Twike 434 in Portland, Oregon

Back on the road again!

2011-05-11T17:18:00.000-07:00

Last night I finished buttoning up both packs after soldering in all the connection wires between the groups of cells and adding in a fuse holder to each pack. I also had to create new carry straps. My first design was a fail as it had metal catches and was designed to be used for a load tie-down. Unfortunately, there is not enough room between the batteries for this to work properly and I nearly had a situation where I get to batteries in the car and could not remove them. After some thought, I went back to the original Twike design which is a knotted loop of rope. I did do a wrap of duct tape on top and bottom to prevent it from dislodging. That worked great. I charged the batteries for the first time and did some tentative drives around the neighborhood. I don't think the cells are balanced yet as they are in various states of discharge when I joined them. The car will do a balance charge when doing a normal charge (jog charge is at a faster rate and avoid the balance phase). I put on 8 miles in the evening giving my kids rides. If it all goes well, I will put in the back shelf cover and try to drive it to work tomorrow (about 16 miles round-trip). If that all goes well, I will attempt to take it to the OEVA meeting in Portland tomorrow night. Only about 9 miles or so but I do have a elevation climb of about 1200 feet (at night with the lights and wipers on :-) Wish me luck.

Pack Assembly

2011-04-20T09:24:00.001-07:00

I've spent two sessions now with the battery tab welder. The first was to create 5 cell groups. I then had to take the 5 cell groups and bend the tabs so the cells were end to end. I used a PVC pipe from Home Depot which was a slight oversize on the cells to assist in aligning them when bending the tabs. This 5 cell group was then wrapped in a tough 5 mil heat shrink to form a "stick". I assembled all these sticks (112 of them) into 4 stick groups. Each of the 4 stick groups has two tabs welded to the bottom, and 3 on the top. It was difficult to find, but I finally found a place to get 10 mil nickel tabs (and did not force me to order 5kg worth). Previously, I could only get 5 mil tabs which I think are a bit small for the top and bottom tabs as they see much harsher physical stresses. I checked each of the groups with a voltmeter and all were within 0.2 volts of each other. This means I have no dead cells (opens or shorts). I did build 2 extra 4 stick groups in case I need to swap them out and I will keep them as a future spare parts. What remains is to install the 2 new Battery Management Boards, install the removable fuse, replace the cover (may think about replacing the fans as some point as they do not move much air) and test the packs in the Twike. I hope to be back on the road soon (and just in time as gas heads for $4/gallon). Expected range will be 30 to 40 miles per charge. I might think about building a mount for my third pack as well as the car supports it (program BMS to bat3 and plug it in). I'm concerned that packs of mixed capacity might cause the charger some problems but maybe not as it can open the charge relay on a per pack basis. I'll leave that to a future project.

Battery Tab Welding

2010-12-29T19:53:00.001-08:00

In the last two days, I have battery tab welded 600 cells into 5 cell groups. The 5 cell groups need to be arranged cell end to end and shrink wrapped. I will do some basic testing to catch any bad cells before going farther. Then, 4 sticks make up one group of cells and I need 14 groups for each pack (560 cells total for the two packs). Once I have that done and two working BMS boards, the Twike will be back on the road. I decided to stop trying to fix the bad BMS boards and just order two new ones from Germany. I'm expecting them shortly. The cells are the "no longer made" SANYO CP-3600CR. I found a place to buy most of their remaining stock for about half of what digikey wants.

Fall Update

2010-10-04T09:31:00.001-07:00

I've been busy with other projects but it is time for an update. My twike has set idle for the last 12 months while I sort out battery issues. The old NiCad cells from 1985 are pretty much shot but I have put together (after much testing) two packs with the best cells from the 5 packs I have. Unfortunately, while installing the packs into the car, I shorted out one of the NTC temperature wires on the mid pack fuse resulting in damage to the BMS board. The car will not charge without two (min) working BMS boards, so I'm down until I get that fixed. I finished my testing of A123 cells and found them of high quality and quite reasonable to work with. To make them work with the car will require me to design or purchase a factory BMS solution. To date, this is more $$ than I am willing to spend, so I'm exploring selling all my lithium batteries, buying replacement NiCad cells, and replacing the battery cells myself. The DeWALT LifePO4 packs are now up on ebay.com (selling slowly) and I found a great deal on 3.6Ah SANYO C size NiCad cells (no longer made). I bought enough cells to replace 4 packs with the idea of doing my two packs and 2 packs for a fellow Twike owner in the USA. He agrees with me that the cost of the lithium upgrade when bought from Europe is just too expensive at this time (most of the cost is importing the cells). Next steps are to fix one of the broken BMS boards (or order a replacement from Germany for >$500USD), then begin the process of replacing all my old Panasonic 2.8Ah cells with the new SANYO 3.6Ah cells. I have friend who has a battery tab welder (makes his own A123 packs) who will rent me time and I just need to order some more Nickel tabs (only have 100) and thermistors, some shrink wrap for the cells, and it will be time to perfect the art of pack creation. I hope to have the packs refurbished by the end of the year (given time constrains).

