support, never positives unless asked for. Ergo this thread.

Hi @freakoid9000,
Did you check for custom settings for the battery? My budget 2.2kva inverter has a lithium setting which offers an additional display but does not have the same voltage settings as my lithium battery so I just use the custom setting that sets the max, float & cut-off voltage to what my battery states it's good for.

I'm currently using it as a UPS & the transfer time from grid to battery has been sufficient enough so I was hoping that the overload bypass would be good enough for me to connect it straight to the db board so that there's never an issue while the grid is available but I know now that it's not feasible...bigger inverter required.

It's a clone, so practically all hope of a high rated relay are gone. But you proved that with your 2 kW load test.

Sadly, they typically rate the internal changeover relay to about the same as the maximum output of the inverter.
So if it's a 1.8 kW rated unit, at say 2.0 kW it will soon end up stopped with an overload fault code and no output.
I know that's now what you would want, but it's cheaper that way.
Even 5 kVA models with 40 A relays behave that way;  they don't let you get close to the 40 A that the relays are supposed to be rated for. 40 A at 220 V is 8.8 kVA, which would be a nice overload capability. I think it's because it's cheaper to use PCB tracks than to wire the relays properly with bus bars or actual copper wire and crimped connectors.

Depending on the inverter but I doubt it. 
What is the inverter model?

So with 2 batteries in parallel where a busbar is not being used then a single fuse would be fine I imagine as you would only have 2 cables coming from the batteries (Positive & Negative).

 
 
If you were to connect batteries to a busbar, then each battery would require a fuse between the battery & busbar.

My only thought and don't know your circumstance is it always worth doing agood job and keeping it tidy, although you may be comfortable with a relaxed diy setup it can look and be safer for others if you spend a little more time.
As you sugest some conduit and wall plugs would be a good step towards a better system. 

Waiiiit.   RJ45 - Once a standard for cat 5 Network communication. Then adding Power over ethernet added, Now rs232 then RS485 then Can-Bus then remote switching, then combinations of RS232/RS485/Canbus and seeing positive +12V and or +5v . all in a 8 wire termination.
And I still dont understand Earting (1 wire) on a DC system

May I sugest just making one.
Crimps are cheap cable even cheaper.
Lots of wiring diagrams for different inverters and lots of help here.
There is not much you can do wrong with a data cable it works or it doesn't work if common sence used.

So...
I ended up getting a Inkwenkwezi pure sine wave 12v 2.2kva (1800w) inverter & in my searches for a 12v lithium battery, I stumbled across a new, unbranded 12v 100ah lithium Lifepo4 battery on Facebook Marketplace that i've been testing over the last few days. The battery looks exactly like the HALO S100 12.8V 1.2KWh with the exact same technical specifications.
Still trying to figure out the best settings to use before I get a professional installer (with COC) to wire it up to my db board (minus geyser & Kitchen plugs)
The lithium setting on my inverter has a fixed "Bulk charge" of 14.1v & low dc cut-off of 10.5v but my lithium battery has an "Equalized Voltage" of 14.4v & low dc cut-off of 11.2v so i've opted for the custom user setting at the expense of losing the additional lithium display that is available when selecting Lithium battery option. I also don't know what to set the float voltage at so I just left it at the default of 13.5v until I can figure it out...I don't want to only have 11.2v - 13.5v usable as it seems like a waste based on what's available to use Cost so far is R4 915
Thanks @Scorp007, @meetyg, @TaliaB, @Bobster. & @PsyCLown for the advice/guidance so far, it's been a joy learning from all of you!

So...
I ended up getting a Inkwenkwezi pure sine wave 12v 2.2kva (1800w) inverter & in my searches for a 12v lithium battery, I stumbled across a new, unbranded 12v 100ah lithium Lifepo4 battery on Facebook Marketplace that i've been testing over the last few days. The battery looks exactly like the HALO S100 12.8V 1.2KWh with the exact same technical specifications.
Still trying to figure out the best settings to use before I get a professional installer (with COC) to wire it up to my db board (minus geyser & Kitchen plugs)
The lithium setting on my inverter has a fixed "Bulk charge" of 14.1v & low dc cut-off of 10.5v but my lithium battery has an "Equalized Voltage" of 14.4v & low dc cut-off of 11.2v so i've opted for the custom user setting at the expense of losing the additional lithium display that is available when selecting Lithium battery option. I also don't know what to set the float voltage at so I just left it at the default of 13.5v until I can figure it out...I don't want to only have 11.2v - 13.5v usable as it seems like a waste based on what's available to use Cost so far is R4 915
Thanks @Scorp007, @meetyg, @TaliaB, @Bobster. & @PsyCLown for the advice/guidance so far, it's been a joy learning from all of you!

