Category Archives: Projects

Craft, Hardware, or Software projects I’ve done

Salvage 2013 Nissan Leaf Modules – 8 year age capacity test: 75-80%

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six nissan leaf modules with capacity test values written on the sides
Back in 2015 I bought a wrecked 2013 Nissan leaf and salvaged it’s 48 battery modules to use in my s-10 electric pickup truck. At the time, the batteries had 18,921 miles from the Leaf on them, (10 quick charges and 775 Level 1/ Level 2 charges) and the leaf BMS reported a capacity of 64 amp hours (98% state of health). [The modules are rated at a minimum of 60 AH new, but most exceed the minimum specifications a bit.]
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Nissan Leaf (2015) Hitch Receiver – CURT 11396 Class 1 Trailer Hitch

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1 1/4 inch hitch receiver mounted under Nissan Leaf
I installed a CURT 11396 Class 1 Trailer Hitch receiver onto our 2015 Nissan Leaf. The procedure was relatively straightforward, but took me around three hours (the instructions say the novice install time is 70 minutes).  If you don’t already have a jack and set of jackstands, I’d recommend buying a set of auto ramps for this procedure, as it doesn’t involve the wheels/tires.
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2017 Kia Optima Plug In Hybrid Electric Vehicle (PHEV) Missing maps SD card fix

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When we bought a used Kia Optima PHEV (off lease) it was missing the Maps SD card that plugs into the infotainment unit, so the onboard maps & navigation did not work. Given that every phone now comes with multiple GPS navigation & mapping options, this wasn’t a deal-breaker, but I was worried that this would be a very expensive dealer only purchase if we ever wanted to get it working.

I was very pleasantly surprised to find out that Kia will sell and ship you an SD card with updated map data and infotainment software for only $25!
The magic website is easy to find: https://update.kia.com/

I was even happier to find out that if I didn’t want to pay the $25 and wait for shipping, I could buy my own 32 GB Class 10 SDHC UHS-1 card (For $10), download their (Windows or Mac only) software and use it to write the data out to the card myself at home!

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My Glowforge Glass Lid Detached!

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Remember how the handle on the front of my Glowforge’s glass lid fell off back in 2019? Well today when I went to lift the lid, the entire glass lid was detached from the back (hinges!).  I am NOT impressed with the adhesive that Glowforge used on this unit.

Glass lid detached from the hindges

Last time I was able to simply epoxy the handle back into place. I’m hopeful I can do the same thing for the back of the lid, but unfortunately this time it will be very important that I be able to get the lid as close to possible to the original position, as the calibration of the under-lid camera may be negatively impacted by any offsets.   On the plus side, since my last issue, Glowforge has introduced a “beta” Calibrate Camera feature which should hopefully give me the ability to re-calibrate the under-lid (wide angle) camera “in the field”.

Somebody on the Glowforge community forums suggested that they had used E6000 (a flexible adhesive) to repair their lid, so I decided to give that a shot. I made this choice based mostly on the fact that E6000 is a single part adhesive that comes in a squeeze tube with a nice nozzle for dispensing. Getting a good bead between the lid and the hinge mechanism was going to be a little tricky because the lid is still attached to the main unit by a flexible circuit board/wire and it wasn’t immediately clear how to detach the connector. (I was worried that getting 2-part epoxy between the two of them without spilling any would be difficult. In retrospect, I should have ordered one of those “mix in the nozzle” dispensers for the epoxy….).

So, I laid down a few beads of E6000 and then clamped the lid down onto the hinges for 48 hours.

Rocks holding the lid down

Clamping force provided by gravity.

When I opened the lid, the E6000 mostly held, but there was a noticeable “glue stretching” sound, and the right hand side of the lid (nearest the flexible wire, and hardest to get the nozzle under) detached.  The E6000 was holding the lid on the hinge in an upright orientation, but I didn’t want to risk closing and opening the lid more.

So I ended up using JB Weld Clear 2 part 5 minute epoxy all along the edge of the lid and the hinge mechanism (using a toothpick to push it down in the gap on the right hand side) and then clamping the lid to the hinge in an upright position  (using a real clamp this time) for another 24 hours.

The Epoxy is currently holding the lid onto the hinge very solidly. I’d feel better if I’d used epoxy between the entire lid and hinge mechanism, instead of just the edge and what I could force down the crack on the right hand side, so I’ll be gentle with the lid (but then again, I’ve been gentle with it ever since the handle fell off….)

