Some are spitters. Some are swallowers.
This week, we send the Cadillac Elescalade over to Slingblade for a brake conversion. This will allow us to use the excellent power brakes on this vehicle WITHOUT having to deal with simulating engine vacuum. Muc of GM’s truck line of course features diesel engines and they rather fail to produce sufficient manifold vacuum to run such auxiliary devices. The Elescalade already has a hydraulic pressure pump to run the power steering. By replacing the brake pack with the hydroboost version used on the diesels, and swapping out this pump for an identical one with a few more ports, we can run both brakes and steering off the same pump AND keep everything completely stock in a sense. All parts readily available and recognizable. We’ve already made provisions to mount this pump on the aux shaft of our electric motor pack.
Meanwhile, Lee Morehead of Denton Texas visited at the 2011 Electric Vehicle Conversion Convention. He brought a vehicle, purportedly just needing a new battery set, he called a Swallow. Originally designed
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by Bill Bishoprick of Salem Oregon, this is a very lightweight vehicle based on a 1968 VW beetle, with a custom body reminiscent of a Jaguar. In 1922, Wilson Lyons founded the Swallow Sidecar Company to make motorcycle sidecars. That grew into Jaguar and Bishoprick then named the car after them.
Originally 1650 lbs with 523 lbs of Optima Yellow Tops, the vehicle got a scant 30 miles range. We’re going to replace all that with 253 lbs of China Aviation Lithium Battery Company 100 Ah cells bringing the curb weight down to just over 1400 lbs.
That was the original scope of the project. Unfortunately, we’ve gotten a bit into it and found a bad clutch cylinder, some very bad connections between the rear suspension and the pan, and a seized motor.
So we’re going to upgrade the motor and controller to an HPEVS AC-50 and Curtis 1238-7601. We’ll put in an Elcon charger to charge the cells. A brake line pressure transducer to manage the regenerative braking, and a set of Bridgestone Ecopia LLR tires to replace the low profile Toyos.
The result should be a very lightweight, slightly overpowered but balanced fair-weather vehicle. I think we’ll be up in the 80 mile range even using 100AH cells. Lee originally wanted to stuff it with 180Ah cells. We just couldn’t’ figure a good way to get them all in there, and it would have brought us back up to about the original weight, which we think was a touch bloated. With some new seat work, we think we’ll be at 1500 lbs or less and very sprightly. The car is destined for use by Lee’s daughter.
Meanwhile, we have had a bit of a development in the land of chargers. This has been a pernicious problem since we first started converting cars.
Our first charger was a Brusa NLG-511 or 513. It is really pretty good at 3000 watts because it is endlessly configurable. You can set up multiple stages and have them cycle on time, amp hours, current level, voltage, really almost anything. It’s quite good at measuring voltage and current.
Unfortunately, it comes from Switzerland – no support at all. If you burn one up you get to keep all the charred remains. And with the Euro exchange rate, they reached $4000 each. I was 26 years old before I owned a car that cost over $4000. Much less a charger.
One of the staples of the EV world has been Manzanita. This is a non-isolated charger. You CAN configure the CC/CV voltage but its not very accurate and the point moves around with the current level. You “tweak” this with a kind of blind pot. And the termination is actually done by clock. It’s really not designed for LiFePo4 cells. It can be made to work, but you have to do it carefully and it’s a bit tricky. They have an add on Rudman Regulator that serves as a BMS and controls this and there have been a number of “incidents” involving fires related to this combination.
They are also a bit pricey with a 30 amp version starting at about $2400 and the big 75 amp model going for $4750. A lot more power per dollar at the expense of configuration and control.
DeltaQ makes a lot of the chargers for neighborhood electric vehicles like the GEM and THINK and so forth. Because of liability issues, they simple will not sell or configure any of their chargers for EV conversions. And they complain bitterly that the Chinese firm Elcon has ripped off their design.
If so, Elcon has presented designs with much more useful and higher voltages than DeltaQ, and it must be pointed out that the reason they were available to be ripped off is DeltaQ was having theirs manufactured in China. This is kind of a double edges sword faced by many companies. You can have your electronics product made in China at much less expense than in America. But when you do so, you often find remarkably similar products showing up to compete with you, with remarkably similar designs, and often a few improvements to boot.
The Elcon is the low priced leader. We can get a 3000 watt version for about $900. We got a 5000 watt version for the Cobra delivered in one week. They will load up to 10 “charge curves” into the machine for you and you do have the ability to pick from these 10 curves. This gives you a little bit of a selection of voltages. And they work well and reliably. But if you change your battery pack or car very much, you are stuck with a charger that just no longer works.
In September 2009, Simon Raferty, a UK engineer started a thread on DIYelectric on a $200 build it yourself charger. This thread has now spanned two years and about 50 pages of comments – one of the more popularly read threads on the service. In it, he describes a simple buck circuit controlled by an Arduino.
The Arduino is an Italian open source project to make a small board with an Atmel multi controller on it. They added an IDE and programming language to it and a USB port so anyone could easily program these in C++ on a PC. They have produced millions of these and it has given rise to a stunning open source community involved in home automation.
Rafferty adapted the Arduino as a controller to switch a pair of IGBTS’s to make a functional buck circuit that could charge at 320v and below to any voltage and current desired.
