Cromotor + MethTek Monster 24FET + 20S lipo build

[Lebowski]

Maybe regen is not possible in the beginning because it would overcharge the battery ?

 

[hjns]

Maybe regen is not possible in the beginning because it would overcharge the battery ?

Hmm. Could be. I will try lowering the regen voltage and see if that makes a difference.
Thanks!

 

[methods]

In other words, the first 10 minutes I can activate the E-brake all I want, but it only shuts down the throttle without activating regen. After those first 10 minutes, when I brake the regen is also activated, applying a very nice braking force and very nice regeneration of energy (5%), which is great. [/list]
Anyone any idea?

Just like the controller has an overall pack LVC to stop you from a gross over-discharge the regen feature also has a pack HVC to stop you from over-charging your pack on Regen. The controller can not see "regen current" and it controls regen only by PWM calculation on the mosfets and R12 voltage. To get your regen to work the entire time you need to modify R12.

R12 is the lower leg of a voltage divider that comes from system voltage. Just like soldering the shunt fools the controller into thinking it has less current when it has more... lowering R12 does the same thing for pack voltage. Be aware that this will have the side affect of raising up your LVC.

If you go back to my 100V/100A 18 fet thread you will see that I calculated a max regen voltage of 90V back in the day and modded R12 to be the desired value to get that. This was back before we knew we could push the 4110's harder... today I would mod to 100.0V

Good luck
-methods

 

[hjns]

Thanks, methods,

I will take a look at R12, and start doing the calculations for 84V. I do not want to go higher than 20S lipo (84V HOC at 4.20V cell level) for the simple practical reason that I would like to keep using my 10S packs. So it is either 20S or 30S, the latter being way overspec for the 4110 FETs.

thanks again for your help. I actually remember parts of that discussion, and will go back to that famous thread.

edit: I do have some 5S packs lying around. If I go to 25S and charge not higher than 4.00V, I would be right there on the edge. What is the collective experience with these 4110 FETs at 100V max? If I go 100V 80A peaks, 100V40A continuous, will it hold for a reasonable amount of time (aka, one year daily commutes)

Henk

Just like the controller has an overall pack LVC to stop you from a gross over-discharge the regen feature also has a pack HVC to stop you from over-charging your pack on Regen. The controller can not see "regen current" and it controls regen only by PWM calculation on the mosfets and R12 voltage. To get your regen to work the entire time you need to modify R12.

R12 is the lower leg of a voltage divider that comes from system voltage. Just like soldering the shunt fools the controller into thinking it has less current when it has more... lowering R12 does the same thing for pack voltage. Be aware that this will have the side affect of raising up your LVC.

If you go back to my 100V/100A 18 fet thread you will see that I calculated a max regen voltage of 90V back in the day and modded R12 to be the desired value to get that. This was back before we knew we could push the 4110's harder... today I would mod to 100.0V

Good luck
-methods

 

[methods]

Undercharging a 25S pack is actually quite different than fully charging a 24S pack. We can get away with running 24S on 4110's because that 100.8V is really just a surface charge that blows off as soon as load is applied. The only time 100V is on the fets is while it is sitting idle. Any time you are applying load there will be 5V or 10V or more ripple voltage... so by undercharging a 25S pack instead of being at the top of the charge profile now you are down deep in the flat part of the curve. That means that the cells are going to hang at much closer to 100V even under heavy load - especially with these super high C-rated packs.

For 4110's the absolute maximum that you can get away with is 24S. If you want to be the first to prove differently it may be possible.... but I suggest making sure you have really good capacitance on your rail and that you be ready to replace fets if it comes to that.

-methods

 

[hjns]

Hi Methods, no, I do not want to further experiment. I conclude that 25S is a bad idea, and thank you for putting my feet back on the ground, again.

First, let me introduce my Cromotor Commuter ("CC") to you:

What you see is the following:

• Cromotor hidden behind the pannier bags, laced into a 26" HALO SAS rim with black 14G Sepim spokes from JRH
• Lyen 18FET 4110 controller behind the seatpost
• FS Fusion-bikes.de frame painted blue metallic with a rear Fox SL shock. There are two watertight grey boxes (in the traingle of the front fork and lower main tube, and in the triangle below the controller) that contain the main connections. All electric wires from front to rear (or vv) are led through the black wire cover at the lower tube.
• Rear Avid 203mm rotor with Juicy Seven hydraulic caliper. DIY double switch for regen and rear brake-light attached to the brake handle (Left).
• Front 160mm rotor with Elixer Seven hydraulic caliper (Right). No regen or brake-light switch attached.
• Front Rockshox REBA air SL (100mm) fork, painted blue metallic.
• Touring steering bar, with DOT-approved 12V MoFa light and two blinkers. On the left hand side I have the 3-speed switch, regen, brake-light, mirror. On the right hand side I have the blinker activator and the throttle. In the middle is the CAv2 with current throttle hardwired. You can also see the GoPro (movies to follow).
• Rear pannier bags (completely watertight) are attached to the sideframes of a Freeload frame that is attached to the frame. Therefore, they do not benefit from suspension, and I need to be careful when hitting bumps. The rear light / brake light and the rear blinkers are also attached to the Freeload frame. A 74V-12V DC converter is attached to the underside of the Freeload frame, as well as a strobe for the blinkers.
• Single speed freewheel with chain tensioner, and attached to the 44t front cog. Front and rear derailleur have been removed.

This morning's commute was very enjoyable. Yesterday evening I had calibrated the CA up to 0.1A using the foam-cutter function of my ICharger (9.9A at 40.0V from the battery negative to one of the phase wires). So the results mentioned below are as correct as I can get them.

I took a very hilly trajectory (up to 20% inclines) with a total distance of 30km.

I started with a voltage of 83.8V, ended with 75.3V, and used a total capacity of 645Wh. My total pack capacity is 1kWh (74V 13.5Ah), so I am at 65% discharge. Perfect for a commute.

The 18.2 Wh/km really reflects the fantastic regen facilities when going down hill. I regenerated almost 120Wh, aka 21.3%. That really makes a huge difference!

In order to save juice and to NOT push the motor / controller to their limits, I limited the controller to 40A/100A and the CA to 40A as well. Still, going uphill showed some nice peaks at 58A max, and going downhill generated currents up to 32A (2.3kW). Don't try this with anything else than Lipo's! With my 13.5Ah pack, this means I was charging with more than 2C.

Issues encountered:

• Chain still keeps falling off, despite the chain tensioner, due to misalignment of rear freewheel and front cog. I need to buy another chain guide.

So, the next building efforts will be in finalizing the battery box for within the triangle. I don't want to work on the fiberglass box with the kids nearby, for fear of their health. At the moment the battery is in the left pannier. Due to it's low position and due to the counterbalance of the 3kg charger + 2kg laptop in the right pannier, there is no real unbalance between left or right. But the front-rear balance is obviously not preferable.

Anyway, I love it !

To do list:

• Finalize the battery box
• Post pics of the build and make some nice vids
• Get the CAv3 that is still stuck in customs
• Attach the temp probe and start logging temps when going uphill

 

[methods]

First, let me introduce my Cromotor Commuter ("CC") to you:

Very sneaky. I also did not even catch the rear shock on first glance.

What you see is the following:

• Cromotor hidden behind the pannier bags, laced into a 26" HALO SAS rim with black 14G Sepim spokes from JRH
• Lyen 18FET 4110 controller behind the seatpost
  Turn it up to 11!
  ...
• Touring steering bar, with DOT-approved 12V MoFa light and two blinkers. On the left hand side I have the 3-speed switch, regen, brake-light, mirror. On the right hand side I have the blinker activator and the throttle. In the middle is the CAv2 with current throttle hardwired. You can also see the GoPro (movies to follow).
  mmm.... I like lights. Have a look at the euro-standard housings. They throw a flat beam that is very attractive - flat across the middle and up on the right.
  
• Rear pannier bags (completely watertight) are attached to the sideframes of a Freeload frame that is attached to the frame. Therefore, they do not benefit from suspension, and I need to be careful when hitting bumps. The rear light / brake light and the rear blinkers are also attached to the Freeload frame. A 74V-12V DC converter is attached to the underside of the Freeload frame, as well as a strobe for the blinkers.
• Single speed freewheel with chain tensioner, and attached to the 44t front cog. Front and rear derailleur have been removed.

Sometimes you can find a 54T or bigger for nothing on ebay. I presume you are still running your front derailer - if you are not - put it back on and it will help solve your chain issue. Also - with my bikes I just look down the line and bend the rear derailer a few mm until it lines up with my front chain-ring. I know that is ghetto - and higher end derailers probably have an adjustment for this - but I rarely change gears so I just throw whatever I have on the back.

Look that chain over for a weak link for removal. Procure a chain-break and remove a fist-full of links from that chain. This will force the rear derailer to articulate and put more spring tension on your chain - this too will keep it on the front chain ring. I use an 11T on the back and a 54T on the front so I just measure it out to maximize spring tension and shorten.

