Battery Warmers

EDIT - DO NOT USE THIS TECHNIQUE - IT DOES NOT WORK. See this post for why.

Despite a healing arm, I managed to find time over the past month to do some work on the battery warmers. I started with GroQuick heater cable. The instructions say not to allow the cable to self-intersect, so I designed a foam structure to hold the cable in place:


It goes between the batteries, like this. Fortunately, the AGM-1280T batteries are just smaller enough than the US-8VGC that this all fits in the existing box:


I laid out the pieces so I could make a PDF template for cutting:


Since I'm healing, I enlisted the help of a henchman. This is my daughter KatC's friend Naiche:


He helped me cut the foam and aluminum pieces for the warmers:


I used a Dremel with a 1/4 inch bit to rout nice even grooves for the cable in each piece:


Here is the biggest warmer in progress. First, the cable goes in the grooves, up to the point where it must go *through* the warmer to catch the other pieces:


A loop is pulled through to the back:


And one of the other pieces put in place, with the cable inserted in the groove:


Most of the extra pieces have two sides, a mirror image of each other. The cable goes back up and around:


The last piece on the rear warmer ends like this:


As you can see, the warmer cable is just a little too long. So, I cut it off. To make it work again, I need to crimp the two internal heating elements together to make a circuit. First, I stripped off about an inch or so of the exterior insulation. You can see the copper grounding braid peeled back and about ready to cut off - you don't want to accidentally ground your heating elements:


In this blurry picture, you can see the next step - the red central insulator is split to reveal the two finely wound heating elements:


The two elements are twisted around each other and bent over to create a larger footprint for...


...crimping a closed-end connector on.


Finally, heat-shrink tubing (with built-in glue) is applied - the glue lets you pinch the end shut:


Lastly, the aluminum facing pieces are installed. They are held in place with heavy-duty duct taping - actual duct tape, of course, withstands heat (since it is intended to be used with heating ducts):


In the new year, these will all get installed into their racks. I hope everybody has a safe holiday season and a fantastic 2010!

Been on hiatus

This video shows why:



Arm is getting better, but won't be doing any major work until January at the earliest.

Miscellany

October was a busy month on non-car activities, so not much got done. I did find some time earlier in the month to add an in-line high voltage 400A fuse (Ferraz-Shawmut A50QS400-4). It is in a link with a Cam-lok connector, and is located between the front battery boxes and the rear battery box:


Yesterday was much better, sunny after a blizzard, generally a good day to work. I spent an hour or two cleaning up tools that had been placed in haste during the month, and then got to work. I started with the battery charger mount. I installed 1/4-20 RivNuts in the rear compartment - the orange-handled tool is a RivNut tool that I got for the ElectroJeep project. Much nicer than the allen wrench tool I used before on the Porsche:


Here is the charger snug and happy in its new location. The only concern I have is that the charger gets quite warm. I will rig up an active air circulation system for the rear compartment, both for charging as well as operating (to help keep the DMOC cool).


I also test-installed the battery warmers. I decided to go with Gro-Quick soil heating cables. Since there is space between the batteries (due to them being smaller than the original batteries) I think that will be a fine place to put the warmer cable. This cannot be the final configuration, though - the documentation has fairly dire warnings about crossing the cable or allowing the cable to touch itself. So I will be routing cable channels into the plywood battery spacers to hold the warming cable.

In the meantime, here are a couple of pictures showing how the cable loops back and forth between the batteries. The rear box:


The front box:


I also cut the clear acrylic tops for the regulator boxes. This shot is a test-fit of the tightest spot. Looks like there will be plenty of clearance, even if the regulator boxes are on top of the hold-down straps (which I think they will have to be):

Relay and Regulator Boxes

This week, it snowed. And stayed cold all week (cold enough to kill my sprinkler system's backflow vacuum breaker valve because I did not think to drain it). Oh, well. I found some things to keep me occupied inside where it is warm.