Jan 2010 update, part 2

2010-01-03T22:44:00.001-08:00

More battery pack construction. Here I am balancing groups of 8 cells. I'm connecting 5 eight group cells in parallel so it results in groups of 8s5p. I'm using the Chargery DB8 balancer and a lab power supply to charge the cells. Only takes a few minutes to achieve a full balance as these cells are brand new. I'll do some full charge/discharge curves on each group of cells before putting them into the pack to identify any cell defects upfront. I'll have more pictures and descriptions as I get further along on the pack construction. I can not tell you how careful you have to be with metal around these very powerful cells. I remove my wedding ring when I work and have a fire extinguisher handy to deal with any meltdowns. Also, note I place the cells into a fire safe container even though it should not be possible to get these cells to burn (safe LiFePO4). Also, I've got 70 8 cell Dewalt DC9280 tool packs to harvest cells from so it will take a while.

Jan 2010 update, part 1

2010-01-03T22:23:00.000-08:00

I drove the Twike more almost all of my driving in July and August (>800 miles on the odometer now). Unfortunately, very hot temperatures (>104F), some long drives (>15 miles), and some other circumstances resulted in several of the old Ni Cad cells shorting out (death for a Ni Cad). Thus my two 12-13 year old packs were unbalanced and would not charge correctly anymore. With the start of school in September, I parked the Twike while I resumed driving my gas car and plotted the repairs. My first attempt was to charge and discharge all the 20 cell groups to locate the bad boys (which I did) and to attempt to fix them. The easiest way is to charge/discharge candidate groups of cells and measure the capacity of some other packs to locate a candidate group of cells. I was able to do this after a month or two of testing. I replaced one group with the new group but the BMS in this battery failed to come up in the car after I placed it back in the car. Not clear why. In frustration, I swore to give up on trying to use the old Ni Cad cells and move on to my A123 M1 lithium cells. To that end, I finished the design of the pack and over the Christmas holidays, I drew up the design for the new battery packs. I went over to Tap Plastics (right at the start of a big snow storm) and picked up parts needed to build them. Two days of construction and the new packs are done. The picture above is a test fit of the two new battery packs (just the plastic boxes) into the car with the old batteries removed. Fits perfectly with not even a 1/16 inch to spare. I like the very secure fit into the old battery wells. I using ABS plastic. I went with 3/16 rather than 1/4 because I want to maximize cell area. I hope this is strong enough to survive heavy bumps with the cells inside. I'm now into heavy battery pack construction. My goal is an exact replacement for the old packs but with LiFePO4 cells (A123 M1 cells). I'm planning on a 112s5p configuration with the 2.3Ah cells which works out to 4.24KWH pack and a range of 50 to 60 miles (assuming 60WH/mile).

600+ miles on my Twike

2009-08-17T21:04:00.000-07:00

I'm at 664 miles mostly commuting from work to home and back. Some of the trips have been to downtown Portland in the evening to attend a OEVA meeting which makes for about 36 miles a day (with two charges since my range about 20 miles). Yesterday, I went for a hike in Forest Park with my son Paul. We picked out a nice starting point, drove the Twike there, did a nice 2.5 hr hike and drove the Twike home (10 miles round trip and lots of elevation gain). A true green activity since I charge with 100% renewable electricity from PGE at home. On a more technical note, last weekend I replaced the differential oil with a synthetic brand. This seems to have fixed a lot of the noise problems I was having at 40-50 mph. There is still some noise but much less. I may still need to look at the motor mounts and see that they are lined up and tight. I think next on my list is to fix the canopy from opening so far that it hits the plastic windshield. Over time I think this contributed to is loosing its grip/glue on one half. I still on occasion have problems with the speed sensor going out, mostly when its hot and usually after lots of regen (like on my trips into Portland). Pulling over for 2 minutes and restarting seem to fix it for now. I have email from a friend in England who suggests the speed sensor needs adjusting and gave me details on how to do it, but it is involved and may involve dropping the motor/differential. Not a 5 min job. I have driven every day to work since July 1 except for 3 days when we had 106 or near 106 (really high temps mess with the charging), when I went to Boy Scout Summer Camp (drove my gas car, ugh), and went to Florida on vacation (took a plane!). Every day it gets more and more natural to drive and a gas car feels more and more foreign when do I drive one. My Lexus needs a 90k service and it may be its last ;-)

