JasonS

Thanks so much

I don't think @Steve87 meant physically taking the batteries back to the supplier, but rather take the issue with firmware upgrade back to the supplier.
Maybe contact Sunsynk CEO and let him sort it out.

The High Voltage 50kW Commercial machine also has some very peculiar behaviour. The most unfortunate of that machine is that because a lot of installers got good confidence with the other models that they think that this HV model is the same old piece of takkie. Stand alone also not bad. But when you start to parallel units with not the same battery Bus then this is where I get lost. 
So they in parallel & get Comms but they don't share the same Battery DC bus. 
Further to the mess, there are 2 Battery ports. Each takes 50A & they need battery cables in both ports to unlock the 100A rating. With 2 BMS ports in case you have 2 different batteries. 
Now that is a mouth full & a mess. What could possibly go wrong here with this arrangement....
@WannabeSolarSparkyI have to agree with you, they should stick to what they know well: LV 48V Hybrid inverters. Leave the Lithium battery manufacturers & HV commercial manufacturing to manufactures that have that as their core business. 
Not to mention the idea that these are HF in architecture. So transformerless. That works very well in the residential market. But when you start playing with heavy Capacitive, Inductive & Resistive loads found in the Commercial gamespace & don't have a LF Transformer design, then you are taking risks. 
Victron is so robust & rugged for that very reason: Transformer based. Only draw back they never evolved to HV. 
ATESS has taken that big step forward. Transformer based, HV & built like an antique toaster. Serviceable in the field. Not a box that needs to be taken in & wait for 6 weeks while they decide on what is wrong. 

Age old problem, become a well recognised brand with a very good product.
Then spoil it by trying to get in to selling other related products under the same brand.
Not many companies can pull that off correctly.

Guys I'm really sorry to admit that this sort of sour treatment is becoming more & more common. I belong to a Sunsynk support group and there is endless issues with their batteries. Stand alone battery no problems because you only have single firmware. However, when you have more than 1 you have the fun and games. It's easy to flash new firmware on an inverter, there is Logger that can do that & remotely so. The batteries & now that's a whole can of worms. 
So many ppl jumping at the warranty extension...great but what's the point when they cant even support in the way of a miserly firmware update. 
A recent visit to their facility for an RMA totally unrelated had me asking the question once again: Are these guys really worth the hype? The honeymoon is over...

You'll be fine, I usually just use red or black insulation tape just to mark the + and -. Most of the regulatory stipulations are around the cable width, how the cable core is made etc. So for PV, you just need to use cable that can easily handle your max PV current and it is recommended that you use a cable with loads of thin strands at its core. Its the same kind of cable used for welding, car jumpers and other high current applications. (It has something to do with how heat and losses work for these cables over a cable with a handful of thick copper strands.

Thanks so much Jacques.