First, I worked on the relay box for the front compartment. Previously, the front relays / terminals / fuses / etc. were mounted on an exposed board on the front battery box. I never really liked this, especially because it exposes high voltage close to where fingers might pry. So, I found a box that would enclose all of the front relays and contactors and fuses - an 8x8x4 box from my local hardware store. I drilled holes for wires to emerge, installed grommets, and bolted relays / terminals / contactors / fuse holders in, and then wired it up approximately according to the wiring diagram I previously published:


Here is the same photo with labels. The "Heater" contactor controls the heater via the heater swith. The "Horn" relay is to hook up a new louder horn. The "Key +12" relay is a booster for the +12 keyed signal, to run a front compartment fan plus a couple of lights. The "Charge Intlk" relay sends a signal to the controller that the car is plugged in to the wall. It also activates a light on the dashboard. The Crydom solid-state relay in the lower left controls the HV voltmeter as well as the DC-DC converter (which should never draw more than 3 amps or so!). And, finally, I separated the high voltage from the low voltage fuses. And wired it all up:


I then put connectors on the end of the cables and put plastic spiral wrap around most of them (I'll add it to the 10-gauge high-voltage wires later as well). Note also the blue tape - it labels what each wire is, in case I forget:


With that out of the way, it was still cold and snowy outside. So I tackled another problem - how to protect the Mk2 Rudman Regulators from the elements and from prying / curious fingers. I found 18 PVC outlet boxes at my local hardware store. My vague memory of the size of the regulators made me think they would fit without much modification. I was wrong. I ended up having to cut the four internal screw posts out - making a lovely dusty mess with my Dremel. I also cut a rectangular port for the 6-pin telephone-style RegBus to come in / out. And I cut a rectangular port for the wires which connect the regulator to the battery. Here is my first prototype:


Seemed to work well, so I made 17 more (sitting on top of printouts of the templates I made):


I then took nylon screws and standoffs and inserted them appropriately...


and bolted all of them together. Here are all 18 stacked neatly on the stove. My wife is a very understanding soul:


I still need to cut the tops from 1/4" transparent acrylic. I will *not* seal the holes - I need a place for air to get in / out. Eventually I will add little fans to each one to keep them even cooler. But this was enough for now.

Next up - my daughter has a production of The Witch of Blackbird Pond at the local theater, so I'll be doing only sporadic work on the Volt914.

Rear Batteries In

Today was a busy day. The goal this weekend is to get the car moving again. Failing that, I at least want to get all the boxes and batteries in place. However, before I can do *that*, I need to do a few mods to the car. First, due to the larger size of the PFC-20 charger, and due to the need to have the Rudman Regulators on top of the front battery box, I need to move the charger to the rear trunk. Also, I've been frustrated with voltage drops in the 12V system - the ElectroAuto kit pushes everything from the front via a 10 gauge cable, which has proven inadequate. Finally, I want to make provision for some sort of heating system for the batteries - a water bed heater is likely for each box, but I have not finished thinking about this. Regardless, I'll need a 120V power line for the front and rear to handle this (I want the battery heaters on a separate circuit from the charger).

So, I need to drag a lot of cable from the front (where the 12V aux battery and power inlets are) to the rear (where the charger and original 12V battery was). I procured 20 feet of 4 gauge cable for the 12V system, and 25 feet of 16 gauge 120V extension cord, as well as 50 feet (overkill) of 10 gauge 240V extension cord. I laid them next to each other and taped the mess together, thus:


The red cable is the 4 gauge power cable; the thick orange cable is the 10 gauge 240VAC cable (longer because it goes all the way to the rear trunk) and the thinner orange cable is the 16 gauge 120VAC cable.

And now the fun begins. I need to route all this through the passenger's side heater tube. The driver's side, if you recall, has the DC cables from front to back as well as a variety of control signals. Up until now, the passenger's side only had the PakTrakr cable from back to front. So, it was natural to use it for this harness. I taped my trusty plumber's snake to the harness and fed the snake through the heater duct:


Here it is fed all the way through, with feeding into the front compartment just starting:


And here it is fed all the way into the front compartment:


I routed it under the middle battery rack and through the hole left where the fuel pump used to be mounted. I then zip-tied it to the middle rack:


The Porsche 914 12V battery was originally in the engine compartment. The original kit just had you tie all the 10- and 12-gauge wires together and tape the whole mess up. After unwrapping the tape, I decided the ring ends of the original battery cables were in poor shape. So I cut them off and crimped them all into a 4 gauge lug. I then crimped another 4 gauge lug on the 4 gauge cable. I also crimped a ring terminal on a 10 gauge cable which was fed through from the trunk - this will power cooling fans in the trunk (for a future project). It all got bolted together:


Not shown - I taped that up and then put red heat-shrink tubing over the entire assembly.

