Powerwall killer

I am in the beginnings of negotiations with an electrical engineer to contract to me to write me a simple set of instructions to build my Powerwall killer. It'll use the little bit more expensive LiFePO4 battery technology, with the advantage it's far more stable than 18650 cells. It's a smiliar system to my Mums electric car she built, hers was at 144VDC, mine will be at 48VDC.

I'll keep you all updated. I have some upcoming posts about alternative suppliers of railway wheels and bogie construction...

Comments to the rescue...!

From down in the comments section of that insideevs article. I admit, not having a BMS on a pack like that would ensure I couldn't sleep at night.

Future reference! But shouldn't it be Captain Jack Harkness?

Can't touch this Powerwall...

"Can't touch this...!" as the old song put it. Yes, the heady days of my youth back up at Home in the 1990s. Wishing I could have a backyard scale model layout, and yet to realise that my stepfather would beat the trains, as well as a promising career as a draftsman, straight out of me.

I got back into trains in 2007, and started drawing again in 2013. I'd not lost my skills on either. Oddest thing.

Anyway, walk down Memory Lane completed, can you do as the song says, and touch this Powerwall? I'm thinking, this could be something good.

So Jeramiah at Ollin Board Company put me onto to Bestech BMSes. Now, I know the value of a decent BMS, given that I had looked through all the design documents that related to my adopted mothers converted 1983 Starion, that she modified with a bootful of LiFePO4 batteries, and a 22kW bus motor. Mum had made her own ATTiny battery balance boards, due to reversing a diode, the battery bank looked like a Christmas tree with flashing lights under normal operation. Which was quite cool I thought!

I'm going back to tried and true deep cycle SLA battery technology for the solar electrical system quote here for the office at the park. Obviously I'd like to build a Powerwall, but I simply don't have the time, or the funds, to tool up, so SLAs are my next best bet. The upshot is, I'm going to train myself on the same technology a "-1" series locomotive is going to use, albeit, at a different voltage, but exact same equipment. Powerwalls are laudable goals. But in the meantime, I gotta do what I'm familiar with as part of my trade, and what's easily accessible, and deliverable in a decent timeframe. Retrofitting a "-1" series to a "-1500" series is not outside the realm of possibility, but I think I'd like SLA as well as Powerwall technology, even just to compare the two.

I thought about it long and hard, and noted the Victron BlueSolar controllers I had been recommended for the job by my brother Andrew have what's known as a VE.Direct port, a TTL serial port, easily adapted to a USB port. Looking at all the specs of the MPPT controller, it does all pertinent energy measurements, and for the $500 I'm spending, also can adapt to a 48VDC system easily. I'm going for 12VDC as part of this contract, to power a laptop, an EFTPOS machine, some LED lights, and possibly a small 600W inverter. (See AtoB Magazine Issue 108, by David Henshaw - http://www.atob.org.uk/store/products/b-108/ - for information on low energy draw kettles). As part of it, I'm going to use a small Raspberry Pi, with a wifi interface, so I can download the data out of it once a week, and check all the health of the system. That'll be my interface to the BlueSolar controller, and allow me to package up the weeks data in a set of nice CSV spreadsheets that'll make pretty nifty charts and graphs. I'll probably keep records of these backed up, in case there is ever a fault with the system, I can show the clients. They'll know in advance if I'm in Sydney or Newcastle on business or visiting family.

This is my hard hitter for a LiPoly 18650 cell Tesla Powerwall ripoff:

http://bestechpower.com/481v13spcmbmspcbforli-ionli-polymerbatterypack/BMS-D270.html

And using a spot welder, made from a microwave oven transformer to spot weld the tabs onto the 18650 cells, like this:

http://www.avdweb.nl/tech-tips/spot-welder.html

And have the fuse wire from cell to bus bar, to protect the integrity of the pack.

My upcycling obsession doesn't end there. Wait till I got kids...!

http://diy-alternative-energy.com/10-not-so-usual-things-to-make-with-55-gallon-plastic-barrels/

The dog house particularly piqued my fancy. Dogs don't care about how much you spend on their house, as long as it's dry and warm. A 100L drum with a saw and a blowtorch suits the bill.

Honestly, I'm not usually one for videos, as my bandwidth remains so pitifully limited, but this was a good video:

http://insideevs.com/cant-wait-afford-tesla-powerwall-build-300/

Now you see why I want to upcycle a busted microwave!

