Got tired of bringing the hand crank Prius transmission to renewable energy fairs so I got busy mounting an Insight IMA motor on an exercise bike chassis. The main task was to make a core for the rotor and mount it on bearings. I used aluminum for the rear bearing and coil assembly which I removed from the stock cast aluminum housing to make it lighter and smaller. I hope to also add red green leds to show the frequency and polarity of the generated voltage. Works great. Added a small 24 V battery and a 600W sine wave inverter so energy could be out into the battery slowly (I am not in shape yet) and then power up to a 600W load from the battery.
The IMA battery can be completely removed from the car, and the car will still function, if the DC/Dc converter can have the HV input it requires. The typical way to do this is to remove the whole connector/relay board from the pack, and use it to make those connections. If the fuse and connector from a used pack is available, a much safer and simpler IMA bypass can be construced. You remove the DC/DC connector, the 30A fuse, and make up some wires with ring terminals, and make a short bypass connector with those components. It is important to keep everything well insulated, and prevent ant possible shorts, so here is how I made mine. If you can leave the HV battery in the car, just pull the "A" connector of the BCM and turn off the HV battery switch location of BCM A connector
many people have asked if the MaxIMA and other replacement sticks can be used in the later civic packs. The answer is maybe. The sticks them self are actually 2 of the 6 cell sticks, but instead of the big screw connections that we see on the replacement sticks, we see a welded buss bar making the far side connections. The sticks also do not have the PTC sensors. I would expect that a copper buss bar could be used, but the end cap would not work as designed, so the stacking of the sticks could have difficulties. If I ever get a pack to play with, I will design a solution.
A typical discharge graph for one of the MaxIma sticks. The little wiggle in the trace is caused when labview stops recording the signal for a few seconds while writing a PDF file, and is not a problem in the battery. We see nearly an additional AH of capacity, a higher discharge voltage (less Internal resistance), and less heating even with the additional AH. All good.
testing to the cell level at currents similar to the car
I revived my labview based stick tester and will be using it to test the new MaxIma sticks. Here is a trace of a stock stick at the 75-80A load. Note that we see 5.8Ah and a temperature rise to over 120 F
Max IMA batteries show improved internal construction
Several people have picked up the ball that was dropped by Hybrid battery repair, and are offering new sticks for the civic and the insights, so it is time that we see just how well the sticks are built and how well they perform. I got 4 sets of 20 subpacks from Bumblebee, and am in the process of evaluating the performance, but we also know that the construction of the cells is a big factor in how well they can handle the currents involved with use in a Hybrid car. The first photo shows the inner cell construction of the MaxIMA cell more and longer weld points on this cell allow the current to flow with lower internal resistance, so in theory that should translate into less voltage drop under the same load as well as less heating.
Wanted to do some charger/discharger test on a pack that was pretty bad, so I took off the covers, and made this chart, which should be a nice road map for any battery explorers. ********Danger********* Adding the jumper across where the big fuse and switch was located as shown here removes any protection from shocks or short circuits, so proceed only if you know what you are doing. May be better to use a DC rated fuse in the jumper to maintain short circuit protection.
After several hours of trying to find the BCM connector that is the mate for the battery tap harness connector,I gave up. Using a pack that had no cells,so the connector would not have power. I took a small clear plastic bag, and carefully taped the cut up bag over the harness connector,and secured it with black tape near the base, where the wires come out. Next I inserted the pins pulled from one of the 104Pin headers used in the MIMA plug and play adapter, through the plastic into the harness connector female pins. Making sure that the pins were inserted fully,I covered the plastic covered connector with epoxy putty, allowing the pins to stick through the epoxy. I taped the epoxy with black tape to hold the shape. When the epoxy cured,I soldered a ribbon cable to the pins, making the order of the ribbon follow the taps from the - end to the HV + end in sequence. An aluminum duct tape dam that was adhered to the epoxy, made a cavity on the rear where the ribbon attached to the pins.The cavity was filled with hot melt, casting the wires and pins in place. I put a 12 pin .1" OC straight male header on the other end of the ribbon. The voltage taps can be read here, or I can plug in another female 12 Pin header, also attached to a ribbon, into a pill bottle(it was handy). I mounted a 20 position break before make dual pole rotary switch on the base of the pill bottle, and two terminals on the cap for the volt meter. I also made the conector for a civic pack, that plugs into the same female header on the rotary switch /pill bottle, so the same switch can do either. To use it, one unplugs the voltage tap connector from the pack, and attached a voltmeter to the two pill cap terminals, and I can monitor each 12 cell stick , in sequence, as well as the whole pack voltage. It took less time to build than I spent looking for the connector, and It can do both a civic and insight. The connector plugs in reliably and securely, after the plastic is removed. Not pretty, but it works well and is pretty rugged and safe.
