eLofty Direct Drive Discussions-read before buying

Ok let me explain what’s going on on each solution.

@mmaner is suggesting to up Regen amp, which will make your braking harder and more responsive.

The problem with DD isn’t that the brake sucks. It’s the full brake low rpm rolling resistance is low. So it will roll at full brake at low speed.

@mishrasubhransu’s solution is to use active braking instead of what the Vesc do in current no reverse with brake mode, which simply just short the 3 phases on full brake. Active braking allows the Vesc to push reverse current to brake. Therefore, it solves the issue of rolling. This is especially important for big wheels or AT on DD since theres a lot more torque applied to the wheel while staying in place and the shorted phase wire resistance is not enough to keep you in place.

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Perfectly explained Wing! I am gonna add this above.

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Makes perfect sense now. Gracias!

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I’m gona experiment to see how to completely get rid of reverse while getting active braking when I get back. Exway hobbywing ESC has it and I love how hard it brakes.

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I did the math:

7km/hr to rpm

7 x 1000000 = 7000000
7000000/60 = 116,666 mm/min

116,666/55 (radius of 110mm) = 2121rpm

So…
7km/h = 2121rpm

This is based on what Google told me to do.

2121rpm will be set to max reverse rpm to try.

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kh/hr to erpm

speed_in_kmph= pi*D_in_mm*rpm*60/1000000 = pi*D_in_mm*(erpm/pole_pairs)*60/1000000
erpm= speed_in_kmph*pole_pairs*1000000/(60*pi*D_in_mm)

erpm = 7*10*1000000/(60*pi*110) = 3376
BTW, do you have metr pro/nrf51_vesc on your board? If so give the vesc_tool app a try. Sooo convenient.

Dang it. It’s erpm not rpm. Radius is 55 for my 110mm.

Mad DD poles = 28 poles

7km/hr * 28poles * 1000000 = 19600000

19600000 / 60 * pi * 110
19600000 / 14124 = 1388erpm

Is this correct?

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28 magnets means 14 magnetic pole pairs. Basically erpm means how many times a point on stator experiences a complete cycle of north-south-north pole per minute. so erpm = pole_pair*rpm.

7*14*1000000/(60*pi*110)=4726

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@rey8801

Are your DDs 28 poles or 28 magnets? Just clarifying.

28 magnets, 24 poles.

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@pookybear
28 magnets(Or 14 magnetic pole pairs) on the rotor…
24 stator poles. Stator poles don’t count in our analysis.

so this still holds.
7*14*1000000/(60*pi*110)=4726

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Mine arrived today!

All looks good other than the screws look to have the wrong size heads -

I will have another look at them later when I get home

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Sometimes on these they only come finger-tight.

They have used the wrong screws, here is no counter sink in the adaptor. When I went to remove the screws and found that 2 of them have already been stripped with a hex tool and I’m going to need to dremmel them.

I don’t have my calipers on me, does anyone know the size of the screws so I can order some replacements?

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Bummer. Hate to see that. When my board comes later today I’ll see if my screws are proper and I’ll measure for you.

I have the exact same. They have done it to create a flatter profile so that the bolts don’t rub against the wheels.

In order to even attempt opening them you have to heat it a lot by a hot air gun or a small torch.

Screws are m3 if I remember correctly.

BTW, why did you have to remove the screws at all?

I dont have any wheels with kegle cores. I have original ABEC 97mm reflys and 90mm clones. A friend 3D printed me some clone adaptors to use.

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Gotcha. So, yeah. Heat each screw individually using the small blow torch available at the corner stores. And only then attempt to open it. Otherwise they will strip, which is what happened to you. You could also use a grip pliers/locking pliers to remove them once heated up.

Something like this
EAGLE TORCH POCKET TORCH GUN ASSORTED COLORS 4" PACK OF 1 https://www.amazon.com/dp/B01M5BWQ5F/ref=cm_sw_r_cp_apa_i_fAJgDbGQWPSM9

Thanks for the info.

The 2 screws I can’t remove were already stripped. I poped my hex in there and it just rotated around :frowning:

I’ll get some more ordered this evening