rudydevolder
New Member
- Joined
- Jul 15, 2020
- Messages
- 18
Hi to you all, I'm decided, I'll trow all my Daly BMS-es in the garbage bin. ?
I started to hate them after I broke 2 of them because I disconnected them in the wrong way to test and swap to the other again, I should have known better to disconnect the “-“ to the battery as last, but I was already tired and fed up with the extremely bad translated incomplete manuals, the mistakes they made in my order, wrong documentation about the connections and not standardizing their own connectors for UART and CAN-Bus between their different models. I opened up 1 Daly BMS to look what’s under the hood, looks very nice at the outside, inside the electronics are terrible oversimple. I didn't noticed at first they only balance 30mA. I had too much trust in them because Will Prowse really advised them as good quality. In my application I think 30mA is really way too low. And actually selling a 400 Amp BMS that does only a balancing current of 30mA sounds a bit silly, no?
I had a ARGHH moment again!!!
That was my moment I decided, NO WAY!!! Go to hell! I didn't said it that way, but that was my feeling, I think you understand.
At 2 o'clock after midnight I was thinking it's better to design my own BMS. I don't like expensive systems that are like a black box and you don't know whats inside. So I started searching for a good Chip from TI or so that is specialized in BMS and also some open source BMS's. Bad for my high blood but I couldn't sleep before I found something interesting enough so I started searching and browsing the internet.
To be continued....
I started to hate them after I broke 2 of them because I disconnected them in the wrong way to test and swap to the other again, I should have known better to disconnect the “-“ to the battery as last, but I was already tired and fed up with the extremely bad translated incomplete manuals, the mistakes they made in my order, wrong documentation about the connections and not standardizing their own connectors for UART and CAN-Bus between their different models. I opened up 1 Daly BMS to look what’s under the hood, looks very nice at the outside, inside the electronics are terrible oversimple. I didn't noticed at first they only balance 30mA. I had too much trust in them because Will Prowse really advised them as good quality. In my application I think 30mA is really way too low. And actually selling a 400 Amp BMS that does only a balancing current of 30mA sounds a bit silly, no?
- The higher the main-current the higher the balancing current should be. It seems ALL their BMS's are 30mA balancing current only. Ranging from their 20 amp models to 400 Amps, ridiculous. Sometimes I draw 200 Amps for several minutes for my cable-cart motors, I didn't test yet on my batteries but after a few trips, I'm sure I'll need more balancing current than this, maybe not with brand new batteries, but I think when 1 or 2 year old my system will start to show failure and resetting the Daly BMS after an error seems to be a manual job; ARGHHH! I don't want to think about.
- Using a MOSFET as safety breaker is STUPID! It should be a relay that is normal open. The reason is simple: when the system fails because of a current being too high, like a high inrush-current or shortage, the MOSFET will fail as first! And the way a MOSFET tends to fail is to make a short, ALWAYS! You can't disconnect any-more! The Dali has no inrush-current protection what-so-ever! What safety-rating you give this? A relay tends to fail open, I know there is a very slight chance it fails closed because of contacts being welded from high current, but if your relays are strong and big enough, this should NEVER happen.
- A inrush-current protection is not only necessary for the BMS itself, it's also important for the devices connected as a load. Like a BLDC motor controller has big capacitors inside, also DC/AC inverters have big capacitors, at startup their resistance is ZERO for a short period, just like a short-circuit! You can blow them up from the first moment you connect them destroying your Dali AND your inverter in one go!!! If not in one go, it will happen the next time when you switch down the whole system, replace a battery and turn it back on, or the next time it happens. So, you must have a pre-charge circuit first like a extra relay with an in series resistor that limits the current for a few seconds to slowly charge up the capacitors in the load and only than go to full power.
- I bought the newest models with bluetooth, UART and RS-485, on all 3 models of my Daly-controllers the connection scheme is different. WTF!!! They can't respect their own standards! Only after opening one I found out that the naming of the pins was printed on the PCB. But their docs were wrong or insufficient!!! ARGHHH!!!
- After opening I can't find any TVS diodes or any other protection, the system is utterly simple. No TVS-diodes even with a CAN-bus and RS-485!!! This is asking for trouble sooner or later. When in an environment with large currents you get VOLTAGE DROP and EMI ( ElectroMagnetic Interference ), always. This results in very short but high interference peak voltages in your communication cables. TVS-diodes are very fast reacting diodes that short out these Voltages the moment they go above the small 3v3 that your microprocessor is working. In the Daly I saw no TVS and also no buffering at first glance. Very poor design.
- Also measuring the Voltage over the same cables you do send the balancing-current seems not a good idea to me. You always get a voltage difference that's why they recommend not using any other cables and not to make them different lenghts, because you'll get wrong voltage readings because of Voltage drop. It would better to different cable for sensing but if the differences cancel each other out I would say OK.
I had a ARGHH moment again!!!
That was my moment I decided, NO WAY!!! Go to hell! I didn't said it that way, but that was my feeling, I think you understand.
At 2 o'clock after midnight I was thinking it's better to design my own BMS. I don't like expensive systems that are like a black box and you don't know whats inside. So I started searching for a good Chip from TI or so that is specialized in BMS and also some open source BMS's. Bad for my high blood but I couldn't sleep before I found something interesting enough so I started searching and browsing the internet.
To be continued....
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