This video, the Bestech BMS, the work Ollin Board Company and Rory have done, and yes, the spot welder, mean I can live my dream of owning a reasonably priced Tesla Powerwall, and not only that, but adapt that technology to my "-1500" series locomotives. I think this is going to be quite fun!

Until next time...!

Pure magic

https://m.youtube.com/watch?v=S3JKAf5E05A

Increased car body, increased tonnages, recalculations, lumbar support, CAN bus masters

So, when I had decided I was going to make my stock dual gauge, 7.25" and 12", I had nominally increased the car body width to 600mm. And yes, that is indeed suitable for the Casino layout, despite being 100mm over the AALS interoperability standards.

However, I run into this, when I got myself a present of a 2m baby tape measure:

The 20L drum I was going to use is only 300mm wide, which would be dwarfed by the 600mm car body width. The "clap boards" under the rotating drum would be disproportionately huge, and angled totally wrong to allow easy unloading without a shovel.

I had to come up with a better solution. The problem was, I would have to increase my per-wagon tonnage.

Add to this, I had gotten the density constant for the sand wrong. I had used a constant of times 1.44. When I rechecked the site I had done the calculations at, not only had I gotten it wrong, I noticed an option I hadn't before - "Sand with gravel, wet."

The density constant of wet sand with gravel through it is times 2.02. So assuming a 100L plastic drum can carry a nominal 100kg of water, multiplying 100kg by the constant of 2.02 equals 202kg weight of load. Round that to 250kg for each wagon, four wagons make a tonne loading.

A 100L plastic drum is 445mm diameter, by 800mm tall. The wagon would need to be 1,000mm long at least, and would best be a bogie wagon to allow operation on tighter curves. This, however, forces the costs per the wagon through the roof, especially considering I have to have most of the parts custom made. At some point, a laser cutter and CNC mill of my own are on the agenda.

Now, the problems with my back are no secret, my lumbar, ie, the lower back, is twisted, and even since I hurt it at Wards River, I have been in constant pain pretty much. I was thinking about assisted support, but it come to a head when Glen said "My recommendation to you is Gauge 1 - anything larger, and you can't physically move it, and hired help is not able to get it right..."

I beg to differ on both points.

While I'll need to be careful with my back, and certain activities I physically won't be able to do, I am able to assist my lumbar with a powered supporting brace, like a wearable robot. Don't ask me the price, but I will find out soon enough:

http://www.cyberdyne.jp/english/products/Lumbar_LaborSupport.html

If I have to go to full leg support later, I just will do it. I'd like to be able to operate my trains.

Note the name of the company - Cyberdyne Systems. As in Terminator. Cyberdyne was also featured in the Aliens novels, which is today's piece of pub ammo.

I noted an ex-worker of Cityrail was laid off when she failed a medical, the railways stipulating that her oesto-arthritis in her knees and hips affected her ability to walk on ballast, leading to the fears the damage incurred could give her cause to sue on OH&S negligence. My own railway will be earthen ballast, at track level, allowing a mower to run over it easily, so if there is any concerns that walking on actual ballast would aggravate my back problems, it simply won't happen with at grade earthen ballast.

That gives you the general idea of what I'm thinking.

So, with all of this in mind, I now have a 4.6 metre long train, at one tonne, with four wagons, but the wagons are considerably more expensive due to the need to construct dual gauge bogies. The superstructures will remain wood, perhaps with some metal bracing/ framing. Add a tonne and a half for the loco and brake van, and that's a 12 metre or so train at two and a half tonnes weight.

Hired help? I'm quite articulate and detailed with my needs and specifications, I'm used to explaining to various tradesmen what I am requiring, I've made a damned good foreman in my time, never paid for it, but I am able to run a worksite, or a radio operations centre, just as easily as one another. I would incrementally test the tradesmen, the next issue is cost. Looks like I'll have to earn some money, right? I was going to get Casino Engineering to make me up a track welding jig in any case, so I'll start getting an idea of wha this will all start to cost me soon enough.

Speaking of being articulate with needs and specifications, I emailed Benjamin about the details of the VESC programming I was needing. However, the VESC being open source, I can just look at the source code, and examine it myself. I have this great start, I imagine a stub in the traction control section to run a custom program to pulse the pin to activate the sand blower under the wheel as it slips would be the ticket here:

http://vedder.se/2015/08/vesc-writing-custom-applications/

I don't normally program in C, but I know enough to get myself into trouble.

