In order for the Battery Monitoring System (BMS) to monitor all the batteries, there has to be some sort of device that attaches between each post on each battery. For the Elithion BMS, there are banks of these monitors and they all report to the BMS itself. It’s a bit complicated. Fortunately, the Elithion website has some very good hints on how to go about this. In the picture below, I have one bank connected up, with two more to go in that bay.
Someone that dearly loves to “help” with the conversion is our dog Zoe. She was rescued from the pound 3 years ago, and has been a delightful addition to our household (with notable execptions dealing with destroyed shoes and semi-random barking).
So for the past few days, I’ve been making a super effort to clean up the battery boxes, and surrounding area. This means putting the trunk lids back on, vacuuming up all the odd pieces of metal, and taping off all the exposed metal that could be hazardous in the battery boxes.
Then I went and lifted all the batteries into the boxes and put shims in around them to stabilize the batteries. Well, shims, pieces of wood, spare plastic tubing, whatever works and is generally non-conductive.
Here’s the rear trunk:
And here’s the front trunk:
Next step is to start wiring all the batteries (109 of ‘em) together.
Long weekends were made for working on cars, especially when turning them into real electric cars! This weekend was no exception. I finished up all the battery communication cables and hooked them up to the BMS. I also added in the battery disconnect to the rear trunk (with some necessary re-arrangement of the cables). Next up is adding in the control wires between BMS, Motor Controller and Charger.
I also took the opportunity of adding in the rear trunk shocks and replaced the rear trunk lid – really nice to have the lid back in place. Still a bit of cleanup near the shocks, but really nice items from camp914.
The new guages are installed – one is for the pack voltage, the other is the pack current. Both are left and above the dash. Speedo is also reinstalled, so the passenger compartment is (mostly) done.
Working on the BMS battery connectors now. A lot of fiddly little parts that require a magnifying glass (for my somewhat older eyes) and a good soldering iron. Elithion did a very good job with their battery connectors – they actually show the color of wire to hook up where. On the end of each battery group there is a connector that will have two wires attached – either black/red or green/white. If you look carefully at the two wire connector on their part, it says B R / G W (or something like that). Nice job. 
I still have the rear battery pack to work on, and then it is time to fuss once again in the rear trunk – I now have a quick disconnect for the battery pack that I need to fit in.
Since the trip reset cable was missing, I took the opportunity to have the speedometer rebuilt. At Sean’s suggestion, I sent it to North Hollywood Speedometer after getting a quote from them. Very fast turn-around, very nice work. When I realized I hadn’t asked for a reset cable, I called back, they remembered my speedo. They were able to build up a cable and sent it to me the next day….another amazing company.
I finally figured out which of the interconnects are which. This took some careful reading of the Elithion website (my fault, not theirs) and as a public service present to you which connector is which:
I’ve gotten the current sensor put together, but these tiny wires are enough to drive an older guy crazy. I had to go and buy one of those soldering stations with those clips and the magnifying glass. Sheesh.
The holidaze were great – warm weather, no stressful driving anywhere, and time to take care of the small details. Cutting the boxes to proper size, attaching the fans to the boxes, running BMS signal cables (which involved pulling and re-running the power cables through the driver-side tube) and so on. Ready to start putting batteries in and hooking up the BMS cables. Oh and mounting the BMS with a power supply as well. LOTS of small stuff.
Well, the braided copper cable is cool and all that, but for the vast majority of connections, just plain copper bar is gonna be fine. So I bought a whole bunch of pieces made to order at Industrial Metal Supply (very nice people, although you will need to go into the place to make special orders if you don’t have an account). I also picked up the new license plates for the car. Busy day (in addition to doing actual work).
Copper interconnects and the new license plates.
Well, due to the usual delays of business travel, pulled muscle, Thanksgiving and shopping for Christmas, not much was done until this weekend.
I was able to trim the battery boxes to a lower height – making a much better fit in the various compartments. Apparently, the trick is to use a carbide blade with 60 to 80 bits in the power saw. Worked great!
I also started working on the battery interconnects. I’m looking into flat braided copper cable, with silver-solder for the ends. However, I’m not happy with the way the ends have worked out – I don’t think they are flat enough yet. This will take some tinkering to figure out.
Battery Interconnect sitting in the Silver Solder
I had been having some trouble trying to find a local source for braided copper grounding straps suitable for making battery interconnects. No idea why it is hard to find, but there it is. Sean suggested I try a few sites, and one of them is www.mcmasters.com. Wow. 460,000 different parts, just about anything you can imagine you would need for just about anything. (who me? impressed? Heck yeah!)
