My lithium battery management BCU [ I think everybody else calls it a BMS ] suddenly died . In a panic I rang the company here in Western Australia and they said I'd have to send the unit back to them for them to look at and the boss would ring me back that day so I said send me a new one because it clearly says don't charge the batteries without one .They shipped me a new unit immediately express post which took 5 days for me to receive because they spelt my name and post code wrong [ illegible writing was the problem ].Plugged the new one in and everything up and working perfect so I posted the faulty one back with a tracking number for repair. Still no response from the company owner so I emailed him and he then emailed me back that he needs to see the old unit [ 4 months old ] and I hadn't filled out a return paperwork before sending it back.Tracking said they received it and 5 days later after hearing nothing i emailed them and the response was " busy sorry" we are looking at it now and trying to figure out what had happened to it .I wasn't interested in what had happened to it I just wanted a replacement as I was travelling and didn't want to hang around an outback post office in WA for days . Finally after many requests for more information and photos of my setup they are sending the repaired on back under warranty with a message that fault was due to and "over voltage event" and if it happens again there would be no warranty .Their specs clearly say unit has " over voltage protection ".As it turned out I believe they just replaced the $5 circuit board and took nearly 4 weeks [ 27 days ] to do so when they could have just sent me the board . Spent nearly $3500 with that company have been recommending them to other travellers but never again.Just a bad experience where retailer set out to fix his problem first rather than the customers.