Ivanovitch_k wrote: ↑
Jul 07 2018 6:41am
I just got a Neptune 15, here is what I intend to do with it + mini review of the BMS itself:
I'm currently designing a custom logging and control board with all the connectivity you can get ( 3G / 4G / Wifi / BT / GPS ) embedded in the bike. The end goal is to access it with a website, possibly extended to iOS and watchOS apps in the long run.
I searched a good BMS to get infos on the battery health and runtime stats. It also needed to be more reliable than the generic Chinese BMS.
The Neptune fitted the bill but with one small problem, it doesn't exposes it's data any other way than through BLE and it's Android app.
Fortunately, it uses the popular HM-10 BLE module
to which it sends and receive data through AT commands over an UART link.
I will need to reverse engineer all the AT commands and replicate them with my board. Not hard but a bit long
I plan on installing the Neptune in a Reention downtube-integrated battery
, mounted on a Frey AM1000 bike
where my custom board will sit. This battery uses a discharge connector with 4 auxiliary data pins so I will forward the UART and BMS on/off lines through them.
An obvious benefit is that the main board will be able to automatically switch on the BMS only after the battery connector is firmly seated, hence no more arcing !
A nice upgrade I'll probably look-into will be to tie the BMS on-switch with the battery key lock. A proper ingition switch
Let's go on with the BMS hardware review:
The clear shrink-wrap was removed. I noticed those 4 hex screws were barely tightened.
a bit of thread-locker would be welcomed.
nice board, STM32L brainbox, the aforementioned HM10 module running a Ti CC2541, a very good TI BQ7694
monitor & balance chip, connectors for the on/off switch, a speed sensor and a pack temp sensor.
There is also a Spansion / Cypress SPI Flash chip (128 Mbit ? cannot find datasheet) the neptune uses for logging.
only brand-name parts, they sure didn't skimped on the BoM:
Charge mosfets are International Rectifiers IRFS3607
, discharge ones are Infineon OptiMos 054n08n
, rectifiers are On-Semi and Diodes INC. Charge traces are beefy and tin-plated. Discharge ones have brass (?) bus bars.
Overall, a very nice BMS.
Still, there are a few points I have mixed feelings about:
- No conformal coating. Easy to add DIY, but I reasonably expected one on a high-end part like this,
- The power wiring is surface soldered. No pulling and lead-securing away from vibrations mandatory !
Selastic or a clamp would have helped.
- The distance between the battery leads is VERY SMALL !!! Why not have them at the opposite end of the board like on many other bms ? With the lack of coating, less than a millimeter is protecting the pack from an dead short . I will add a fuse on the pack lead (+ polyfuses on the balancing leads).
could look into for future Neptune modules is to make cutouts in the thermal backplane to allow through hole soldering. It would probably good to do it also on the charge / controller side.
Similar to this (minus the crappy soldering job
And an even better approach would be to have the leads crimped with eyelets ends
and have them screwed in.