MU (multiple unit) detail:

http://www.railway-technical.com/muops.shtml

Rather than needing a "cross over" the insertion of a MU jumper cable will signal the Arduino CAN "Master" which serves as local throttle and reverser. According to this quote:

"

0. The Controller Area Network (CAN) bus is a multi-master message broadcast system that is suitable for systems where data contained in short messages are needed to be received at multiple locations simultaneously. Because messages are sent to all the nodes in a system, CAN is especially suited to systems where consistency in the received messages at all the receiving nodes is needed 

"

Source: http://www.ti.com/lit/an/slla159/slla159.pdf

The CAN bus is a multi-master bus, meaning the "Slave Mode" of the VESCs is higher up in level on the OSI model and can easily be programmed for. Again, the source code, and thus, protocol, is open, so I'd be able to craft up a control scheme using a "Master" controller per chassis, but each "Slave" VESC will defer to any Master, and if any Master signals them (within reason, there needs to be a time delay, so two locos can't literally be commanded to pull apart if someone was riding in the second units cab, then again, possibly a key to put into the controller as a token?) the VESCs will Dial-A-Power and all that. I'm thinking I might make electro-pneumatic wagon brakes to compliment the independent and regenerative brakes on-loco, based on CAN bus. Once again power will be passed through at +24VDC, and a set of two small 7.2Ah SLA batteries hooked up in series will save the day.

I use those two on long train trips to provide extended power to my MacBook and Surface, as well as 4G phone and iPad. I believe they were $30 each from Jaycar, minus the bags and cigarette lighter sockets. They'd work great to provide on board power for a wagon. Little sensor package over the CAN bus, why not, we can do it. Always wanted to play with CAN bus, nows my big chance!

Speed, tractive effort, tonnages

A cute little diagram I come across in my searching:

While this is for a life size SD40 heavy haul locomotive, I presume the curve demonstrated would be similar for whatever size and scale you are using. Jay tells me that 9kg of H0 scale Broadway Limited Pilbara locos can haul a bucketload of weighted ore cars up a helix no sweat. Again, mod the numbers, you'd probably have the same curve.

That's the general outline for a sand dumper wagon as built by me. The superstructure is wood framing, the dumper part is a upcycled 20L drum, with wheelsets and bearings from DNC Systems in Fairfield. Each wagon would cost approximately $300 - $350 in parts. A 20L drum could carry near on 30kg of wet sand. Add another 10kg (max) for the wagon, and you have a load of 40kg per wagon.

To get to one tonne, you'd need 25 cars. Assuming a length of 700mm including coupler rods between cars, but not including locos, that is a 17.5 metre long train. In terms of costs, that's probably enough for a couple of cartons of Crown left over out of $9,000.

You can see my "three to four tonne" estimate was way out, and while hauling almost two tonnes (now inclusive of locos and batteries, as well as a guards van) for an 25 or so metre long train is definitely a laudable goal, I can feasibly use the overestimate in haulage capacity to go up a steeper grade than a 1 in 40? Perhaps a 1 in 30? Or what about a 1 in 20? At a 1 in 20, I'd definitely need to be able to drop sand on the tracks underneath the wheels as the traction control in the VESCs takes over. This is pretty much an analog to anti-wheelslip technology used in mainline AC traction on the real railway.

I'm guessing I'm going to have to talk to Benjamin about coding up the custom firmware to allow an MU jumper to set slave mode, and traction control activation generate an interrupt pulse to drop sand.

In some ways the above diagram is similar to what I'm trying to do, though certain elements are different. I'm actually using that diagram to guide me in building a 250W brushless DC motor Dutch trike that I would use to ferry Lady Iona to and from the test tracks at Casino Miniature Railway.

Realistically, I'd probably want to haul about ten wagons at a time, 400kg load, plus around a tonne for the loco and guards van, for a length of about ten metres. Cost for wagons - $3,500.

And who says I can't do order of magnitude calculations?

