First 300v charge! And The Future of Transportation Symposium and Car Show

Progress has been very slow lately, it’s been cold, I hurt my shoulder, (insert 20 other excuses here). Now the shoulder is basically better, and to add some outside motivation there is The Future of Transportation Symposium and Car Show coming up next weekend.

FOT v2

http://solaralberta.ca/events/future-transportation-symposium-and-car-show

For anyone in the Edmonton area, I encourage you to attend!  I will have the car there in running condition, but not “complete”.  It should be a great show, and there should be a lot of great cars and great people.

 

In preparation for the show I have to get the car to a level of completeness that is both safe and informative to the show attendees.  First step was sorting out the battery and charging system to ensure that I can charge the car.  The 2nd was to mount and wire the dc/dc converter, it turns out I was able to reuse the mounting holes for an aftermarket CD changer that was installed in the side cubby, this serves to plug the existing holes and mount the converter all in one shot.

A short video of the beginning of the first charge is below.  The pack started off at the bottom balanced 255v and quickly increased to around 280 as you can see below, it continued to increase quite quickly to around 300v from there it increased very slowly.

first charge

 

The first thing you’ll notice is the very high “runtime” count, this is what happens when you need to charge a 300V pack off of a 120v 15A ciruit, to maintain a safety margin on the circuit (the garage lighting is also on this circuit) I’d like to keep it below 13-14A, but I also never intend to run the pack this low ever again.  This reinforces the need for a high current 240v circuit in the garage.  A 240v 50A circuit would allow me to make use of the full 10kw and charge the car in less than 2 hours from completely empty (vs 15 hours for the charge I just completed).  In the future I will likely build a new version of the EMW charger, they are in the 15kw range now and water cooled, this would allow me to mount it in the side panel opposite the dc/dc converter which would allow me to install 8-11 more cells.

 

First charge finished

 

During testing I measured my smallest cell at 61.08Ah so as the charge was coming to completion I watched that cell along with a few of the other “small” cells.  Sure enough, at 61.2Ah my smallest cell was coming up on 3.65v and the charger terminated shortly after as the cell got close to 3.7v.  I think this is the perfect charge level to fill the cells, however I may visit undercharging a bit more as that would extend the life of the cells with a small decrease in maximum range.  The front pack of A123’s is significantly undercharged as the smallest cell groups are around 76Ah, but only charged to 61, they also won’t be discharged too deeply which uses them in the middle section and should make them last for a very very long time.

I have a lot of small things to do before next weekend, including installing the wiring harnesses that I showed in previous blog posts.  Make new brackets to install the fan/radiator and pump for Soliton cooling.  Since I will be towing the car up to the show, it just needs to make it on and off the car dolly and to and from the parking spot at the show.

 

 

Fixing an image issue with the Blog.

I don’t always fully test the blog after I make a post, I just noticed that images were not working correctly with the pop up gallery.  I have fixed the problem and tested the last few posts to make sure images work as they should.  I also updated the plug in that controls the images and enabled a couple of the new features.  The gallery will now cycle through all images in a single  post in a continuous loop either by clicking on the image or using the arrow keys.  Escape now closes the image taking you back to the blog.  Hopefully this corrects the poor interface where the images were linking to a new page then clicking that image would bring up the full size image but requiring two back clicks to return to the blog.  Sorry!

porsche3

If you notice a problem with the blog let me know and I’ll fix it right away.

Creating wiring harnesses, and working on the little things

Although I’ve driven the car for a few months it was never 100% complete.  With the installation of the CALB’s in the rear and the A123’s in the front for the first time the battery system is finished.  I do have one cell to keep an eye on, but that can be replaced very easily without having to remove the entire pack.  I could have started driving the car again with temporary wiring and unfinished pieces but I’ve decided the best thing to do is just complete the car properly.  There is a to do list about a mile long ranging from creating wiring harnesses and installing connectors to building an insulated box for the fluid heater and installing the aluminium channel the length of the car to protect all of the wiring for the HV pack as well as 12v and signal wiring.