Next, I assembled a Weather Pack 2-way connector on the end of the 120VAC cable. Weather Pack connectors are water-tight and lock, a close relative to the Metri Pack connectors from the previous post. Very handy for preventing short circuits and corrosion. This will eventually plug into the rear battery heating solution:


One more thing needed to be done before putting the rear box in. I needed keyed +12V to switch the relay for the rear fans. So I attached it to the lower terminal block on the rear wiring assembly - it's the yellow wire in the lower right hand of the photo. I also assembled a red and black 10 gauge cord with ring terminals and split loom. This was then attached to the most negative power pole (black) and shunt (red). The other end will plug in to the charger. This is actually nicer than the original - I'll be able to look at the actual amps pushed by the charger:


I drilled a new hole and put a grommet in it to feed this assembly through to the trunk. On the passenger's side, I also drilled an identical hole to feed the 240VAC cord and 10 gauge fan power wire and 16 gauge keyed +12v control signal wire. But you'll have to imagine it from this picture of the driver's side:


Finally - I drilled holes in the battery box where the assemblies from Thursday night feed through. I installed the battery box, put a generous dollop of silicone sealer along the edges, and bolted it together. And, finally, I dropped the batteries in place. Note that the AGM-1280T batteries are 0.55 inches narrower than the US 8VGC, so I cut some 3/4 inch and 1/2 inch plywood shims to put between the batteries to keep them from shifting:

You can see one of the regulator connectors fed through - I was testing to make sure it would fit (it does).

Tomorrow - installing the middle and front racks and batteries. And redoing the front relay assembly. And then building and attaching battery interconnects. And (maybe) taking the car for a spin if I'm lucky.

Rudman Mk2 Disconnects

For my AGM batteries, I purchased Rudman Mk2 Regulators from Manzanita Micro. The regulators will sit outside the battery boxes in little boxes of their own, with fans to keep them cool and transparent tops so I can see the lights flashing. This means, though, that I need a disconnect system so I can service the batteries when needed. The disconnect will also serve as an easy way to charge individual batteries if needed.

After some Googling, I found the disconnect I wanted - Metric-Pack 480 sealed interconnects from Delphi. Waytek Wire has everything I need - the male/female housings, the male/female terminals, the silicone seals, and the strain relief clips. You do have to order many of the parts in multiples of 50. Oh, well. I'll have leftovers for some future project. I also got some 10 gauge wire. The crimpers are from previous projects - one is a standard crimper for solderless terminals, the other is designed for Weather Pack / Metric Pack crimping:

The Mk2 manual says that the wires connecting the regulators to the batteries must not show more than 10 millivolt voltage drop at the desired ampacity. I want to be able to bypass up to 8A, so that means 15 inches of 10 gauge wiring. I cut them to 14.5 inches because the interconnects add some length / resistance:


For some reason, I had the urge to consume some licorice at this point. Anyway, the next step was to crimp a faston to one end and a ring terminal to the other end of each wire:


I could theoretically have stopped here - I could have just used the faston as the disconnect. However, all those metal ends are just screaming, "Short me! No, short me!" and I did not feel like blowing up my carefully constructed wires or setting my car on fire. So, I cut all the wires in two parts. The short part is 4 inches long, leaving the long part at roughly 11 inches:


Here is how a Metric Pack 480 disconnect is assembled. The little purple things are silicone seals which go over the wires. The metallic terminals crimp onto the wire and the seal, and then the wire/terminal is inserted into the housing. A strain relief clip then goes on to finish it off. I took this picture before I had decided that the *short* wires would be female - the male connector is a good 2.5 inches long and would have taken all the slack of the short wires - I need a little slack...


First, you slip the seals on, before stripping the wires:


Next, you crimp the terminal over the wire and seal. There should be a little bit of wire showing on both sides of the wire crimp. GM recommends soldering at this point. But I'm lazy.


Here are all the female ends crimped on:


About to insert the female ends into the housing:


Ta-da! All done, with the strain relief clip attached. Kind of pretty, I think:


Here's a close look down the business end of the female disconnect:

And here are 18 complete female disconnects. The stripping / crimping is the time consuming part; snapping the disconnects together goes very quickly:


The male is just about the same. Here you can see the length of wire to strip and how it should fit in the crimp area of the terminal:


Here is the crimper in action. You put the top of the "A" on top of the crimps, and the tang pushes the terminal up into the concavity, folding the little crimps over very neatly. I only had one mis-crimp out of 72 crimps - and that one was because I got over-zealous on crimping the silcone seal and I tore it:


Here are all the male terminals crimped on:


And here is a complete housing (but without the strain relief clamp):


A look down the business end of the male disconnect...


And here is the complete male and female disconnect clipped together:


And here is the whole mess - 18 male and 18 female disconnects:


I did some sketching, and the 11 inch length of the male ends should be plenty to get outside the battery box for all the batteries. I also plan on making a couple of battery charger female disconnects. But my hands are tired, it will wait for another day.