Whats up boys and girls,
I’m building a battery backpack with the cells that I have laying around from broken packs and cells that are not suitable for esk8. The backpack will be a 12s11p (TBD depending on weight) with 25R cells. All of the cells are mostly in the start of their life cycle and I am going to balance them all before welding them together. The backpack will feature a 48v DC - 12c DV buck converter to power a 120 v AC power inverter. The Inverter will feature USB ports and 2 120v AC outlets for charging my boards as well as other peoples board on long trips. Not only will the board have outlets but it will have a 3 foot long cable extending out of it which carries raw 12s power. That cable will parallel my 12s Mono drive board and my 12s 4WD Trampa. The backpack will have a BMS, voltmeter, Percent display and on/off switch.
Along with the backpack, my mono should reach about 80 miles in range and my trampa should be about 30 miles range. This is going to be used pretty much just for my Trampa because the 12s7p already on it wont get me much range with 4WD. Together that board will be at a massive 12s18p.
I needed a project to recycle all of the cells I had laying around from warranties and other things and I think this is the perfect project.
I had to step it from 48 to 12 and then from 12 to 120ac because the inverters that step from 48 to 120ac are too expensive. Unless you all have found something cheaper?
Looking forward to that
I think this is the perfect solution for those of us who cannot afford two boards and want a lightweight board for commuting during the week but also enjoy to go on long rides on the weekends
Just need an elegant and safe connection on top of the board, I think it should be strong enough to keep a solid connection when riding but to also easily disengage if you have to bail
interesting cell recycling project.
It would be interesting to have JUST a large battery backpack (with BMS & meter) with a long cable with an XT connector that plugs into a lightweight battery-less esk8. Rides a bit weird, but great for long range and use with multiple lower cost boards. Definitely something @squishy654 should think about.
I agree. I am going to use either an XLR connection or XT90. There will be a steel cable attached to the connection to make sure any pulling force is not applied to the wires.
@Mikenopolis I agree, that would be a neat project. I usually ride with a backpack anyway so it wouldnt be a burden.
Have you thought about using cooler or camera backpacks that have top and bottom partitions so you can use bottom for battery and top for other stuff…great, now I’m thinking about having you make me a pack like this so I can deal with my current 10s3p limitations due to deck/enclosure choices.
waist straps for the backpack are going to be key, especially for that many cells. All the weight on the shoulders is going to be very straining, especially if you’re actually planning to drain the whole pack on one ride…
I looked at hundreds of backpacks and I settled on the shell or hardcase style backpacks that drone owners use to transport their equipment.
The reason i chose the hardcase style is to have a solid area where I can mount the display and charge port. It also has more structure, which i believe will help if i fall back first. There will be a whole lot of shock absorption materials in the pack to make sure it doesn’t vent if i fall.
But I think that style could work too, the compartments would be cool.
Hmm okay I didnt think of that, thanks for the tip.
Agree with the steel cable, but if the connector is not too tight the wires should be perfectly capable of taking the load
My idea is to have the board connector free from the board, this way the force is always normal to the connection in case you have to bail, that would guarantee that always the disconnection can happen
How will you manage the surges / drops?
Nice project. I’d love to see how it goes.
Yea but the way I’ll be using the pack is on my mountain board. I can’t bail off my trampa because I’m attached to it with bindings.
I don’t understand your idea though can you explain it more
he means normal as in, 90 degrees or perpendicular to an upright rider. Versus having a plug on the side of the enclosure, which would not allow for disconnection as easily if the rider were to suddenly fall forward or back.
picturing running off the board with the cable attached. may cause some issues without some kind of quick release.
also the connection from backpack to board, what kind of wire will you use? something more robust than the 10awg silicone wire? would it be inefficient at such lengths?
Maybe a magnet connector?
I prefer to keep all the weight on the board itself and not on my body, I like to ride and skate and carve and move around on the board and wearing a heavy battery in a pack doesn’t sound pleasant or comfortable, not to mention the inconvenience of a cable.
When I skate long distances I use a small satchel or hip pack, that’s it, just enough for a small tool kit, snacks, a small water bottle and so on. I don’t even wear a backpack at all and always felt it messed with my skating. I like the hip pack because I have it over just one shoulder and I can shift it around from front to back, get into it while riding if I need to, I would have to stop if I needed to grab anything outta a backpack.
You would think the weight of the batteries in my board are just crazy, but it only matters when you have to push (or carry it, omg!), which I barely have too, lol. I think of riding on top of that weight as a better solution, not carrying it and adding to my fatigue. It’s better to get use to riding a heavy board than training to carry a heavy pack…I already do that when mountaineering and have some nice load carrying packs, but I don’t see the need when I can fit enough battery on a board itself and just stand on it…
Oh yea that is still TBD. Im not sure at what angle the connector will be at
The main purpose of this is for my Trampa so Im not super concerned with running off. Also, I think a large cap bank and 10awg silicone wire should do fine.
I dont think 15 pounds of weight on my back will really discomfort me all that much. Ill be updating this thread as this build matures and we’ll see how it feels in real life.
For my next build I was thinking of doing a extended range battery pack also. 12s5p under longboard deck kaly style and extra 12s5p on top for longer rides barajabali style in a type 500 case. How do you plan to run the batteries? Do you plan to run the 12s7p till it’s dead then connect 12s11p after. Want identical packs because i heard it’s best to have same capacity batteries if you plan to run them in parallel. Thinking of the wiring and would ideal if I can run them in parallel and also each pack independently if needed. Also would be cool to be able to charge them together but probably only possible without BMS.