Looks like it’s here, price is £200, and appears to be charge-only…
It appears to use the Analog Devices LTC6813 18S cell monitor chip which gathers data for the “brain” MCU chip and does passive balancing under MCU control. How well this BMS handles balancing is up to the firmware Trampa has written.
20Ω resistors are used for balancing but the LTC6813’s internal MOSFETs, which turn the balancing current on/off, have about 10Ω of resistance each and one or two of them are in the balancing current path. Balancing current should then be at least 100mA for each cell. That board should be able to handle that heat with that heat sink plate.
It looks PTC (resettable) fuses might be used for each balancing channel? They appear as green chips near the balancing connectors. They’re labeled as resistors but their appearance is like PTC fuses (which are, essentially, heat-sensitive resistors).
A TI bq76200 high-side MOSFET driver is to turn the main MOSFETs on/off used but I do not know what MOSFETs they use. My guess is about 10A for a conservative charge current rating. It could be higher depending on the heat sinking of the MOSFETs.
I have no idea if it’s worth £200, or how well it handles balancing and protection, but this BMS uses good components and seems to be set up to handle the heat from balancing very well.
The LLT’s are not bad BMS’ but in my opinion they have to make compromises for that size and cost. The LLT’s are independent too, not tied in with the ESC. For these products you take a greater chance that the unit will fail versus using a better designed and built unit that costs more, maybe a lot more. Whether that potentially greater reliability is worth the cost increase is up to you, based on your priorities and preferences. Some take the chance, some would never do that.
Of course. sometimes the higher cost for some products is not only due to better design and components. Some companies just charge more.
For £200, and being that size, you can create a BMS that can last a lifetime. But you can do that for less money too. I don’t know what Trampa’s profit margin is but low volume product manufacturing can be frightfully expensive. The higher sales volume, lower component costs, and lower labor costs for the China BMS’ means they can price them at a point that no BMS made in the US or Europe can match.
We can’t yet say this Trampa BMS was designed well but at first glance at least the component choice and board layout/design looks good. The firmware is an unknown for now.
It talks to the VESC through CAN. It can tell the vesc to reduce power if an individual p group gets below a set voltage, or the battery pack gets too hot for example… provided the VESC firmware supports all this. The LLT can’t. It works independently.
I think once the official firmware releases full BMS support, all CAN style BMSs will work with the VESC. Ennoid made some progress on that recently too.
I wonder if they’ll put it on “sale” then just permanently sell at a reduced price once 5.03 is released and other smart BMS will be able to communicate over CAN/UART
Looks good. Price is a bit higher than what I was expecting, but I can understand that almost all IC they are using for this BMS are B.O. or very expensive at the moment.
20ohns resistor is quite aggressive and will generate a lot of heat/stress for little gain IMO. (considering trampa’s actual targeted market, althought some might disagree with this statement)
I wish they would finalize their BMS firmware soon, because staying compatible with a moving target on my side is quite difficult.
There are one or a two (not sure which) internal MOSFETs in the balancing current path that add 10Ω or 20Ω to that though. Even then I agree that the balancing current is pretty high for esk8 use. But it could be okay for larger packs IMO and perhaps that’s what they are targeting?
LOL…hoping their firmware is finalized soon. I would find your situation incredibly frustrating!
That’s ok, I will live with it. Just that I had to adapt DieBieMS to new VESC BMS commands and not the opposite. Some commands on the VESC for setting the allowed cell upper and lower voltage values are still missing afaik… So, VESC-BMS seems to be feature incomplete at the moment for a complete VESC & BMS integration despite what is claimed. I might be wrong, but I spent quite some time looking at both VESC & VESC-BMS firmware code in order to adapt my BMS firmware to works with VESC over CAN bus. I did as much as I could to integrate both, but I can’t decide on the implementation of those features on the VESC firmware…
I don’t know what Trampa’s profit margin is but low volume product manufacturing can be frightfully expensive. The higher sales volume, lower component costs, and lower labor costs for the China BMS’ means they can price them at a point that no BMS made in the US or Europe can match.
