Laser cut acrylic terminal covers

cover_with_bms_topview

I laser cut some covers that place an acrylic wall between each of the busbars of my battery, as well as covering the top. They are designed to keep a falling screwdriver, wrench, or bolt from bridging the bussbars and causing “excitement”. I have a lot of air holes to try and allow a normal amount of air flow, as well as exposing the bolts and screws for occasional tightness checks.

busbar_layout

You can download the textual openscad design file here:
battery_shield.scad

Or, you can just download the PDF files if you want to laser cut them exactly as they are:
battery_shield
battery_shield_reversed

A “how to assemble” video is here:

Youtube Video link

Acrylic could be a bit brittle for this application, and using 3mm craft plywood could provide a bit more impact resistance. However, the covers are inside the “sidewalls”, plus the batteries will be mounted sideways and the current “top” will be mostly protected by insulating foam in my battery boxes,so I chose to go with the less smoky option. (Plus, I think the semi-transparent nature of the acrylic just looks cooler.)

EVSE Install: JuiceBox Pro 40

JuiceboxInstalled

This is my new J1772 EVSE, a JuiceBox Pro 40 (Amp) unit. Georgia Power is offering a $250 rebate for installing a Level 2 EVSE with dedicated circuit this year. I already had the dedicated NEMA 14-50 (50 Amp) circuit previously installed for electric truck charging, and since the JuiceBox plugs into a NEMA 14-50 outlet, installation was as simple as anchoring it to the brick wall of the garage (with concrete screws) and plugging it in.

I especially like the small plastic cable and “gun end” management system which is screwed to the wall above the JuiceBox. Continue reading

Leaf battery module differences – 36 “normal” and 12 “special”

The 2013 Nissan Leaf battery pack that I disassembled had 48 battery modules in it. Previously, I had separated the modules that were in the front half of the pack, packed in stacks of 2 or 4 “flat packed”. However, I had only removed the 24 modules are located in the back of the pack (under the passenger seat) as a unit, and had not unpacked them yet. When I unpacked them, I discovered that 12 of the modules (every other one) had some differences from what I consider to be the “normal” modules (the other 36).

module_differences_mounting_plate4
In the picture above, a “normal” module is at the top, while one of the 12 “special” modules that supports the mounting brackets is on the bottom, with the removed mounting bracket. Note how the tin plate sticks out a little bit more on the “normal” module, taking up the same amount of space as the steel mounting bracket on the “special” module.

The “special” modules have small metal plates that mount to the top and bottom of the modules. These metal plates then bolt into support brackets, which allows this set of 24 modules to be supported “sideways”. I started to worry that these extra pieces of metal would change the spacing of the modules (from my previously measured 1.3333 inches per module), but as it turns out they don’t. The modules themselves are shaped slightly differently (just a bit narrower at the top and bottom) to allow for the extra width of the steel mounting brackets. The main body of the modules should still be compressed to 1.333 inches in size.

Looking inside, the pouch cells extend up past the main body just slightly, so I decided to leave the steel plates on as shims, but cut off the bolts as they would get in the way of my busbars. The bottom of the pouch cells don’t extend appreciably past the main body on the bottom, so I’ll be leaving the bottom steel plates off.

module_differences_mounting_plate3

The metal plates have circular tube like supports that reach inside the holes on the modules, supporting them, and are also spot welded to the thin “tin” outsides of the modules. They can be pried off with a flat bladed screwdriver, popping the spot welds out and leaving small holes in the tin plates.

I just used a cut off blade on an angle grinder to cut off the parts of the brackets that I don’t want hanging out on the top of my battery.
modified_steel_panel
screwtops_cut_off

Building a battery from Leaf Modules – The Plan

I am in the process of replacing the twenty (20) six volt lead acid golf cart batteries that power my electric pickup truck with 48 Nissan Leaf battery modules. Because the battery bays in the truck are specificity designed to hold 20 golf cart batteries (and the Leaf modules have a different form factor), it’s not a straight-forward drop in replacement.

My initial design (not showing the compression plates that hold the six modules together in compression):
sixGroup
In the image above, the black bar is negative, Continue reading

How to open a 2013 Nissan Leaf battery pack and remove the modules

battery_open_front

I have opened my 2013 Nissan Leaf battery pack and removed the modules. The tools needed are:

  • 500 volt class 0 (or better) electrically insulated gloves
  • One or two full rolls of black electrical tape, for covering your tools and the terminals of the modules when you remove them.
  • Regular leather gloves
  • Side clippers and needle nose pliers for removing wire tiedowns
  • 1-1/2″ putty knife or chisel and hammer. (or preferably an air chisel)
  • 10 mm wrench (preferably a socket with ratchet)
  • 13 mm deep socket
  • 16 mm wrench and hammer (or impact driver w/ 16mm socket)
  • small flat bladed screwdriver for prying clips
  • # 1 Phillips screwdriver for removing screws on the sense terminal of the modules

You can watch the 13 minute youtube video here, or spend about the same amount of time wading through my wall of text below….

First: Remove the twelve 10mm bolts Continue reading

How to drop a Nissan Leaf battery pack (without an auto lift)

battery_pulled_out_from_under_leaf

NOTE: The battery pack has 400 volts inside of it. Be sure you know what you are doing and have the proper protective equipment, as it can kill you! It also weights 600lbs, so it can crush you!

I needed to remove the battery pack from my Salvage Nissan Leaf. The 2013-Nissan-LEAF-DG.pdf (Disassembly Guide) I found on the Nissan website has good instructions, but they assume you have an auto-lift (and custom battery moving system).

I didn’t want to purchase an auto lift, so I did it with the following tools on my concrete driveway.
tools_used

  • Class 0 – 500 volt electrically insulating gloves. Necessary when pulling the service disconnect, and the high voltage cables leading from the battery to the motor and interior cabin heater.
  • Continue reading

Booting up a Nissan Leaf

Hojas, the wrecked 2013 Nissan Leaf that I purchased at an auto auction site was delivered to my house, and appeared completely dead. The first thing I did was to check the 12 volt “accessory” battery, and found that it had drained down to 1.5 volts. I think this was because in the collision one of the rear doors was knocked ajar, and the interior lights were illuminated because of that, but it could have also been due to the 2-3 months it had been sitting in the auction yard, or perhaps somebody initiated the emergency shutdown procedure.

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After charging the 12 volt battery back up, I was able to put it into “accessory” and “on” mode, Continue reading

Hexagonal wooden mirror frame

This is my finished hex frame mirror, which is the last piece of the downstairs bathroom we renovated.
hex_mirror_finished

frame_ready_to_stain

I built a hexagonal wood frame out of ceder planks for the new bathroom mirror. I had originally wanted to build an irregular three sided “triangular” mirror, but once I figured out that my compound miter saw wouldn’t make cuts sharper than 50 degrees I decided I needed more than 3 sides…and 8 pieces would have been a nightmare to assemble.

frame_assembly

I used a table saw to rip a groove in each piece to hold the glass, and then I used the flattest surface I had available (the mirror glass) to assemble and glue the pieces together. The mirror glass was original to the house, and has a 1961 date printed on the back.

glueing1

Once I had the frame built, I traced out a template so that I could mark the mirror glass exactly where it needed to be cut. (Due to a few holes I was avoiding in my scrap wood, the frame is not perfectly symmetrical….)

measuring_the_mirror

If I hadn’t already built the frame, I would have strongly considered making a “Superman” mirror at this point in the glass cutting phase.

SupermanMirror