Grounded battery cable shields and thermistor
Battery boxes with lids
Showing posts with label battery boxes. Show all posts
Showing posts with label battery boxes. Show all posts
July 8, 2015
Signed, sealed, delivered battery boxes
The fit between the battery boxes and the frame was not 100% so I had to seal the spaces with sealant. As can be seen in the image below the shields of the battery cables are now grounded to the battery box. All battery and motor cables are shielded to reduce the electromagnetic radiation that appears due to the motor controller.The light grey cable in the middle is the thermistor that senses the battery temperature. The charger uses this information to stop charging if the temperature goes below freezing.
July 7, 2015
The project is on again - battery boxes mounted
At last some free time and the opportunity to continue the project. It has been a long winter with all work and no play ;)
Actually I started about a week ago, but my blogging is lagging as usual.
Anyway, yesterday I mounted the two rear battery boxes to the car frame. I used Casco Superfix glue and aluminum rivets to keep it together during the gluing.
Before I mounted the boxes to the car I made the battery holders that will hold the batteries to the box. According to regulations the battery holders (and and boxes themselves) must withstand 4.5 gs of vertical acceleration in case of a crash, which these do with substantial safety.
The holders are made from aluminum L-bars covered with heat shrink to minimize leakage currents in case of severe condensation in the battery box.
Actually I started about a week ago, but my blogging is lagging as usual.
Anyway, yesterday I mounted the two rear battery boxes to the car frame. I used Casco Superfix glue and aluminum rivets to keep it together during the gluing.
The rear battery boxes mounted
Details of rivets (and some sticky glue)
Before I mounted the boxes to the car I made the battery holders that will hold the batteries to the box. According to regulations the battery holders (and and boxes themselves) must withstand 4.5 gs of vertical acceleration in case of a crash, which these do with substantial safety.
The holders are made from aluminum L-bars covered with heat shrink to minimize leakage currents in case of severe condensation in the battery box.
One of the battery holders and a mount for the lid
The lid
September 18, 2014
Front battery box and connection
Time for the front battery box that goes on top of the motor. Also here I had to compromise due to space limitations. Instead of having 3x8=24 cells it will have 3x7=21 cells. So the total of the car will be 2x22+21=65 cells. The total pack voltage will be 65x3.2=208 V instead of the 218 V that I first designed for. This will reduce the range with 5% (95 km instead if 100 km) and the maximum power with 10% (72 kW instead of 80 kW). I think it will be enough though, the max power of the gasoline engine was 55 kW! It will also reduce the power of the heater from 4.5 kW to 4 kW. This is more of a concern in our cold country!
The battery box is bolted to the U bars using nut rivets.
There will be a couple of components mounted on the battery box. Today I mounted the front connection box which holds a couple of connections bars and the fuse for the DC/DC and heater. On top of the connection box goes the Anderson power plug by which the battery can be disconnected from the motor controller and other systems.
The front battery box with insulation
The front battery box is mounted on two 30x50x4 mm aluminum U bars which in turn are mounted transversely on the front bars of the Audi frame. The frontmost bar is bolted to the frame using nut rivets and the rearmost bar is glued and riveted to the frame. This way the front bar can easily be removed in order to remove the motor and transmission.The battery box is bolted to the U bars using nut rivets.
There will be a couple of components mounted on the battery box. Today I mounted the front connection box which holds a couple of connections bars and the fuse for the DC/DC and heater. On top of the connection box goes the Anderson power plug by which the battery can be disconnected from the motor controller and other systems.
The front battery box, the front connection box, and the red power plug
The + cable from the rearmost batterybox goes into the front battery box on the left and the resulting B+ from the whole pack goes out the other end (obscured) to the power plug.
September 17, 2014
Battery boxes
I had the battery boxes manufactures by IB Svets in Umeå. This is a small welding company specialized in aluminum welding. The boxes are made of 3 mm aluminum which makes them very sturdy.
I will glu and rivet the boxes to the frame. This way I will not compromize the frame by welding, and the combined glue and riveting will hold for accelerations of 44 g vertical and 210 g horizontal! This is a factor 10 compared to the requirements. Of course the accelarations to accomodate for are not achived by the motor, but from braking and rolling the car in case of a crash.
I will glu and rivet the boxes to the frame. This way I will not compromize the frame by welding, and the combined glue and riveting will hold for accelerations of 44 g vertical and 210 g horizontal! This is a factor 10 compared to the requirements. Of course the accelarations to accomodate for are not achived by the motor, but from braking and rolling the car in case of a crash.
The battery boxes are insulated with 10mm foam (camping mattress) to reduce the cooling in the winter.
First test mount of the rear battery boxes
The rear seats still fit!
And the trunk space is preserved
Time to grind the surfaces of the frame where the boxes will be glued
The boxes with insulation, connections and battery cells
The battery cables are kept in protective tubes. These are ordinary construction tubes painted orange.
The "drive shaft tunnel" has lots of space for the battery cables. The short black tubes are heat shrink that will eventually cover the cable glands
September 16, 2014
Space for the rear battery boxes
The most exiting thng that happened this summer was building the battery boxes. First thing to do was to cut holes in the car under the rear seat and trunk.
The A2 is built using a technique calles Audi Space Frame. It means that there is a frame of aluminum tubes that supports the load rather than a monocoque that is the common way to build cars.