Nice and not a bad price at all, how much was that battery from Facebook?
This should help you with the voltage settings, provided it is a LiFePO4 battery:
 

So...
I ended up getting a Inkwenkwezi pure sine wave 12v 2.2kva (1800w) inverter & in my searches for a 12v lithium battery, I stumbled across a new, unbranded 12v 100ah lithium Lifepo4 battery on Facebook Marketplace that i've been testing over the last few days. The battery looks exactly like the HALO S100 12.8V 1.2KWh with the exact same technical specifications.
Still trying to figure out the best settings to use before I get a professional installer (with COC) to wire it up to my db board (minus geyser & Kitchen plugs)
The lithium setting on my inverter has a fixed "Bulk charge" of 14.1v & low dc cut-off of 10.5v but my lithium battery has an "Equalized Voltage" of 14.4v & low dc cut-off of 11.2v so i've opted for the custom user setting at the expense of losing the additional lithium display that is available when selecting Lithium battery option. I also don't know what to set the float voltage at so I just left it at the default of 13.5v until I can figure it out...I don't want to only have 11.2v - 13.5v usable as it seems like a waste based on what's available to use Cost so far is R4 915
Thanks @Scorp007, @meetyg, @TaliaB, @Bobster. & @PsyCLown for the advice/guidance so far, it's been a joy learning from all of you!

They might have been re-branded as i used them in a ups system to keep desktop pc's running matured lady giving math classes to scholars. They still going strong didn't have any complaints since day 1 now 1 year later.

I would not go for an Nenergy battery, someone I know has 2 of the 48v 5KWH units and he has issues with them dropping SoC rapidly and not acting how they should or performing consistently.

@cam083gp The Solarix Nenergy 12V 100Ah LiFePo4 Single Battery Module contains new Li-ion prismatic cells rated by supplier as 0.2C(20 amps) charge current and 0.5C(50 amps) discharge current. Also be aware that there is no communication port on these batteries. I would rather try and get 1C discharge and 0.5C charge like the Raystech or Linergy they will serve you better little bit more pricey but worth it.
https://acdirect.co.za/product/raystech-12-8v-100ah-lithium-ion-battery-rt-1280s-pro/?sfdr_ptcid=22117_617_697150844&sfdr_hash=f979b5b1abc688c955267360d0afd9f1&gclid=Cj0KCQjw9MCnBhCYARIsAB1WQVVQP0Rm_s5m_Oa2Jkn22pwvFWgVEnGn033_OD4oyu05121a5u5YCgoaAp-REALw_wcB
https://www.livestainable.co.za/product/linergy-12-8v-100ah-lifepo4/?gclid=Cj0KCQjw9MCnBhCYARIsAB1WQVUDRuELhjhl2LCkFJCdx7tHsLkoenidEQkPCOxI5EldECEh2IrRbGMaAhejEALw_wcB
 

Only OK if you are going to limit your 3.5kW inverter to never use more than 600W or charge at a higher rate than 20A.
It leaves you R600 for the inverter? 

12v 1280wh lfp battery is 6k for better quality 8k.

Thanks, this is some very useful information for me👍🏼Not so worried about higher stages of load shedding, have a generator for that...In terms of cables, I will use the best ones available for the maximum possible draw of the inverter as they will be short because the installation is close to a plug point & the wall mount battery will be mounted close as well...same goes for the fuse between battery & inverter I.e. highest required fuse that will prevent damage either way. Do I need a fuse between the 3 pin plug & inverter for protection in case of a surge too?
I assumed that the AVR & sub would be a step too far but I will only add that if there is enough headroom...if not, I will just have to rewire my setup to use tv speakers...also, no class d in my audio chain, only AB so no efficiency there

Sorry for the late reply.
Just for some reference, here is a good explanation:
https://samlexamerica.com/differences-modified-sine-pure-sine-wave-power-inverters/

No for lead acid and constant charging 13.5V would be fine to extend life but even lead acids need to be fully charged on a regular basis. 
Charging a lithium only to 13.5V you might end up with only about 70% capacity. Quite a waste to not be able to use 30%. Also this level will have a big effect on the time taken to recharge. 
Charging at say 10A @ 13V you only putting back 520Wh in 4 hrs. If you used more than this during LS then you have less power for the next LS cycle. After a few days your battery has very little to provide power to loads. 

Sorry i deleted previous post to much info🫣Basically lfp charge cc/cv charge regime 14.4 to 14.6v.   Cv after reaching the target voltage the charger maintains a constant voltage between 14.4 and 14.6v while decreasing the current until very little current flow indicating the battery is fully charged.
 
       

Just Google some spec sheets on 12V lithium and refer to the charge voltage for Hubble, Revov and some other known makes. 
May be consider your budget to over the indicated R10th level. 

It looks OK but try and get a manual before you buy. The DC for charging from AC given as 13.5V looks a bit low for charging lithium. Check in the manual that it can be set to at least 14.2V.