As anyone that has pulled the battery pack on their insight can tell you, it is just heavy enough to hurt your back, and it requires you to lift in a very awkward position. Honda has a special lifting frame that the techs use, so I thought that with the requirement that one pulls the Insight pack to do a clean grid charger install,it was time to see if a quick and dirty version of the lifting frame could be fabricated. Randall sent me a photo of one he made, using some handles, and a piece of plywood.
I made one with long handles, that allow comfortable lifting angles, and full control of the pack while removing or installing.
Front end accident shifted IMA motor coil knocking it against rotor
I acquired a complete insight motor/transmission from an insight that had been in a front end collision.I was preparing to shim the IMA rotor so I could remove it from the engine,and discovered that the rotor was shifted sideways from the coil assembly to the point where it was rubbing on one side, and the other side had a big gap.
The mass of the coil assembly and severity of the impact seem to have shifted the coil on its mount. I could not see where the aluminum block or IMA housing had shifted, but do see some abrasion on the front of the block ? the problem is that if the casting was bent there the gap would have been on the other side???
When I get a chance I will eventually remove the coil assembly from the casting, and compare it with one that was not hit to see what actually moved?
The point here is that if you get in an accident, the coil can shift and rub the rotor causing some future failure. This should probably be inspected after a front end hit, but I really doubt that it ever is???
While most of the nice OBDII code readers can tell us which P code is causing a check engine or IMA light, it cannot tell us the subcode ( Blink code). The photo shows which pins need to be shorted together on the Insight OBDII plug to have the car report the blink subcodes. Short with wire and the codes are reported.
When reading the IMA blink codes, the IMA light blinks and if the check engine light is on, it will blink Example: a 74 IMA code would be 7 slow blinks, and 4 fast blinks, if there is more than one code, the blinking will have a long pause, and then blink out the second code.It will cycle through all the codes in a circular fashion. Say there was a 74, and a 78, and a 63. The IMA light would bilnk the 74, then the 78, then the 63, and then start back with the 74 and repeat until you release the short.
When shooting the MIMA video, I needed a way to hold the camcorder so it would shoot the dash display,with no hands, as I needed both to drive the car. I cut an oak board in a triangular shape with two soft rubber feet for the driver door side,and a square shape that fit into the steel square tube on the other. A locking screw was made by welding a nut over a clearance hole on the end of the square tube. It works just like a tripod leg. The telescoping arm is put between the two front doors and forced open so it presses against each, then lock it. A tripod head was attached so the camera can look at the dash while driving. The MIMA videos were shot using this technique.
Ok I can test the subpacks down to the cell level, so the bad cells can be identified, now how do we get the cell replaced. Grabbing the stick with plastic strips in the milling machine vice, I milled off the welds being careful to not machine into the stainless steel case. Once the welds were removed, the cup just slid off the underlying case with hardly any force required. The case only needed a light sanding to make it like new. The two end caps also were quite easy to remove and they were left in a reusable condition. All of this is good news. With a proper fixture to hold the sticks, I could separate the end caps and cells on a whole stick with everything ready to become part of another subpack. No new parts required. Time to get on the welding machine.
Ok now that I have a good electrical test fixture and have identified a cell that was shorted, recovered, but not back to full capacity, it is time to take a look at the insides of the cell. The first thing that jumped out at me was the really nice welds. they are deep, show little discoloration in the heat effected zone,with no surface oxides, so they were probably done in an inert gas. The welds were so strong that the sheet metal tore rather than the weld separating. I made a test fixture to see how much force it would take to "crack" the stick at the cell to cell boundary. Amazingly I was not able to break the welds, even up the the 300 lb max that the scale would take. I had to bend it back and forth 4 or 5 times to get the welds to break out of the metal. I sanded of the weld stubs, and put the cell in a vice to drain out all the energy. I turned the cell in my lathe and cut off the top. The top inner welds were also solid, but I was a bit surprised to find that the top terminal and bottom terminals were simply pressed into the spiral wound plate.The cell must have been assembled in a press to give adiquate contact pressure. I carefully unwrapped the perforated nickle strips which measure about 24 inches. I looked at the plates and separator blotter material, and saw no signs of holes or burned areas(Capacitor Zapp), so this somewhat supports that the capacitor discharge did not blow any holes.Very interesting.