I finally installed all of the final ring terminals with proper heatshrink for the battery system, I have a a bit of work left  in the motor loop then all of the high voltage / high current wiring is complete.

A portion of my product line with RW Audio is custom cables.  These are high quality audio cables that look better, last longer and sound better than your typical radio shack variety.  I will be using these same techniques to assemble wiring harnesses and cables to complete the EV wiring in the Porsche.

rcacable

sencable

power2

I’ve started with the “14 pin” connector near the firewall that allowed me to use factory wiring to interface with most of the required connections on the Soliton1.  That worked well for testing, but wasn’t finished and had many unused wires dangling all over.  Below is the old messy wiring.

Water cooling2

Below the water pump for the Soliton1 cooling loop, the 14 pin harness that connects to the Soliton1 and other terminal blocks, as well as the 8awg cables to connect the charger.

wiring

Close up of connections including the cheap 2 pin weather proof connector I bought on ebay for the pump, and will be using for a few other items that need an easy disconnection method.

wiring2

The replacement harness uses the stock connector, but new wire and terminals that are protected by techflex and heatshrink.  There will be a few new harnesses in the car, all using the same assembly style and provide plenty of protection while being serviceable.

With the new 4kw heater that’s replacing the Kats heaters I also decided I should build an insulated “heater box” so that as much heat as possible makes it into the cabin and I’m not wasting heat in the engine compartment to the cold ambient air, especially while driving.

heaterbox

The top and bottom of the box are made from an aluminium extrusion I had laying around, the sides are made from raw double sided FR4 PCB boards that I use for prototyping using my CNC router.  This makes for a very light yet strong box that should work well with some 1/2″ foam insulation.  I still need to decide on what to use for the ends, perhaps a couple more pieces of extrusion since they are the correct width.

heaterbox2

I used the CNC router to drill the holes in the PCB material as well as the extrusion so that everything would line up nicely.  I will need to do further machining on the top and bottom panels to make cutouts for the reservoir, wire glands and drain hole.  This box will be mounted on the passenger side of the engine compartment beside the motor.

As I get closer to installing the heater system permanently the question comes up of how to turn on the pump and 4kw heater.  They simply require 12v, however I was not looking forward to the idea of some sort of “out of place” switch with a cheesy label saying “heater”.  To make the heater behave just like the ICE version I should just be able to turn the temperature dial from cold to hot and the system just works.  So to make that happen I had to remove and disassemble the climate controls which involves desoldering the main switches from the PCB.  Once it was all apart I found just enough room near the temperature dial which is simply a 10k potentiometer to mount a microswitch.  When the temperature is set to cold the switch is closed, so by using the NC contacts on the switch, in any dial position other than cold, the switch is “on”.  This will trigger a relay to turn on the pump and heater.  The car has “automatic” climate controls, meaning that once the cabin reaches the preset temperature the system then controls the flow of coolant through the heater core to maintain the preset temperature.  It uses a temp sensor in the dash and a vacuum operated valve.  Since I don’t want to interrupt the flow of coolant I’m simply using the vacuum valve to control another microswitch that will turn off the heater once the cabin reaches the preset temperature.  This switch closes when the valve would close to cut off the coolant flow, so again using the NC contacts to run the heater only the system will turn on and off automatically as it tries to mimic the original function.   When the valve opens to increase the temperature of the cabin the heater turns on again.  The pump and fan will continue to run during this time drawing more heat out of the coolant.  I don’t have to worry about a fan interlock since the fan comes on low as soon as the ignition is turned on.