The Audi Space Frame technology has been used for the Audi A8, R8, TT and the little A2. The advantage with the space frame is that the body panels do not take any load and it is possible to remove them without severely affecting the structural integrity of the car.
After making the holes I could measure for and design the battery boxes. It turned out that the rear axle and the frame bar are not aliged on top of eachother and this limits the front-to-back size of the box that is on front of the axle. I also realized that I need space for the connections to the side of the box so instead of having 12x2+5=29 cells the box will only accomodate 11x2=22 cells. My plans were to have 12+5=17 cells in the box behind the rear axle, but to compensate I made it the same size as the one in front of the axle. So, the net result is 44 cells instead of 46. This will shift the weight distribution of the car backwards, but I think I can live with that.
The holes for the rear battery boxes. Note the frame bar above the rear axle.
Here it can be seen that the frame bar and the rear axle are not aligned on top of eachother.
The A2 is built using a technique calles Audi Space Frame. It means that there is a frame of aluminum tubes that supports the load rather than a monocoque that is the common way to build cars.
The Audi A2 Space Frame
The Audi Space Frame technology has been used for the Audi A8, R8, TT and the little A2. The advantage with the space frame is that the body panels do not take any load and it is possible to remove them without severely affecting the structural integrity of the car.
After making the holes I could measure for and design the battery boxes. It turned out that the rear axle and the frame bar are not aliged on top of eachother and this limits the front-to-back size of the box that is on front of the axle. I also realized that I need space for the connections to the side of the box so instead of having 12x2+5=29 cells the box will only accomodate 11x2=22 cells. My plans were to have 12+5=17 cells in the box behind the rear axle, but to compensate I made it the same size as the one in front of the axle. So, the net result is 44 cells instead of 46. This will shift the weight distribution of the car backwards, but I think I can live with that.
November 4, 2012
The Audi A2
The Audi A2 is a compact MPV, or supermini, built by Audi during 1999 and 2005. The A2 was no big success to Audi. It didn't sell so good mainly due to its rather high price and the A2 program was shut down in 2005.
The reason for me to chose the A2 are several.
It is a cult car that was manufactured during a rather short time period and they are not so common.
The body is built from aluminium using the Audi Space Frame technology, which is the same as is used in the Audi A8. The aluminium makes the car light, which is good if you build an electric car, and resistant to corrosion, which is good when building on a car that has seen some miles on the road.
The A2 is a four seater with plenty of leg room in the back seat thanks to its height and just enough room for a couple of dogs in the rear. Actually the trunk space is the same as the VW Golf which looks like a larger car.
The cockpit feels almost like a bigger Audi from the time. The main difference compared to an Audi A6 is the smaller distance between the driver's and front passenger's shoulders.
Maybe the best known conversion of an Audi A2 is Simon Kay's conversion the he published as a series on Youtube.
The German company L.E. Mobile have converted quite a few Audi A2:s.
Please comment if you know of other A2 conversions!
The reason for me to chose the A2 are several.
It is a cult car that was manufactured during a rather short time period and they are not so common.
The body is built from aluminium using the Audi Space Frame technology, which is the same as is used in the Audi A8. The aluminium makes the car light, which is good if you build an electric car, and resistant to corrosion, which is good when building on a car that has seen some miles on the road.
The A2 is a four seater with plenty of leg room in the back seat thanks to its height and just enough room for a couple of dogs in the rear. Actually the trunk space is the same as the VW Golf which looks like a larger car.
The cockpit
The cockpit feels almost like a bigger Audi from the time. The main difference compared to an Audi A6 is the smaller distance between the driver's and front passenger's shoulders.
The trunk
The trunk
The back seats fold up and reviel a pretty large space.
Underneath the back seats is the gas tank today. A battery box will go there instead.
Beneath the trunk is the muffler and the 12V battery and tools box. Another battery box will go there.
I'm sure I won't get a job as a 3D artist after this ;-) but I tried to show the two rear batttery boxes in a 3D drawing (Jörgen, forgive me ;-). The exact space is still to be measured, but I think they will both hold one layer of standing CALB CA100FI (100 Ah LiFePO4 cells) which are 22cm tall.
The original 12V battery will be replaced with a smaller one, maybe located in the double floor in the front.
The rear batttery boxes
The rear battery boxes from underneath.
In the front I plan to put another batttery box, right where the radiator is today. I'm hoping to get enough height to have two layers of cells on top of eachother there.
The front battery box. Note that the hood is taken off.
You don't open the hood on the A2, you take it away! Instead theres is a small service hatch that is used to check oil and fill up windshield washer fluid and coolant. I might put a charger inlet there instead :-)
The service hatch.
The double floors in the front seat
The double floors in the front are great places for putting stuff away since the engine compartment is quite small. The depth is about 15cm. Today there is the ECU (Engine Control Unit) that I might try to get rid of. It won't have an engine to control, but it might be involved in other activities as well.
In the back seat there is no double floor.
The back seats passengers have a much more upright position thanks to the deep floor. Behind the back seat passengers foot box is where the space for batteries start (which is now gas tank, rear axle, muffler, tools box and 12V battery).
In the back seat there is no double floor.
Other Audi A2 conversions
The German company L.E. Mobile have converted quite a few Audi A2:s.
Please comment if you know of other A2 conversions!
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