My Twike meets its first Tesla

2009-07-11T21:33:00.000-07:00

Today was the OEVA EV Awareness day in Portland, Oregon. We had vehicles of many types from conversions, to factory production vehicles, to motorized bikes. I was there all day with my Twike since I can now drive from my house to downtown and back and I'm also part of the OEVA group. What made my day though was when a Tesla showed up. The owner is David Stiers who you may remember as the actor who played Charles Winchester on MASH! It turns out his is retired and lives just south of Newport Oregon. He heard indirectly that there was something happening today in Portland around Electric Vehicles and thought it would be great fun to show up. He found our web site and just took it upon himself to drive the 130 miles from Newport to Portland (good to have a Tesla with 240 mile range). Thus this afforded me several things. One, I got to meet him and a fine gentleman and in good humor he was. Secondly, I got to see my first Tesla in person after reading about them for ages. And thirdly, probably not the first but one of the few shots of a Twike and Tesla together. I have a 2kwh pack in the Twike and can go 20 miles, the Tesla has a 50kwh pack and can go 240 miles (and of course top speed is 150 miles per hour). I have him in efficiency but he has me in every other category (except luggage space, I think I win there). Thanks to David for just showing up as he is one of only 3 Telsa vehicles in Oregon (so I hear). In regards to the Twike, it is doing great and it getting regular use as I drive it to/from work everyday.

2009-07-10T01:12:00.000-07:00

Today I put on 36 miles (a new 1 day record). I drove the 8 miles to/from work and worked out at Bally's during a late lunch. I zipped home and did a quick top off charge so I could drive all the way to downtown Portland for the monthly OEVA (Oregon Electric Vehicle Association) meeting. Coming home was kind of a challenge in that it is 10 miles, climbs over 1000 feet in elevation and I had it do it with my lights on which suck more power. No problems and I made it with about 30% battery power remaining. With 12 year old NiCad cells, I am not quite sure how much capacity I can rely on. BTW, the picture is of my license plate "Oregon TWIKE". It is a motorcycle plate because in the state of Oregon, a Twike is licensed as a motorcycle.

Daily Commute started on July 1, 2009

2009-07-02T21:24:00.000-07:00

Starting yesterday, I am doing my daily work commute via the Twike. The missing piece was getting a second battery pack working well. I drove yesterday and today to and from work which for me is just under 8 miles. I don't yet have a good feeling for how much power it is taking to do my commute but today it only took 1.2Kw to charge it when I got to work (and that was after it ran the fans for a while to cool the batteries). The NiCads can deliver lots of power but they do heat up in doing so and right now we are having a heat wave in Portland which does not help. I got lots of thumbs up and waves today. One guy was keeping next to me and yelling out his open windows. "hey! really cool. Where did you get it? Did you build it?" that kind of stuff. Kind of hard to drive and answer questions in traffic. Work is cool about letting me charge there (used 12 cents of power today). I'm not sure, but I might have enough charge to go roundtrip without charging at work. Tomorrow I'm going to try a trip to someone's house that is 13 miles away so we will start to test the range a little more. Currently, my longest single trip is the 8 miles to work. Since I brought it home, I bought 3 new tires, had them mounted and balanced, and I installed them on the vehicle. I also did a lot of cleaning up in the battery compartment and on all the removeable panels (bottom and sides). With two reasonable battery packs, the car is pretty snappy on acceleration. I can keep up with traffic no problem and can even hill climb at a reasonable rate (not as fast as a car but at least I *can* accelerate uphill now). I have been taking a less direct route home to minimize the hill climb time (I climb the hill by winding through a neighborhood as this allows me to drive slower without annoying anyone). On the way to work however, I go straight down the hill with regen on full sucking amps back into the batteries. Tonight my odometer read 204 miles. Expect a lot more miles in the weeks ahead.