wiring3

Connecting 300V and Modifying the JLD404

The CALB battery pack went together very smoothly and easily, in a bottom balanced fashion in series with the remaining A123 pack.  The final pack is 92S with the smallest cell being 61.08Ah giving me total pack size of about 18.26kWh (using 3.25v as the average voltage during discharge).  This gives me a 97-117km range at 100% discharge, which is not something I would do every day but represents the drop dead range of the car.  The safe range is 78-94km at 80% discharge which gives me a very usable car.  My commute to work is only about 16km each way giving me plenty of range for errands, going for lunch or being able to absorb a cycle or two of not being able to charge either at home or at work.  I have one CALB cell which has internal discharge, when it arrived I flagged it as having a lower open circuit voltage (OCV) than the rest of the cells, after cycling and bottom balancing the pack I revisited the OCV before I set up the charger.  This same cell is the only cell in the pack that now has a lower OCV than what I bottom balanced to.  I’ll have to contact Don and Keegan and see if there is anything they can do, I believe the cell will need to be replaced.  It’s other specs are quite good, it has low IR and high capacity, I would say it easily falls in the top half of the cells for performance.  The decreasing SOC with no load just doesn’t work though, I will be able to use the cell for awhile as long as I don’t discharge 100% and I keep an eye on it’s state of charge relative to the rest of the pack.  This won’t work long term and takes me back to the issues I had with the A123 cells (constant monitoring required).

ferraz_shawmut_fuse

With the decrease in available battery current with the replacement of A123’s with CALB’s I needed a new smaller fuse, I went with a 500V 400A Ferraz Shawmut semiconductor fuse that is mounted with the service disconnect in the rear of the car splitting the two halves of the CALB pack.  The service disconnect is the same one that Jack R. has started to use in his vehicles it’s made by Blue Sea Systems it has very solid 1/2″ terminals and is rated for 600A continuous, 900A for 5 minutes and 2700A for 10 seconds which is well above what the battery or motor can do.  The down side is it’s rated for 48v, so it’s not a switch that could be reliably used as a safety disconnect, one instance of breaking 300V @ high current would likely destroy the switch.  This switch will be used to break the circuit only when there is no current flowing, IE for storage or servicing.  You can buy it from EVTV or find it at some marine supply stores.

3000

 

 

The EMW Dashboard is a bit finicky and although it is very attractive and provides a great deal of information (when it works) just isn’t at a state of hook it up and go.  I’m not going to give up on the system, however I am going to supplement it with what is already known to work.  The JLD404 from Lightobject.com or EVTV isn’t the most attractive meter out there, but it runs off a shunt, displays voltage/current/Ah and has been shown to be very repeatable and reasonably accurate.  I will be mounting this meter in the glove box to make it accessible but hidden.

Since I will be using the JLD404 as a backup system I’d rather not have to think about it, which includes resetting the meter to Zero the display after charging.  It’s likely the meter will be very close to zero due to the efficiency of charging LiFePO4 cells however I don’t want to have to open the glove box, hold the down arrow just to reset the meter after a full charge.  The first step in automating the reset is to bring out the terminals to the down arrow switch.  On my version of the JLD there are some unused terminals on the back, 11, 12, 13 and 14 aren’t connected to anything.

The first step is opening the meter, which is simply two tabs at the front and the rear cover slides off.  Next remove the front face by sliding it off the latches on the PCB’s.  De-solder the daughter board with the small transformer on it to gain access to the 2nd terminal on the down arrow switch from the inside.  (If you are uncomfortable de-soldering and re-soldering the daughter board, you could solder the wire to the front of the board directly to the switch, this may make it difficult to re-install the front or rear cover)  Once the meter is stripped down to this state simply solder in two wires as shown below:

JLD rear switch

JLD rear switch2

 

Then re-attach the front panel, this photo shows the relationship between the new wire and the location of the down arrow switch.

JLD rear switch3

Attach the rear cover and put some kind of marking on terminals 11 and 12 to represent the newly wired switch.

JLD rear switch4

This simply allows you to put a momentary switch or relay in parallel with the existing switch to activate the Ah reset function on the meter.  I will be looking at interfacing this with the “charge complete” signal from the EMW 10kW charger so when the pack is charged it automatically resets the meter.  I’m sure there are other chargers that have some sort of charge complete indication and this could be used to reset the meter.  If the pack is only partially charged the meter will continue it’s count uninterrupted.  Doing this for many cycles will accumulate an error over time that will not give you a true representation of SOC.  Allowing the charger to fully charge the car and reset the meter will counter this.

