New Ground Up DIY for Mark

looks like you’re left with plenty of airspace and room in there.
That enclosure is a monster

 

Hi Max
First test ride around the river yesterday
It carves like a dream!
Still to resolve a few vesc settings for braking and finish off external BMS Box.
Cheers

 

Wow. It’s up and running!!!
Did he end up
Having to top mount the trucks??
Didn’t look like a lot of clearance.
What a fast build!

 

Still to fit in another remote receiver , a horn , 8V to 5v converter , bit of switching electronics for horn and strip leds and BMS wiring to socket. There wont be much room left .
Leaving air space above vescs clear for heat dissipation

 

Mark has moved mounting plate for trucks below board and added a riser spacer to give about 70-80mm ground clearance

 

Under the guise of further testing ( or I love riding Mark's board) I used it for my commute to work today.

See metr for details

A few salient parameters of interest were

• Max Battery Current 31.4A Max Motor Current 58.4A
• VESC Mosfets max temp 40 degrees Celsius ( ambient is 28 degrees so mosfet temperature rise is 12 degrees)
• Total energy consumption was 69 Wh over 5.6km on mostly flat path with a few steep rises for bridges/overpasses which gives 12.3Wh/km . My estimated consumption for range calculation was 13.0 Wh/km so all good. This is on AT wheels . As a point of reference I get about 10.3 Wh/km on my streets.
• Extrapolating the measured Wh/km consumption on this trip (12.3 Wh/km) and the measured Wh of battery during discharge test (690 Wh) gives an estimated range of 56km. Of course there are many variables in this such as rider weight , path condition , wind , amount of carving etc.

 

Further progress on external BMS Charging box. This design is identical to mine except location of charging port.
Incoming cable from board 11 pin connector contains 11 connections from battery pack +42V through to battery pack 0V .
These 11 connections are wired to front panel led voltage indicators to display each of the ten cells voltage - and then these 11 connections are connected in parallel with the BMS balance plug wires.

Wiring from 11 pin plug to BMS box is high temperature silicon flexible wire 0.75 sq. mm.

The front panel LCD display that shows charging volts , charging current , charging power , cumulative charge Ah and cumulative charge kWh. The -ve output from charge port connects to C- port on BMS and the B- port on BMS to the pack 0V .

So in this design , the battery pack charging current utilises the balance wiring system - a bit novel but technically sound.

The BMS is a smart configurable BMS with a uart connection for PC cable interface and a Bluetooth module for android phone connection.

Programmed up BMS settings as per photo . Set cell balance target to 4.00V with a 30mV window.

Then first power up of BMS (on my board- same plug connections) and all works OK .

 

The last bit of stuff to build is the harness internal to board from the battery pack balance wire connectors to the 11 pin socket on side of enclosure.
The design includes some nifty little alarm modules that have a audible alarm if any pack drops below 3.0V .
These are designed to sound an audible alarm if the board is accidently left on for an extended period unused and the cells discharge to 3.0V
They also display individual cell voltage - but of no use being internal to enclosure.
Fitted 5A wire fuses to balance leads ( under large red heat shrink) to protect battery pack against balance wire or BMS faults. The battery pack balance leads connect directly to the battery pack cells - so a large potential fault current exists. These fuses should never blow so wire fuses will be OK.

Wiring from 11 pin socket to battery pack balance plug is high temperature silicon flexible wire 0.75 sq. mm.

All connections have double heat shrink

 

Well, stage one is complete... what a board! This thing is awesome! Smooth control, app for full board telemetry and hooks in to my Apple Watch too for instant board information I.e. volts and kilometres travel etc... first major test run... 60km’s! Yes that’s right 60 kilometres!

 

Awesome stuff.
Any pics??

And the charger. (I might have missed it skimming through the comments) what’s your charging current?
Going to set it to cut off at storage voltage, then full charge before planned rides?

 

Hi Max,

Currently I’m using the standard Evolve chargers, both the standard 2A and Fast 4A. I can either charge directly to the board or through the balancing box. As per my Evolve batteries, I’m currently charging back to full after each ride...

 

Max
Have set up BMS to balance during charge when pack is above 40V with a target voltage of 4.1V per cell with a balance window of 50mV ( will continue to balance until all cells are within 50mV of each other)
Cheers

 

Sounds great.
If it’s any help I have a bunch of 10A power diodes that I use in series with the evolve chargers.
They’re cheap as chips and I’m sure you’ve got it sorted, but anyway I have some.

Great build!!!!!!!

 

Next item is to design and build brake light system - after a lot of searching , concluded that there is no available complete stand-alone system to illuminate brake light when remote is in braking function.

Nearest I could find is a Hobby King Multirotor LED light set which is designed for RC planes to show throttle status and braking
Stock standard this comes with neutral red leds , braking blue leds and throttling green leds but it works off the PPM signal from standard RC receiver (which is what we have in this build) . Ordered from HK Aust and took three days to receive it.

Wanted to operate an external brake light system so had to design an interface from the HK pcb to clean contacts via a relay.
After calibrating the HK light set it worked perfectly for neutral , throttling and braking operating the pcb leds. After a bit of probing with a multimeter , I found a connection point on the HK pcb that went high ( +3.3V) when braking and went low ( 0V) when not braking or throttling.( yellow wire connection on pcb in photo below and S+ on schematic). This point is a direct mcu 3.3V output with probably a few mA capacity and could not drive a relay directly.

So I designed up a MOSFET interface circuit to accept this 3.3V signal and operate a relay to drive brake lights. Mosfet is an N Channel type. The relay is a miniature telecom 5V coil relay with dpdt contact system. Both from Altronics.

See circuit diagram for details. Tested on breadboard first and after successful testing - mounted relay and Mosfet on back of HK pcb. Hot glued when complete to hold everything in place and I will put heat shrink over the whole pcb when installing in board. 5V supply for Mosfet and relay is from HK pcb.

The brake light system has an in-built tail light . See this for operation https://www.youtube.com/watch?v=NBOOSV_I9U4

Mark is going to make some nice brackets to mount this off the back truck deck mounting system - so should look quite cool.

The brake leds are designed for a 12V system but only have 8V (headlights ) and 5V (controls) systems in board .
Will try on 8V first and see if it is bright enough and if necessary see if brake light led system can be rejigged for 8V operation.

 

Great work!!

 

Fitted brake light module inside enclosure and fitted three pin socket to rear of enclosure to plug in brake light . Mark made up a neat mounting bracket from angle aluminium fitted to truck mounting bolts . Wired it up so that a dim red light is on when main switch is on - and set up bright braking light to come on at about -35% duty cycle . Seems to work OK .

 

Hello, SkaterBoy58,
Can you, please share the link where to download that BMS application from?
I suspect the Evolve BMS is talking the same language, and I would like to perform some tests.

Thank you in advance, waiting for your answer.

Victor

 

Victor
no worries
will complete in next day or so
Cheers

 

Victor

BMS PC Software is at link below

Dropbox - JBDTools-en V1.6-20170622.exe

with android software at

Dropbox - xiaoxiangprotection-2.1.1011.apk

Cheers