I just started learning longboard a few weeks ago and discovered the DIY eskate community at the same time. I start to really enjoy the sport/hobby and as I live in a really hilly area in Bristol in the UK I thought going electric could be a good step forward.
I’m however not yet willing to pay the price for a £1000+ board knowing the battery could die in a few years with me not being able to replace it. A DIY build is therefore a good solution for me I believe. I’m also an Engineer so I kind of enjoy that sort of design project.
Before pulling the trigger, I am willing to get some advice from experienced builder about the build I designed.
My requirements are:
A skate that will be easy top ride – I am not an experienced rider
Good torque to climb hills
Good breaking power and regen
Speed does not matter too much for me – Not planning on dying on a skateboard :), let’s say at least 15-20 mph
Around 10 miles range from a charge
Safe and convenient charge of the battery
As water-resistant as possible to withstand the UK weather
Cost less than £500
I did some initial calculation and created a little script in Matlab to start designing my build. I still need to make some assumptions on the motor curve to calculate how fast I could climb some hills in my area:
Gearing – Not found a suitable solution yet – hesitating between chain or belt and will tweak the gear ratio based on my calculation for torque required to climb some hills in my area at a decent speed.
Some folks use this as a primary method of transportation. It also is more convenient for some folks than an automobile and it’s pollution-free. It’s better for all of us to just call it “esk8ing” or electric skateboarding.
[Wheels](Big 80mm 87mm 83mm 90mm 97mm Longboard wheel SHR78A Red Color PU Wheels High Level Soft Wheels Resistant PU Skateboard Wheels http://s.aliexpress.com/7fIJz6NR?fromSns=Copiar para a área de transferência), go with 90mm.
40/44T wheel pulley, 15T motor pulley, 15mm belt
Avoid maytech if you can. Get Hobbyking ESC or even flipsky.
Get the KEDA 6364 AS @pat.speed said. .
You’ll probably be spend 15/20Wh/km. Means 240/320wh battery.
@marcmt88 or @fottaz mount
Cheap mini remote from eBay.
The rest of money you save, invest in custom li-ion battery with charge only bms and charger. 30Q or 20700b.
Thanks, this confirms what i was also thinking with the 10s instead of the 12s.
Another reason to do that is that I read that if you go over the max ERPM of the VESC it is possible to fry it and my 12s build theoretically goes over with no load on the wheels.
Look for the hobbyking sk8 series.
Sealed motors and relatively cheap.
Would look for 150-170kV motor which should rise up your torque.
Get a higher c rated lipo. 60-65c min. They more expensive, but if you climp mountains often, you also need higher currents more often.
With higher c rated lipos the voltage sag will keep minimal and the batteries run cooler which results in longer lifespan. For the long it will safe you some money.
When you talk about voltage sag, do you mean the voltage drop of the cell during discharges? If I understand you correctly this drop goes up with current but can be minimised by buying better C rate cells.
Every cell has a internal resistance.
The higher the resistance, the higher the voltage drop under high loads.
The higher the c-rating, the lower should be the resistance. It’s not 100% like this but manufacturers usually don’t give information about the internal resistance.
The c-Rating shows you how much current the battery can handle constantly.
You can calculate it like this
Pack size(ah)c rating = max constant current
That’s the theory…but as there is a marketing in everything which is sold now adays you can take from this value about the half. That should be your max constant current.
So 5000mah25c=125a /2 =62.5a
As you said you climp a lot of mountains I guess you can go up to 80a quite often.
This would result in getting your batteries run hotter and your voltage under load will drop for example from 3.9-3.5 in time of the load.
After you reached the top the voltage will swap back. So as long as your batteries fully charged it’s not a problem.
But when you already around the 3.7v for example you can come under 3.5 and your vesc will cut off your battery.
So on your way home you will need to walk up the mountains with low c rated batteries, with high c rated batteries you still can drive.
hope that was somehow clear and not confusing
Leave that hk motor mount alone its pretty cheapo.
Hk sk8 motors are good as are the vescs
and I would consider the graphene lipos from hk too they are in a different league, bit more money but if you are going to spend, spend on the battery.
I’m sure they did not change…
I’ll need to check the clearance with my deck for the 90mm wheels but will consider, maybe with raiser pads.
For the battery I’ll also have a look at the graphene option. I’ve also spotted an 8000mah 5s option at 30C. What would you advise between more capacity or a better chemistry cell?
Discharge rate is what you want so the higher the c rating the better and the less sag you’ll get. I think the graphenes are all fairly high and unfortunately so is the cost but its the heart of your board so its money very well spent. Cheap batteries are false economy as you will upgrade them later trust me.
Wheels make a world of difference to riding comfort and if you are going to go on the pavements then bigger the better with some nice soft risers to help cushion. I run 97mm but am upgrading to 107mm for that reason and here in oz we have pretty good sidewalks and roads but the concrete beach tracks with expansion joints every 10m really work on your calves after a while. Anyway hope this helps and keep the build here with pics! good luck
Just an update on my build. I have now ordered most of the parts (except the batteries):
I am still studying the battery as I am still unsure whether I go 25s or 52s 5000mAh batteries.
As I am also over my budget already and will probably finish around £550, I try to find a good solution without compromising too much on C rate.
I am tempted by the graphene range from Turnigy expecting that those cells will last longer.