Battery Cart Help

I was wondering what would be a good robot cart design for our team, I have been assigned to make a battery cart or well get started and I am not very well versed on other teams robot carts and design.
thanks for your help.

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We designed a new cart this summer and used it at the Texas Cup. It worked very well for us and it’s relatively simple to build out of 1x1 aluminum extrusion, 1/2" plywood, and a round tube handle.

We have moved the design to OnShape but haven’t made instructions for it yet. CAD model here: Onshape

These are the 5" casters we used https://www.amazon.com/dp/B08BTM4RD3?ref=ppx_pop_mob_ap_share

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Thank you for sharing sharing yours, im gonna take a look at it with a few members.

wait i meant BATTERY CART I SAID ROBOT CART OOPS

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Here is our team’s battery cart design from a few weeks ago -https://drive.google.com/file/d/1Tz3QVWWN4e8uWwqMWYILYiSR52pyOeKu/view?usp=sharing

I am sure the students will share CAD details if you are interested. It worked great at Chezy Champs.

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Thank you for your help, I am going to go through it. I think we were thinking a portable battery cart, but this might be something we might wanna look at. Thanks

I have attached a link to directions (cut list, assembly, etc.) for making the Killer bee battery cart as well as an instructional video. We have been iterating on this battery cart for a while and it’s current form gets the job done!

Directions: http://www.killerbees33.com/wp-content/uploads/2020/11/Battery%20Cart%20Build%20Instructions.pdf

Video: https://m.youtube.com/watch?v=XOAfVUXOnXo

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thank you so much i appreciate it. This is exactly the kind of battery cart we were thinking of.

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We don’t have a trailer or other ramped loading for travel, so I’m pushing our students towards a 3- or 4- bay design with a 3-bay charger on it that will be possible for a single student to lift up into a van (under 50 lbs loaded). Not sure about wheels.

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Well I can tell you what not to do, our current batt cart is about 4 foot high, 2 batts wide, and holds like 8-10 with 2 of the AM triple chargers. All on 2 wheels, moving dolly style. That’s waaay too much weight, too low, on too tall/narrow of a box, to move easily. It’s so bottom heavy it’s a fight to move more than 3 feet at a time, especially with a small storage trunk style handle.

It’s hard to reach in a lot of pit configurations, and always leads to a lot of bending over to check charge states (hellooo back pain)

tldr don’t put the weight all at the bottom of a tall, narrow cart, and you want 4 wheels.

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we came up with a design we decided today at our meeting, let me share a photo of it but I like the 4 wheels and vertical but slanted for batteries not to fall out.


image

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Think through all aspects of how you will use the battery cart, in your shop, pushing it across a parking lot (possibly with rough pavement), loading it into a vehicle, fitting it into your pit at competitions (you might not get 10’ x 10’). Think through how you keep track of the charge batteries and the ones needing charging. Consider how stable the cart will be when it is moved across the various surfaces you will encounter. Consider how and where you mount your charger(s), how visible they are, how accessible they are if they fail and need to be replaced (possibly with a different model). Consider what materials and manufacturing processes your team has ready access to.

3946 had a pretty involved wooden cabinet that utilized volume more efficiently for several years, but after going to a custom mid-pit robot stand, we found that space wasn’t all that tight. Two wooden boxes with heavy duty carrying handles, each capable of holding three batteries and two of the three-channel chargers from Andy Mark that we would set on a table or work bench met our needs nicely. We usually travelled with a seventh battery in the robot.

Ramageddon Robotics just recently finished our new battery cart. Here are a couple of pics and a video link showing the removable front cover.

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Working on our upgraded battery station in our cart. Wire management and adding the drills & chargers will come next year.

That’s a nicely built cart. Does it have wheels so it is mobile? Is there anything keeping the 6 batteries in the upper section in place as the cart is moved? It also looks like there may be space to store another one or two batteries in the lower row.

The removeable front panel, latches into place and holds the charging batteries securely. The battery wires provide spring/tension against the front panel to keep them from moving. The video shows the front panel being moved from transport mode to pit mode. We thought about wheels, but decide to go with a separate dolly to move it and other assorted equipment. We thought about 6 batteries at the bottom, but decide with the wires, 5 would be more manageable, and realistically 11 batteries will get us through any competition unless there is catastrophic failure.

It is generally not a good idea to put stress on the battery cables. That stress gets transferred to the battery terminals and can crack the seals around the terminals. It can also break the strands inside the insulation right at the end of the crimps leading to a high-resistance joint (and large voltage drops when pulling high currents) that are difficult to detect. You are better off doing something like adding a stiff piece of foam on the inside of your cover to press against the body of the batteries to keep them in place.

It looks like you can cut holes in the vertical front panel to accommodate storing two more batteries between the ones labelled “5” and “6”.

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Roger on the stressed battery cables. The amount of pushing on the cables is small , but not 0. Will probably go with the foam. I see now about the extra batteries, but will probably leave as is. Want to try and keep the CG low as possible and that is where we have cables and surge strip. Also, getting tired of 3D printing bezels to go around cutouts :sunglasses:

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Curious where you sourced/purchased the digital Volt/A meters from? Are they just wired in series to the leads on the battery charger banks?