Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

skeetab5780 · Oct 6, 2020

John in CR said:
The overheating means you need a smaller rear sprocket, not a larger one. You seem to keep forgetting that it's a relatively low power motor in that casing. What's the no-load current of the entire drive train in low gear vs high gear?

ya but it hasn't overheated and i'm doing mostly road riding no crazy climbing and I want more top speed. I want the motor to overheat so I can replace it with a better one. I've been doing good with starting only in 1st and 2nd rolling

skeetab5780 · Oct 6, 2020

So I finally got pulled over by the cops one town over from where I live. I was riding slow down the right side of a main road with no helmet when he stopped in front of me. I shut it down said hello, got off and handed him my license per his request. I told him I can have it picked up with a truck since I could tell he wasn't letting me ride it home. He asked if I could pull it over by the library we were near and get it off the road. He did not write me up and gave me a verbal warning and handed back my license.

He asked how fast it was and I said around 35mph, he said I could probably get it licensed as a moped if I get all the lights working. They are almost all working now just need to fix the rear brake lights. But MA moped laws state they cannot have more than one gear so I would have to technically lie on the form. Thoughts?

skeetab5780 · Oct 6, 2020

skeetab5780 said:
John in CR said:

The overheating means you need a smaller rear sprocket, not a larger one. You seem to keep forgetting that it's a relatively low power motor in that casing. What's the no-load current of the entire drive train in low gear vs high gear?

Click to expand...

edit: I do own the new LRHDD XL motor that is a beast and same physical size

John in CR · Oct 6, 2020

skeetab5780 said:
John in CR said:

The overheating means you need a smaller rear sprocket, not a larger one. You seem to keep forgetting that it's a relatively low power motor in that casing. What's the no-load current of the entire drive train in low gear vs high gear?

Click to expand...

edit: I do own the new LRHDD XL motor that is a beast and same physical size

Hopefully the new one can handle more. Gearing is so important. To set the goals posts out there for you, I just got a escooter/emoto going with a pair of Nuc's pushing a HubMonster. This is my lightest HubMonster in service, but I still run the same wheel size, about 19.5" OD. With speed limit set to 100% and no field weakening, I get 101kph no-load with a full 16s battery. Full for me because I choose cycle life as important is 65V. It took it out on the highway and got a 94kph top speed in both going and returning, which surprised even me, especially in just a normal upright riding position.

goatman · Oct 6, 2020

id select a gear that the bike will start in like 2nd or 3rd, take the shifter off, go through inspection and then put it back on after inspection but thats me

no different than programming a controller to 3000 watts for inspection and then bumping it to 5000 watts afterward

skeetab5780 · Oct 9, 2020

goatman said:
id select a gear that the bike will start in like 2nd or 3rd, take the shifter off, go through inspection and then put it back on after inspection but thats me no different than programming a controller to 3000 watts for inspection and then bumping it to 5000 watts afterward

then the top speed would be 25mph in 4th gear wide open with a huge 84v 35ah battery....that sounds real fun

goatman · Oct 9, 2020

thats why you put the shifter back on after inspection but if your going through the bother of legalising it you could also just register it like a street legal enduro

skeetab5780 · Oct 12, 2020

goatman said:
thats why you put the shifter back on after inspection but if your going through the bother of legalising it you could also just register it like a street legal enduro

Oh I misunderstood you, I thought you were saying to gear it like that forever...not just to pass inspection. That would work if we had to inspect it, but in my state MA, mopeds are registered with one simple form and you yourself are responsible if you get pulled over not meeting the moped criteria

-under 30mph
-49cc or less
-one speed transmission
-blah blah

mannydantyla · Jan 5, 2021

Thank you skeetab for this very helpful thread, it was fun reading through it all and it helped me decide on what motor I need for my project.

I love the form factor of this gearbox but I have decided that it is not for me and my project (a small, classic Honda ev conversion). The one they're selling now has a 4kw motor and from what I've seen on youtube, it can get top speeds of 110 mph! I only need a top speed of around 60mph. Faster would be nicer but not with 50-year old hub breaks lol.

Or if I could use the gearbox to get away with a smaller, weaker battery pack then that could make it worth it but the shifting is still not great even with a clutch, and I'm building the bike for my wife to ride and she refuses to learn how to use a manual transmission. That's actually one of the reasons I chose an EV motor for her bike.