Terminals 13 and 14 also remain unused so if I don’t need to break out any other signals to make the auto reset work I may use them for the other switches, which would make it much easier to cycle through the Volts, Amps, Ah, Time display.  All of the switches share one common terminal so it would only require 4 terminals to break out 3 switches.  Using the Set, Right arrow, and down arrow would provide full functionality for the meter since all menus continue in a loop making the up arrow optional.

 

Installing CALB’s and Some Good Customer Service

I received 2 crates of CALB’s on Wednesday the 19th, it’s now Friday the 28th and all of the cells are tested, bottom balanced, and assembled into 7 cell groups for easy final connection when I move them into the car.  In contrast after receiving A123’s it was months before I had enough cells tested, grouped, assembled and usable, and that was just a test pack, not a complete battery system.

There was an issue when the shipment arrived, 72 cells fit perfectly in the two crates but that didn’t leave any room for the bus bars and hardware.  I emailed Don right away explaining the issue along with my requested delivery date.  Since I’m on vacation till the new year I had hoped to get the CALB pack installed in the car before going back to work, so I would need the bus bars on or before Dec. 27th.  Sure enough, mid morning on the 27th UPS arrived with a bubble envelope containing the missing items.  It’s easy for a company to look good when there are no problems, it’s how a company deals with a problem that really shows how dedicated they are to their customers.  Don Blazer and Keegan from CALIB Power came through, delivering what I needed when I needed it even during this very busy holiday season.

The 2nd issue was based on a lack of availability of the proper bus bars for the CALB CA60FI cells.  For side to side connection the cells require a 41mm bus bar, however only 46mm bars were available when I placed my order.  The simple solution was creating a larger “bend” in the center of the bar to reduce the center to center hole distance.  Given the laminated nature of the bus bars they are very easy to bend by hand, I simply clamped an aluminium bar to the desk using some bus bars as the perfect spacer.  The clamps are placed just outside the spacers to bend the aluminium bar up slightly in the center, making it easy to slide bus bars in and out for quick bending.

A fresh bar is bent “up” at a 45° angle, rotate and bend the other side up at a 45° angle as well.

Finally the bar is bent in the center against the square edge of the desk at ~90°.  The result is a new suitable center to center distance for use with the CA60FI.  Care must be taken to ensure the individual layers don’t move out of alignment too much to obstruct the use of one or both of the holes.

The final issue relates to the end to end connection of two CALB CA60FI’s.  I had purchased a metal punch when deciding how to make holes in the A123 tabs, it’s heavy duty and I didn’t end up using it on the A123’s but it was perfect for punching a new hole and slightly elongating the existing holes in the bus bars.  The bar was also flattened slightly to help increase the center distance.

A finished end to end connection.  The cells are shrink wrapped together to hold them in the desired cell groups for easy handling.  There are 10 groups of 7 and 2 groups of 2 cells making up the final configuration of the rear 74 cell pack.  The cells were assembled in order based on the bar code numbers the cells and documentation arrived with.  I will be able to easily match existing cell information with future data collected from the pack linking it to a specific cell.

In all of this there is one place where the 46mm bus bar actually works perfectly without modification.  When doing an end to side connection, IE transitioning from rows to columns or vice versa you need a (drum roll please) 46mm bus bar!  In my pack there are only two of these but perhaps it will let someone out there order the correct bars for every connection type and eliminate the type of modifications I had to make.

The bus bar sizes for CA60FI’s are as follows:
Side to side = 41mm
End to end = 51mm
Side to end = 46mm

The final layout of the pack is shown below, the negative most cell is the top right cell on the left block, the most positive cell is the top left on the right block.  This matches my layout plan for the A123’s making use of the existing 2/0 cables.  The bus bars not shown will be attached in the car, leaving simple to handle blocks to carry out to the car.  The bottom right cell in the left block and bottom left cell in the right block will be connected together through a fuse and maintenance switch.

This layout makes efficient use of the existing battery box, keeping the 10kW charger in the bottom center.  If I ever want  to add cells there is room in place of the charger to add 11 more cells, plus 19 in the front battery box would take me up to just beyond the limits of the Soliton1 at up to 104 cells.

