Again...3T, 4T, 5T, 6T difference

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minde28383   10 kW

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Re: Again...3T, 4T, 5T, 6T difference

Post by minde28383 » Nov 24 2020 1:28pm

Sparfuchs,
but don't be to too happy by higher Ts stroger acceleration either. Higher T means higher resistance (more copper turn around teeth) and higher resistance means you sooner reach temperature limit using the same power. So you get better acceleration but you reach temp limit sooner too. Without FF and sinks it takes ages to cool down. You should not go over 120c or 150c.

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Sparfuchs   100 W

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Re: Again...3T, 4T, 5T, 6T difference

Post by Sparfuchs » Nov 24 2020 5:32pm

The more i understand about all that stuff, the harder it gets to make the right desission :roll: :lol:

It would be much easier if i would allready have a controller and a battery i have to use and if i don't want to be prepaired for futur upgrades ;)

could someone explain why for example the cyclone venom insane has a huge battery and a stong controller and has 27 !! kw but they use a 7.5 T qs 205 motor ? Yes of course the motor is rewired with better copper and tuned with ferrofluid, hubsinks and some other stuff to protect from overheating but if they have so much power avalible would not everyone reccomend them to a fast winding motor theoretical ?

there own motor tuning explained:
https://youtu.be/zzhucASLiUs

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Re: Again...3T, 4T, 5T, 6T difference

Post by minde28383 » Nov 24 2020 6:37pm

There is no right decision. Everywhere compromises.

The same story. They use 5T (in subtitles says 7.5 but I doubt it, true strand number is their company secret :) ) because it is more acceleration with the same power compared to what they would get from 4T or 3T. But it does not mean that 4T or 3T is worse or something. And it heats a bit faster than would heat lower T but they don't mind it because it has insane torque.

Yes they rewire better than in factory but cost more and you get better acceleration and can feed more amps. There are ways to improve most motors but almost nobody is ready to pay for these things. For majority it is enough how it performs.

These 27kw is electrical input power. Some kilowatts are wasted into heat. Twice kilowatts does not mean that it will be twice better dynamic. Of course it is insane power. If you would shove these kw into 273 4kw hub (4kw nominal) it would accelerate even faster than 205 3kw hub you plan to acquire. There is always more to look for. After a while you get accustomed to dynamics and want a little bit more.

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stancecoke   100 kW

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Re: Again...3T, 4T, 5T, 6T difference

Post by stancecoke » Nov 25 2020 3:22am

It's very helpful to play around with grin's motor simulator to understand correlations between (max) phase amps, (max) battery amps, battery voltage, torque and max speed :thumb:
For a given motor the acceleration from standstill is only defined by the motor amps, as the motor torque is proportional to the motor amps. There is the simple rule battery amps = motoramps * duty cycle. The battery voltage is only important for the max speed.

Example: for an accelaration of about 12kph/s you'll need 94A motor amps for the grin 8T motor, for the faster 5T you'll need 150A motor amps. The battery amps only differ by 9A.
comparison 5T vs 8T.JPG
comparison 5T vs 8T.JPG (154.19 KiB) Viewed 461 times
regards
stancecoke

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Re: Again...3T, 4T, 5T, 6T difference