I’m hopeful the bond will remain at least as permanent as my repair on the handle has so far.

Update: My laser tube gave up the ghost, and GlowForge exchanged my (well out of warranty) unit for a Refurbished one for $500.  (Yes, they were informed about my lid repair activities with Epoxy and approved the exchange anyways…..)

High Accuracy GPS with RTK in Orlando

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Global Navigation Satellite Systems (GNSS)  receivers have made incredible improvements over the last twenty years. I remember having to stand outside for 10 minutes waiting for a US only Global Positioning System (GPS) receiver to lock onto 4 satellites so that I could get a fix with less than 100m accuracy (due to selective availability).  Now, you can buy a $220 GNSS receiver that can track 60 satellite channels simultaneously, start from cold in 25 seconds, lock into signals from satellites launched by four different countries (the USA, Russia, European Union, and China) and gets 2.5 to 5 meter accuracy all on it’s own without correction signals.

Here is a plot of the calculated location for a stationary antenna over time without correction signals (3D fix mode):

GPS location wondering around a 1m accuracy circle
As you can see, all of the readings are within a 1 meter circle of accuracy, which is quite good for finding your location on earth, but not (quite) accurate enough to drive a robotic lawnmower around and miss the petunias. [And from day to day you may be off by a few more meters…]
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Build an 8×8 play structure with dimensional lumber

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How to build an 8×8 play structure out of dimensional lumber.

8 foot by 8 foot play structure around a tree

360 view of the play structure. – Spherical Image – RICOH THETA

List of materials and tools for the basic structure (part 1)

Lumber:

  • 4x Pressure Treated (Ground Contact) 4×4 posts, 12′ long (8′ or 10′ possible for shorter platforms)
  • 2x Pressure Treated 2×8 beams, 8′ long
  • 9x Pressure Treated 2×6 Joists, 8′ long (possibly 10 or 11 needed if building box around a tree)
  • 6-8x Pressure Treated 2x4s (6 required for fancy corner braces and assembly bracing, but 8 suggested to make things easier. A few small pieces of scrap 2×4 are very useful for temporarily shelves to hold up boards if you are working alone.)

Hardware:

  • 12x 5/8″ galvanized lag bolts, 4″ long – mounting beams to 4×4 posts
  • 8x 5/16″ galvanized lag bolts, 4″ long – mounting end joists to 4×4 posts
  • 16x galvanized joist hangers (may need more if boxing the tree)
  • 100x 1.5″ galvanized structural screws – joist hangers to beams (can be replaced with 9 gauge galvanized nails if disassembly is not anticipated)
  • 100x 2.5″ galvanized structural screws – joists to beams (can be replaced with galvanized nails)
  • 1lb box of 3″ deck screws (used for attaching bracing together and temporarily mounting beams/joists, not actually part of the finished play structure)
  • Water sealing wood stain (to color/preserve the wood)

Tools Required:

  • Digging tools: Shovel & Post Hole Digger (+ clippers to cut small roots)
  • Wheelbarrow or other way to transport dirt and mix concrete
  • Hoe or concrete mixer, razor knife to open concrete bags
  • Cordless Drill, drill bits, screw drivers
  • Framing Level (4′ or longer suggested), large framing square
  • Tape Measure & pencil,
  • Metal rod (probe for roots), spraypaint or pegs to mark digging locations
  • Adjustable Wrench and/or ratchet driver and sockets for lag bolts
  • Hammer for setting the joist hangers and “persuading” joists into position.
  • Step ladder if you are building a tall platform, or are short.
  • Brush or sprayer for applying wood stain.

List of materials and tools for the flooring and corner braces (part 2)

  • 2x 4×8 exterior grade plywood (for floor)
    or
  • 17x 5.5″ composite deck boards (for floor)
  • 2 lbs of 2″ deck screws
  • Circular saw to clean up the edges of the deck boards (if used)
  • 4x-6x Pressure Treated 2x4s (8′ long) for the corner braces
  • Miter Saw (chop saw), circular saw, or hand saw (for simple corner braces)
  • Compound miter saw (if doing fancy corners)
  • 8x 5/16″ galvanized lag bolts (3″ long) for corner brace to beam/joist connections
  • 8x 5/16″ galvanized lag bolts (4″ long) for corner brace to 4×4 post connections
  • Premium waterproof wood glue for corner brace assembly
  • 2.5″ galvanized nails (or extra 2.5″ structural screws) for corner brace assembly

 

2×4 Basics Bench Brackets

I used 10 2×4 basics bench brackets to add bench/walls to 2 sides of the play structure. They come with all of the hardware you need, but I also purchased/used the following lumber for the bench seats & backs:

6x  2x6x10 Pressure Treated boards for seats & top-rail.
6x 2x4x10 Pressure Treated boards for back rests.