Finally got a look under the black and clear covers of the PTC strip. It turns out it is really 6 discrete PTC devices that are connected by stainless steel strips, so the active temperature sensitive area is located right in the center of the cells.Very interesting, I will run a resistance to temperature profile on one, and see what the actual characteristics are.
Protecting against a short like a self resetting fuse
Several years ago I did some experiments to figure out what the red thingies on the battery packs were, and what they are for. I hit one with a heat gun, and saw the resistance shoot up from ~ 160 ohms to over 600 with a quick blast. I explained my findings on Insight central, but someone else tried the test in an oven, and was not able to duplicate what I found. I finally found myself with a loose Insight side terminal plate in my hand, and decided to put my original theory to a different type of test. I set up my lab supply with 30V, and the current adjustment was set to the 1 A maximum for the supply, so no power supply current limiting would be involved. I clipped two probes to the thermistor leads, and used one of the banana jacks as an on off switch. On first application of the voltage, the current pulsed up to just about the expected 185mA, but rapidly over only a few seconds the current dropped to only 25mA and the thermistor was at 250 degrees F. I held it for a minute, and the thermistor stayed at the 250 f. If the battery tap cable was crushed and all wires shorted, all that would happen would be for the battery end plate to get warm. Nice safety. Swap crushed cable, and the battery pack is good to go. A self resetting fuse.
If a larger capacity battery pack is used in the Insight, we must "fool" the BCM into allowing the full AH capacity of the new pack to be used. I setup a BCM and junction board with current sensor, to determine the best way to fool the current sensor into thinking that only 1/10 of the actual current is passing through it. After a thorough analysis of the system, I determined that the Insight battery current sensor was outputting a current loop signal with ~.20mA/A, and since it is a current loop, a simple current dump resistor to BCM ground should do it.
The battery packs of all hybrid cars have a very special fuse to protect the circuits and the pack from short circuit and over current conditions.An Insight owner came over so that I could help him diagnose his IMA problem, and we found tht the main 100A fuse was blown. He had already replaced the inverter stage, which must have been the cause of the fuse failure. Opening a high voltage high current DC circuit requires a special type of fuse. It is called a semiconductor fuse, but this name is misleading. There are no semiconductors in the fuse, the name describes it's ability to blow extremely quickly so any semiconductor devices it is powering will be protected, and this means rapidly quenching the hot arc that forms when a high power DC circuit is opened. The metal element is similar to a regular fuse, but the fuse is filled with an insulating glass like powder that rapidly melts and quenches the arc.I opened the blown fuse so we could see how it is constructed.
Back in 2002, I decided that I wanted to let the other drivers on the road know what I was getting for MPG. I mounted a tiny color video camera on a bent piece of solid # 14 wire, which I stuck into the slot between the dash bezel and the steering column bezel. The camera was carefully focused so that only the bargraph and MPG displays were in the field of view. I made a waterproof rear LCD video display and fed the video signal to the monitor. It was a bit too dark for full sunlight viewing, but was quite readable under most other conditions. I hated it. I felt compelled to drive in my most efficient way, since everyone was watching, and finally took it out for that reason. Now if I were a hard core hypermiler that always got super numbers, it would have been another story.This was before MIMA, so maybe I need to dig it back out?
As any owner will tell you, when you are pumping charge in and out of the pack with MIMA, it can get hot, especially in summer. The battery is cooled with a two speed fan that draws air into the battery pack from behind the passenger seat inlet vent.MIMA will force the two fans on at full speed when the temperature of the battery gets over 95F. I made a Turbo Cooler for my pack by ducting the passenger foot AC outlet to the battery pack input duct. I set the fan on high, and the duct to foot only. The driver side vent is ducttaped over, so that all the air comes out of the passenger side. The increased air flow helps a lot, with mild MIMA use, but if you are really pushing the hybrid ratio to the electric side, the pack can still get into the 100 F range. Because of the large thermal mass of the heavy batteries, it takes a lot to cool them even a few degrees. To Turbo Cool the pack, I wait till I am going down hill, so the power is nearly free, and turn on the AC to full, set to 60 F. A long hill and you can cool the pack several degrees.
Genesis One, LLC
If you would like to get involved or support any of these projects, please contact me at (860)935-5569.