I measured space under the hood and made a model of front box cross section to give me a feel how high the box will sit under the hood.
I found out i have like 4cm of space above the engine space, since the hood is curved upwards a bit. So i decided to designed a box in full height 28cm. That will allow me to install the Volt batteries standing. This will take less space up front.
But in the end i had to account for the front curves. I must be able to replace the light bulb and service the connectors there. So i decided to take an edge off from the right side of the box. Material will be 3mm aluminum.
While i am getting the box made i designed the fittings and frame to install the box.
The simplest method would be to simply weld an inverted U channel into motor space. I decided against this since then this would restrict access to component dissassembly in case i should need to take something out.
What i decided on is the right angle fitting welded on to car frame with a bit of console on both sides.
Console will accept U channel frame fastened by M8 bolts and that will carry the weight of the front battery.
On to the U channel and under the box i will adapt a straight brace to carry the weight and keep the box in correct (slightly canted forward) position.
The box will be fastened to the brace by M6 bolts with countersunk heads so the box will have a smooth surface inside.
The front fittings will carry another U channel, but box will lie on it directly. I welded that with my new MIG inverter welder with flux wire. I consider the process rather easy. The device is easy to setup. 0.8mm wire is elegant and good for most sheet metal. The only real problem is flux emits a lot of smoke that shields the arc. This remains on the weld as ash that has to be cleaned off after. On the pictures you can see the difference before and after cleaning. Otherwise the welds are strong and good looking.
I got battery box home.
The 60mm x 60mm dent in the right side will allow me to still get access to right light to change the headlight bulb.
EDIT: I figured i will have to modify the dent some more. I will make it 60mm x 120mm so there would be more space around the box.
I made both braces from U channel slightly larger than welded fittings. This will brace the box and i use them to accept bolts from the box. I made a lot of holes for M6 countersunk bolts. This allows me to still keep relatively smooth box floor. Also i used another bent sheet to support the box at correct height. This allowed me to have the fittings welded easier, much lower and with more support on carrying member. I bolted all holes together and welded the nuts on the underside so i only have to access bolts from the upper side. This greatly helps with dissassembly.
The shock brace however seems that will be very close fit. I am thinking of cutting the box down some 15mm so there will be enough space to fit the box under the brace.
I also tried to fit the inverter along the box. I made a very heavy square fitting which i dont like since it eats the space for contact box.
I decided to make a 5mm alu sheet spacer which will reinforce the left battery box wall so i would be able to mount inverter directly to it. It fits rather snugly.
In the end i fastened all the bolts and enjoyed the smooth surface. I got a helper to test the box.
Next i tried fit some finished Kokam batteries from my Mazda to see if they will fit. I may just transplant the batteries to keep the range as before. They fit nicely with spare space for 2mm isolating rubber matt. I would be able to fit 10x of mazda bundles of 8cells. That is like 80% of mazda cells in front box only!
Before i assemble everything for good i decided to paint all added metal parts with epoxy primer paint. This should last for another 10 years :).
Jože made me a cover for battery box out of 1.2mm stainless steel sheet. It looks really good.
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