Home at last

2009-04-27T12:08:00.000-07:00

Last night I drove the TWIKE 8 miles from Northwest Portland to my house for the first time. It had to climb over 1000 feet in elevation. This was a real test of the 2nd battery I got working and only the second charge cycle on that battery. I know from experience from the other batteries that it takes several charge cycles to wake up the 10 year old NiCad cells. I expect the range now with two batteries is around 15-20 miles on level ground. I am working on a third pack that should extend that to nearly 30 miles. I have lots of other small things to work on and some larger ones. I need to replace all three tires. I noticed that one has large cracks (not surprising for a 10 year old tire). This must be fixed before I can consider much serious driving. It was amazingly stable at speed and at one point I think I was exceeding the speed limit without realizing it. EV grin here I come!

Legal to drive in Oregon

2009-04-03T17:17:00.000-07:00

Today, I found an Insurance agent that would insure my TWIKE and not just for liability, but for collision and comprehensive as well (all at motorcycle rates which is far cheaper than any of my cars). Once I had insurance proof in hand, I stopped by the DMV and applied for a title (including vanity plate). One big smile later, I had a 3 month temporary sticker in hand ready to apply to the back window. Look out, I'm fully street legal with no inspection required.

First 5 miles

2009-03-31T11:49:00.000-07:00

Last night I put in the second battery pack I put together with the old Ni Cad cells and one of the 5 tested BMS boards. I was able to set the controller to 2 batteries, download new BMS software from the controller (it did not like seeing 5.24 BMS software when it is 5.1), and do a normal charge to top off the batteries. I put air in the tires, cleaned the outside of dust, and took it for a spin. I gave rides for the better part of 2 hours until I felt I should charge it up again. The odometer read 5.1 miles! I noticed that one pack is stronger than the other as one was supplying more of the current and took more current on the recharge. I'm thrilled that the charging system works as well as it does. I have so much more technical understanding of the entire BMS/BATTERY/CONTROLLER system now that I have debugged all the problems bringing up these old battery packs. I estimate each pack is about 2Ah (2.8 originally) and that puts me at about 16 mile range for the two packs. I should be able to build up the third pack in the next couple of weeks which should get me close to 25 miles of range per charge. This should be enough for my daily commute while I work on getting my lithium battery built (expected range 40+ miles). I'm thrilled! I still have a long list of little things that need attention including the seat belts (retractors are sticking .... may replace seat belts), wood steering handle is split (patch for now), one of the plastic panels under your feet is broken (someone stepped on it while it was out of the car), etc. Also, I need to start the DMV/Insurance stuff now so I can get the vehicle home from Northwest Portland. If all goes well, I will be able to *drive* it home.

First Success!!

2009-03-18T20:49:00.000-07:00

On Monday night on March 16th 2009 I put my partially charged reconditioned battery pack in the car with the intent of having the car charge it. Even though with level 2 access I could tell it it only had 1 battery, I could not get it to charge the battery. Then I tried just powering the car. It worked. I was able to put the car in reverse and move the car a few feet! I am working hard on getting the second battery pack reconditioned enough to get about 2Ah out of it which should be good for about 15 miles between the two packs. This is assuming the car will charge them full up. I should know in another week or two if this is possible but it was great to see the car move under its own power. I continue to work on my lithium based design which will eventually replace the Ni-Cad pack.

