A few months ago I finally finished my first build. It’s a Potato deck, with a 190kv APS motor, an UNIK control and two ZIPPY Flightmax 8000mAh 5S1P 30C. All packaged in two 3d printed cases.
Everything is running just fine, never intended to build the board for speed, just for endurance. Haven’t really tested all this because I missed my main point of the build and that was a light and nimble board.
I know loosing the big lipos will shave off quite some weight, but don’t know what to replace them with and not end up with a granny board.
Can you guys give me some tips on how to decrease the board it’s weight?
Lipos usually have the highest energy density to weoght ratio so going for liion pack would probably increase the weight.
Doesn’t seem like your board should be super heavy, how much does it weigh?
You can save a lot of weight on trucks and deck
To be honest it’s just a feeling. When I pick it up I just think by myself this is too heavy for such a small board. Atm I don’t have scale that is a able to weigh it, but will get one soon.
What I know is the lipos together are 2 kilo. Right now I’m looking at the possibility to change the 10s to 8s. And maybe lower the Mah cause I won’t be going around the world with it hehe.
Thanks for the tip on lipo already having the highest energy density, so I don’t need the explore the lion packs.
Right now I have the Caliber II Fifty like most of the builds. Any tips for replacements?
The thing is bro, if you go to 8s at best you save 20% (400g) battery weight and you could drop down to 2x5000mah which might save you collectively 50% or 1000g but smaller Lipos often start to weigh more so that is really best case scenario.
So for 1kg or the weight of 1L of milk you have to buy 2x new battery and will have 20% less power and 62.5% of the range. To save a kilogram your board will be half what it is now and you have to buy new batteries…
I wouldn’t bother sorry dude
What does your board weigh now? we could work out a % weight lost, but it will be a low number
Don’t bother trying to get lighter longboard trucks. Cast aluminum is cheap. Trucks made of a magnesium alloy is costly. Trucks made of carbon fiber with metal inserts for the axle, kingpin bolt, and pivot nose is even more than the first two. There is no other material lighter than carbon.
You can change your deck to carbon fiber.
What motor are you running? If it’s a 63mm motor, you are probably not using all the power it can offer so you may want to downsize to a smaller motor, say 50mm. That’s the easiest way to lose weight without affecting performance/range
This is wrong. Li-ion has the best density to weight ratio, LiFePo4 has the worst. Upgrading to li-ion will help a little with weight.
The way I see it why not add another few batteries in parallel then you will have a huge range and you’ll never need to carry it again. Although you will have to pick it up occasionally when taking it out side and stuff.
Thanks, these are things I didn’t look at. What I’m mostly looking at is the boosted board to at least match that or better. Their board is 15 pounds and has half the range I have now.
Maybe most of my weight is in the board like @chuttney1 mentioned. I’ll take a look at that.
@pennyboard I am using a 6355 Sensored. This because I could not find a reliable smaller motor with 190kv at that moment.
Thanks for all the help, I’ll get a weigh in soon. Hope this will give me a better insight.
What is the average board weight here anyways? (maybe a better question)
You should cut down wherever you want but the battery. Keep what you have or do the same with Li-ion if you really want but don’t cut on it.
If you have a lathe or CNC access or skills you can try many stuff.
Slice the deck and reinforce remaining layers with carbon fiber ones and / or Kevlar aramide. This should save kilos. Next, choose wheels and trucks accordingly but careful with your use. Smaller wheels are lighter, do you run belt drive or hub motor? If belt drive then get 83mm flywheels and adapt gearing. Replace pulleys with either PETG or aluminum if not the case right now.
Cut unnecessary plastic areas from your connectors (not the whole plastic casing). Get shorter cables or slimmer caoutchouc sleeves around your cables.
Look if you can find titanium bolts for everything (or try and risk the Alu ones if you dare).
As you see, many options are possible I just touched the tip of iceberg. Every part can be lightened to suit your needs if you have patience and ideas.
Easier to shave an ounce everywhere than a whole kilo on a single part. Just like race cars!
if li-ion have a better density to weight, how come the rc guys are using lipo’s then?
@Cobber That’s because of max continuous amp discharge. It is harder to find Li-ion with high amps. Also RC stuff is mainly low voltage with electronics geared for low voltage high amperage, it is cheaper to do that and weight moved in RC stuff is always lighter than a manned vehicle.
AFAIK only high discharge 18650/21700 cells able to pull more than 30 amps continuous safely per cell are LG HB2 / HB6 and Samsung 21700-30T. HB2 are 1500mAh, Samsung 30T are 3100mAh.
For each format you will also find other cells with way more capacity but lower amperage.
We have enough space to carry big battery packs though so max amps can be bend however you like it.
so for the weight li-ion can not discharge the amps…
Well yes and no
Note that I was answering your question as to “why RC hobbyists use Lipo instead of Li-Ion” feel free to calculate by yourself the energy to weight ratio with any 18650 cell vs any lipo cell. A match up between Samsung 25R or LG HG2 (popular builds here) and Hobbyking Turnigy might be a good start.
I’m personally sold for Li-ion because for my exotic limited space I obtain smaller pack for my Wh goal. I can also modify by simply switching cells models without changing volume. I manage to get more than 3200W continuous in 8S4P from my cells for less than 1.4kg total. All in triangle packs.
Duh, can’t even complain about safety. It is easier to manage 18650 cells for dummy user like me than Lipo.
Though if I wanted to draw 6000W for same size I’d go custom Lipo pack from SMC or Lonestar. And I’d still need bigger space too so not exactly same size. See, that’s yes and no.
sorry dude I do not understand what you are saying
I was able to shave some weight by using smaller mechanical parts to offset a larger battery and more powerful motor. Right now Im running 360wh 10s4p block into a single 149kv Turnigy motor. Even with the low kv, I still only ever use half throttle at most. Im going to reduce wheels from 83mm to somewhere in the 70mm’s and maybe go with smaller pulleys as well. That will shave weight and also reduce the unneccesary headroom that in 2 years I havent used, hopefully giving me more torque and efficiency. Should also mention that my board is smaller than a pennyboard and also much more lighter weight. Board is surprisingly comfortable to ride and is very maneuverable if you can balance your body weight effectively. Trucks are currently pretty tight to account for speed wobbles, still finding the sweet spot.
Now that’s a neat build, how much does it weight? Looks pretty dangerous and fun too!
@Cobber if you don’t get something simple like what I wrote why bother asking about energy density? Just nevermind and build with simple proven parts then.