Broken brush set by excessive amount of dirt

Replacing the drive axle rubber boot was a quite labor intesive task. I had not done it previously to any car so there were many new things to learn on the way. After a few late evenings both outer and inner rubber boots were replaced and Corolla was ready to hit the dirty winter streets again!

One day while driving my usual trip to work I suddenly noticed a clear lack of power. I was just getting on top of an uphill about 1km away from my workplace and tried to figure out what could have caused the power loss. As soon as I turned down the volume from the car's stereos I heard some loud whining. Luckily I was just beside a parking area where I rolled the car and walked to work. While rolling the car without the motor spinning the whining noise disappeared so it was pretty obvious that the motor was damaged.

After the workday the Corolla was towed to its garage to get repaired. All electrics were working nicely so I could concentrate on finding the problem from the motor.

 After removing the brush set cover it was easy to confirm that the motor was hurt. The commutator looked very bad and the smell of burned brushes was strong.

 Inspecting the removed brush set made it clear that the brush set was destroyed and it would not be able to be repaired. Brush springs had been cracked, conductors had detached from brushes and some brushes had been welded on their housings.

I crawled back under the car to see if the rest of the ME1003 motor could be rescued. Cleaning the motor and sanding the commutator strengthened my conclusion that this failure was probably due to excessive amount of dirt on the commutator and brushes. Possibly a small stone was the final cause of the sudden breakdown since the commutator had a deep groove that did not look to have been originated from any of the brushes.

My repairing plan is to purchase a new brush set and to sand the commutator back to its original shine. Also not to let this happen again I will build some air filtering on the back of the ME1003 motor.

While waiting for the spare parts to be imported I've been driving our gasoline Mondeo again. I miss driving the Corolla, hope to get it back on the road soon :)

First annual inspection passed

Corolla eFX has been in service for a full year now and it was time for the annual inspection. I knew the car was in good shape so I was not worried to have it inspected.

Time flew quickly as we discussed about electric driving with the inspector while the car was being checked. Everything safety related was ok so Corolla passed the inspection. A bleeding drive shaft rubber boot shown in the picture below was found though, it will be replaced soon.

It was the most pleasant inspection visit that I can remember, thank you Lempäälän Autokatsastus!

The car is now working very well and I'm using it every day. Daily driving is now a lot easier as the range of about 75km gives more freedom and I don't have to charge it everywhere I go:) I do not have much plans for upgrading it now, although I have to admit that I have though of different ways of increasing its power..

But in the meantime I will concentrate more on my open source motor controller: motocone.blogspot.com. Also during winter I am going to get more experiences by electrifying a small Stiga Garden lawn tractor using Motocone motor controllers and a couple of automotive alternators as its motors. This low cost project will be shared in: the-electric-machine.blogspot.com

Finishing touch for trunk interiors

The doubled battery capacity has made driving a lot nicer by keeping the battery voltages higher under load on these coldening autumn days. Increased driving range also gives new possibilities, such as visiting Tampere city (24 km away from home) without having to find a charging place ;) The functionality of the battery update has now been flawless so I am ready to cover the pack to regain a nice and clean trunk. 

First a simple cover was made from 12mm plywood. It is mounted to the battery pack housing with 4 30mm M8 bolts.

A new removable floor was made from 18mm plywood. A handle was cut in the middle of the plywood so that it can easily be lifted off to gain access to the spare tire space.

The battery pack cover was finished using black felt that was glued on top of the plywood and secured with staples from its sides.

Same felt was used to cover the spare tire space floor.

The spare tire space now works as a place for all the necessary items that I want to keep in the car but hopefully never have to use :)

The new plywood floor covers up the spare tire space with its items.

The original trunk floor felt was cut to fit on its place with the battery pack installed. It was glued to the new floor plywood for easier handling. Now the trunk looks usable again, with still quite a good space left for shopping bags.

 

Corolla eFX's first annual inspection will need to be done soon. I think the car is ready for that now!

Rear battery pack ready for work

Installing the rear battery pack is finally done and it is connected parallel to the front battery pack as shown in the circuit diagram posted earlier. The rear battery pack is electrically a copy of the front battery pack, but mounting it in the trunk is a lot easier environment than the engine room. In the trunk no waterproof encolures were used for the electronics.

This picture shows how the rear pack cable feed through looks from inside the trunk.

The first attempts to make a full charge resulted in a state where the Signalab PCM board blinked two leds next to each other and on the same time it switched its charge protection fets on and off with a frequency of approximately 1Hz. In this state the PCM kept its discharge protection fets off not allowing me to drive. The only way I could find out how this state could be resetted was by disconnecting the PCM from the battery pack. At first I had no clue what was happening and if I could rely on the PCM or not. I could not find a manual or functional description of this Signalab PCM so I did not know if it was some error state or if the PCM was broken.