Dont be cheap like me and skip out on the nice chain-break pieces. SO nice to have at any cost. Learned that with my miss-step into chain drive with the Cyclone. (EDIT: I am talking about the links you put into the chain for breaking it by hand)
...

To do list:

• Finalize the battery box
• Post pics of the build and make some nice vids
• Get the CAv3 that is still stuck in customs
• Attach the temp probe and start logging temps when going uphill
• Increase current limit to insane levels

You sound like you are having a really good time - I am jealous.
-methods

 

[hjns]

mmm.... I like lights. Have a look at the euro-standard housings. They throw a flat beam that is very attractive - flat across the middle and up on the right.

Actually, I find myself hardly driving in the dark. The DOT approved lights are really only to pass the Swiss cop evaluation. I still have some CREE superled lamps lying around.... but they will blind everyone and everything in front of me.

Sometimes you can find a 54T or bigger for nothing on ebay. I presume you are still running your front derailer - if you are not - put it back on and it will help solve your chain issue. Also - with my bikes I just look down the line and bend the rear derailer a few mm until it lines up with my front chain-ring. I know that is ghetto - and higher end derailers probably have an adjustment for this - but I rarely change gears so I just throw whatever I have on the back.

Look that chain over for a weak link for removal. Procure a chain-break and remove a fist-full of links from that chain. This will force the rear derailer to articulate and put more spring tension on your chain - this too will keep it on the front chain ring. I use an 11T on the back and a 54T on the front so I just measure it out to maximize spring tension and shorten.

Dont be cheap like me and skip out on the nice chain-break pieces. SO nice to have at any cost. Learned that with my miss-step into chain drive with the Cyclone. (EDIT: I am talking about the links you put into the chain for breaking it by hand)

Yes, I looked for a 54T on Ebay and on the local Swiss version of Ebay. However, they only offer them for 5-bolt crank systems, not for my MTB 4-bolt system. And at this moment I don't want to change the complete Bottom Bracket (Shimano Hollowtech 2).

However, I put the front derailleur back on, repositioned the chain tensioner, and all should be well. Thanks for the tips.


To do list:

• Finalize the battery box
• Post pics of the build and make some nice vids
• Get the CAv3 that is still stuck in customs
• Attach the temp probe and start logging temps when going uphill
• Increase current limit to insane levels

Yeah, I will increase current as soon as I have the temperature sensor functional.

You sound like you are having a really good time - I am jealous.
-methods


Yes, I am having a really good time. Weather is perfect, my bike is functional, family is healthy, what else can a man want?

 

[hjns]

This morning's commute:
Distance 32km, Amax 58A, Amin -26A, Vmax 67kmh, Vmean 32kmh, total used 850Wh, 22Wh/km.

I do not completely get why the CA gets the distance right, but when I calculate total used capacity versus total distance, I get 26Wh/km.

I had started to push buttons on the GoPro, and it kept telling me NOSD. I checked the slit for the SD card, and look: no SD card... What a communicative thing it is...

edit: looking back at my commute this morning, and seeing the numbers, it is amazing how much fun is actually hidden behind those clean numbers. I should add another parameter, like "funfactor". So, this morning the FF was like 200%

 

[hjns]

My commute this morning:

 

[methods]

Yes, I looked for a 54T on Ebay and on the local Swiss version of Ebay. However, they only offer them for 5-bolt crank systems, not for my MTB 4-bolt system. And at this moment I don't want to change the complete Bottom Bracket (Shimano Hollowtech 2).

That is why I specifically called out a 54T
They make much larger for 5 pattern but the largest I have ever found for 4 bolt was a 54T and that is what I run on both my Kona Stinky and my KMX Trike.

-methods

 

[hjns]

I removed the single speed chain tensioner, and reassembled the rear derailleur as well. Much better tension, I actually had to add a couple of chains again to make everything work, but it is great pedalling now. Not that it is ever great to pedal around a Cromotor....

Added the CA analogger connection to my CAv2. Still have to test it. Might end up connecting the 10k NTC thermistor within the Cromotor directly to the analogger. My new CAv3 was sent back by customs to Grin. Will take a lot more time befor I receive it....

Been searching for a 54T 4Bolt chainring, but the largest I can find is a 50T:
http://www.ukbikestore.co.uk/product/54/ta_chinook_outer/ta-chinook-104-bcd-outer-chainring.html

Any recommendations where to source a bigger chainring for 4 bolts?

 

[SweKen]

http://www.rennendesigngroup.com/store.html 52T

 

[hjns]

Thanks for the link, SweKen! Great find!

