I gotta agree that riding around with a heavy backpack really sucks when your on a longboard. The wait makes it hard to turn and balance properly and overall makes you feel like your gonna fall off constantly. I’d try riding your board with a backpack full of weights or something to just get a feel of what it would be like before building something you can’t even use. Also about the 48V converters I found a bunch on AliExpress for under $70. Here’s a 750W one but there’s also 300, 500 and other wattages available.
@barajabali you may need capacitors like said above so a tip : better use an array of smaller ones (pack multiple 220uF if possible instead of less bigger 2200uF).
Another thing you might want is add shunts to the end of cables to bleed any spike the caps couldn’t withstand.
Weight distribution is everything, why not start from a superflat backpack instead and add guards padding on it by yourself? Even start from a laptop pouch and add layers of fireproof material.
Odd thing is : the closer to your gravity center it is, the better handling. The worst too in case something goes wrong 
That was my thought too, the packpack battery would just supply “long term” energy. Im not an EE though but it makes sense to me.
I was thinking to have a 15lb max with inverter and all. I hope i can fit at least a 12s8p in there. Ill be doing some weighing once the components come in. Im not sure what the wh/m is yet because im still waiting for the last 2 motors to come in. But im pretty sure its going to be the highest possible. I have no evidence to back this up but its 4wd with low pressure 8" pneumatic s and chains (and the bearings are shot from last years snow lol) 25mm belts and i weigh 230 lbs. SO I think 120 wh/m is a fair estimate… Pretty bad!
Okay Yes I did read that before. Smaller capacitors are more efficient or something. Thanks for the tip.
Can you educate me on what that is?
I will be using a flat drone backpack, im going to add a waist band strap to it to help with the weight distribution on my shoulders. The pack will be constructed with cell holders, rubberized heat shrink, insulation for temp differences, Fire proof layer (if i can find some), and last shock absorption layer for drops.
In regards to fireproofing, here is what im thinking.
If I go with the ceramic fiber it will not only contain the fire but insulate the pack against temperature changes… Also act act a layer of shock absorption. I may go with a lipo bag and ceramic fiber
Just some ideas.
I also think im going to go with this inverter. Its the cheapest 48v to 120ac that ive found and it has good reviews.
Although this one seems much better quality… Hmmm
How about ride and charge at the same time? It would only take 24 hours for a full charge is my best guess.
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Damn that is a good idea. But I think trickle charging lithium ion batteries is a bad idea. I gotta do research about it
Let’s just dream and say we get 10w in direct sunlight… that’d take about 33 hours for an 8s 10ah pack
I think 300W isn’t really enough to charge other people’s boards off of, especially more than one at a time. And you have to remember usually companys like to inflate there ratings just like the C ratings on LiPos so a 300W inverter might be only capable of 200 or 250W continuous.
Damn I already ordered it
Hey you can always upgrade lol
Haha yea whatever. We’ll see how it holds up
Great project, always considered something like this with the mountains of cells I have, but I’ve never needed to travel far enough to motivate me to get it done lol
300W should be able to charge 2 peoples 10S boards with standard chargers at the same or a single person with a fast charger
Nice that’s all I need homie.
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I have a 300w built into my truck and charge off it all the time 
Damn the vender I bought it from just told me they ran out of stock. Now I have to upgrade
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Lol, sounds like your back psck just got heavier lol
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Right you are! lol.
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Super late reply sorry for that.
The shunts would be interesting to avoid amps surges (as capacitors should smooth out voltage spikes and drops).
I understand that you want to be able to parallel your backpack through your batteries? So juice would run through your batteries first? Not sure how you can do it (parallel is in the end parallel).