I decided to double check the wiring if I had done some mistake that would have caused this problem. While checking I noticed that I had missed to install one blade fuse which resulted in a situation that the PCM did not have a connection to one of the cells in the battery pack. To make sure that the problem was linked to this forgotten fuse I charged the battery pack to get the fault state back again. Once the fault was active I installed the missing fuse and the fault disappeared. What a relieve!

Looking back I realized that the fuse was missing between the two cells whose balancing leds were blinking on the PCM. Without any proper manual or schematic I do not know if this was a designed feature of the Signalab PCM or not, but its a good indicator in such cases where connection is lost between a cell and the PCM.

After assembling the missing fuse the Signalab PCM has worked just like the one in the front battery pack. This regained my trust in it and I am hoping for a lot more careless kilometers just like with front battery pack alone.

The rear battery pack cells were not balanced manually in any way before use. The cells had a very consistent 3,3V reading so I decided to give the balancing task to the Signalab PCM board and see if it could handle it without having to help it manually. In the picture above the lit leds tell which of the cells are being bleeded by the balancing circuity at the time when the charger decided that the battery is fully charged and stopped charging. At this same moment the highest cell voltage I measured with my multimeter was 3,8V. I think a few more full charge cycles will be enough to make a good top balancing for the rear battery pack, just like with the front pack where nearly all balancing leds are lit just before the charger ends charging.

Things seem to be working as they are planned and I can enjoy driving with increased power output and efficiency due to lower voltage sag of the cars doubled battery capacity! Next step will be to cover up the rear battery pack nicely.

Installing the second battery pack

The second battery pack installation has been done in very small steps not disturbing the every day driving needs for the car. The pack takes about 1/3 of the space in the trunk which still leaves me with a good enough space for a few shopping bags.

 

The pack is mounted in a housing made from plywood. Each cell is attached to the housing bottom using threaded rods.

 This photo shows how much 24pcs of Winston LYP60AHA takes space from a -87 corolla hatchback.

Using this type of PCM causes a lot of wiring inside the batterypack. In here the cells are connected in series and the PCM's cell voltage monitoring wires are connected.

A 50mm diameter PVC tube was mounted under the car to the place where the exhaust pipe and gas tank used to be. The tube acts as a conduit for the rear battery pack cables.

Power and control cables to the rear pack are fed to the spare tire space under the rear battery pack enclosure. Now all the hard work is done for the second battery pack installation. A few more late evenings will be needed to finish up the connections and to prepare for functional tests!

Circuit diagram update 8.8.2014

Adding a second 76,8V 60Ah battery pack to the trunk means changes also to the circuit diagram. The low cost LiFePo4 PCM (Protection Circuit Module) that I am using is not designed for parallel connected battery packs, so I got to design how they could be used in this case.

The schematic above shows how I am going to connect the batteries. The circuit is designed so that it fills the following simple rules:

1. Stop charging if overvoltage is noticed in any cell of either of the battery packs
2. Stop discharging if undervoltage is noticed in any cell of either of the battery packs

Once I have installed the new batteries to Corolla's trunk, tests will show if the two rules will be filled or if more changes are needed. Once the rules are filled I am expecting many more carefree kilometers just like it has been so far.

Corolla eFX will get double range

I decided to build a similar battery pack into Corolla's trunk as there is under its hood. Due to a temporary www.ev-power.eu stock shortage 24pcs of Winston LYP60AHA were ordered in a format of 6pcs LP12V60AH.

The LP12V60AH contains 4 LYP60AHA batteries, and as I want to have access into each cell I need to dismantle the LP12V60AH pack's. It sure felt weird to start cracking open these brand new finely packed 12V batteries! The picture shows all of the tools I used to open the case.

Here is a picture of the LP12V60AH with its cover removed. I think its a quite nice assembly:

To compensate the weight of the battery pack to be installed, I removed the gas tank (13kg) and spare wheel (14kg). This way the Corolla will gain about 30kg weight after the new battery pack is installed, but it will still weight about 20kg less than original.

Cycle Analyst installed

I found the Cycle Analyst while reading these great finnish EV-builders blogs:

http://kwsaki.blogspot.fi
http://electricfinn.wordpress.com

Thank you guys for sharing!

Having got positive recommendations of the Cycle Analyst, I was expecting for a nice product. However it still managed to exceed my expectations. I had reserved a lot more time to install the than what was really needed, and the useability is excellent.

