Well, I’m not upgrading the battery pack. I’m donating the 914 to Formula Slug instead (https://www.formulaslug.com/). They are the local University EV enthusiasts, and they are totally interested in working on Sparky. I’m donating the car and a lot of extra parts. They get the joy of finding a battery for it, and spiffing up the car.
This is a bittersweet moment for me.
I finally got a break from house repair, so I pulled all of the connectors off of the old, swollen batteries. Next step is to find a place to recycle all 110 of them.
I’m still pondering whether to buy new or just update Sparky.
I’m still not done removing the old batteries – household updates are taking priority.
However, I’ve been pondering whether it is worthwhile to continue working on the EV. Especially when there are some very nice EVs and PHEVs out there.
Pros for the new EV/PHEV:
Cons for the new EV/PHEV:
I think for now, I’ll keep working on the 914, if nothing else to fix the rust that came back – will make it easier to sell the roller if push comes to shove.
I’m still looking into new EVs – especially now that the wireless charging is closer to reality.
I was chatting with a friend who also has a home-made EV about my pack issues. She also uses CALB batteries, but went with the CALB100AH (blue) instead of the CALB60AH. She’s in the process of parting out the EV, so I get her batteries.
This means I will rebuild the pack using CALB100AH – lower voltage but much better current. I now need to figure out how many I can fit into my existing space.
She had another suggestion: take the good CALB60AH and double it – turning two 60AH batteries into one 120AH battery. I’m going to play with that idea and see how well it all works out.
On the bad news front, CleanPower has sold their business, so I’m not sure if I can get more of the MiniBMS. I’ll just have to be careful with what I have for now.
Well, here is a link for serious inspiration for the new battery pack:
http://www.wolftronix.com/E10_LithiumUpgrade/index.html
I’ve been driving the 914 for 11,000 miles. The current controller does not let me do regen, so I’ve been having to use the brakes.
The 914 is currently in the shop to get all of the brake pads and rotors replaced. They also discovered that the rear calipers were frozen, and one needed to be replaced. *sigh*
Note: this was a draft I had forgotten to post, so this is about a year old – sorry.
I was able to replace the failed battery without trouble, however, due to that misbehaving battery, the rest of the batteries were no longer in sync – meaning some had a lot more charge than others. I tried bringing the new battery down to the rest of the pack level using a 0.4 ohm resistor (50 feet of 16 gauge wire) – doing this for 5 minutes at a time. It came close, but when charging, the rear half of the pack reached top charge before the top half.
So, after some consultation with battery experts at work, I realized that if I did a REALLY slow charge (2.3A at 110v), then the resistors on the BMS would be able to discharge as fast as I was charging, thus allowing ALL cells to reach that same point. Please note that I have 108 cells, so I had to do some math. 2.3A * 110v = 253W. 108*3.4 = 367v. 253W / 367v = 0.69A. So I’m pushing 0.69A through the pack…ok, resistors can handle that… V = I*R, or I = V / R. Resistor on the BMS is 4.7 ohm. 3.4 / 4.7 = 0.723A. Easy. 🙂
As a public service, I hereby proclaim:
DO NOT USE PERMANENT LOCTITE!
At some point in the future, you will need to dismantle your machine, and using permanent loctite will make this a very painful experience.
Use blue loctite instead.
(This was discovered as we were trying to dismantle the old motor adaptor).
I just got the car back from the mechanic. I had a problem with intermittent electrical issues (the 12v system, not the electric drive). For some reason, brake lights and turn signals were getting confused and not working. Turns out it was a the ground connection for the main wiring harness being rusty and not connecting properly.
My advice to you: convert the latest car you can.
A coworker’s advice: convert the largest car you can (she has a Kewet – tiny little thing). 🙂
I finally got tired of the rain pouring through the roof (even with the targa top on) and got Sean to replace all the rubber seals in the roof. Naturally, he had to take the seats out to do this, as it requires clambering about inside the small cabin. Of course, when he did this, he checked for rust (this is something you should always do with an older car, especially one without rust protection). Of course, he found rust.
Of course, he fixed it. AND added in a frame stiffener (914s are a bit weak along the cabin frame). VERY nice work.
Well, I got tired of trucks passing me on the freeway (I *do* live in San Diego, and people drive very, um, aggressively here). While the car does go 70+ mph, it does not have a lot of acceleration left at that point.
So, I have ordered an 80kw BLDC motor from www.currentevtech.com. Dave says it will take from 3 to 6 weeks for delivery. Meantime, I am looking into new motor mounts, contactors, fuses and such.
The new motor weighs 98kg, and produces 250nm torque. In US units, that motor weighs 216 pounds and produces 107 Horsepower, and 184 ft-pounds.
I am really annoyed at the BMS (Battery Monitoring System to non-EV people). I have followed ALL of the directions from Elithion, and it STILL has communication faults and STILL cannot keep the SOC (state of charge) figured out.
Time for a different system. I can no longer recommend Elithion as a BMS. It could be because my car is running at 370v, or it could be because of the huge pack of batteries in the back (around 50). Whatever the reason, it won’t work with my car. I’m not going to waste any more money on shielding or wire for this.
Argh.
Ok, sorry for the delay. Over Thanksgiving weekend, with the aid of my brother-in-law, the new cables were installed. MUCH better on the ground fault problem. I also got to move the power cables to the right-side of the car – away from the communication cables.
So I found a VERY cheap way to solve the GFCI tripping problem – a $0.25 “cheater” plug. Yeah, it’s not elegant, but it solves the problem of the charger tripping the GFCI all the time. I’ll keep looking into why the charger behaves the way it does.
I’ll post pix later of the new cables and the new crimper.
Thanks to the fine folks at KTA-EV, I have a new Elithion main board. I still need to add some more EMI shielding (for the faults that occur during regen), but for the most part, it is working well.
Now I need to figure out why the GFCI is tripping when charging. (Hint: probably had to do something with switching the house over to the underground power). Will keep you posted.
Ok, so in the process of trying to “optimize” the driving experience, I made a few mistakes. Fortunately, I’ve been able to fix almost all of them. The regen circuit now is activated by the brake lights, so the car now drives just like a car. Very cool.
While I was fussing around in the controller compartment, I tried to get the DC-DC converter to work. However, this resulted in me frying my DC-DC converter (fortunately, this is an relatively inexpensive mistake). The good thing is that EV Components has more of them.
I’m hoping to get the tachometer working tomorrow. I spent about 3 hours getting a neat circuit put together that will drive some indicator lights. One is the “ready” signal and the other is the “fault” signal – both from the motor controller. Since I know I’ll want to see these lights while driving and while testing, I set it up so there are two of each lights – one set in the dash and one set near the motor controller.
Radio Shack was my friend, as was Tim Kutscha for his diagram. Naturally, I didn’t do it exactly his way, but that is the fun of all of this. This version uses 2 resisters – one for each input and 4 transisters – one for each light. The box has 12v ready LEDs, the other lights are the more usual incandescent lights.
The circuit is inside this box:
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.
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:
And then after the rearrangement of wiring to Wye:
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.
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.
Sean took the car for a week, and added a new front sway bar (21mm) with chassis re-inforcement, poly-graphite front bushings, and a new rear-trunk release. All very spiffy, and all done VERY nicely. I continue with the minor wiring work for now.
The new sway bar has a minor problem, in that it interferes with the middle battery compartment battery rack. New metal was required.
The new rear trunk release has the knob just under the driver’s seat. I wouldn’t have seen it if Sean hadn’t told me where to look.