Post by Sparfuchs » Nov 25 2020 5:24am

ok, an other thought..
In austria the law is quite strict and only allows up to 600w peak/250w continous motor power and max 25 kph speed. I want to use my e bike in a reasonable way in traffic with a hidden 3 speed switch, so i don't want my e bike to look to conspicuous. So my daily use will be up to about 45kph with a lot of start-stop at traffic lights and normal city traffic. Thats one of the reasons why i want a lot of acceleration. To be honest an other reason is to show off and impress by quick starts, burn outs and wheelies.. i'm only human :lol: I also think driving with insane top speed is less fun than accelerating quickly and also very dangerous in traffic or if you crash so i want more acceleration than top speed but would also like to go about 75kph offroad if i dare. If e biking is as much fun as i hope it is, i'll also go for some bike tours on the mountain or offroad. Now you know my personal reasons. I'm thinking of using a 19" motobike rim because its still smaller than a 26" bike rim but would not look to crazy or conspicuous on a normal mtb or dhb with a 26" front wheel (maybe a 18" would). I'd also like to avoid hubsings because of same reason. As i don't want to use a stealth bomber frame because of the high weight and the conspicuous look, i can't use a too big battery pack. My triangle Battery (20s6p,72v,21ah,120 samsung 35e cells) and the sabvoton 72150 controller fit exactly in the triangle of my mtb frame and its only 7,5 mm slim. The problem is that there is no rear suspension. Thats why i'll one day change to a downhill frame and build a costum battery with about 200 cells to keep size and weight down. So i'll have the choice of more serial or more paralel connections than now. I'll find out what's best for me. Now that you know the whole story of my live you might be able to help me find the right solution ? :wink:
Some options i thought of are:
20s Batterie and Sabvoton 72150 unlocked with qs 205 5T 19" and Ferrofluid but without hubsinks (to conspicuous).
costumized battery 20s,21s,22s,23s,24s,ect. with Sabvoton 72150 unlocked (datasheet says max 95v) or Sabvoton 96120 unlocked ..then max. 4T i guess ? Or do you have other ideas ?

Does someone know how to simulate a qs205 4T vs. 5T in the programm ? Couldn't find them.

Sorry for the long text and thanks a lot for your help

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Re: Again...3T, 4T, 5T, 6T difference

Post by minde28383 » Nov 25 2020 8:05am

If those starts from stand still so important than maybe better 5t plus you battery is small, otherwise it's not so important and faster gives you more speed. Basically it's the same motor.
For weaker and smaller battery and bigger wheel 5t, if opposite is true than - faster motor. Choose according speed you want to reach also.
If you feel that you want to play in 50-90 speeds than fast version, otherwise slower version.
Better do 72150 and 20s or 21s or 22s but regen might be an issue with fully charged 22s.
Not having suspension will make you want suspension even more after you start riding.
FF makes bigger positive difference than sinks.

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minde28383   10 kW

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Re: Again...3T, 4T, 5T, 6T difference

Post by minde28383 » Nov 25 2020 8:47am

Does someone know how to simulate a qs205 4T vs. 5T in the programm ? Couldn't find them.
simulate similar motor, mxus 45xx, can modify its values by entering different kv.

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Re: Again...3T, 4T, 5T, 6T difference

Post by Sparfuchs » Nov 25 2020 7:34pm

aaaaall right.. now i played around with the simulator and got neven more confused :shock: :lol:

i tried it with the mxus 4504 vs. 4505 and with cromotor 5004 at 11.39 kv vs. 9.03kv. Maybe i don't really understind the curves, but to me it looks like they perform allmost the same and the only real difference is that the 4t can go to higher top speed. Especially at the beginning up to 25kph it looks like there is not a real difference. But i thoaght exacly there are the benefits of a 5t motor and also in the video of cyclonebikes 4t vs. 5t it was obvious that the 5t accelerates defenetly faster that the 4t ?
Maybe i don't understand that right or maybe i messed up with the controller or battery settings i had to chose ? Could you look at it ?
Screenshot (5).png
Cromotor 5004 11.39kv vs. 9.03kv
Screenshot (5).png (482.39 KiB) Viewed 424 times
Screenshot (7).png
MXUS 4504 vs. MXUS 4505
Screenshot (7).png (475.13 KiB) Viewed 424 times

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minde28383   10 kW

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Re: Again...3T, 4T, 5T, 6T difference

Post by minde28383 » Nov 25 2020 8:19pm

They perform almost the same because they are the same motor but slightly with different Nm per amp.
Look at different parameters in simulation, look at power, efficiency lines in graph too, it not all the same. One is faster, but to go faster you need more energy. 5T better in woods and for smaller battery. 4T or 3.5T better for street and higher speed.
They have different winding and supposed to be run at different power levels therefore should be compared with slightly different settings (amps and volts) and then you would see that they actually perform the same. To reach the same speed different kv motors can to be in different wheel diameter.
One more thing to find out is that slower and faster motors has different resistance. Try to change amps in simulator, for slower motor you should use less amps because it heats up sooner.