The biggest reason for replacing my old led panel meters was to get an Ah measurement, but all the other statistics that the Cycle Analyst can give are also very nice to have. It is really fun and enlightening to see the Ah reading run while pedaling. Its even more fun when the reading runs backwards while braking!

Bad contact in ME1003 motor brush holder

One day when I arrived at work I noticed an unfamiliar smell coming under the hood. I thought the smell was originated from some insulation material that was overheated, so I looked through all battery terminal connections which seemed ok and did not smell at all. The smell wanished pretty fast after the car was stopped so it was not easy to find its source.

After one short drive when I once again tried to find the source of the smell I noticed that one of the motor terminals was very hot while the other one was cool. The terminal connections looked tight and identical so I realized that I'll have to search for the problem inside the ME1003 motor.

First thing to do was to remove the brush holder cover:

Quite a lot of sand can be seen on the brush holder. At this point no faults could yet be seen.

Next the brush holder was removed for closer examination. It was far easier than I thought, this motor is clearly made for easy maintainance.

Once I got the brush holder on a table the problem could be seen:

The terminal on the left had blackened due to a bad contact caused by a loose bolt. By smelling it from a close distance it could be confirmed that this is the source of the smell. The terminal on the right looks healthy and its bolt connections were tight.

I also noticed that the brush springs were all not identical. One of them was significantly weaker than the majority:

In the picture above two spring on the left represent healthy springs in my opinion. The one on far right had loosed its form possibly due to overhating due to the loose contact as that spring was located on the brush closest to the overheated terminal. I tried to give back its original form but not with a very good result. As my brushes are still quite new the sping force on their current position is quite good also with the damaged brush spring. But as the brushes get smaller the damaged spring will not be able to deliver the designed amount of force, so I'll have to keep an eye on this.

To get back on the road I replaced the overheated bolt and nut and cleaned the contact surfaces:

The picture above shows the result of the repaired contact. I also checked the tightness of all other current carrying bolts and I would consider that 40% of them were too loose! After tightening all of them I reassembled the motor and I've been driving again with no mysterious smells;)

Knowing that I have a weak brush spring and that the current carrying bolt connections can get loose again I searched the internet for others experiences. I was more that happy to find this link:

http://evmc2.wordpress.com/2012/11/17/motenergy-brush-holder-me0804-rev-a-dept-of-a-closer-look/

I am seriously concidering of ordering that improved brush holder version with those welded connections and larger buss bars. It seems like an excellent solution for my brush holder situation!

Time for summer tires

It's been a long wait for the days to warm up as summer gets closer. Hoping for no more freezing days this spring I changed summer tires.

The car has worked great! No brakedowns and the only maintainance has been keeping the tire pressures high to keep the rolling friction low.

Corollaefx has now done 3900 km electrically and it saves me about 100€/month compared to a gasoline driven 2002 Ford Mondeo that I used to drive. These savings are based on calculating gasoline vs. electricity cost and smaller insurance and tax costs.

The co2 emissions have most likely dropped only to a fraction of the Mondeo's 185 g/km as most of the battery charging is done at the moment at home using hydropower purchased from Suomen Energiayhtiö.

Winter came eventually

The temperature has been between -15..-22degC for a week now and I got the cold driving experiences I was waiting for. I installed a simple indoor/outdoor temperature sensor in the middle of my battery pack to see what happens there while driving. I learned that the temperature rise was about 15..20degC so the temperature would climb up just above 0 on a -15degC day.

With such low temperatures the battery pack was struggling to keep up the voltage during uphills and I had to be patient not to give too much throttle or the battery voltage would have dived below 50v and the BMS would have cutted off for sure. As there was less than normal power available from the batteries due to their temperature it was hard to keep up with the traffic at some points.

To improve the situation while the cold weather came here to stay, I decided to seal the engine room and insulate the battery pack as well as I could.

I used bubble wrap to insulate the battery pack. Then I blocked the airflow from the engine room using foamed plastic (the gray sheets in the pictures). I also covered the bottom of the engine room from all bigger holes.

This had a dramatic positive effect for winter driving! Today morning the outside temperature was -22degC and the battery temperature was +4degC when I started my every day work trip from garage. When I got there the battery pack temperature showed +22degC and the battery performance was close to what it was in summertime!

Another positive surprise was that when I went to lunch four hours later the pack's temperature showed still +15degC while the outside temperature was 30 degrees less!

I think the rest of the winter will be easy driving unless any super freezing days will be ahead.

Almost forgot; when I reached work the car's cabin temperature was -12degC.. To fix this I ordered a new warmer hat and a pair of gloves ;)