Love and Love

Dear friends and followers.

A lot has happened since the last post. I am now a married to the most wonderful, and understanding, woman in the world, Lisa Wildare. I Love you!

The car is back on the road after changing brushes, brush holder, installing a fan and limiting the current to the Agni.

After restoring the commutator I installed the brushes and set the timing. The default timing marks cannot be used and in order to find the new "zero" I used the following procedure.

Brush holder with brushes fitted by Joztek.
The cardboard helps during installation.

1. Attach the brush holder and tighten the screws just so you can move the brush holder with your hand.

Brushholder from Jozztek, fitted with screws to aid set timing.

2. Apply a low and stable voltage, I used 13.8V from a charger with supply mode.
3. Attach an amp meter to monitor the amps used by the motor.
4. While the motor is spinning, read the amp value and carefully turn the brush holder in either direction. Find the position were the amp reading is the lowest, this is our new "zero". Make a mark on the motor and on the brush holder.
5. Turn the brush holder against the direction in which the motor i spinning. I turned the holder 1.5mm. See the Agni workshop manual for more info.
6.Tighten the screws on the brush holder CAREFULLY!

Let the motor run for 20 minutes or so before steping on the gas.

After the timing was set and the brushes were run-in it was time for a test run. I made a configuration change to the Kelly before the first run. Max amp's was set to 360A. During hard acceleration I could feel the smell of hot brushes so I backed it down to 300A.

I haven’t had time to work on my water cooling of the Agni but I have a lot off fans laying around so I decided to make a cooling fan to the motor. There is not a lot of space left between the Agni and my batteries so I have to put the fan on top.

A (D1238B12B9) 12V fan capabel of pushing 5.25m3 of air per minute.

The fan sounds like an airplane when it's running. The plan is to use a thermal switch that will control the on/off of the fan. For now it's hi jacked into the circuit for the lights. I can't hear the fan when driving.
Air is pushed down in parallel to the Agni's rear plate. As you all know the Agni sucks air through the backplane and out through the stainless ring. In order for the air to get into the Agni I put a small piece Plexiglas in the bottom of the Agni.

The fan on top and the plexiglas in the bottom.

When the fan is running and the motor is still air is coming out under the car. When the Agni starts to spin you can feel that the air flow under the car gets weaker, the more RPM's on the Agni the more air is used for cooling. At max RPM almost all of the air from the fan goes through the Agni.

With the fan installed I hooked up my Ohm-meter to the thermistor in the Agni and went for a ride. The fan, in combination with lower the amps, is working fine. The Ohm-meter never goes below 10KOhm when the Agni is spinning.

Restoration

As you all know I got a bit too cocky chasing Porsches on the highway and the Agni had a brush meltdown. The first thing I needed to do was to get a new brush holder and new brushes. As it turns out one of my friends from the diyelectriccar.com forum is the distributor of Agni in Europe, www.jozztek.com, Jozztek has a deep knowledge of the Agnis and a lot of racing experience as well. I could not reuse any of the old parts so I got the brush holder fitted with brushes. Jozztek matches all brushes so that the voltage drop/resistance is the same between brushes.

Meltdown brush holder

New brush holder from Jozztek with matched brushes

Next thing on the list was to restore the commutator. When the brushes melted there was a lot of arching going on and the surface of the commutator, where the brushes connect, had to be refurbished. In order to refurbish the commutator surface I needed a "grindstone". Luckily I found a company just outside of Stockholm that specializes in DC-motors. www.karma.se has a wide range of brushes and tools for restoring electrical motors.



Commutator before resurfacing

You need to spin the motor in order to resurface the commutator. The RPM of the motor should be around 500 when using the stone from www.karma.se. Jozztek shared his bright idea to use the old brush holder and two old brushes to drive the motor during grinding. Split the brush holder in half and attached two brushes, one negative and one positive.

The Agni gives you 71 rpm/V so if you connect is to a 12V battery it will spin at about 800 rpm. Cut the grind stone so that you can fit it to the commutator. Use a vacuum cleaner during the grinding to collect the dust. You don’t have to apply a lot of pressure to the stone and you will feel when is working. Change position of the stone often and keep it steady.

Stop the motor every now and then and inspect the result. Don’t overdo it!

The picture above shows the commutator after it's been resurfaced. Next on the list is too fit the new brush holder and adjust the timing of the brushes.

Fried!

Just to show you what happens when you push the Agni above its limits:

I need to replace both the brush holder and the brushes. I need to get my foot of the gas and the water cooling in place J

This is a picture showing the armature of the Agni. I might have to prep the surface before installing new brush holder and brushes.

Street legal!!!

After two years of hard work the car is now done! I got "him" street legal today.



Performance modifications

I ran into an interview with the designer of the Agni 95R, Cedric Lynch, on the net and I found an interesting part about water cooling the Agni in order to boost performance. Now I know I'm not ready yet but this is FUN!
Apparently one can run about 50% more power into the agni if these steps are followed:

"It is possible to cool an Agni motor with water spray. The best place to spray is on the inner part of the armature opposite to the side the brushes run on, and you need about 40 millilitres per minute which you get from a 1mm jet fed by gravity with a 250mm head. Turn the water off before stopping the motor, so that it does not remain wet when it is not in use."

This is what I'm looking at right now:

The tank is located 250mm above the spray nozzle. The cooling water is controlled by a solenoid, normally closed. The solenoid is in turn controlled by a bimetal thermal switch, normally open, that triggers at 80C.

It just might work!

Test Drive

Hi all!

It's alive! I've been out on two small runs, only about 60km/h and it sounds and looks good. More data will be posted.

Here is a video showing the car in action:

 

 

Battery Installation

Battery installation

I wanted to get the batteries as evenly distributed in the car as possible. In fact it turned out that I didn’t have much of a choice when it comes to battery installation. I had one rule, NO BATTERIES IN THE BACK SEAT! So that leaves me with the rear engines compartment and the small space under the front hood.

4*90Ah

2*90Ah

Four batteries are to be placed in the back of the car, two on each side of the Agni. The other two are to be fitted just behind the front of the car, where the original 12v battery was located.

In order to support the 60kg's of batteries in the rear I had to design a support beam that also would act as a rear motor/gearbox support. I decided to make it out of aluminum since it is light and it doesn't rust. This also gave me a splendid opportunity to learn how to TIG-weld.

After hours of puddle control practice and 20 liters of Argon I started with the battery frames. These are made in 3mm L-profile aluminum and the will hold the two pairs of batteries togheter.

The two frames had to rest on something and after consulting a friend I came up with a design that consists of a support beam made of 6mm U-profile aluminum that stretches from side to side in the engine compartment.

Rear support beam

The support beam is fastened on both sides of the engine compartment and also has an "arm" that connects to the original motor mount found on the fiat.

The battery frames fits tightly into the frames welded to the support beam and pack straps will be used to keep them from moving up and down.

This is the finished support beam with batteries mounted.

The battery frames and the support beam have a total weight of about four kilos.