SZZS specific CEF50-main thread (initial builds and troubleshooting related only)

voigtkampff

Member
Oct 18, 2023
96
96
Poland
But if the motors are all using materials for the 36v then then the 48v will not have any lower heat than the 36v. Given that the heat dissipation was adequate for 36v it is going to be just as adeqaute at 48v.
yes, but…. this is based on idealized view that engineers design sth that is „100% accurate for 36V” while I believe the real approach is to design sth that is „~95% accurate” but cheap so that it will statistically break right after the warranty period
 

voigtkampff

Member
Oct 18, 2023
96
96
Poland
I started noticing sudden drops in battery level on the dislay. When it happened for the first time I thought I wasn't paying attention and I wasn't sure this happened but today I'm sure I've seen battery level drops from 43% to 19% in a blink of an eye. Is this something normal or should I be worried about this? After a moment the battery level raised again to like 33% but then it was depleting very fast and again it instantly dropped from 27 to 22%. The battery is 480Wh made by SZZT, so far I've made like 300km on it, never discharging below 15%. This is very unsettling, I'm happily returning home from nearby bikepark, there's like 20km left to ride, display shows 34km range so I know I can push the assistance harder and get home faster and suddenly range drops to 16km and the bike enters the forced E mode... Very disappointing.
 

92se-r

New Member
Dec 23, 2023
161
60
United states
It is not going to be less heat if the conductors are properly sized for the amperage.
It absolutely will. Heat is dominated by I, not r, because power dissipation is p=i^2*r. The dominant heat sources will be from the motor and motor controller. They cant just go and use double the size winding wire on the motor and the motor controller switching losses are not going to be different.

After getting some more ride time on this, my cef50 is noticeably warmer than other full power bikes in our group ridden by much larger guys. The heat density on the cef50 is much higher than on full power motors just from thermal mass. But yet the cef50 motor essentially puts out full power compared to last gen full power systems. My e8000 shimano "full power" puts out less torque on paper than the cef50. So imo, i wonder if some of the motor issues people are having are from premature heat related failures, especially in the motor controller. So in my mind, 48v is the way to go, no question
 

mike_kelly

Well-known member
Subscriber
Aug 11, 2022
929
759
US
The point is that if the 36v motor is designed correctly then the 48v having less heat will not make any difference, if they are basically the same motor. If the 48v is different and has smaller conductors it may not make any dif.
The question then is what motors are having "problems" 36, 43 or 48?
 

92se-r

New Member
Dec 23, 2023
161
60
United states
The point is that if the 36v motor is designed correctly then the 48v having less heat will not make any difference, if they are basically the same motor. If the 48v is different and has smaller conductors it may not make any dif.
The question then is what motors are having "problems" 36, 43 or 48?
I can tell you after long climbs, the outer housing temp is warmer than I would like, roughly 40-50c. That translates to significant operating temp rise on internal components, and junction temps are going to be through the roof. This was on a relatively cool ambient day. The rule of thumb is for every 10C operating temp rise, it roughly halves your lifespan of components. I dont hold my breath that the designers did any thermal analysis on this in terms of longevity. Theres no disputing that the 48v system will run cooler. The real question is whether or not that translates to premature failures. The 48v system will also be more efficient due to less thermal losses. Just my opinion backed by 20 yrs of power system design in aerospace and ev oem experience.
 

ficorama

Active member
Oct 9, 2021
350
301
Croatia
here is the first picture. it is not complete yet, the battery is missing. the battery should arrive Mon-Tue. and I will switch it to mullet. full 29 is BB 36.5 cm and fork angle 65. at 27.5 cu try offset bushing, it should be BB approx. 35 cm and fork angle 64.

weight without battery 17 kg. battery about 2.5 kg and small accessories about 1 kg

20240406_115108.jpg
 

Myalteregohamish

Active member
Jan 4, 2023
294
240
Vancouver, WA
here is the first picture. it is not complete yet, the battery is missing. the battery should arrive Mon-Tue. and I will switch it to mullet. full 29 is BB 36.5 cm and fork angle 65. at 27.5 cu try offset bushing, it should be BB approx. 35 cm and fork angle 64.

weight without battery 17 kg. battery about 2.5 kg and small accessories about 1 kg

View attachment 137668
The mullet should feel better in the steeps. Also make it feel a bit more slashy.
 