The Denzel is a very cool product and part of me wishes it would be what I need. Thank you again for documenting and sharing your build.

skeetab5780 · Apr 7, 2021

mannydantyla said:
Thank you skeetab for this very helpful thread, it was fun reading through it all and it helped me decide on what motor I need for my project.

I love the form factor of this gearbox but I have decided that it is not for me and my project (a small, classic Honda ev conversion). The one they're selling now has a 4kw motor and from what I've seen on youtube, it can get top speeds of 110 mph! I only need a top speed of around 60mph. Faster would be nicer but not with 50-year old hub breaks lol.

Or if I could use the gearbox to get away with a smaller, weaker battery pack then that could make it worth it but the shifting is still not great even with a clutch, and I'm building the bike for my wife to ride and she refuses to learn how to use a manual transmission. That's actually one of the reasons I chose an EV motor for her bike.

The Denzel is a very cool product and part of me wishes it would be what I need. Thank you again for documenting and sharing your build.

Thanks for the kind words, i still love this dirt dike even though i can only take it out on trails now the cops are nice about it but dont want me riding it on the streets anymore so typically take a more bicycle looking bike when i ride with the kids.

This drive is sort of like a tank though and i have a feeling they will last for a very long time, bullet proof besides overheating motor if feeding it way too much power or your a fool riding in wrong gear. This bike has no clutch but you need to know what your doing.

Going 110mph on a coverted bike seems crazy, i am aiming for 50mph on the Honda CRF im converting now with the Denzel D9000M motor. That is plenty fast for me unless your commuting hwy everyday

skeetab5780 · Apr 7, 2021

I also want to make a note that the Ebay BTR 72v 35Ah battery i purchased is a big pile of crap and it was another bad investment. I only got a month or two out of it then stored it for the winter. After only 3 months i go to use the bike and it does nothing, i go to charge it and it doesnt charge...i end up opening it up to find that it is made from 20s1p lipo pouch cells and one of the cells right in the middle of the pack has a huge puncture it is swelling and leaking chemicals all over the rest of the cells. This was not done by me so it happened from sitting dormant 3 months i guess. Also the negative battery terminal had a really bad cold solder joint that just fell off the cell pouch tab making the bms shut down randomly since the connection was intermittent.

I am not sure if i can revive the battery but very big waste of money. Im sure the other 19cells will work but removing the one pouch in the middle will not be fun since each pouch has a positive on one end and the negative on other, so there is solder joint on both end of battery, the bms also will not work with 19s only

I did shop this battery and bought it when it was over 10% off paid just under $700 and its worth over $800 new

skeetab5780 · Apr 26, 2021

So here are some pics of the junk BTR Ebay battery you should never buy! And never keep in your house!

Also I would like to note that I paid a little bit extra to get the 35ah version over the 30ah since this dirt bike was heavy and I wanted good range, but if you look at the pictures of the cells you can see they are clearly labeled 30ah cells!!!

Here is the picture process of me removing the bad cell and trying to put it back into a usable 19s battery pack...can you get a 19s BMS? Not sure

larsb · Apr 26, 2021

I feel sorry for you.. would recommend getting some used hybrid auto cells. Top quality, low price.
I paid 150usd for 10s25Ah modules in the past. Still ride them. If you find the right seller then you could get even more wh for that price

skeetab5780 · Aug 20, 2021

Oh my goodness, after removing the puffed cell from this pack, I have just left it sitting on my work bench without a BMS or any sort of parasitic drain on the pack with no time to work on it lately. But now another 30ah outer cell has completely puffed out awful just like the last one...Now I have to remove one more cell and it will become a 18s pack, which is going to make the top speed even slower on this bike. I will likely need to build a new pack for this bike to come alive again

skeetab5780 · Jan 31, 2022

So we got two feet of snow and I was bored so I figured it was a good time to slap together a very cheap 24s4p A123 26650 pack out of the $1 cells from forum member Hummina Shadeeba

I would like to note that these cells are second hand and they have had their original spot welded tabs ripped off which could potentially be a major flaw in them, leaving holes in the cathodes of the cells in numerous spots

Either way its a $100 battery pack and I am not even running a BMS at the moment(I did order 6s JST balance leads to solder on)

This is my first time spot welding a123 cells and it required tons of power, I finally got the best spot welder you can buy and let me say it makes life so much easier! The kweld with Ultra cap module

I ended up making two 12s4p packs then stacking them together with a partition between them