Latest update on Twike restoration

2009-03-06T12:02:00.000-08:00

I have not posted since November, 2008. Sorry about that. Here is a summary of what has happened on this project since then. I purchased the rest of the A123 M1 cells I needed for $5.50/cell. I have 450+ cells now. I have been looking at BMS designs so I can protect these cells (they need to stay between 2.5 and 3.7 volts for best life and safety). Apparently, this is an area that is lacking in good off the shelf solutions. I will either need to pay lots of $$ for a solution (i.e. more than the cells themselves cost) or build my own so I can customize it to my specifics. As part of this effort, I have a demo board of the Linear Technologies LTC6802 chip. It seems to function with my testing so far but I will have to add up the cost of the parts to build a functioning BMS (shunt based design) to see the true cost. In the meantime, I started to do a serious attack on the TWIKE battery BMS setup. At this time, I am not pursuing the software based BMS any further as it became too difficult to see what was going on to try to emulate it correctly without any working real BMS boards. I turned my focus to the hardware itself and will the help of a friend at work, we got 5 working BMS boards to talk to the service program. I also located a disassembler for the BMS software to get a better understanding of how it works. That was fun as I looked at 3800 lines of assembly code! Over the last 30 days, I have been doing charge/discharge cycles on one of the best looking old NiCd packs. I was able to restore about 60% capacity by cycling the old cells. Last night at Synkromotive I carefully soldered back in a working BMS board (14 temp sensors, 7 voltage monitor wires, 14 cell to cell connections, 1 power connection, 1 RS485 4 wire communication connection). As I wired up the last connection, the board red led started blinking! After connecting it to the car and putting the car in charge mode, the car downloaded BMS software to it and began to read out the battery pack voltage! This proves the car charge/controller system is working properly and the other battery pack I was trying to charge has a bad BMS. I also discovered how to get into service mode on the controller (TWIKE Access Level 2). This lets you set all kinds of good stuff on the controller including the number of batteries. I tried setting it to 1 battery (which I did not know was even supported) and it seems to be working happily with 1 battery. When I tried to charge the battery, it complained that the battery was too hot (77 deg C). Clearly, I messed up one of the temp sensor solder joints. I'll have to run the service program to find out which one and fix it before trying to charge it for real. Next steps are to put another working BMS into another candidate battery after I do the battery testing to make sure the cells are good. With two old tired batteries, I should get 10 to 20 miles of range (for testing) while I work on my Lithium solution. I'm thinking 112s4p would be a good starting setup. Even with LION cells and my own BMS for Low Voltage Cutoff and Shunt Based overcharge protection, I may integrate 1 or 2 old BMS boards to make it trivial to keep the onboard controller happy (Both on charge and discharge). A hybrid solution may be the path of least resistance. We'll see. Stay tuned for more.

A123 Lithium Battery Testing (DC9280)

2008-11-18T11:26:00.000-08:00

Last night I decided to start testing my lithium batteries in preparation of building a battery pack for the Twike. I have a RC Electronics Watts Up Meter and a West Mountain Radio Computerized Battery Analyzer. I previously found a way to purchase A123 M1 cells (new) in dewalt packs for $6.50/cell so I have 120 cells to build my first pack. I'm going to go with 112 batteries per pack in series (112s1p) to best match the voltage requirements of the Twike, and then parallel multiple packs to get range. The old setup with NiCad batteries was 280 cells in series. That gave a lower voltage cutoff of 280 volts (1.0v/cell) and a upper charge limit of 420 volts (1.5 * 280). In my case, the A123 cells wants a upper charge limit of 3.64 volts so my 112 cells will need to reach 408 volts to fully charge. The low voltage cutoff for a A123 cells is 2.5 volts so this works out to 280 (which happens to match NiCad). So, that is my design target. I took apart my first pack of 8 cells using a T10 security bit (get a long skinny one or drill part of the case). I clipped off the two black wires and one red wire to the internal BMS which I am not going to use. After disconnecting the per cell balancing connectors, I could extract the cells. I had charged them once on the standard Dewalt charger so I knew the cells were all reasonably ok. It will detect and fail to charge a pack if any cell is below 2.5 volts (a possibly harmful condition for a cell if that way for long). A quick check with a meter showed them all pretty close in voltage. I did a 3 amp discharge down to 20 volts (2.5 * 8) to measure cell capacity and see if I had any bad cells. Came out to 2.1 Ah (and 52.8 Wh) which is fine given I did not have it on the charger for several weeks. Both CBA and the Watts UP meter gave the same numbers for Ah and Wh delivered from the pack. I then measured each cells voltage and found them pretty close. No need to do more balancing. I then used a regulated supply to charge the pack back up to 29.12 volts (8 * 3.64) at 3 amps. Took 58.4 Wh (2.156 Ah) to charge it back up. Looks good to me. Now on to pack and BMS design and purchasing more lithium packs. NOTE: I figure the Twike uses about 80Wh/mile so that one pack of 112 cells gives me about 10 mile range (and weights about 17 lbs). I'd like to get to 40 miles range to cover 98 % of my daily trips so I can use it to commute daily to work so I'm looking at building 4 packs (with 448 cells).