[an additional 4x 2x4x10 pressure treated boards are needed if you want to include the bottom safety rails.]

If you have a VR headset, or just want to wave your phone around in the air, you can watch this 360 video of my son running through the play structure:

 

I used OpenScad to mock-up the basic design to determine what lumber to buy for the basic platform and visualize what it would look like. You can download it here: plan_boxtree.scad

Salvage 2013 Nissan Leaf modules – 7 year old range update

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Back in January of 2016 I put a set of battery modules harvested from a salvage 2013 Nissan Leaf into my S-10 conversion electric pickup. In march of 2016 I drove the truck for a while to see what its range was. [More than 46 miles, as I got tried of driving. The pack had a capacity of at least 15 kWh at that point in time.]

37.4 miles on trip meter.

Today I drove the truck for 35.8 miles before the low cell warning beeper from the BMS started to alert. After I got home [37.4 miles total], the average cell voltage of the pack was 3.75, while my (one) lowest cell was down at 3.3 volts. As it turned out, that cell must have started the trip out at a lower state of charge / voltage from the other cells, as it was still low when charging finished and I had to manually add charge to it individually. [My BMS does a good job of alerting at high/low voltage conditions, but does not do much for balancing the pack.]

According to my JuiceBox, the pack required 14.74 kWh to recharge, which is a good estimate on the battery pack’s current capacity. [This is almost exactly the same amount of power that I used in the trip in 2016, but I didn’t go as far due to different driving conditions. And I also hit the bottom of (at least one cell’s) state of charge.

The 2016 trip averaged 322 watt-hr/mile. This trip consisted of a lot of stop & go city driving as well as a few lengthier stretches of 49 mph arterial streets, and I wasn’t light on the accelerator. My measured watt-hour / mile (from the wall, including charger losses) was: 394 watt-hr/mile

Assuming that the pack has a 15 kWh capacity, this is 63% of the brand new 24 kWh capacity, which means I lost 37 % of the capacity over 7 years. (Some of that was in the original Nissan Leaf, but most of it was in my s-10 conversion.)

I’ll repeat the test after balancing my cells a bit better and see how things go.

Update: I drove the truck until the low cell beeper came on again. I went a total of 38.5 miles, and recharged the pack with 16.69 kWh (16690 watt-hours). The relatively higher  433 watt/hours per mile number is a result of the weather being a lot cooler so I was running the heater in the truck and more 45 mph roads. Balancing the cells got the usable pack capacity (measured from the wall with charging inefficiencies) to 16.69 kWh (which could have theoretically gotten me to 42 miles at 394 watt-hour/mi or 51 miles at 322 watt-hr/mile)

The main take-away is that at 16.5 kWh, I still have access to 68% of the brand new 24 kWh capacity Leaf pack, which isn’t too shabby for a 7 year old battery.

 

 

 

Thermoelectric cooler mark 3.5

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I took my version 3 prototype ThermoElectric cooler and removed two of the four TEC modules, bypassing them in the cooling loop, to reduce the power draw.

Running two TEC’s at 12v each (in parallel, a sort of “turbo” mode) the whole system draws 136 watts. When I put the TEC’s in series (6v each, or “eco” mode) the whole systems draws 46 watts. This breaks down at 5 watts for the power supply, 11 watts for the fans & pump, and 30 watts for the two TEC’s.

Later on, I also moved the fans to 6v each and reduced the total power draw to 41 watts (the fans went down 5 watts when I reduced their voltage by half).

I’m using a cheap low-efficiency 12v power supply that draws 5 watts all on it’s own just idle, so we could get a 4 watt savings by running if off of a nicer power supply, or a 5 watt savings by running it from a 12v battery directly.

The cooling power is significantly reduced from the 4 TEC version, but I think that having a “turbo/eco” switch that would allow the unit to go from 12v operation on the TEC’s and fans to 6v operation (jumping from 136 watts down to 41 watts) would give the user flexibility to either cool things down when excess power is available, or just maintain temperature when operating off of battery power.  However, even in “eco” mode it takes almost a kWh per day of operation.  But at least it outperforms the Chefman TEC.