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Re: Again...3T, 4T, 5T, 6T difference

Post by minde28383 » Nov 25 2020 8:46pm

I think you already found many things. Next is - resistance. These 5T and 4T have different copper wire thickness, different copper wire length. That's the reason why one is slightly faster than the other.
Yours simulation is alright. If we would take into consideration that different motors have different resistance and write to 5T ~120A and to 4T ~150A, but to see best performance we set maximum - 150A, 350A, for both different T versions. Slower motor has more resistance therefore should be used with less power. But we set the same power on slower motor and possibly have that better initial kick and better controllability on bad road too worth to mention, but less speed.

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Re: Again...3T, 4T, 5T, 6T difference

Post by stancecoke » Nov 26 2020 6:52am

Sparfuchs wrote:
Nov 25 2020 7:34pm
Maybe i don't understand that right or maybe i messed up with the controller or battery settings i had to chose ? Could you look at it ?
You have set the motor current limit to 350 amps :shock: . This limit is never reached in your simulations, so of course you can't see a difference in torque. Again: The motor current is the main parameter!!! This parameter is limited by the controller's capabilities or settings, not by the battery (at the start from standstill).

You can drag the dotted lines in the graph to move to the speed, you want to analyze.

regards
stancecoke
Current limits v1.JPG
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Re: Again...3T, 4T, 5T, 6T difference

Post by Sparfuchs » Nov 27 2020 4:45pm

Screenshot (8).png
Screenshot (8).png (470.42 KiB) Viewed 358 times
stancecoke wrote:
Nov 26 2020 6:52am
Sparfuchs wrote:
Nov 25 2020 7:34pm
Maybe i don't understand that right or maybe i messed up with the controller or battery settings i had to chose ? Could you look at it ?
You have set the motor current limit to 350 amps :shock: . This limit is never reached in your simulations, so of course you can't see a difference in torque. Again: The motor current is the main parameter!!! This parameter is limited by the controller's capabilities or settings, not by the battery (at the start from standstill).

You can drag the dotted lines in the graph to move to the speed, you want to analyze.

regards
stancecoke

Current limits v1.JPG
ohh, did i ??
is phase current and motor current the same ? I just used the settings for a sabvoton 72150. It say 150A Battery Current, 350A Phase Current.
What would be the right settins for my simulation ?

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Re: Again...3T, 4T, 5T, 6T difference

Post by Sparfuchs » Nov 28 2020 6:49am

minde28383 wrote:
Nov 25 2020 8:46pm
I think you already found many things. Next is - resistance. These 5T and 4T have different copper wire thickness, different copper wire length. That's the reason why one is slightly faster than the other.
Yours simulation is alright. If we would take into consideration that different motors have different resistance and write to 5T ~120A and to 4T ~150A, but to see best performance we set maximum - 150A, 350A, for both different T versions. Slower motor has more resistance therefore should be used with less power. But we set the same power on slower motor and possibly have that better initial kick and better controllability on bad road too worth to mention, but less speed.
If i would take a 25s battery instead of a 20s battery with a 5T motor i could get a bettery top speed but would also produce heat. But is higher voltage a lot more heat ore is it more the amps that make the heat ?

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Re: Again...3T, 4T, 5T, 6T difference

Post by Sparfuchs » Nov 28 2020 6:54am

Another strange thing that confuses me, is that in both of my shared simulations the heat of system A is higher than of system B with same settings. But the faster motor with less windings (system A) schould have thicker wires and heat up less than the system B with more windings right ? Is that a mistake of the software or why is it like that ?

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Re: Again...3T, 4T, 5T, 6T difference

Post by stancecoke » Nov 28 2020 7:03am

Sparfuchs wrote:
Nov 28 2020 6:54am
But the faster motor with less windings (system A) schould have thicker wires and heat up less than the system B with more windings right ?
The faster motor needs more motor current for the same torque. The motor current heats the windings. The heat loss increases quadratically with the motor current P=R*I²
Sparfuchs wrote:
Nov 27 2020 4:45pm
I just used the settings for a sabvoton 72150. It say 150A Battery Current, 350A Phase Current.
:shock: With this controller settings, the motor and the battery will glow within a few seconds, if you really push your bike into this limits.
What is the inner resistance of your battery pack?

regards
stancecoke

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Re: Again...3T, 4T, 5T, 6T difference

Post by minde28383 » Nov 28 2020 8:56am

you can open link and see the sim.
https://ebikes.ca/tools/simulator.html? ... bopen=true