Then I spot welded them together

Then I made some discharge leads out of Turnigy 200c teflon cable

Getting ready to add the insulating partition before flipping pack

flipped the pack on itself

Then I wasted a roll of 33+ 3m and applied it over the cell ends, then duct taped over that quickly in excitement

stupid me since I am not familiar with A123 cells I put the red and black wires on backwards...DOH the negative looks like the positive on these cells...Good thing I use the Cycle Satiator to charge the pack or else i would have fried my kelly Controller and have been really pissed! I was able to correct this downline
Here you can see the negative reading I also did not see since I wanted to ride

skeetab5780 · Jan 31, 2022

Overall the pack seems to work great, but since I am not too familiar with A123 there are a few things to note

I am keeping this battery in my 10x12 shed I built outside just incase anything bad should ever happen, it will only cost me about $10k instead of $300k

The cells are second hand so take this with a grain of salt
The cells are very powerful but sag like crazy
the nominal voltage is 3.2v
the max charge is 3.6v
but under load the spec sheet says they can hit 2v per cell!!
the spec sheet says 4000 cycles...I doubt it
spec sheet says they work good in cold weather!

So hot off charge its 86.4v but under heavy load it can hit 60v. But unlike really cheap chinese 18650 that have low C rating...the second you let off the throttle the A123 cells spike back up to 80v range until you obviously deplete the small 10ah pack

But lets put it this way it put out 50a continuous for 30 minutes riding thru almost 2 feet of snow, then we used some pink paracord from the dollar store and tied the kids sled to the dirt bike and I pulled my daughter around town for about 30 minutes straight completing about 5 miles in first and second gear

The battery hits the 50v lvc on controller and cuts out, but when I get back to the shed to check the voltage it is over 72v...

weird but fun cells

Also the dirt bike is still performing excellent this drive may not be crazy power but it is bulletproof and will last for years of fun and utility

skeetab5780 · Feb 21, 2022

Well I had a bit of time to charge my A123 pack after killing it the other day during the snowstorm. Looks like the Cycle Satiator pushed 8.41ah into the 10ah pack which seems pretty good to me for a first discharge in the cold. I will keep the updates incase someone is actually reading this thread and wants to know

skeetab5780 · Apr 12, 2022

last two charges on the A123 pack were 8.89ah and 8.9ah so the pack seems pretty consistent and for $100 cost you cannot go wrong with the power output!

We got the bikes out today and rode around the trails it was fun! The Denzel is my new favorite bike to ride its comfortable and fun switching gears and first gear is a wheelie machine!

Milo my good boy got in on the pic

trazor · Apr 13, 2022

SlowCo · Apr 14, 2022

Really nice indeed :bigthumb:

skeetab5780 · May 15, 2022

Super windy day, but it was nice and warm so I just had the itch to get out on the bikes for a few hours messing around in the yard...
https://www.youtube.com/watch?v=QeYFkBl5FhA
[youtube]QeYFkBl5FhA[/youtube]

SlowCo · May 16, 2022

Nice big back yard. I'm a little jealous :mrgreen:

The neighbors are glad you've converted to electric I presume :wink:

skeetab5780 · May 17, 2022

So we had a little accident with the Denzel bike, these a123 are very powerful...I may have been drinking around the fire for a little then decided to go for a ride, I flipped the bike over and broke off the rear fender while wearing flip flops...but I am completely fine and I didn't even drop the bike, I jumped off the side kept my hands on the bars and rode it down.

Then a few minutes later my son Vinny (who is the size of me) went to ride the bike and he has not ridden it in a few years since it had the old throttle on it with weak batteries, and the new twist throttle is very responsive...He immediately whiskey throttles the bike in first gear and cannot control it, he comes off the side of the bike and it crashed into a huge log wall breaking the front headlight assembly and bending a few things...The bike completely moved all the huge logs thru the log wall

We are both 100% ok which is the important part, but the bike definitely needs some work now, I fear we have bent the motor brackets yet again looking at the chain being too slack

These are the new throttles I am using I have bought 4x already I really like the feel of them, I have one for my new Honda dirt bike, one on the new Voloci and one on the Denzel and one spare

skeetab5780 · May 17, 2022

SlowCo said:
Nice big back yard. I'm a little jealous
The neighbors are glad you've converted to electric I presume :wink:

Thanks! we just took down like 20 trees so we have brush piles and logs everywhere, hopefully we can chip most of it once it dries out a bit. I would feel bad if I rode loud gas bikes in our neighborhood for sure

larsb · May 17, 2022

Is it only me that can’t see linked youtube videos anymore here on ES?
I guess something was supposed to show up here :|

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