Im designing a way to hold the battery in a swerve drive. What’s your opinions?
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Quick swaps are really important, how easy is it to take off the aluminum piece?
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4 screws only
That seems like a lot given how frantic swaps tend to be, would you be able to take out 4 screws, put in the battery, screw it back in and plug it in fast enough?
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it will be located under the robot and I think it fast enough to take off as the screws are short
A few questions:
Am I correct in assuming the aluminum piece is a lid of some kind? How fast is this to take on and off? what kind of fasteners? wing nuts?
How do the battery leads get out of the box?
How is this mounted to the robot? If the battery is “hanging” at all from those 4 tubes then I am the exact opposite of onboard.
Why are the mount tubes joining on 2 of the sides vs the corners where they could provide support in compression vs just shear? The tube attachment points are massive stress risers. In the age of swerve rapid deceleration can come from any direction.
My primary concern in the 3dprinting not being particularly strong as you have is laid out (connecting on 2 of the sides). I see the attempt at adding foam/“squish”, but a battery with cables is 15ish lbs, thin 3dprinting alone does not stand a chance at arresting that momentum from a full speed hit. You at minimum need to have something other than that small plate with the logo holding this printing together, ideally as a hoop. Maybe a make the corner fillets larger and put a giant hose clamp around the whole thing?
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One thing that has me concerned, in particular in your last picture is that all the box is 3D Printed. From mentor and other experience having a heavy mass and 3D prints aren’t good together. F = ma and in particular since batteries are so heavy compared to other components I could see a hard stop causing that box to break.
To pick up on Skyehawk’s concerns, you should imagine that your robot will somewhat regularly experience 50g’s of acceleration, meaning your 15 lb battery will exert 750 pounds of force against its enclosure. Probably multiple times in quals.
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Battery holding is one of those things that if you don’t get it right, you will pay a price. Whether that’s a self-disable, a field staff disable, or damage from the battery bouncing inside your robot.
And this design has 3 problems.
- others have touched on the advisability of using 3D printing for holding a battery. So I’ll just say that I agree with them.
- I don’t see a place for the battery leads to exit the holder. That, alone, makes it a flawed design, because the entire purpose is to hold a battery and its wire leads!
- takes up a lot of room with the tube legs that you may want for other mechanisms.
As far as 4 screws… I work with stuff that needs to be quickly released. If we THINK we want a quick turnaround, the first thing we do is try to design screws out of the design.
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Let me just say I think this is a really cool concept and I love the way that you jumped into doing this! You should be proud of the work you have done, the things you’ve learned, and the effort you have put in.
CD has a lot of people who have a lot of really good knowledge, even if its hard to hear sometimes. Use this to not give up, but instead push forward to improve your designs and achieve your dreams.
Side note- Our team has disliked battery replacements when we have to tip the robot on its side to get to the belly pan. Its not a deal breaker, just not easy.
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this!!! people are trying to be helpful even if it’s a little hard to hear sometimes
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often those of us giving the advice have been getting hard advice in yeas past (and still) too…
OP
apologies if I may have been blunt in my post. It’s not the best system sometimes. Putting your stuff out there for feedback can be a tough thing to do. I find revisiting my work after a break is the best way to make sweeping changes without being too attached to stuff (e.g. sunk cost fallacy)
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Thanks for the feedbacks any suggestion how can I keep the battery in the midlle and aslo fitting PDH on one side and roboRIO on the other side with 26x26 chassis. The space is limited!!
Note: Im doing a secong layer for mech
We have been using this battery holder design for the past 2 seasons.
Fully 3D printed. Everything is under compression when impacted by a side load. We had some early failures of our battery plug coming momentarily disconnected during a really hard impact because of the lack of compliance in the Anderson connection. We have since improved it last season and never saw that failure mode again.
This is underbelly loaded which we are used to but can be more painful to change out the battery.
Happy to answer any questions. Definitely avoid elements that are placed in bending under impact. The forces can be pretty extreme.
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I like the design but how do you take the battery out?
Assume: mechanical will take over any inch, square inch, or cubic inch that they can. Give them a full deck and you’ll have to fight to keep them out of the area clearly marked “reserved for electrical”.
In other words, you will probably end up getting as close as you can, while working around the constraints mechanical put on you. Like robot-center pickups, which can sometimes be quite handy, but would force you to put the battery elsewhere.
So I would probably have a Plan B for battery locating and mounting, because you may not get Plan A.
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Well my plan was to design 2 robot one in the centre other on the sides.
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There is a single 1/4 aluminum plate that is bolted on under the belly. It allows for the battery to be slipped in and taken out.
You probably have a pretty good reason, but can I ask what the thought process was behind leaving the battery centered in the robot? It can make accessibility a lot worse in some cases, although if you are bottom loading you will probably have more of a pain with wiring than accessibility.