Look at motor (mtr) and batt (battery) amps. Look at graph. Different battery
fast slow
Mtr Amps 192.1A 164.8A
Batt Amps 147.4A 84.9A

This graph is not accurate but it might give you one more glimpse for a slower or faster motor difference. *Slower and faster have slightly different resistance which is not set in this sim.
You might need way less of a battery amps to have similar torque in slow speeds. With slower motor you will use less energy because you might set less amps with your setup. Faster motor is more energy demanding but it goes faster. So question is if you need go faster and are you ready to have battery which is able to supply 150a or even 200a with your unlocked controller without too much voltage sag.
Find out about your future battery, if you will have good battery than fast version is an option, otherwise will have sag which decreases performance. That's is why I say that slow motor is better for weaker battery packs.
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Re: Again...3T, 4T, 5T, 6T difference

Post by John in CR » Nov 28 2020 6:26pm

The single best thing always with a DD hubmotor for performance is to run as small a tire as you can live with. Sure it makes getting the eye appeal a little more difficult, but with the kind of power you're talking about pedaling the bike is a bit silly...like having functional pedals on a motorcycle. That means you can run a somewhat smaller tire on front too and put shorter cranks so you don't have to worry about pedal strike.

The QS205 V3 is a better motor than the others you discussed because it has a significantly lower slot and pole count. Where that helps is having less iron core losses at higher rpms.

Regarding the winding choice, just make sure you get one with a low enough turn count that you can go as fast as you'd ever want with a battery voltage of a 22s pack and that small wheel. That gives you more options for controller later on to get the most out of the motor. All the different winds available for a motor have the same torque potential and make the same heat for a given amount of torque. That's why a smaller wheel on a hubmotor always outperforms a larger wheel, because it lowers the gearing providing you with more thrust and a cooler motor. Personally I always go for the fastest wind (lowest turn count) of any motor, and I use rims and tires with a 22" OD or less (19.25" OD on all each of my ebikes that have over 100mph top speed. That way I can run lower voltage on bikes that don't need highway speeds. It does require more capable controllers in terms of current, so I never come up short in terms of acceleration, but it gives me the flexibility for maximum performance for a given motor.

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Re: Again...3T, 4T, 5T, 6T difference

Post by Sparfuchs » Nov 29 2020 8:23am

Sparfuchs wrote:
Nov 27 2020 4:45pm
I just used the settings for a sabvoton 72150. It say 150A Battery Current, 350A Phase Current.
:shock: With this controller settings, the motor and the battery will glow within a few seconds, if you really push your bike into this limits.
What is the inner resistance of your battery pack?
[/quote]

So i can't use a sabvoton 72150 which has 150 amps battery and 350 amps phase current or did i missunderstand something ??

This are the specifications i found about my battery:

Battery Model:72V 21Ah
Nominal Capacity (AH) :21ah
Nominal Voltage (V): 72V
Cell Source Resistance (mΩ) :within 38mΩ
Cell Specification :Use Samsung 3500MAH Cells
Cell Combination :6-parallel 20-series

Lifecycle:more than 800 cycles
Battery Size :300*200*80*260*50*70MM
Battery Weight : About 6kgs

Charge:
Way of charge:CC/CV
Standard charge Current:5A
Max Continuous Charge Current:5A
Charge Cut-off Voltage: 84V
Cell Overcharge protection Voltage:4.2V
Charge Temperature Range :0 - 45°C

Discharge:
Max Continuous Discharge Current:50A
Peak Discharge Current:150A
Discharge Cut-off Voltage:60+/-1 V
Cell Overdisharge protection Voltage:2.75V
Discharge Temperature Range: -20 - 60°C

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Sparfuchs   100 W

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Re: Again...3T, 4T, 5T, 6T difference

