Chris_H

I doubt it, Hubble sell the cable themselves or you can get it here:

https://www.voltex.co.za/product/hubble-cable-rs232-to-usb-cable01/?srsltid=AfmBOoqnq68lCG5v-xO_4rYtWHpYuS-F84xcoHYAjMqToO7KBREnF7-6

I live around the corner from Hubble so just picked up a cable from their offices, maybe they can ship one to you?

Sunsynk 12kW 3 phase
Updated very early this morning, didn't even notice other than I could tell from some appliances that power had cycled at some point. (update happened about 6-8 hours after I requested it, I didn't touch the inverter before, just left it running, it did seem to reboot though).
 
SW Ver.：M 2005-1140 / S  18-07 / C 1001-E037
 
PSA
I know this has been posted before but it bears repeating:
to update go to
https://sunsynk.freshdesk.com/support/home
Register
Log a support ticket for the firmware upgrade and provide them with your inverter serial and your wifi gateway (dongle) serial.
Both can be obtained from SunSynk Connect at https://sunsynk.net/plants  under "equipment"
Alternatively the serial number for my gateway was on the physical dongle sticking out of the inverter.

@Charl Yazbek the geyser being a 10kw battery is exactly why it's such a good option to use excess pv. The geyser is already there. A new solar geyser or a pv conversion means additional investment which is not necessary since most people already have excess pv production.
If grid feed in was more incentivized then it would make sense to invest solar geysers and feed into the grid all day. Currently the geyser is the best place to dump pv when the batteries are full.

yes the reduction in battery AH capacity was as a result of the battery firmware upgrade.

The XH-M-609 will work for you. At the lower stop discharging a relay will be de-energized. A N/C contact from a relay driven by the output will then give power to your buzzer. The moment the battery voltage picks up the relay will be energized and your buzzer will be off. Optionally you can add your own on/off switch once you hear the buzzer. Disadvantage is if you forget to switch it on again. 
Here is a basic circuit that you might try as well. At times one will need a zener in series with R3 as the off state can have a output of a few volts. 
This is how I remember it of very long ago. May be our electronic guys can add feedback and filtering and correct errors. 

@BritishRacingGreen

I got it through eBucks. They had it on 40% discount a few weeks back.
https://www.ebucks.com/web/shop/productSelected.do?prodId=2056532378&catId=854105660

hi Modina, thank your for the detailed response.  Although my system is AC, the inverter has a fairly good efficiency of 90%, compared to some of these backup trolleys with inverters that has as low as 60% efficiency, the downside to a DC only system is you cut out your AC devices for utilising it, as well has the complexity of having to cater for different DC voltages.
MY main selling point is having batteries with 3000+ cycles compared to the Ecoflow/Gizzu's etc you looking at 500 to 1000 Cycles. Mine is modular so you can easily upgrade or replace components. When these other small fancy boxes fail after warranty period you sitting with a big door stop.

Most people, especially end users, have barely a grasp what an inverter is, let alone understand that these devices are not very efficient.  20 to 50W idle consumption is not uncommon.  So to put this in context, if the end-user wants to run a laptop and a WiFi router, then it means the the inverter can self-consume as much precious battery power than the required load.  This is a frightening thought, considering the expense of the batteries.

The above reason is why am so against inverter use.  There are many, many instances where an inverter is not warranted.  The problem is that nobody provides inverter-less solutions, and yes, there are some hurdles to overcome.  Sadly, there is no plug and play solution.

@Chris_h, I would like to refer to your Juicebox as an ACJuiceBox.  At R8750 it is very good value, I think your margin must be quite small.  There are many commercial products that offer similar performance.  Many use Lead Acid batteries which is obviously not ideal.  I propose that you, or someone else that has the time and wants to fill a gap in the market, makes a DCJuiceBox.  I have yet to see such a product.

The DCJuiceBox would be similarly packaged but would NOT come with an inverter.  Instead, you would mount two Boost regulators that are pre-set to output 19VDC.  (These typically cost R100 each.) You would also include two cigarette lighter sockets for raw battery voltage and some high current USB sockets.  Individual outputs should be switchable (so as to reduce quiescent current consumption further, by turning off circuits that are not required).  Cheap and readily available car fuses should be used to protect the 12VDC outputs and also the various regulators.

Most laptops run from 19VDC.  Many PC monitors as well as miniPCs also use 19VDC.  And a few 32" and smaller TVs (Samsung for instance) run from 19VDC.   More and more electronics make use of USB chargers and you can get 3W and 6W 12V spot-lights.  Set-top boxes and routers are normally rated for 12VDC as well.  Yes, a charging battery can go up to 14.5VDC, it ***SHOULD*** not be a problem but one cannot say with 100%.  I personally would not hesitate to power a set-top box from say 13.5VDC as they all use further switching regulators.  To be on the save side, one could add 2 or 3 silicon diodes in series with the output.  In charging mode, these diodes are left in circuit, when the charger is done, a relay could short-circuit the dropping diodes.  Or one could forgo the power loss and leave one or two diodes permanently in series.  Still better would be some voltage monitor that could switch a relay or MOSFET, but that would add some cost and might not be so easy to source.