Vedders ESC, high torque BLDC traction motors, and overhead traction in large scale model railways

With the help of Rory from the Minimal Gauge Railways group on Facebook, and Jeramiah from Ollin Board Company, I've come across a scheme I wish to use for high torque brushless DC traction motors for my heavy haul 7.25" gauge large scale model trains. The loco will, pursuant to my article in Issue 30 of Miniature Railways Magazine, be based on the example of the Wootton Light Railway, based in the Isle of Wight. The trams on the Wootton system have 48VDC worth of deep cycle SLA batteries on board, hooked up to the overhead at 48VDC, and to the motors at two sets of 24VDC (effectively doubling the current). Power to the overheads is supplied by a cheap Chinese manufactured stick welder, and is good for a section of 100 metres (quoted is 100 yards, but that's pretty close to 100 metres by new money). Cross section of overhead is 1.9mm^2 according to Howard of Wootton fame, he says it "gets a little warm." However, he can easily obtain the cabling by stripping surplus 10A mains cable, and it is easy, and cheap to replace. Corrosion is fought by using a V section in the sprung trolley pole that uses friction to clean the corrosion off the overhead contact wire.

So I'm presuming Howard uses standard PMDC motors, as his railway is quite a bit older than the current crop of reasonably priced equipment. I intend on having a ZG100 Bo-Bo loco with 24VDC 500W PMDC motors for shunting, a number of ZG150 Bo-Bo-Bo locos with 2,000W derated BLDC motors, and the grandfathers of them all, the ZG200s with Bo-Bo-Bo-Bo trucks, and a thumping 10 horsepower. Lady Iona, my speeder I'm using to enter Chris Stockdales competiton on the Minimal Gauge Railways group on Facebook, will use two 12VDC 250W BLDC motors, and a single 12VDC SLA battery, to keep costs down. I'll be talking some more with Jeramiah about the batteries used in long boards (see further down for some details).

ZG100 loco

ZG150-1500 loco

ZG200 loco

Or at least, that's a general idea. Cabs will more look like this:

Of course, now you can see why I'm wanting a Tesla Powerwall killer, and now you can guess what voltage it'll run at - 48VDC. Of course, the onboard storage of the locos themselves is a Powerwall killer on its own, my "1500" series will indeed be Li-Ion battery locos, with benefit of overheads.

Anyway, here's Benjamin Vedders ESC, which according to Rory, and confirmed by Jeramiah to have what you would call "low end power" in the internal combustion engine world - a high torque output.

http://vedder.se/2015/01/vesc-open-source-esc/

I personally think Benjamin has come up with a decent open source controller here, full of features, good embedded chip, Linux based configuration program, ability to slave multiple controllers over CAN bus, and ability to use an I2C based Wii Nunchuk controller to provide input. Of course, the VESCs are more designed for the long board world, and a one inch thick, 10kg long board full of 18650 cells has reported to get 80km range. That's not bad, considering my Mum got 165km of range out of her electric car, with a bootful of LiFePO4 batteries, and a 22kW motor. I need a couple of hundred metres, potentially up to a kilometre in later stages, up a reasonable slope (anything near a 1 in 40) hauling a couple of tonnes. My application is wildly different to a long board, but in some ways, it's kind of similar too, in terms of needing torque.

These are the BLDC traction motors I plan to get, that were recommended to me by Jeramiah:

http://www.hobbyking.com/hobbyking/store/__18129__Turnigy_Aerodrive_SK3_6374_192kv_Brushless_Outrunner_Motor.html

They'd have to be derated from the near on 2.7kW output, down to 2kW output peak, using the Ollin heatsinked VESCs, with blowers on the traction motors and traction packs (VESCs). I had quoted my normal maximum would be near 1.8kW per motor/ traction pack, but once underway, and not going up a slope the current draw would be minimal from the inertia.

That's an Ollin VESC, in all its glory. Quite a nice bit of kit, US$135 will call one of these puppies your own, and international postage (for us Aussies, and my UK friends) is US$40. You'll want something running Linux to get the VESC configured. I plan on using a Raspberry Pi as a go to. Then again, I was thinking of using the Sinclair Poco Open Source version on the trains as a computer, so it's all good. Arduino to run the control system (ie, throttle and reverser), running over I2C to the master board, then CAN bus to connect the slaves. A quick change of parameters on a loco can MU the locos, just make sure there is a common electrical connection at 24VDC from chassis to chassis so there is no ground loops between VESCs. Perhaps a jumper in an MU cable can set that parameter?

That's a controller I have seen on Minimal Gauge, using a cheap Chinese reversing switch off eBay and a potentiometer under the throttle. Of course, the high currents in my locos won't be at the reversing switch, rather, it's at the traction packs. A simple +5VDC TTL signal will go through the reverser, same with the throttle, it's output is analog.