Post by Sparfuchs » Nov 29 2020 9:29am

so as i understand it right, every motor has the same potential of torque or power but not every motor has the same potential of top speed ? So if i get a 6T motor i'll not need as much amps and so i can use a cheaper/weaker/smaller/ battery and controller and it will do it's job and have good performance in lower speed BUT will NEVER be able to do as much top speed as the 3T. If i get a 3T motor i'll bee able to get the same torque than with the 6T but will need way more amps and so a bigger/stronger Battery and controller with the big benefit that there is way more possible top speed. If the heat is the same at different windings on the same level of torque that would mean that the slower motor does not heat up faster, it just means that the slower one gets a better torque with lower amps and therefor just heats up faster at SAME input. Is that right so far ?
So if i got the theoretical part right i'd like to get to the practical part :wink:
what do you think will be realistic top speed with my 72v, 21mah, continous 50 amps, peak 150 A battery, a unlocked sabvoton 72150 and a 5T motor in a 18 inch rim ? i think the simulation does not do field weakning right ?
So as i already mentioned i'd really love a lot of acceleration but would also like to be able to get up to 80 kph. As i think now with a 4T Motor and more amps both is possible right ? Insane acceleration and a good top speed ? but will a unlocked sabvoton 72150 will be strong enugh to do its job ? and how do i calculate the amps of a battery pack ? is it the amps per cell times the serial connections or how do i know what i can get from different cells and different serial connections ?

and again thanks a lot to everyone for the great help :bigthumb:
maybe one day i'll be one of the guys who helps out newbies here :D

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Re: Again...3T, 4T, 5T, 6T difference

Post by j bjork » Nov 29 2020 11:01am

A qs 205 50h 6T will have the same torque, power and speed at 200V and 200A as a qs 205 50h 3T at 100V and 400A.

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Re: Again...3T, 4T, 5T, 6T difference

Post by minde28383 » Nov 29 2020 11:31am

every motor has the same potential of torque or power but not every motor has the same potential of top speed
yes, it has difference top speed.
slower motor has more resistance and needs less amps to achieve the same torque.
Anyways, 5t better for slow trails. 4t better for roads. 5t less amps hungry but less top speed.
yes, field weakening is not in sim.
slower motor does not heat up faster or slower. People say that that it heats faster because people supply it with too many amps or are not able to cool it down fast enough.
Motor max power much depends on how fast it can shed accumulated heat. When you pump lots of amps into motor its temp raises faster compared when you pump only few amps therefore prolonged high power usage increases motors temp and motors performance capabilities depends how fast you can eliminate that heat. When you go fast you pump lots of amps, you generate more heat, you need bigger better battery to sustain high speed, also you need more amps.
use a cheaper/weaker/smaller/ battery and controller and it will do it's job and have good performance
It's heavy powerful motor. You current battery is too weak even for 5t, but you still can ride with it but with better battery ebike would run better. Your battery is 50a constant and 150a peaks. With 3kw motor I would recommend at least two such battery packs, 12p20s instead yours 6p20s.
compare following battery packs:
6p * 8a = 48a
12p 96 = 96a
18p *8a = 144a
Mpre p more amps you can draw from pack. With higher discharge cells you need less p but usually get less capacity.
what do you think will be realistic top speed with my 72v, 21mah, continous 50 amps, peak 150 A battery, a unlocked sabvoton 72150 and a 5T motor in a 18 inch rim ?
~70kmh and ~90kmh with fw but you will finish your current battery if will use fw.
speed depends on battery voltage. These speeds are with fullu charged battery, when it discharges you will get less and less speed. When it's discharged you might have ~55kmh without fw.
Speaking about FW.
If you will turn ON fw to gain speed than you will have more amps demand and even higher voltage sag.
So as i already mentioned i'd really love a lot of acceleration but would also like to be able to get up to 80 kph. As i think now with a 4T Motor and more amps both is possible right
no, too weak battery. 4t will have high sag in top speeds. Also sag in acceleration. But it is still usable.
Insane acceleration and a good top speed ?
Insane is very strong word. I would say it will be rideable and better battery is required especially with faster wind motors.
how do i calculate the amps of a battery pack ?
usually who builds pack writes it on it. Otherwise you can determine yourself. Its discharge capabilities depends gow well it is built and mainly depends how many cells in parallel, in you case 6cells in P and it says 50a constant (parallel cells number multiplied by constant one cell discharge capabilities, 6 * 8 = 48A, about 50A.) Battery building is whole another story.


One more example from true case scenario with your to be setup:
Assume you get 4t and the controller and run with your battery and set it for best performance by settings amps to 150/350. You accelerate and see big voltage drop, your battery heats, battery life shortens drastically, because of voltage drop your top speed less than it would be with better battery.