The first half of the rear pack is installed, the charger needs to go in before I can install the 2nd half and connect everything together.

I’m finally putting the finishing touches on the 10kW charger.  The final panel has been milled/engraved, the wiring is almost complete.

There are still a lot of small tasks to get out of the way but the car is on track for being “complete enough” to resume daily driving early in the new year.

Speaking of new year, happy new year to all!

 

 

 

Installing the Front Battery Box

The original plan was to have all of the batteries in the rear of the car in a single battery box.  The very compact A123’s would have made this possible.  The CALB CA60FI’s that will be going in the rear aren’t as compact.  The battery box that would have held 96S3P worth of A123’s will only hold 74 of the CALB 60’s.  Since my goals include a cell count in the 90’s I needed room for some more cells.  The “engine” compartment was never designed to hold a battery box, however there was a space in front of the motor that remained unused.  After some quick measurements I found enough space for the battery box that I built in the previous update.

Now it’s time to figure out how to mount it.  I raised the front of the car on jack stands so that the battery box can be installed from the bottom.  There is no room to fit it in from the top because of the hood latch and pop up headlight mechanism.  Because of some careful measuring before building the box it fit the space exactly, I did get lucky as to where the top of the box sits though.

The top edge of the box is basically level with the “frame rails” of the car, it’s a unibody car but there are distinct frame rails front and rear.  The box is also basically centered below the mounting position of the pop up headlight mechanism.  By inserting a plate between the frame and the mechanism it allows me to suspend the battery box from the frame rails very easily.

I sketched a bracket design on a post-it turned that into a CAD drawing and milled a pair of them.  The CNC router is one of those tools that I simply couldn’t live without now.

The bracket fits nicely under the pop up headlight mechanism using the factory hardware and mounting holes.

Both sides test fit, and everything lines up as it should.  The top of the battery box will get a plate with 3 studs on each side that will align with the 3 holes in the aluminium bracket.  Raising the box up from the bottom with some guidance should put the studs in the holes, with some lock washers and nuts the top will be secure.  I’ll paint the brackets black for the final install.

The bottom of the box aligns with the bottom of the old radiator mount so a small bracket between those two points will ensure the box can’t move.  Although the box is fairly far forward it sits very low and should help even out the front/rear weight balance.

The whole reason for the front battery box is to hold the displaced A123’s from the arrival of 72 CALB cells that recently arrived (plus two I already had).  The cells were well packed arriving in two small crates, from CALIB Power out of the USA.  Thanks to Don Blazer for being the retailer in this transaction and providing a very good price.  You can find Don on the Diyelectriccar.com forum here.

I just hit the half way point in my testing, much faster than the A123’s since there are far less individual cells to test.  I’m testing two at a time using a pair of PL6’s with similar settings to the A123’s except charge/discharge at 40A and a CC-CV discharge instead of just a CC.  Using the CV portion on the discharge is providing the bulk of the work in bottom balancing.  Shown below is one of the only good uses for Lead, I borrowed a group of gel’s that use to power Wade’s Solectria Force since his EV got the upgrade to 56 of the CALB 60’s recently.

I really like the form factor of these cells they are tall and slim giving them a small footprint and making the best use of a deeper battery box.  They also match the height of the A123’s very closely making them fairly interchangeable.

As shown in the above picture I am now using kapton tape on the edges of the A123 cells.  This should help eliminate the chance of the edges shorting which seems to be related to the electrolyte leakage I was experience in many cells previously.  The aluminium heat spreaders in the bottom of the battery boxes also has a very tough 3M film on the top to give another layer of protection.  Anyone who still wants to use A123’s must tape all of the edges of all of the cells, this is not a suggestion it’s a requirement.  Kapton tape is available on ebay or from some soldering supply places.

I created a simple gland plate for the high current positive and negative wires along with a multi pin connector for the heater wiring and power for the Cell Log 8 Breakout Module.  The studs that align with the mounting plates are also in place, the last step is creating a watertight lid to seal the box, I’m deciding between a simple aluminium plate or plexiglass lid.

