Carbon fiber is much stiffer than glass.
| Material | Young’s Modulus(GPA) |
|---|---|
| E Glass | 30-40 |
| Carbon Fiber | 125-181 |
| Kevlar® | 70.5-112.4 |
| Epoxy | 3 |
The actual maximum tensile strength is closer between the different fibers (500ksi vs 300 ksi carbon vs glass), but the behavior of the composite depends on both strength and stiffness. Fiberglass will be much more bendy, and will bend farther before it breaks.
Thanks! You always got the best answers lol
Quick question:
What would your go-to choice for a gear drive with a high gear ratio that work with 115mm Kegel type wheels?
(yeah, yeah, I know. You don’t really NEED a high gear ratio for rather small wheels like that. But the thing is: I am heavy and I don’t need speed, I need torque. If I max out at 30km/h that is alright for me, as long as I can go that speed uphill too ^^. Hence the question).
Thanks!
I sometimes run 50T kegel from eovan and 14T Motor pulleys on 110mm wheels. Dickyho on ebay has great 44t pulleys too.
**Friggg- missed the gear drive part lol
I know you said gear, but a 15/44 or 15/48 belt ratio on 115mm wheels is going to be super torquey. You can also get some pretty big reductions using chains, even more I think.
Or the open steel gears on the SRB drivetrain uses a high Kv motor and has an extremely steep reduction, maybe look into those.
Also, I just wanna say how much I freaking appreciate @b264 and @MysticalDork in this thread. I learn so much from you two!
Where on earth can I buy 10mm speed rings in the US? I’m getting these from McMaster but I’m not 100% sure they are the right ones.
These may work. The ID tolerance isn’t great (10mm, +/-0.3mm), but if they fit, I’d prefer them over aluminum or copper for compressive strength. They’re also a little cheaper than the aluminum ones.
I’m 95% sure those are the ones I tried and they don’t fit. At least mine didn’t. The error tolerance there leaves a lot to be desired.
@MysticalDork is right, as usual; the copper ones can smash a little bit if you torque on them.
I got some concerns. My left motor wasn’t starting up. I have FS6384 zenith v2 on moondrives with mbs wheels and matrix II. At first I thought the motor was shorted both I turned if on and off again and it ran for another 2miles. Now I’m paranoid obviously I’m going to check all the parts when I get home but what do you guys think? Is if it was shorted then would the short just go away like that after restarting?
One of my fs6374 motors took a hit awhile back. You can see the gap between bell and the stator gets larger and smaller (min is basically zero) as you spin it, meaning something is cockeyed. Seems to still run fine as far as I can tell.
Should I disassemble and investigate, or is this normal wear and tear?
sounds like a slightly bend shaft, if it bends more, then the can is gonna grind against the stator
I’ve heard it is recommended to not let the board stay plugged into the wall after it is fully charged. Is this true?
Is it okay to leave the board plugged into the wall of the power is off? I’m planning to use a smart plug to cut the power and monitor the board via smart BMS.
Depending on the exact behavior of your specific charger, this can be either a non-issue, or actually important. Because it’s unreasonable to have everyone check the behavior of their charger and then pick the appropriate course of action, the blanket recommendation is to err on the side of excessive caution and never leave your board unattended while charging, and also not leave it connected to the charger for excessive periods after charge completion.
With that said, it is a good idea to leave the battery on the charger for at least a few hours the first time it’s charged after assembly, to give the BMS a chance to make sure everything is balanced the way it likes. Obviously with a smart BMS this isn’t as big an issue because you can see the cell voltages easily.
Yes, that should be fine. You just don’t want to leave the charger powered and connected to the board. If, however, your charger happens to show signs of parasitic drain (power flowing back from the battery to the charger when the charger is off), then I would recommend not leaving the charger connected and unpowered either.
It 100% depends what charger you have.
Cheap charger? No
Charger with trickle behaviour? No
Good charger with float cutoff? Yes
Also, leaving it on for a couple hours after charge at least occasionally is good to balance the cells. Multiple days or weeks is where it gets dicey.
Thanks for the comments. This is the charger I’m planning on buying - YZPower charger. Is this a charger with float cutoff?
Follow up question about chargers: It is recommended that I use low amperage charger if possible? Asked another way, would a 4A charger be “safer” than 6A?
You’ll need to ask the seller.
The graphics there seem to indicate it cuts off for charging lead-acid batteries but not for lithium-ion batteries. It’s not super clear about it.
Best way is just to test it yourself.
YZPower is a good brand though.