Lithium retailer

Plucka

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.

mike95490

That's Big Problem #2 for Li batteries.  Junk BMS.  Every company builds differently, data commands are all different, and circuit design to standard 10% tolerances is questionable. Reliability goes down as complexity goes up.   Vampire Bleeder board failures have ruined many cells .   Is a simple vampire board, a BMS ?  Depends on who you buy it from !

Plucka

Hi Simon , I bought the BMS from him and that is what failed nothing else failed .Its red light started flashing ,my solar controller was saying the batteries were full when they weren't and the red light went out all in a period of less than one minute.Bought a new BMS plugged it in and every thing worked fine.Don't know what a battery control unit is ,if it is the solar control unit  ,I didn't buy it from him and the cell modules came with the batteries and are all fine-green lights on.

karrak

Is the BMS a BCU-PPAK looking something like this, and if so was it this module that was replaced? The battery control unit I was talking about is part of another BMS that EVPower sells.

Plucka

Yes that's it but the box is solid white and has + 4c on the label.

karrak

Well, if this is the BMS there is no way there could be "an overvoltage event" as the BMS is only connected to the battery and should disconnect the battery before any overvoltage event could occur.

When the red light started flashing on the BCU what was the colour of the lights on the boards connected across the battery terminals?

Simon

Plucka

I don;t know at that precise time but they were all green before and after I installed the new BCU

Plucka

I do not know the colour at that precise moment but before and after I installed the replacement BCU they were all green.The batteries are contained out of sight in an aluminium box.

Plucka

karrak

From the information you have provided I would say that a fault developed in the BCU which initially made it think that one or more of the cells in the battery had gone outside its safe operating voltage range  and disconnected the battery from the Charge Controller and activated the red flashing light. Shortly thereafter the BCU died completely which left the battery disconnected. With no battery connected to the Charge controller the output voltage of the charge controller would have risen to the programmed bulk/CV voltage and the charge current would have gone to zero making the charge controller think that the battery was full.

Although it is hard to say for sure without seeing the damaged BCU, I would hazard a guess that the fault was likely in the power supply in the BCU that supplies power to the BCU electronics from the battery.

I can't see how you could be responsible unless you disconnected the BCU and connecting it up to a voltage much higher than the battery voltage or reversed the polarity. If the BCU was well designed doing this should not damage it.

The one saving grace is that the BCU failed safely.

Simon

Plucka

That thin red wire is not tight it just appears to be and it is for a 12 volt fuel pump as is the green wire.The lithium system is not connected to the van's chassis. I didnt touch it -the red light flashing caught my attention-it had been running fine up till then.Thanks for your help.

Plucka

New BCU tripped out today for no apparent reason .I switched it on again and and it seems to be okay. -I checked all the wiring nothing was warm and green lights were all on on the batteries and they were 13.6 volts with 28 amps charging.The temperature leads from my solar controllers won't reach to the batteries area .The batteries are about 18C to 20C but where the temperature pickups are it's 34 degrees --is that a problem .

Dave Angelini

Are you doing arc welding? Do you have surge protection in your system? Is there lightning? Are you connected to the grid? Is everything single point ground? The temp 34 should not do this. Why there is there such a difference is pretty weird?

These are all things that can cause unexplained failure of electronics that are past the infant failure stage.

Plucka

No arc welding - the bcu is suppose to have over voltage protection - not connected to the grid - everything is grounded.The temperature difference is caused by the 34c being inside the old caravan which does not have insulation and the 20c is because the batteries are under the van and insulated from the heat but the temperature pickups won't reach the batteries so the solar controllers only read the temperature in the van.