 

Another Battery Box and some new Cells

As with all things related to this conversion there is a change.  The battery system is moving from just A123’s to a group of A123’s and some CALB CA60FI’s, the rear battery box is actually the perfect size for the CALB’s and will house 74 of the 60Ah cells along with the EMW 10kW charger.  This means there is a new battery box that will be in the front of the car to hold the A123 cells that will remain.  The 3P groups have been reconfigured to 4P so that all of the groups exceed 60Ah, the lowest CALB cell will determine the pack capacity.  As 4P groups that will never be fully charged I am hoping they will be trouble free.  In an attempt to go easy on the CALB cells, the battery current will be turned down to 500A for normal driving, (meaning just over 8C peaks) and possibly as high as 750A in a “sport” setting (12.5C peaks) based on Jack R’s 12C testing of the 40Ah version of this cell.

The battery box is fairly compact at 24″ x 8″ x 12 1/4″ and will hold either 20 groups of 4P A123’s or 19 of the CALB 60Ah cells if I choose to swap out the A123’s in the future.  This box will fit between the frame rails in front of the motor but behind the AC condenser.  Due to the placement of the hood latch and pop up headlight mechanism this battery box will need to be removed or at least lowered to access the cells.  It will be raised up from the bottom and bolted in place.  This box will be insulated and heated the same as the rear box.  Due to the lack of access, a Cell Log 8 Breakout module will be installed for easy measurement of cell voltages.  The cell log 8’s won’t be on all the time and will only come on by pressing a momentary push button that turns them on and allows the voltages to be read.

As usual I start with a simple rendering, this also lets me generate a cut list for the steel that I need.

Front battery box

Then the actual frame with a layer of primer/paint.  This time around it was much easier, I learned a lot building the first box.

front battery box

Then on to the aluminium skin, it’s riveted on just like the last box, but that process also went much smoother.

The box, ready for some rubberized undercoating to protect and seal it.

Test fit with some A123’s and CALB’s to confirm I got the sizing right.  There is 1/2″ foam insulation as well as a resistive heater in the bottom of the box.

The other notable change is the switch to bottom balancing.  Given the hybrid pack of A123’s and CALB’s I would prefer to use the bottom portion of the A123’s capacity and limit how much they are charged.  Each of the cell groups measures 76-78Ah but they will never be charged over 61Ah (estimate of the lowest CALB 60Ah cell).  Since the pack will seldom be discharged near 100% the A123’s will effectively be used only in the middle 60% or so of their capacity.  Along with the lower battery current settings and the move to 4P from 3P the A123’s should have an easy life.  This does change the normal charging scheme slightly, since the A123’s will never reach 3.5v a new calculation is required for safe CV voltage.  During charging the A123’s are around 3.35v as they pass 60Ah so 20×3.35 + 74×3.5 = 326V or 3.468V per cell.  I will likely charge to 3.45v/cell as a safe starting point and see if the charger terminates as expected when the CALB’s are nearly full, I may need to raise/lower the final voltage accordingly.

 

EMW EV Dashboard, and turning up the Heat

The EMW Deluxe EV Dashboard hardware has arrived, mine is apparently the first copy outside of EMW’s test cars so documentation and instructions were a bit lacking.  Valery did provide me with a copy of the PCB layout which has some pin markings on it which points to some basics like HV Gnd, mV, bV, mC, bC, bCC, t_mC, t_bC +5v.  With these markings and a growing understanding of how Valery designs his products I got the basics sorted out and wired up, some quick tests on the bench had it talking to the tablet and displaying battery voltage, discharge current, power and wh/mile.  It looks like Valery took note of Jacks criticism on the floppy hall sensor that was attached to the basic version and has now created a very simple but solid mounting for the new shunt like hall sensor blocks.  There are two different sensor blocks, one for the motor loop and one for the battery loop.  The app of course doesn’t yet do anything with motor voltage or current so I haven’t hooked that up yet.  The set up is the same as the basic version, there are two buttons that guide you through the set up and enter configuration values.  The core of the Deluxe hardware is an arduino like microcontroller with a breakout board on top with a group of eight db9 connectors, two of which are used for voltage/current/temperature for both motor and battery.  This leaves six more db9 connectors that are wired to various digital/analog inputs and outputs along with other functions that appear to be preconfigured on the board.  There is a trim pot for tweaking the displayed battery voltage when compared to a trusted volt meter.  A bluetooth module plugs into this board which does the micro to tablet communication.  The high voltage monitoring for battery and motor voltage are isolated using a very similar design as used in the 10kW charger.  The system looks like it will have an incredible potential for expansion and customizability when the right people get their hands on this hardware.  The controller code will apparently be released for end user tweaking which will make this a powerful starting point for EV instrumentation and control.