A DCJuiceBox is certainly not for everyone but it would be good to have such an option available, at least for those user that are a bit tech savvy.  The cost savings on the inverter, battery savings or longer run-times (when using same batteries) and silent (fan-less) operation are all huge advantages.

I needed to find a solution for my parents and mother in law to watch tv and run Wi-Fi etc. during 4 hours continuous load shedding.
Built 2 system 9 months ago in a plastic utility "ammo" box and works very well, their friends and my people at work asking me to build for them to , so "JuiceBox" started.
350W pure sine wave inverter, 640wh Lithium battery and 7ah Victron lithium capable charger.
Here's my FB page, I sell them for R8750 each and can ship anywhere in SA.
 
https://www.facebook.com/JuiceBoxSA
2 page Brochure.pdf

The life4po battery you want to charge i assume have an BMS? or what brand is the battery?
 
I think as Scorp007 suggested , any solar charge controller that you can set the bulk/absorption voltages should work. The voltage relay should also do the same job.
 
Cheapest i would say a 18V-24V power supply connected to the mppt/pwm input of solar charge controller. Connect battery to output. Set the voltages or select the lithium option. Fine tune the voltages by measuring the amps drawn , when bms switches off the internal charging. to get close to 100 percent SOC.  Or any comment why this wont work?
my opinion taken the temp coefficient of life4po you actually do not want to charge the battery to full/100 percent to reduce the chance of over voltage or ddamaging the battery if the ambient temp rises, but this is my humble opinion. The amount risk of damaging the battery  vs capacity you loose i would say charge battery to less than 100 percent and stop.
 
https://www.power-sonic.com/blog/how-to-charge-lithium-iron-phosphate-lifepo4-batteries/
 
also ,
 
What are the proper charging voltages for the 12V, 24V, and 48V lithium batteries?
Our Battle Born Battery charging parameters consist of the following: 
Bulk/absorb = 14.2V–14.6V.  Float = 13.6V or lower.  No equalization (or set it to 14.4V if possible).  No temperature compensation.  Absorption time is approximately 20 minutes per battery, if possible. For a 12V system, we really want to emphasize reaching 14.2V – 14.6V for bulk and absorption and float to be 13.6V or lower. 
For a 24V system, we suggest a bulk and absorption rate of 28.4V– 29.2V and float to 27.2V or lower. No equalization is required, but if it’s possible we suggest 28.8V. No temperature compensation is required either, and absorption time is approximately 20 minutes per battery if that is an option.  
For a 48V system, we recommend a bulk and absorption rate of 57.4V and floating it at 56.5V to 57V. Sometimes, one of the batteries may trigger a high voltage disconnect in your system. The battery’s internal BMS will help handle a high voltage disconnect. Our team wants to emphasize that, overall, there’s no harm in playing around with charge rates to optimize your system.  

None. Their approach goes like "its a trade secret".

Our 12kw Sunsynk is in a cupboard and does not get past 33 degrees. Made ventilation holes in top of cupboard for air to escape into celing and vents at bottom of cupboard doors to suck in cooler air. Cupboard is inside house so much cooler than say our garage. 
I guess our inverter runs cooler as it does not work close to it's max capacity. Also in the cupboard are 3 hubble batteries 
I attached 2 fotos
 

Our 12kw Sunsynk is in a cupboard and does not get past 33 degrees. Made ventilation holes in top of cupboard for air to escape into celing and vents at bottom of cupboard doors to suck in cooler air. Cupboard is inside house so much cooler than say our garage. 
I guess our inverter runs cooler as it does not work close to it's max capacity. Also in the cupboard are 3 hubble batteries 
I attached 2 fotos
 

Our 12kw Sunsynk is in a cupboard and does not get past 33 degrees. Made ventilation holes in top of cupboard for air to escape into celing and vents at bottom of cupboard doors to suck in cooler air. Cupboard is inside house so much cooler than say our garage. 
I guess our inverter runs cooler as it does not work close to it's max capacity. Also in the cupboard are 3 hubble batteries 
I attached 2 fotos
 

Press the screen on the dials .. press grid

Thanks guys, my cupboard is very similar to Chris_H so that might work perfectly. Thanks guys for all the info.

Our 12kw Sunsynk is in a cupboard and does not get past 33 degrees. Made ventilation holes in top of cupboard for air to escape into celing and vents at bottom of cupboard doors to suck in cooler air. Cupboard is inside house so much cooler than say our garage. 
I guess our inverter runs cooler as it does not work close to it's max capacity. Also in the cupboard are 3 hubble batteries 
I attached 2 fotos