Twike BMS emulation in Software

2008-11-18T10:40:00.000-08:00

It's been a while since I have posted, but I have not been idle. I have just about given up with trying to get the old BMS boards working (looks like a marginal design when exposed to the elements of the batteries). I'm not sure I have any working boards out of the 5 I have. But, because I must get 2 BMS boards (or something that looks like them) to get the Twike controller firmware happy, I decided to play to my strengths and write a software emulation of the BMS. Documentation of the protocol is non existent from the manufacturer but I found a german open source project doing some of the same things to support running Lithium-Ion battery packs. Armed with a RS485 converter, the knowledge of the fact it runs at 2400 baud and a reference code base to answer some of the hard questions, I coded up a program that allows me to emulate all the operations of the firmware based BMS. I should test it this week now that I am done coding it. If this works, I will be able to try putting a partial charge on one of the battery packs and drive the car around the block. Also, I can verify all the electrical devices and switches and see which need more attention. Also, I have the twike service program (version 3.6) which is a DOS application that does all kinds of magic in talking to the BMS. To debug my program, I installed vmware server and booted DOS 6.22 on a floppy image. I installed the service program to the floppy image and could then run the service program in a window talking to a COM port. Next, I downloaded a trial version of "Virtual Serial Port Driver". This program creates pairs of COM ports connected via a virtual null modem. This lets me connect the Twike DOS service program to my C# BMS emulation program. Very cool. When I was done, the service program was completely happy so I hope the controller in the Twike will be also. Highly recommended technique.

Status Update on batteries

2008-10-06T20:54:00.000-07:00

Status update. I've got more batteries (up to 4 or 5 sets now) and 3 BMS boards not in batteries. I've got two batteries that appear at first glance to at least work (red LED flashes) but one of them has many broken battery connections. I got my rs485 to RS232 converter working (had to supply 9v to it) at 2400 baud and running the Twike Battery service program, I can see real BMS traffic between the controller and the batteries. Unfortunately, I'm still stuck at the controller trying to download BMS software state. I suspect both of my working batteries are programmed to the same ID. Once I get my setup able to transmit over RS485 (just passive monitoring mode for now), I'll try setting the ID in both boards and see if that make the controller software happy. I'm getting to be a real expert on all the electrical wiring in the vehicle (I've decoded much of the BMS board and most of the system board). I also just found a way to order A123 M1 cells for about $7/cell so I put in a big order yesterday (should arrive next Tuesday). I've decided to go LiFePO4 and A123 M1 cells seem to be the least risky cells to get (not the cheapest but I don't want to risk dropping lots of $$ on TS or other cells only to have them die in 3 months). The EV Discussion List is always bringing up the TS group buy disaster. I've just about got the German battery service program translated to English making the job of testing batteries/BMS board and reverse engineering the BMS protocol much easier.

More on charging

2008-07-29T22:37:00.000-07:00

I've been busy and have not blogged my progress lately. I'm trying to get a second working battery (which the TWIKE firmware requires for operation) to be recognized. At this point, I have tried two different BMS boards in three batteries to no avail. I'm afraid the BMS is bad in both batteries. Not surprising given the amount of stuff I found growing on them (mold, etc). I'm stuck with either pulling the BMS boards and doing a component level debug or trying to swap for some other unknown batteries. Not sure what I will do. I did get my order from digikey which gives me a set of connectors for all the 3 connector types used by the batteries. With those, I made a set of extension cables so now I can debug the batteries outside the card. Very handy and much safer I might add. If anyone wants the digikey part numbers for the connectors drop me an email (I'm also in the process of setting up a english based wiki for the twike where I can post such technical details for other to find and to share). More on that when I finish getting it setup. I now also have the means to spy on the RS485 bus to decode the BMS protcol. This is all in advance of attempting to build my own Lithium based battery pack (will have to emulate BMS responses to make car firmware happy). I have the battery service program which will give me a let up on decoding the protocol. The program is all in German but I'm part way through in translating all the screens to english. I'll post that on the Wiki when I'm done. So enough for tonight.

P.S. I'm on vacation for the next 3 weeks so I probably won't have any updates for a while.