The board is lacking mounting holes and is likely still a work in progress, I will be machining an aluminium top plate with some engraved wording that will mount and protect the PCB’s.

Since the hardware requires constant power I’ll have to revisit my 12v system to handle the constant draw without causing problems or draining the 12v system.  Since the car itself has virtually no draw on the 12v system when the car is off I hadn’t planned for an always on dc/dc converter or anything like that.  I may use a battery charger/maintainer or other small power supply on the 12v system that’s on whenever the car is plugged in.  I’m also thinking about an automatic cut off system that turns off the 12v battery if the voltage drops too low.  I would lose my state of charge indication but easily be able to restart the car and SOC would reset on the next charge cycle.  Better than being stranded because my electric car has a dead 12v battery!

 

I had some issues with the heater, in the end it turned out to be caused by too much heat.  I’m using the very inexpensive Kats tank fluid heaters meant for 1500W at 120v, it’s just a resistor so it doesn’t care if it’s AC or DC power.  I had tested one at about 140v DC and it worked beautifully, I didn’t have the final reservoir so I tested it in a closed loop sealed system.  The final plan is an open system so that pressure can’t build up and burst.  As it turns out at 150V the Kats heater can produce an incredible amount of heat, as measured around 2300 watts.  The problem is in an open system the fluid will boil at a lower temperature than in a pressurized system.  The 140v test likely worked because it was sealed, the fluid didn’t boil and the pump was able to keep the fluid flowing.  Once I had it all hooked up in the car with the proper reservoir the first test failed, I burnt up the first heater in a matter of minutes.  The heater was boiling the fluid causing the pump to choke on the steam and stop moving fluid, once the fluid stops the heater element heats up, trips the overtemp switch however this switch doesn’t work well on DC, I don’t think it actually opened the way it is supposed to.  The element itself then burned up going open circuit.

The solution is a lower power version of the same heater, instead of the 1500W heater I installed an 850W heater, it’s the same size/shape but the element has a different resistance.  On 150V it produces about 1350W which doesn’t boil the coolant and things heat up and circulate as expected.  I’m now using a pair of these 850W heaters wired in parallel, with the fluid flowing in “series” which gives me about 2700W of heating power.  The system seems to be working well, but only a cold day will truly tell.  I have also revised how the temperature switch is wired in, it interrupts the 12v signal that turns on the contactor which it handles with ease.  I could probably use a pair of the 1000w version for a bit more heating power and still not boil the coolant, but I’ll see how these 850W units work when we get some cold weather.

As with all things in the car I strive for a stock appearance and function, at the moment the heater switch is simply a pair of wires and switch laying on the passenger side floor, however initially I will wire it up in place of the stock rear defrost switch.  This sits to the immediate left of the rest of the heater controls and is the most appropriate.  When I have more time I’ll test the behavior of the vacuum operated fluid valve that is part of the factory heating system, I may be able to install a microswitch on the vacuum valve that would turn on the heater system when the temperature dial is turned up above the cars ambient temperature and to a certain degree turn itself on and off as required based on the heat setting.  This would eliminate the need for a dedicated “heater” switch that isn’t part of the normal and intuitive operation of the car.  If I go that route I will have a hidden manual override switch that turns off the heater if there is ever such a need.  The other option is to put the EMW Dashboard in control of the heating system, Valery has already coded and assigned heating and cooling inputs/outputs designed to monitor temperature sensors in the battery boxes and cabin and turn on heating and cooling as required.  This would be a more complex but easily programmable system that would provide more flexibility and control to the frequency that the heating element turns on and off.  It would require some sort of control input to “set” the desired temperature however that might be able to be hijacked from the existing temperature control knob and be made to operate in a very intuitive way.