92se-r

New Member
Dec 23, 2023
161
60
United states
I started noticing sudden drops in battery level on the dislay. When it happened for the first time I thought I wasn't paying attention and I wasn't sure this happened but today I'm sure I've seen battery level drops from 43% to 19% in a blink of an eye. Is this something normal or should I be worried about this? After a moment the battery level raised again to like 33% but then it was depleting very fast and again it instantly dropped from 27 to 22%. The battery is 480Wh made by SZZT, so far I've made like 300km on it, never discharging below 15%. This is very unsettling, I'm happily returning home from nearby bikepark, there's like 20km left to ride, display shows 34km range so I know I can push the assistance harder and get home faster and suddenly range drops to 16km and the bike enters the forced E mode... Very disappointing.
You might have a loose connection. Since the only way the system measures soc is through voltage, you will only see big drops like that on a high resistance connection when you load the system. At rest or low current, you wont see those voltage drops.
 

mike_kelly

Well-known member
Subscriber
Aug 11, 2022
929
759
US
I can tell you after long climbs, the outer housing temp is warmer than I would like, roughly 40-50c. That translates to significant operating temp rise on internal components, and junction temps are going to be through the roof. This was on a relatively cool ambient day. The rule of thumb is for every 10C operating temp rise, it roughly halves your lifespan of components. I dont hold my breath that the designers did any thermal analysis on this in terms of longevity. Theres no disputing that the 48v system will run cooler. The real question is whether or not that translates to premature failures. The 48v system will also be more efficient due to less thermal losses. Just my opinion backed by 20 yrs of power system design in aerospace and ev oem experience.
All the conditions really need to be known before one can speculate. Bafang said that these were not designed to operate in Boost for extended periods of time.
 

voigtkampff

Member
Oct 18, 2023
96
96
Poland
You might have a loose connection. Since the only way the system measures soc is through voltage, you will only see big drops like that on a high resistance connection when you load the system. At rest or low current, you wont see those voltage drops.
I don't think this is the case. This doesn't happen during high load but rather right after high load ends, like right after steep climb in B mode. I believe the battery level was roughly static during the climb and dropped after the load ceased. TBH I've seen such behavior once with chinese powerbank that had faked capacity. It would charge the connected device with power level indicator gradually decreasing until at approx. 70% it would suddenly drop to 0 and shut down. This worries me that the cells used by SZZT might be poor quality or damaged. I'm going to ask Jean about this but vision of sending the battery back to China for inspection and warranty replacement is sth I'd very much like to avoid. This would leave me without my new toy that I already started to like a lot (except the headset ;) ) for the most of the riding season.
 

92se-r

New Member
Dec 23, 2023
161
60
United states
I don't think this is the case. This doesn't happen during high load but rather right after high load ends, like right after steep climb in B mode. I believe the battery level was roughly static during the climb and dropped after the load ceased. TBH I've seen such behavior once with chinese powerbank that had faked capacity. It would charge the connected device with power level indicator gradually decreasing until at approx. 70% it would suddenly drop to 0 and shut down. This worries me that the cells used by SZZT might be poor quality or damaged. I'm going to ask Jean about this but vision of sending the battery back to China for inspection and warranty replacement is sth I'd very much like to avoid. This would leave me without my new toy that I already started to like a lot (except the headset ;) ) for the most of the riding season.
It really depends on how often they sample voltage to update soc. The fact that its after a heavy load is suspicious. Bad cells with less than advertised capacity do not have ocv recover later after it rests. If you are indeed at the knee of the curve, your ocv would stay consistently low and your soc % would also stay low. However you could be correct if ir characteristics of the cell are poor. That would have similar behaviors to a bad connection. Both would have correlation with a high load put on battery. The thing is, bad connections are free to check, so why not check. Bad ir characteristics of cells is going to be harder to troubleshoot and rectify with supplier.
 

calvintys

Active member
Sep 12, 2023
250
250
Malaysia
Finally after a month down for repair 🤬....the new external wires frame conversion showing for a sunset ride. In this case, it's function over form. With a little extra bling🤔 ZS56 headset from Hope... precision stuff too. 💪

View attachment 137768
See my separate thread if interested in my process.👊
Do you have the link of your hope headset , i am getting annoy with my headset knocking sound.
 

TCFlowClyde

Active member
Feb 26, 2022
1,335
863
Mesa, AZ
Do you have the link of your hope headset , i am getting annoy with my headset knocking sound.
 

calvintys

Active member
Sep 12, 2023
250
250
Malaysia
thanks for the link , its has two version zs56/28.6 and zs56/38.1. I believe the 28.6 its our fork tube size. Standard fork tube its 28.6 right?
 

92se-r

New Member
Dec 23, 2023
161
60
United states
i think my headset also glue in CUP type. which we only need to install the headset bearing itself without lower bearing cup ONLY need to install Bearing top cover.
Unfortunately the 52mm diameter bearing is not a common size. Most of the headsets use a much smaller OD bearing so you would need to change out the cup. Its the reason i am still using the szzs headset and havent converted to cane creek yet.
 

TCFlowClyde

Active member
Feb 26, 2022
1,335
863
Mesa, AZ
i think my headset also glue in CUP type. which we only need to install the headset bearing itself without lower bearing cup ONLY need to install Bearing top cover.
Yeah, I think it's the upper bearing cup that's the issue. Once, I installed the Hope bearing cup no more slop.

Can you tap 'em out somehow without damaging the headtube?
 

92se-r

New Member
Dec 23, 2023
161
60
United states
Just confirmed that loctite 603 is used on headset cups. Reading on how to remove it, seems like you need high heat of 250c, which is not possible with the carbon fiber.
 

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