Charging update

2008-07-21T20:26:00.000-07:00

Last Saturday, my son Paul and I spent half a day working on the twike batteries. After several hours of charging, the Battery2 was at 320 volts and slowly climbing (a good sign) but Battery1 was only at 110 volts. A closer inspection revealed numerous cell venting events and the black areas indicated some fires. I assume these happened over the years when the previous owner tried to revive the batteries. I did get one cell to vent myself when I let a group of 20 cells draw 5A for 100 seconds while trying a technique to revive it. Ok, give up on that battery. We pulled it and decided to replace it with one of the spares that has good looking cells (clean ends, no discoloration) but is lacking a BMS card. I proceeded to drain all the cells to zero in the old pack before beginning the process of unsoldering the BMS to move it to the new batteries. A couple of hours later we had the old board out and soldered into the new battery. I put it back in the Twike and powered up and monitored the voltage. The charger/controller is very smart and will only apply a small current until the voltage comes up to about 340 volts. I'll need to get both packs to that voltage to get the built-in charger to give the batteries a full charge (410 to 420 volts). I'll either have to jump start the cells again (will less current this time) or be patient to see if the cells will get to 340 on their own with the charger. Peter Zeller from Switzerland has been very helpful in answering some questions about the batteries and such. At this point, I have no hope to make the battery pack have a useful range, but I just want it to get to the point I can check out all the operations of the Twike. I need to fix anything that is broken before proceeding. I might have a problem with one of the relays since I notice the DC/DC led stays on even after I push down the red button. The docs I have say this is supposed to remove all power except for the batteries themselves. If so, then why is the LED on? Oh well, more to learn.

First attempt at charging

2008-07-16T23:45:00.000-07:00

Tonight the epoxy on the console repair was ready to I mounted the console and switch panel back into the vehicle. At that point, everything was ready to power up for the first time. I was not sure what to expect as the batteries are 10 year old (Ni-Cad) and have been setting fully discharged for a long time. I plugged it into the wall and lights blinked, the fans came on, and generally it seems to power up. It put some error message in german on the screen and looped on displaying 4 different screens over about 3 minutes. Once I dug out the user manual, I figured out how to get it to speak English. It is complaining the BMS's need new firmware downloaded (yup, batteries were dead) and it was waiting for the 12V to stabilize. I let it run in this mode for a while to see if it would put any energy into the batteries in this state. The BMS in each battery runs of just the batteries so they have to have some charge to bring up the BMS. Meanwhile, I looked through all the settings I can reach easily and found it has only 58 miles on it. I guess that means not too many parts are worn out (except the abused batteries). After an hour of charge, I pulled the 120v plug and low and behold, it kept running for a while. After another 2 hours on the charger, I measured the voltage of both batteries with a meter. With 280 C sized Ni-Cad cells in series, the voltage is supposed to stay between 280 and 410. Battery 1 showed a voltage of only 90 volts. Battery 2 showed a more healthy 289 volts. I have two other batteries (one without BMS that I can take cells from) that with some luck will let me come up with 2 working packs. This would let me debug the rs485 BMS protocol so I can emulate it if I need to (if I go with Lithium). It also would let me try out the motor and all the electrical devices and see if they work. Not sure why it still thinks the 12v is not stable but may be because of the 90v battery. I'm going to try to build a set of cable extenders for the batteries so I can debug them outside the vehicle (much safer and easier). Please be careful if you are dealing with high voltages such as this. I bought some 500v lineman's gloves so I won't get hit with a fatal voltage if I get across the battery voltage while working on it. I'm off to look up Molex connect numbers.

Purchase and transporting to its new home

2008-07-14T22:14:00.000-07:00

On Friday night July 11, 2008, I finalized the deal to purchase a used Twike from its current owner. It was hot and the trailer was just the right size so that with a little padding it was safely on its way to its new home. If you ever need to transport a Twike, the 5' x 9' open trailer from U-Haul (the OA metal one) is a perfect fit. I measured it with a tape measure before I rented it just to be sure. I also used their blanket pads and a inner tube to cushion the Twike for the ride. Right now it is resting at the home of the nice folks at Synkromotive in Northwest Portland. They are the hotbed of EV activity in Portland! It's structure is solid but has a couple of problems. The batteries are shot (10 year old Ni-Cad batteries that were not properly cared for) and some minor parts need fixing/upgrading. The first step is to get some sort of working battery setup to see that all the electronics (controller, charger, battery management system, etc) all work. To that end, I will be trying to condense 4 bad packs into 2 working ones. Tonight I glued back together the two wood pieces that hold the display and keypad. I will reinforce it before I reinstall it to prevent the design flaw that caused the problem in the first place. Once that is done, I can reconnect the display and attempt to charge the existing battery packs. More photos in an album at Fotiki. I also scanned and uploaded photos taken in 1998 in Switzerland by Kent H about the time this Twike was built.