I have a different problem now: I had fixated the steel DrBass TAs with only DP420 to my alu frame, both sides. Both surfaces were completely filed, then made rough, then cleaned with alcohol, left to dry. I had painstaikingly made sure to have the correct ratio of raisin and hardener, and after application it had cured in my wintergarten for 48h at an average temp of 25oC.

Yesterday, during a test ride with low speed - average power (3-4kW), they both came off. I will try and properly document it, but the main message is that - despite the nice vids from DrBass - DP420
ALONE is not strong enough for a high power motor.

 

[SweKen]

Did it happen when you where accelerating or regenerating? If i was going to use this kind of method i would probably drilled two holes thru the plates and thru the drop outs, fixating them with stainless recessed hexagon heads, with the nut facing outwards.

 

[gensem]

Im betting that it was during regen...
Im using moped wheels and tires and regen is really hard on the dropouts with such a heavy wheel.

 

[hjns]

Did it happen when you where accelerating or regenerating? If i was going to use this kind of method i would probably drilled two holes thru the plates and thru the drop outs, fixating them with stainless recessed hexagon heads, with the nut facing outwards.

Tried that. Not enough space between the frame and the hub for either a head or a nut. The frame is not thick enough to allow recession of either.

Anyway, I purchased some nice steel and will create a combination of torque arm and dropout for each side.

 

[hjns]

Im betting that it was during regen...
Im using moped wheels and tires and regen is really hard on the dropouts with such a heavy wheel.

Almost; it was directly after decelleration using regen, and then when accelerating again from 5kmh to 10kmh.

Anyway, the effect is the same. High torque needs, with the combi of dropout + glued-on TAs not holding...

 

[hjns]

OK, got CC working again. I bought 4 steel plates, 150mm x 60mm x 8mm. Two on each side, connected with M6 bolts and nuts to the swingarm. Effectively the swingarm is now 100mm longer. Also, I used my drill press with cobalt steel drills to drill two M6 holes in the DrBass TAs. So the TAs are connected with 2x M6 boltsthreaded into an 8mm steel plate with a 10mmx 18mm hole in it. The axle is thus caught in both the DrBass TAs and 2x 8mm steel plate. Should be enough...

Threading all holes takes a bit of time. However, DrBAss TAs took the longest time. Hard steel, that is.

Anyway, once you strengthen some parts, the weak point will move to another part. I now fear for the frame, but we will see how it holds up. The controller is now programmed for 60A-110A, and the CA for 60A. Want to keep my range up when commuting.. I will save experimenting at 100V100A for when Methods or Lebowsky start distributing one or more of their super controllers....

 

[hjns]

I made another test ride with the CA analogger. Below is a graph that I put together quickly in Excel. I still need to find out some nice combination with the GPS data, but with all kinds of different things going on at the same time, programming CA output and GPS output will probably a project for the dark winter.

Anyway, here is the graph. I rode up two hills with 10-15% inclination. Going down you can see a nice regeneration.
Ah = Capacity in Ampere*hour
V = Voltage (20S lipo)
S = Speed in kmh
A = Current in ampere
D = Distance in km

The horizontal axis is time in hh:mm:sec

 

[hjns]

My (new) CAv3 arrived today. So in the next weeks, it will be very interesting to see the motor/controller temperatures versus kW, speed, and altitude.
I therefore plan to adjust the CA analogger so that it will accept two thermistors. You can never have enough data.....

 

[hjns]

Did some rough calculations. The second hill is indeed around 15% which I rode uphill with an average speed of 35kmh during 4 minutes. Total distance was 2.333km with an increase in altitude of 350m. Therefore total horizontal distance was about 2.307km, making the inclination around 15%. Speed of ascend was 1.458 m/s at 2-4kW. Not bad for a bike...

btw, the graphs also show that I feel most comfortable at speeds between 30 and 50kmh.

 

[hjns]

Visualization of a fast commute home.
Hopefully I can get the Temp data in this weekend.

 

[hjns]

Latest commute home. Took a longer route via France, and I almost didnt make it on my 20S 9Ah lipos. The last 300m uphill to my house I had to walk. I forgot to activate the analogger. Only got Oziexplorer working on my phone, so a little playing around with the track and Google Earth produced this:

What did I learn today?

• For trips longer than 20km, I need more capacity. My 20S 13Ah should work for anything below 30km.
• When taking unpaved roads better balancing of weight is much more important. Back to trying to put the lipos in the frame...
• I love living here and being able to do these kind of things after a days working.

See the 22.6% hill in the picture? I even didnt notice it was that steep! All honours to the cromotor!

 

[methods]

[*] I love living here and being able to do these kind of things after a days working. [/list]

I propose skipping the working part.

-methods