Well, here is a link for serious inspiration for the new battery pack:
Well, here is a link for serious inspiration for the new battery pack:
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.
The pack is about 8 years old, and was subject to a lot of hot weather (over 100F/38C). Several cells have gone bad, and it is not possible to buy the blue CALB 60AH batteries any more.
I’m investigating different technologies – CALB, Leaf, and Volt. Tesla would be lovely, but I’m not a rich guy. 🙂
I’ve been wondering why the BMS light will partially light up for the last few months. I’ve been busy, so I didn’t follow up on it. However, when driving home last week, the BMS alarm went off just before I was about to get on the freeway. I pulled off to a side-street, and called for a tow truck. While I was waiting, I started checking batteries, and sure enough – one was sitting at 2.94v, when the others were almost all a 3.3v.
Over the weekend I replaced the battery and now I don’t have the partial warning from the BMS. (The partial warning is where the BMS warning light just barely glows – it is a standard incandescent bulb. The full warning is when the light is full on and the audible alarm goes off).
The old DC-DC converter was only producing 12.5v – not adequate for a normal charging system. After asking around, I ended up buying 2 Meanwell PSP-600-13.5 converters. These are great little boxes, in that they are designed to work in parallel. This also means that with two boxes, I now have 1200 watts of power to drive whatever I want – such as a new stereo.
Well, the old 12v gel battery has finally died. I tried a whole day charging it, but nope, wasn’t taking in current. So I ordered and received a new Odyssey PC925 battery. I’ll get it charging up today, and should be able to install it tomorrow.
Of course, I still have issues with either a few batteries being soft or some BMS boards being bad. Not sure which. I’ll try to determine tomorrow. Turns out there is a new version of the miniBMS that has a 30 minute memory of good/bad/over/under. Would be nice to get, but then I’d have to spend another $1500 to do that. If it turns out that I do have some bad BMS boards, I’ll re-evaluate the whole BMS market.
Ok, the adaptor is complete, and ready to install. We’ve made a few attempts to put it in, but had a problem with the spacing around the clutch. This has been resolved by allowing the pressure plate to move back 0.2″. During the wait, I’ve rewired the relays, added in a pump and resevoir, and a third brake light. Hope to have the motor and transmission installed on Sunday.
The brake light is a strip of weatherproof side-facing LEDs from www.superbrightleds.com. The wires are hidden behind the chrome.
Since both the motor and the controller use liquid cooling, I had to add in a pump and reservoir. I’ll be running coolant lines from the pump to the controller to the motor to the radiators and back.
The new motor is heavy – 98kg! (216lb). So we have to use this hoist to get the motor and transmission into the car.
The new motor is significantly larger than the old one. The gap between the new motor and the battery rack is about 6mm (1/4″).
There are times when it is faster *and* cheaper to buy parts. Good examples are the motor, controller and stuff like that. Another example is battery interconnects. I had earlier posted that I need to have flexible battery interconnects, and that I was going to build them. Well, my mechanical skills are not so good, and the resulting interconnects are not very good.
So, I ended up buying most of them. From Australia. I have trouble believing that you cannot find these parts in North America….but I can’t find them here.
Good people at Evworks, I’ve bought from them before.
Well, it took a while, but the motor has finally arrived. Spent 2 weeks in US Customs, and another 3.5 days for delivery here, but it is sitting in my garage and smirking at me.
Stats: 11.5″ diameter, 11″ length, 40mm shaft diameter.
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’ve just ordered new power cables. The kit from EA provided 2 gauge cables – those are undersized for this project (big surprise there). I’m ordering 2/0 gauge cables from www.polarwire.com. They have cables that are suitable for vehicles up in Alaska – should do just fine in San Diego. 🙂
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.
I’ve gotten the computer installed and working. It does some very simple processing, that (to be honest) should have been handled by the motor controller.
The embedded computer measures the outside temperature of the motor, and then turns the motor fan on or off, and changes the power level of the motor controller.
Simple stuff, really. I’m sure *someone* could have done it entirely in hardware, but being a computer programmer from years back, this was a better way for me to go.
After getting email from Azure and some really nice folks on the 914 conversion list, I have set the power limit for the motor to 30kw. I’ve also installed some custom-made airscoops.
Net result: no overtemp on the drive home. Yay! We’ll see how this works out for the summertime, but this means I can drive home now without a long stop somewhere. (FTW == For The Win, if you aren’t into the geek slang).
Here’s a picture of the custom airscoop:
I’ve replaced all but the headlights with LEDs and seen a dramatic decrease in current during their usage. What was interesting is that I did not have to replace the blinker relay (apparently you need to on newer cars). I got the LEDs from www.superbrightleds.com.
I’ve also made regen a normal part of driving, so I’ll need to put back the circuit that lights up the brake lights when regen is active. The reason for this is to make shifting easier – when regen is active the motor quickly drops from high RPMs to almost zero within a second or two.
So I’ve done another set of calculations, and I’m getting 350wh/mile driving to and from work. Most of this is freeway driving with some stop-n-go.
I returned from my business trip to Bangkok (long story in itself) to find two boxes waiting for me – the replacement DC-DC converter and new cables for the BMS. It took me about 4 hours to replace the DC-DC converter and the 4 cables, but well worth the effort. The DC-DC converter works as advertised, providing 13.5 volts. The new cables eliminated the intermittent communications problems during charging.
Proof is that the batteries are now fully charged. I can see the car quivering with excitement in the driveway, begging to be driven. I think I’ll do that today. 🙂
BTW, EV Components has been great during all of this – providing excellent customer support and fast shipping of new parts.
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.
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). 🙂
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.
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. 😀