Apollo 250 Dirt Bike Conversion

nutnspecial said:
D7500 has 66,65kV and 48,45Nm
other motor has 69,64kV and 26,5Nm

Wow that seems a pretty dam good increase for just a couple pounds of motor!!!

Imo it's too bad the bigblock and apparently (looking for confirmation) the d7500 have around twice the kV of BHT.

Low kV means you can get more power/energy from the voltage side of equation, which better suits the lighter motors imo, and also you can charge a HV battery of same WH much faster at recommend C-rates.

But still- it looks nice! Glad I found it for ya hahaha, keep up the good work!!

PS Izeman, watch for my new klein build. . . You will love it as a mid direct drive I think- the newer frame/geometry is quite nice to our old ones!

Have you started a new thread for that build? Didn't find but the old klein thread.
 
nutnspecial said:
Skee, could you confirm your final choice of sprocket sizes, voltage, and top speed please?

Unfortunately I have not been able to get a GPS top speed yet, it does seem slow and close to the BHT KV(after testing top speed it is quite a bit faster than the BHT)

BHT was using a 11t front and this motor is using a 13t front now rear is a 60t so 4.61:1 ratio

Will update when I get a few free minutes on the bike
 
So it is absolutely freezing outside! And this bike is a lot faster than I thought it was! I am actually really glad I put a 13t on it now...

top speed of 41mph after two runs back and forth down a empty parking lot. Battery pack was 72v before throttle was applied

calculate off 67v nominal thru a 6" piece of positive 12awg turnigy silicon wire as a bottleneck also(temped out)

Im sure I could have gone a few more MPH but ran out of room for it to wind out.
IMG_1645.PNG
 
I dont think it will wheelie on flat ground as is now, but with double the capacity battery and some body english i think it is possible, if this motor was on the kuberg it would be deadly.

If i end up getting a 20s battery i can get a 14 or 15t sprocket and really push it

It accelerates pretty fast as is now but need to get more batts in it, controller can draw 130a max from batteries but right now its starving a little

If i want in the 10kw club i will need more voltage unfortunately its just under 9kw now

Ktm runs 300volts!!
 
skeetab5780 said:
Ktm runs 300volts!!

because power is Volt x Amps only the product of both matters
 
madin88 said:
skeetab5780 said:
Ktm runs 300volts!!

because power is Volt x Amps only the product of both matters

Ya and??

KTM pack is only 10ah since its 300vdc, lets your run higher RPM and smaller wire AWG
 
Also smaller controller and easier fast charging. 300vdc is crazy though haha!

Ok, so I'm still missing your voltage and would have to guess tire diameter.

So, could you just confirm how fast the bike went with the bht?


From there we can just figure your ~18% higher gearing w/ the 13t and know how close it is to the ~30kV bht. Seems like it's close and not double kV at all??
_____
(And I'm sorry to have to re mention this, but I said 'WATCH' for my build thread. Not 'LOOK'- - bcuz It's upcoming)
 
I bought a 14t sprocket already(on accident not thinking)

Voltage is 18s 66.6v nominal

Bht was geared for 35mph with 12t/60t

Tire diameter is posted on page 1 of this thread with the BHT ratio picture calculated off 20s voltage

Its not double kv by any means but its def faster
 
Seems like if bht did 35mph on 12/60 and d7500 does 41mph on 14/60 they are nearly identical kV ? ? ? ?
/// oh my bad you're running 13t for 41mph now, so ~9% taller gearing and ~18% greater speed.

Pretty close, way closer than LR/ big block for a single reduction running decent voltage!

Wow that is good! I would want to run up to 24s ~15ah on it for up around 10kw and <1hr charge w/ 15amp meanwells.
---
Now why in the heck wouldn't the seller not want to and/or be able to verify a simple detail like that is all I wanna know lol. Might have to order one.
Any other stuff catch your eye over there skeetab? Will they sell us (US) the stuff they don't have marked with 'included shipping'? Communication is a biatch with over there. I think I want an Asian wife btw, maybe since women are already hard to communicate with in the first place :lol: Recently was with one and she kinda kinda raped me a little but that's offtopic heheh
 
nutnspecial said:
Seems like if bht did 35mph on 12/60 and d7500 does 41mph on 14/60 they are nearly identical kV ? ? ? ?
/// oh my bad you're running 13t for 41mph now, so ~9% taller gearing and ~18% greater speed.
kV should be determined WITHOUT load, because under load the RPM will drop.
On the smaller BHT motor it will drop much more than on the larger one, so it well could be that a larger motor with lower kV offers more top-end speed as a smaller motor with higher kV. It's called "rpm stiffness".

The measurements from the russia guy are true because toolman2 measured the same:

https://endless-sphere.com/forums/viewtopic.php?f=30&t=65757&start=525#p1334685
 
because under load the RPM will drop
Right and that has gotta be what we're seeing here. Double kV (if this is definitely BHT and not bigblock VS d7500), plus taller gearing should be going >70mph with adequate amperage!!

Seems like you should be gearing down and not up skeetab, to be kinder for your batteries and perform much better? Or you really wanna go past 60mph on that :?: :twisted:

From my previous calcs 5k rpm is a bit much for a single reduction so I may just wait to see what develops. For now the bht is great and simple and only gets hot in the summer when beaten.

