After my inspiration visit to New Electric I started redesigning my battery boxes again. Main insight is related to the supporting frame for the modules. Instead of sliding it into a opened tube it would be better to slide it on top of a beam. The supports will then be outside of the horizontal beams. As a result the box will be wider. So I checked whether I do have that space available.
If I position the switch as high as possible in the box it will fit exactly. Instead of drawing everything manually I now use the ‘beam’ function in Onshape. There are two main advantages 1) designing it is much faster and 2) I can have the beams lasercut automatically.
Redesign front battery box
Disadvantage of having the beams lasercut is that I can only use the beams that they have available. The increased accuracy and the fact that I can add ‘position helpers’ are well worth it.
So step by step I have designed the frame.
In this way I will first install all modules in the frame and connect them. After everything is assembled and connected I can lift the package in the outer skin box.
The back will be welded onto the box and it will be closed by a lid. I moved the flanges from the box to the lid to create clearance for the frame.
I added the maintenance switch to my dummy battery box to double check it will fit.
And it does indeed.
Redesign rear battery box
In the rear box on top of the increased length I also had the challenge of routing the cables connecting the modules.
There are many possibilities. You could even flip the modules to play around with the + and – orientation. The final – and + can be changed due to different routes. The final – must go to the front via a fuse.
And the final + must be distributed to the chargers and pré-charge resistor.
Which all turns out to be quite tight. that made me look into the high-voltage diagram and the currents in particular.
Only the main current flow is (relatively) high. The pré-charge and charge currents are low. Therefore the 600 Amp power bar is overkill. Therefore I started designing copper busbars.
And added the cables to check the angle feasibility.
And added a new outer skin. This time as much as possible as one part.
The increased size due to the supporting frame caused it to be very tight near the tow bar.
So I further improved the design and added special corner mounts.
Resulting is a proper margin towards the towbar.
There are some things on the To Do list such as adding holes for the glands and the vent caps. But I tend to conclude that my design is getting towards a final stage.