Battery Cart Feedback

I recently designed a new battery cart for my team. I designed it to be able to fit and charge 9 batteries at once. (I plan on widening the battery compartments by an inch. Too tight of a fit right now). If you look closely though, you’ll see that the aluminum actually has a slot on the ends. I plan to put some sort of material in between the slots but I don’t know what material to place. Any suggestions will be most welcome. Also, I designed it to be a bench for my team so on the top there’ll be some sort of covering BUT I want that to be a hinge so then underneath I can place chargers for power tools and such. Lastly, if you look in the front, you’ll see two different colored panels - this is how I plan to access the batteries. The top portion will be rigid while the bottom will be hinged so if we need to access batteries, we open the bottom one down. When closed, it will be latched with the top. Obviously, though still need material suggestions for these panels too. The only issue I see is that the cart may not be able to support the weight of batteries, chargers, and humans. What you guys think of that?

Link: https://a360.co/2Q33y3r

The biggest issue I see if that you have about a foot between the ground and where most of the central mass is. On top of that, it’s on a base that isn’t super wide given how the central mass is distributed. I suspect this is going to be a bit tipsy.

I’d make the panels clear plastic to allow for additional light to enter. …maybe add some LED lighting?

I think the top rigid panel should be shorter (not extend down as far). I think it would be easier to lift the batteries in/out with a shorter panel. Don’t forget you’ll probably have cables attached which effectively increases the height of the batteries. You’ll also want to reach in to disconnect the Andersons.

I also agree the the legs look a bit long. I get you want the batteries higher for easier access. Add gussets to the legs?

Skuke

Good idea but not going to fix the tipping problem. That only gets fixed when you adjust the mass distribution.

It might be good to mock this up using what you have around already i.e. some shelving, some cardboard. The panel might get in the way of how you get to the batteries and may not actually be necessary.

Will you be using this cart at events? If so, you may want to use larger wheels. Will this fit in the back of a large SUV? It would also be good to have a way to restrain the batteries so they don’t come out of their slots and get damaged. Lastly, make some accommodation for a power bar to power everything in the cart including tools, phone chargers etc.

Yeah I was gonna mount a power strip in back and I tbink bungee cord across top should restrain batteries. Also School provides a truck for transportation so we have space for it.

I see that. Didn’t realize. Gotta think of something.

I would suggest looking into cable management before moving forward. With the amount of money and effort being put into the cart, you want to make sure it provides easy access to your batteries in addition to being able to plug and unplug them easily.

The nicest battery carts that I have seen are ones that have integrated the wiring into their designs. I dont see by your current design an easy way to do that. Maybe some kind of bar that runs above the batteries would allow you to attach the connectors to it but that would be awkward from a plug/unplug ergonomics standpoint.

Here are some pics of our teams battery cart in the link below. Each battery connection is mounted under each battery which gives students easy access to pull any battery at any time. This battery cart is around 8 years old but we have had no reason to change/upgrade it as it has been rock solid.

https://www.chiefdelphi.com/forums/showthread.php?t=166088

Hope that helps. Otherwise I think it looks great.

Thought about that, I figured the amount of space I have in there would be enough for a person to navigate with their hands. I’ll look into adding a bar though thanks!

I second this notion. Figure out how you will mount the connectors to the cart and how to fit the batteries (with cables/connector). Try to make it easy for one hand operation. Optimize the design for the thing you will do most often with it… placing/plugging, unplugging/removing batteries.

Since it will be heavy, use the largest casters you can, and some beefy handles to help with loading and lifting over thresholds, etc. during pit moves.

You should be able to do stress analysis in Fusion 360 to determine if your shelf will hold everything. Its easy to learn and there are lots of tutorials online.

This looks like a great cart that will be around for many years !

I definitely agree with this. Lower that bottom shelf as much as you can. With our current battery cart, the batteries sit on the bottom shelf, which is itself bolted directly to the top of 5" wheels (2 caster, 2 fixed) from Home Depot. That puts the majority of the weight as low as possible.

