Top box designing wiring harness ports placement and mounting. (Harbor Freight plastic ammo box)

I found that 12 cells fit perfect in this, enough room for a BMS on top and other junk.

I made the wiring harness but I want advice on where the wires should exit and if/how they should glued in place.

The bms fits in with a little squeeze, I am questioning now why I put it in upside down… something to do with the direction of series connections and how I wanted the power wires by the hinge… I will try flipping the BMS over but I still have other things I am not sure about.

It makes sense to me to glue the output/charge/e-switch on the side under the hinge or latch as it should never be blocked when stacked next to/on another.

By the latch makes batter since that is where you need to access no matter what.

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I know I don’t want them facing up or poking out to be snapped off.

So facing down on that latch face near the latch so that protects it is my logic, interested to hear if that is good.

now I am wondering if there should be connectors in between the BMS and these fixed connectors so
BMS could be removed, although I don’t know why you would want it all the way out because you could still take the pack out with it soldered to glued connectors.

it has occured to me that if I put the connectors there then the action of grabbing the latch and flipping it open could also tear the connectors right next to it out… so if they were not fixed very well that would be bad.


If it was me, I’d print xt90 and xt60 lowprofile mounts and install them @ rear somewhere. Put them about an inch below the latch? Leaves some room to open the box compared to possibly having to unplug them just to use the latch.

Though you might want to swap male ends to female so the mounts can do their function and hold the whole connector instead of just the end.

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in my mind the rear meant the hinge side, then you are talking about below the latch. There is more plastic overhang on the latch side to protect connectors as a plus for that side.

Nah that would never be a thing even how I showed them in my pic you could open it the same way.

This is where I start to not know what I am doing so much. Thinking it was bad practice to have a battery box output be male xt, but with a BMS/fuse it would technically be safe enough. Then you use a female-female for the batt to ESC.

Another thing to think about is having the charge connector face 90 deg (or on a bit of wire to flex) so it can be tugged out if the board got pushed. Although maybe I would want to have a charge port adapters to something with a plug.

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Rear was in reference to which ever side you faced rear. But I was assuming latch would be @ rear

If it was me, I’d put a standard charge port on it. That 5 x 2.1 or whatever the measurements are. That way you will have that ability for it to let go. Xt anything are made to hold each other so they dont come undone.

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This is what I am doing for this first try. YES I could have drilled holes to make it nicer but I might tear this out and I don’t want to redo so much. I could glue them in place now and make a guard around them to prevent them getting hit.

About the charge port I really do want to have two of these in parallel on a board with a bank of 4 total possible to/swap or use at once on something big. Also they kinda can charge above 10A and that might come in handy. That makes sense then using XT30 on the batt itself and a dongle attached to the board that goes to whatever DC plug your charger has, barrel in most cases.

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That’s “diy did I do this” material lol.

I wouldnt feel comfortable riding like that for long lol


If you trash the box too much too use, Ive got the exact same one I use for storage space. Let me know if you need it and it’s yours for shipping cost

because they could get tugged out or shorted easier?

it is a $7 box. unless you fill it with that esk8 junk I love to hoard its not worth it. Maybe 24 belts lol.

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I will go ahead and glue them in now then.

I just gotta pick out a waterproof switch for the BMS, figure out how to route the wires for the the v2 type bms that I have for the other 3/4 of these batt boxes… then test 36x 8ah cells then solder 42 balance leads to foil crimps plus 6 output wires. Crimp then isolate and tape up the other packs and once that is all soldered have some multi use modular battery boxes.

I assume this type is best because it is hard to hit on accident, also $$ so there is that.

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Nothing wrong with those. Probably not very water resistant, but if you dont ride in wet conditions, I wouldnt worry, much.

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This plastic ammo box itself I tested and is only splash resistant when upright. I have a idea about modeling and printing an additional clamp around the edge that would screw it shut compressing the rubber gasket.

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What about just running a small rubber o-ring-ish style gasket around the lip. I havent tried it so just spitballing

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In the first picture you can see the very small rubber gasket that fits into the lid. The issue is the lid is so flimsy it can’t get even pressure especially when the sides are pressed you get a huge opening for a splash to get in. When I realized that it made me think of making a cheap part that would compress the lid given I don’t need to open it easy. I guess you could build that lid compression into the mounting system for putting them on something, that seems like a fine idea the ammo boxes sliding in to a frame then are clamped down over the lid.

I forgot to link the ammo box so I will do that too.

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Yeah I can see where that case would have that issue. Again, if you trash that case, give a holla

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hmm and now I realize the way I put the connectors right on that edge there could be an issue for that but it should still work, just need clearance around there. Modeling this case is a bit of a pain in the butt, worth it though.

Messing with the box right now it seems like the gasket is entirely not making contact on the long sides unless I press the lid down 2mm.

About the extra room in the box, it could be enough for a DC buck to power any random thing.

@Fosterqc what kind of cells are these, SPIM?

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Yea! The one in those pics is actually the first battery I ever made and don’t judge the duct tape I had nothing else at the time.

on the left in this pic you see I have gotten a hell of a lot better. So hopefully I will get the balance wires looking nicer on the next 3 of the 12S1P packs for this project.

This was it lol before some cells got toasted idk how that happened exactly.

now I will get the box modeled… evening activity.

needs handle/lid inside details and the latches and roundness on the bottom.


how have these been performance wise?? I have a bunch of these and can’t decide if I wanna use em for a lightweight jumper MTB or if it’d be better weight efficient for me to use a couple 6S lipos.

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