yes mate! I just hope that the fiber is well stuck to the side panels, because I’m blind now during the curing process. I could try to give it a look but sometimes patience and commitment is key (and a bit of luck too). If I can get to 600 grams max that would be amazing.
I should have the 40mm nickel bands this week so I will be able to progress quickly on the battery. It will just be welding and then wiring. I still need to buy the pneumatic plier for the connectors too.
Update of the day.
Pretty happy with the result. The box is rocket solid and ultra strong and weights 700g. The panels have perfectly stuck to the airex structure, even on the sides and there is very limited resin “overhead”. Of course, I could have saved 50g with vacuum; but so far, so good.
The next step is drilling the box to add the amphenol connectors.
As usual, some photos.
Bravo, without sous vide the result is very good. Indeed not much space for the wiring… how do you plan to fix the cover?
Thanks @Manu. I’ll use F11C and I’ll see how it goes.
I expect the complete “ready to plug” 14S9P with these 21700 cells to 11kg maximum.
I’ve 3D printed two patterns (matching RS232 & Surlok footprints) as PETG parts that I will use to drill in my battery box.
I’ve also received the electronic box. Weight is decent.
battery pack is almost done; at least the spot welding part. I will reinforce the positive and negative of the pack areas tomorrow.
Some photos of the progress up to the final pack.
Each side of the definitive pack welded.
well done ! your spotwelder seems to be a powerfull one to make this kind of spot on such metal thick…
have you an idea of the total number of spot ?
I’m using the Maletrics spot welder
with a powerful car battery and I’m at 43ms pulse (on a scale of 100ms) to get 0.20mm on 0.20mm nickel sheet. To weld a 0.20mm on a cell, I’m more around 20ms.
it depends on the battery size as well, on mine with my car battery 900cca : 9ms for .15
really nice , work well, but as i read , the malectrics doesn’t take in account the voltage drop during process, time is used as a setting, not energy (joules) as the Kweld… i doesn’t think it really matters as long as the supplied power is well sized
and it works on cooper as well like Virus did on his youtube video (spot/cooper/solder/nickel/spot/cell…)
I went for three 3mm width desoldering braid to reinforce the positive and negative areas of the pack.
Next steps for the battery pack/box are:
Is there a reason why you didn’t just skip the narrow parallel strips, when the 30mm strip is going to carry all the current in the series direction?
hey @Jatem - yes, it’s called improvisation. Of course, the 30mm will be enough as you stated 
I could even have gone 2x 0.20 / 30mm.
The parallel cell connections won’t see any real current, other than a tiny bit of balancing.
Next, I’m looking forward to seeing your tidy parallel balance lead wiring, so that there’s no chance of wearing through and shorting between the cells and catching fire.
Are you going to waterproof the outside of the vga connector with a cover or something, so that there’s no chance of corrosion shorting between the pins? One benefit of a BMS inside the waterproof battery case is that you don’t have to worry about those exposed balance pins getting shorted.
Yes of course. I may use dialectric grease and of course a TPU cover to avoid any chance of shorting.
for the balancing cables, it’s going to be a piece of cake because I plan to solder them at the border of the parallel joints… facing the front of the box. I can also weld a 2cm nickel strip and bend it 90 degrees to solder the balancing cable but that’s not needed.
I will have to let some cable length on the balancing wires because I plan to use a shrinkwarp tube; so probably 30cm.
for the male surlok am phenol connectors, I will 3D print two caps/plugs in TPU
You probably know this already : Be carrefour soldering + on cell, the white plastic ring melt easily …
Best to have silicone wire on balancing wiring
Great looking progress!
Looking at the nice fuse holder got an idea. What if not having a holder at all : using the cable lugs as in the picture, but then slide the whole thing inside a transparent PVC tube? Maybe there is a risk that the fuse will brake if tension in the wires.?
@Alexandre yes of course. I never solder balancing on positive areas. For the positive of the pack. The desoldering braid will make a perfect bond
@XSailor hey Tom, That’s a great idea. Actually the holder is pretty strong and I don’t expect any tension on the wires; it’s silicone 8AWG. Very flexible
I’m also hesitating to put a 0.5mm silicon below the pack to absorb vibrations
moving on, I decided to make to top cover of the battery box. My plan was to do it later, but I had 30 minutes on my agenda and it’s going to cure for 1 day (and if it fails, I will learn)
100g of epoxy + 37g of hardener and some sparkling red pigments (yes, I had to do that)
I’m going to see how glassy I can get this thing. Back to OG style.
I hope this is going to work, or I will have a beautiful IKEA glass door… with a top cover stuck to it. A shame I didn’t kept the polyvinylique alcohol but well, I found another way.
Hi Ced, Why two layers of CF and only one layer of glass on the opposite side. Do you have the same weight resin both sides ? By doing so is there a risk of an asymmetrical laminate and some possible warp? If you succeed I will do it accordingly. Congrats, Nice progress on your build!!!