Enter Valery Miftakhov. Miftakhov sports a Phd in Physics from Princeton and has developed an interest in the EV world. He’s started a conversion shop called Electric Motor Werks to convert BMW’s to electric drive. But he was a little put off by the state of some of the components, and chargers rather immediately fell to view. And so he has set out to “productize” this open source charger system. He has further refined the design and published layouts for printed circuit boards, parts lists, schematics, etc. He sells a kit of components for $849. And he’ll even assemble one for you for $1849.
The unit is ENTIRELY configurable, better it is also entirely PROGRAMMABLE if you care to play Arduino, and it will pump out 10kw of power.
Developing such things is actually non-trivial. This week, we test the THIRD version of this we have received, and note that it still has a lot of things hanging on the outside that should be hanging on the inside. But we tried it on Speedster Redux and its’ 192v pack and the device worked superbly. The CC/CV switch was accurate and the termination at 9 amperes was spot on. It is reasonably easy to configure. And it was doing over 8000 watts. I think we could have specified a higher power level yet.
Given the product liability issues with chargers, this may be the way to go. Open source charger projects you can build yourself inexpensively, or of course get some one to build for you for a fee. You kind of have to assume the liability, which you really always did anyway.
Finally, we have located a reasonably priced source for A123 cells. These 20 Ah LiFePo4 pouch cells are mildly interesting. They are high power cells capable of 20C outputs and more. This opens the window to small battery backs and LESS range, but still able to deliver the current levels required for high performance.
It’s kind of theoretical, and we intend to approach it with a bit of caution. But we’re playing around with five cell 100Ah modules and we were charging such a battery at 100 amps. I got involved in a fascinating phone call with Bill Ritchie of HPEVS about their “Secret stuff” coming spring of 2012 and how that might play with an 818 World Car build from Factory Five Racing. In an Alzheimer’s moment, I kind of forgot the batteries.
Brain noticed them when the smoke started billowing out of the battery lab. We used the occasion to do a real world test of a new Kidde ABC fire extinguisher that uses a yellow chemical retardant powder. I was impressed.
Reiterating one more time. If you overcharge these cells, they will cause a very hot fire. Fortunately we were HERE to stop it. They weren’t enclosed but perched on top of a plastic box. They burned through the box and dropped into it, where they were struggling for oxygen. We’re probably going to replace the box and put about a foot of water in it. In this way, future battery fires would burn through the lid,and drop into the water automatically starting the fire and automatically extinguishing it in one smooth motion. I can then just phone in or text in my part in all this.
The interesting thing going on here is that A123 will not sell to us directly. They DO sell through a company called Mavezin who supplies components for electric motorcycles. They quoted us a price of $65 each for these 20 Ah “prismatic” cells. That’s 3x the rate of our current batteries thank you.
OSN Power sold us 16 of these at $50 each. But we recently found a source at a much lower price and OSN has lowered their price commensurately. We bought 36 cells at $30 each and they quoted $23.80 in quantity 600. You can get lower yet if you want 2000 of them. And that starts to get down to the going rate for LiFePo4 cells anyway.
What remains is that you have to do your own packaging. Our initial tests indicate some minor heating around the terminals that could become problematic at VERY high current levels. The essential demand for a good Battery Management System appears to be just as valid as it is for the Chinese prismatics – that is not at all. And so we are looking at module designs that would be light weight, volumetrically of advantage, and inexpensive. This is not an area where we excel and any number of our viewers might do better at this than we do.
I’m playing with cast epoxy resin “tops” that host the cell tabs and clamp them using lightweight copper bars/sheet. Once a mold was perfected for this, they could be produced much less expensively I would think than with CNC machined plastic. But I don’t know. We may try to design some sort of design contest for this project. If you have any suggestions for how that might work.
This is a VERY interesting development. And timely. Thundersky appears to be self cratering. Sinopoly has not apparently sold ANYONE we know any battery cells. We have received notice from Winston Battery that they will no longer market cells in the U.S. and that this will be taken over by their U.S. agent Balqon. Balqon assures all callers they must purchase a Balqon BMS and in any event cells will be 60 days to delivery with full payment required up front. This leaves CALB about our only source for Chinese prismatic cells.
Meanwhile, despite their obstinate reluctance to sell us cells, A123 is losing oxygen fast. The problem is Fisker Automotive. Fisker is just not ramping up their car sales per plan and so inventories of A123 cells are stacking up. Fisker blames it on floods and bad leather shipments and all manner of things in classic GM fashion. But it would appear that their car gets somewhere between 30 and 50 miles of electric range, and after the gasoline kicks in it is 20 mpg and spewing carbon in all directions – all for $95K. Becoming available pretty much in the same time frame as Tesla’s $77K all electric with 300 mile range. And so Fisker is more or less DOA without drastic action.
The A123 cells are actually manufactured in Korea. The manufacturer has their own agenda. And now Chinese traders have picked up the line from Korea and are selling the cells. And they have their own agenda. Methinks A123 is losing control of their design. I think they’ll quickly find their price at about $1 Ah where everything else is, perhaps slightly below given the expense of putting them in modules.
We should at least examine the possibility of using these cells as an option. I don’t know at this point if they are Chinese, Korean, or from Framinham Massachusettes. Increasingly, it doesn’t matter. But it is some work to use them in a car safely. Maybe a plastic battery box with water in the bottom…..