Well I haven’t even posted this update yet and plans have changed again.  Early on I looked at the RM3 and RM4 heaters sold by Metricmind, since that’s where I bought my vacuum pump.  At regular price they are very expensive so I ruled that out at the time.  As it turns out a batch of RM3 200-450V 4kw heaters with attached pump just came up on the surplus market, for a very reasonable $120US, buy a pair and that comes down to $100 each + shipping.  It should look like the one below except the orange connector and wire has been cut off. New the heater was over $400 and the pump was another couple hundred.

RM3Bosch

I will keep one of the Kats heaters in the loop for preheating the car off of 120v but the RM3 should nicely take care of heating the cabin while driving.

 

1000km later…..

I officially have over 1000 EV Km’s on the car, it’s not finished, but it’s working beautifully.  I snapped the shot below just before going for a test drive, I’m now at 1006km.  The Soliton1 cooling system was a great addition and anyone using a Soliton 1 or Jr. should plan water cooling from the start.  I got a new AC switch and tested the air conditioning, it works very well when driving, since the motor stops when the car does so does the AC, I may have to visit the idea of a dedicated motor to run the AC system, but for now it provides plenty of cooling (which likely isn’t needed much more this year).  So the next important task is heating, I have another reservoir like I used for the Soliton1 cooling that will go along with my pair of 1500w fluid heaters and Liang D5 pump.  This will be an incredibly simple system I’m just looking at the idea of an insulated box to keep the cold outside air from steeling my heat, this would also make the system more efficient with most of the heat making it into the cabin.  I’m going to upgrade the dash lighting to LED’s at some point and while I’m in there I might try to “tweak” the odometer just a hair so that my 1006 EV Km’s reads as 61006 instead of the current random number.

I received the EMW deluxe hardware for the EV display, Valery is still working on it and the software, so it will take a bit before I can get enough info out of him to hook it up and start using it.  There are a pair of hall effect sensors, one for the motor loop and one of the battery loop.  The battery loop version has two sensors of different values I assume it’s for trying to keep the charging/discharging currents in the optimum range of the hall effect sensors.  I also got a replacement IGBT for the charger, I had an “issue”, I’ll elaborate more on that in the next charger update.

With my exposure on EVTV I met a local EV’er who’s in the process of upgrading his Solectria Force from Lead to Lithium, this is a shout out to Wade.  I’m not alone!

Battery Box Updates

The battery box is one of those things that I’ve been working on slowly for many months.

Edit, I’ve had this post in the draft stage for so long I don’t remember my initial idea of what I wanted this post to say, but I thought I’d simply post it as I’ve had many inquiry’s about how I built the box and how much room there is around the transmission.

 

It started off as a rendering:

Then turned into a real box:

Then a test fit in the car:

Check the clearances:

Test fit the sides:

Add the final panels:

Most of the aluminium panels are covered in a white protective film that will be pealed off as they are being riveted into place.

The box is insulated with 1/2″ rigid foam and has a resistive heater built into the bottom that will let me heat the battery box in the winter.  I don’t know if I’ll need it but better to have it and not need it than to need it and not have it.

I currently have a 46S3P pack of A123 20Ah pouches along with a bunch of scrap foam taking up space in what was designed to hold a 96S3P pack.

I have a temporary charger in place while I finish building the EMW 10kW charger.  It takes a long time to charge, but it lets me drive the car every day and I couldn’t be happier with the performance which will only improve as I increase the pack voltage.

The box still needs a lid and completion of the batteries and wiring however it’s at a completely usable state and a pleasure to drive.