The measurements from the russia guy are true because toolman2 measured the same:
https://endless-sphere.com/forums/viewt ... 5#p1334685

Thanks maddin that takes all the pita speculation out of it- I had no idea toolman had already gotten and tested one! Must read more of that thread.
 
The bht calculation was for 20s nominal and im only running 18s but yes they are very close otherwise.

No you are correct i need to gear it to go slower but the only way to do that is with a larger rear sprocket. I may try the 12t again with the smaller chain and see if I can get it to run straight.

Its been so long since I've calculated ratios even tho this is only single stage, I bought the 14t sprocket thinking I was gearing down but it was gearing it up....Luckily the place I get them from they are only $5 shipped!

For now i will keep the 13t

NUT: I did not GPS speed verify the BHT setup so I have no idea...just that calculation based off the BHT kv specified on the forums page here
 
So I am going to attempt once more to use the 12t sprocket don't ask me why! I used two small allen bolts this time and shaved them down as small as I could, took a bit of the metal out of the sprocket retainer and hopefully it will work itself into submission...

You can see the top bolt clears the chain but the bottom one is the one that hits it just a tad bit, not much I can do, but id like to get a GPS speed on this sprocket to see how fast it is
IMG_1649.JPG
IMG_1650.JPG
 
So Im a little disappointed in this top speed reading, but this is actual GPS speed and I was in a parking lot full of cars and could barely get to full throttle before having to let off and brake immediately...

I think 35mph is the top speed with the 12t but it says only 33...with that being said this is really close to the BHT
IMG_1652.PNG

Does anyone have KV of both motors?
 
I'm pretty sure every bht build I've seen comes to around 30 for their kV. Mine too, 30rpm per volt.

Let's see, I'm running 40mph hot off charger iirc. 99-100 volts . 24" dia tire. 11/55 reduction.

Yep, 3k rpm /5 should come to around 40mph for 24"x 3.14 circle

And while I never measured mine truly 'unloaded', I can assume with a sag of about a volt at top speed for a 10ah pack I might as well be.

///and as this then applies to the d7500, a single reduction for 100v would be rather challenging unless you want 60mph. I guess maybe 16s x 150a would be good for max power, a reasonable reduction, and 40mph, but then of course batt and controller have to be up to the challenge right? 24fet is pretty big. Charger would have to be big to have capability of 1c charge as well.
 
Why would a single reduction be challenging with this motor at 100v? All you would need is a really large rear sprocket...nothing wrong with that. I preferred the LRHDD over the BHT with both my single reduction and it has the higher KV

I am going to get my batteries mounted in and try a good trail ride with this thing at 18s 24ah 12t/60t and see what I think before I waste time changing the rear sprocket, but if I want more power that will realistically be the only solution for me and this build. I doubt I will get into a two stage reduction...by the time I finish it they will have better technology out :)
 
I am going to get my batteries mounted in and try a good trail ride with this thing at 18s 24ah 12t/60t and see what I think before I waste time changing the rear sprocket, but if I want more power that will realistically be the only solution for me and this build. I doubt I will get into a two stage reduction...by the time I finish it they will have better technology out :)

Agree and that's my take on things too. I hope we have battery tech in our lifetimes to do something similar to that rad jet hover board thing the ?french? dude came up with. One 10lb 'drone' that you can drive. . .

Anyway, Yes it's that >10 to one reduction. 110 (or more) rear teeth on a 24" or 19" moto for any chain that's strong enough didn't seem very easy to me. That's a huge sprocket, when I wonder why can't the motor be a lower kv?
 
nutnspecial said:
That's a huge sprocket, when I wonder why can't the motor be a lower kv?
If it would have lower kV it would just meen that it needs more volts and less amps for doing the same.
But the torque it can produce is the SAME.

for instance a

100kV motor with 50V battery and 100A controller

is in terms of performance exactly the same thing as a

50kV motor with 100V battery and 50A controller
 
That silly d7500 pit bike from china on indiegogo is advertising thier bike goes 62mph top speed on 72v

I wonder what ratio they are running, it must not have much torque geared like that unless its pulling 200amps
 
Nut i think your exagerating a little bit with the 110 teeth but not far off. A 70t in the rear with the 12 in front is 5.83 ratio

24s nominal is 88.8v

88.8 multiply by kv of 30 is 2664 rpm

Wheel size 25.5 inches

Calculates to only 35mph

Seems pretty easy to me
 
skeetab5780 said:
That silly d7500 pit bike from china on indiegogo is advertising thier bike goes 62mph top speed on 72v

I wonder what ratio they are running, it must not have much torque geared like that unless its pulling 200amps

Is it this bike? https://www.indiegogo.com/projects/the-most-affordable-electric-dirt-bike-under-2000-motorcycle#/
This bike is made by the same guys that makes the Denzel bikes and Denzel carbon fiber bikes, and also the Denzel d7500w mid drive motor, their website is eastgem.net

Not sure silly is the correct used with their products. Seems they know their shit, and it seems they are working hard to bring things to another level. I am really looking forward to what their product line will be in another year or two as they seems to bring various models and motors to market keeping a steady development pace rather then milking the cow to the final drop for each product. As a consumer I can really dig that approach.
 
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