It’s not clear how you’re going to get the batteries in and out - lift them over the chargers? I would recommend finding a more ergonomic way. With our cart, the chargers are mounted directly above the batteries, giving us full access right in the front, with additional storage deeper inside the cart. Batteries can be pulled forward along the smooth shelf right into your hands. This helps reduce the urge to lift the batteries by the cables, something that should never be done. You’re going to be accessing the batteries frequently, so make it easy on yourself! Remember, the pits can be cramped, so opening and closing doors can be difficult.

For the top, get a butchers block or an old solid-core door and cut it down to size - that’s what we did. It’s a bit heavy, but extremely durable and can take a beating when you need to do work, I have no problem putting something on it and beating it with a hammer if I need to. Attach it to the top with some door hinges and it’ll stay put - you won’t even need a latch on it. As a bonus, with something that durable, you can mount a vise to it, which always comes in handy! We also put some gas springs on it - they assist the lift, and when it’s fully upright they can hold it up so you can dig around underneath it safely. Also, plan to get under it as infrequently as possible - you’ll accumulate a lot of stuff on there, and the last thing you want to do is spend a bunch of time having to clear it off just to open it up.

Make your drill chargers easily accessible - you’ll be swapping out drill batteries a fair amount.

You may want to use something like a non-conductive bar (wood?) that gets locked on top of the batteries and is visible from outside the cart when it is in place. Bungee cords will work if they are not too loose and if they are actually installed correctly. When they don’t work, you can end up having to clean up the acid from batteries broken open by bouncing around in the cart.

Does the school own the truck or does it rent one each time your team goes to an event. You will want to make sure you have sufficient clearance under the cart to go from a ramp to the truck bed. The steeper the ramp, the more clearance you need. The team I currently mentor has a bunch of large cabinets that a previous mentor built for them. The casters give only around 6" of ground clearance. They have to rent a low deck trailer (no steep ramps) to get them to events. The trailer rental apparently cost them over $600 last year.

how do you guys usually attach casters to the bottom?

Tbh, I have no clue about school truck situation. First time they’re giving transport so gotta see what they come up with.

No I plan to have a door in front of the batteries than will open down. Batteries can be lifted up and out pretty easily.

I thought about making it a workspace but we have a enough workspace, one cart and the table that’s provided is enough I would think

Hmmm, what if I mount the chargers on the outside, that would be pretty interesting I think

I took into account the comments and redesigned the cart. The three hinges on top are for mounting some sorta piece to work on. The wall in front of the batteries will be hinged on the bottom so it can open down to allow access. Also, behind that wall, you can see how I plan to secure the batteries during transport. It’s not the correct size but the idea will be the same. It will repeat for each battery. I also added the two cross bars on top to mount the connectors for the chargers and provide additional support for the work table on top. Also, on the side I have a panel that can fold down and when folded down (haven’t added hinges in CAD), it’s where chargers for power tools will be mounted. Although I haven’t added the wheels, I plan on using four 5in casters. I’ll also create some sort of bar to push/pull the cart. Any feedback will be most welcome.

Link: https://a360.co/2Qpv37f

Heres some pictures in case you cant open the file




It’s definitely improving.
While the casters aren’t in the pictures, it still looks like you’re planning to mount them to legs? If so, then this doesn’t implement some the first (and repeated) advice to lower the center of gravity.

I removed the legs that the casters were mounted too. They’ll mount directly to the bottom of the frame in the picture so I think that should fix the problem?

Yes, casters on the bottom will lower your COG. I was making an assumption that the top was workbench height, (32-36") so the overall design looked a little short without legs. Also consider that if your front door hinges down, make sure it can swing 180 degrees, otherwise it might be constantly your way.

Keep updating your cad, so you can get more accurate feedback.