Anyways, I ordered the flexible braided copper cable (equivalent to 2/0 AWG) and melting pot for solder last night. This afternoon – they were delivered. O_O
Wow. Color me majorly impressed.
Yay! I am now the proud owner of 109 Sky Energy 60Ah batteries. All 690 pounds of ‘em (however, some of that weight is the boxes and pallet they arrived on). Gosh, all I have to do now is (list redacted). Shouldn’t take too long. 
Battery Porn:
109 Lithium Iron Phosphate Batteries
Well, now that I’m getting ready to hook up the high voltage, I feel good enough about my terminal block and relay hookup diagrams. I’ve put it into a PDF for your viewing pleasure, and it can be found here: 914_AC24_Layout_V1. I hope this helps with other people trying the same sort of madness.
Since I’m going to go with the higher voltage, I have to change the wiring of the motor from Delta to Wye (hence the bad joke in the title).
Getting to the wiring was challenging, since one of the hex bolts holding the protective plate was stripped during initial installation. Thanks to Sears, I now have some nice tools to remove stripped screws and bolts. Fortunately, my wife went with me to the store, otherwise who knows what I would have ended up bringing home! (called the “ooooh it’s shiny!” syndrome)
Once I got the wires exposed, I thought a before picture would help explain. Here is the Delta wiring:
Delta wiring for the AC24
And then after the rearrangement of wiring to Wye:
Wye wiring for AC24
Now I have to put the cover back on, but that requires instant gasket goop to seal the wires in. *sigh* Yet another trip to the store.
I’ve had a busy weekend adding in the plug and getting the wiring set up. The plug is an interesting model – it will automatically eject the plug when the key is turned – very nice feature.
The AC is routed to the relay panel, the charger and to the EKM meter. The EKM meter has a ring around the live wire to the charger so it can record how much power the charger is using.
Rear Trunk with AC lines
Here’s a picture of the new plug.
AC Plug installed
Well, as I mentioned in the last post, I am completely rewiring everything. About the only thing remaining in the same place are the battery racks and the wires going from engine to mid compartment. I’m still cleaning up the wiring in the rear trunk…and as you’ll see from the picture I’ve got the controller out (for reprogramming).
New relay panel in rear trunk
I’ve also moved the potbox to a location closer to the relay panel (and out of the most nasty of the weather).
Potbox moved to a new location
Also note the new battery (red), charger (green) and DC-DC converter (black)…so I’ve been keeping busy.
Well, nuts. The new charger won’t fit into the front trunk, so it will be installed in the rear comparment, along with the new DC-DC converter. I’m also putting the aux battery in the rear compartment.
Net result: no need for relays in the front compartment or engine compartment. I’m creating a new relay panel that will go in the rear trunk, and will move the DC shunt to the mid compartment (nearest the amp meter). Lots of rewiring, and re-organizing, and most likely a new set of connectors in the engine compartment.
I’ll post pictures once the relay panel is installed.
Well, along with the 109 Sky Energy 60Ah batteries, I am getting the Elithion Battery Management System (BMS), the Manzanita PFC20B battery charger, and EVComponents touchscreen interface to the BMS. Oh, and a new DC-DC converter.
All told, this is $15K worth of batteries and support equipment. (YIKES!)
However, I knew that the job was going to be hazardous when I started. Nothing more exciting than being bleeding-edge, is there?
Now that I know what the parts are, I’ve been making mock-ups of the new parts and will be figuring out where to put them into the car. Once I have the new locations figured out, I’ll post photos.
Well, I got smart – I talked to the people that actually manufacture the motor and controller and asked their opinion. I gave them the possible battery packs, and let them choose. Turns out that there is a “no-mans land” that all but the high voltage pack would hit. So I’m going to use the 349 volt pack (consisting of 109 batteries with 60 Amp-hours capability). Not cheap, as I was warned, and completely found out, but it should do the job admirably.
So, I await the billing and will get the controller updated at the factory. Meanwhile, the minor stuff continues to get cleaned up.
I went and did some initial testing on the 12 volt system in the car, and it doesn’t have any obvious shorts, so it is ready for testing.
However. A number of disturbing reports on how badly the car will perform with 1200 pounds of lead acid battery has me very worried. I’ve read several real-world scenarios of max 50 miles and very weak acceleration. Since I need need to have freeway speed and the ability to climb some steep hills, this is just not acceptable.
The only solution is to go for a higher voltage battery pack, and lead acid batteries won’t do it.
Time for Lithium. Lithium Iron Phosphate. Trouble is, that these are only made in China right now. And they are expensive.
Comparison time (shipping not included):
That last pack will take up the same space as the lead acid batteries, but provide much more voltage and almost twice the available capacity. The cost is just astounding though.
I’ll keep you posted on any further thoughts on this.