You can't ask many amps from battery which is not built to do so. Actually you can, but it will decrease in performance, generate excessive heat (not desired effect), voltage drop (less speed), brake prematurely.

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Re: Again...3T, 4T, 5T, 6T difference

Post by Sparfuchs » Nov 29 2020 3:34pm

Ok..so i'll definitely build a new battery soon. If i use just f.e. a cell with 20 amps CDR i'll need 10 parallel cells to get a battery pack with 200 amps continuous discharge and 20 serial cells to get nominal 72v right ? so 20s 10p at least ?? But i don't wanna change the topic. Batteries are a different chapter :)

so i guess with 72v and 200 Amps battery i should have enough power to feed a sabvoton 72150 unlocked to 200 amps right ? Or should i even take a stronger setup like 22 or more cells parallel and a stronger controller to ?

As i already mentioned, i want to use it in vienna city traffic, so my daily top speed will be at about 35,40 kph with a lot stop and go. If i visit my parents in the countryside i want to go up to 80 kph maybe sometimes faster and also some trips on a little hilly roads. I'm still not sure witch motor i should buy and don't want to make a wrong decision. I hope you are understanding :?

Do i have enough power to feed a 4T with the 200 Amps Battery and the unlocked Sabvoton 72150 to get a great acceleration and enough high speed ?

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minde28383   10 kW

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Re: Again...3T, 4T, 5T, 6T difference

Post by minde28383 » Nov 29 2020 6:04pm

Ok..so i'll definitely build a new battery soon. If i use just f.e. a cell with 20 amps CDR i'll need 10 parallel cells to get a battery pack with 200 amps continuous discharge and 20 serial cells to get nominal 72v right ? so 20s 10p at least ?? But i don't wanna change the topic. Batteries are a different chapter :)
20s10p cells with 20 CDR sounds good.
it could be LG HG2 (20A, 3000mAh)
you would get 3kwh battery pack.

so i guess with 72v and 200 Amps battery i should have enough power to feed a sabvoton 72150 unlocked to 200 amps right ? Or should i even take a stronger setup like 22 or more cells parallel and a stronger controller to ?
22s not necessarily for faster motor, 20s is enough for faster motor (if speeding about 80kmh), better more in parallel for more current. For slower motor 22s would preferred (because you want to approach 80kmh), but 22s might be not enough to sustain such speed. If you want 80kmh then better stick with faster versions. For traffic and not only you might take even 3.5T (even slightly faster than 4T).
With 5t you won't be able to sustain or even probably reach 80kmh for prolonged time because battery voltage decreasing during battery discharge and speed decreases even more.
As i already mentioned, i want to use it in vienna city traffic, so my daily top speed will be at about 35,40 kph with a lot stop and go. If i visit my parents in the countryside i want to go up to 80 kph maybe sometimes faster and also some trips on a little hilly roads. I'm still not sure witch motor i should buy and don't want to make a wrong decision. I hope you are understanding :?
Quite often it is safe to have extra speed, for traffic it is better faster version. Yellow vest is good but to be visible in traffic and escape situation it is useful to have that extra acceleration. But then again, when one rides in forest or difficult roads, it is better slower version.

*If you need to sustain 80kmh you have no choice but fast version.
Do i have enough power to feed a 4T with the 200 Amps Battery and the unlocked Sabvoton 72150 to get a great acceleration and enough high speed ?
yes. you mentioned new battery will propel you good with any version including fast one with the controller. In high speeds energy consumption increases noticeably. Wind resistance in high speeds over 70 - 80 kmh increases dramatically especially with such not aerodynamic regular riders posture.

with 20s and 5t version it feels less dynamic in speeds over 40kmh but it better in forest.
with 20s and 4t or 3.5t version it feels way better in speeds over 40kmh compared with slower version but it less good in forest but still rideable anywhere.

If you need to sustain that high speed than you have no option, but if you willing to sacrifice top speed than with slower version you might be less demanding on your battery.

As you see pivot point is speed you require to sustain.

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Re: Again...3T, 4T, 5T, 6T difference

Post by Sparfuchs » Nov 29 2020 7:10pm

okay, i'm almost done and got thanks to you all the information that i need to make a decision.
just one last thought i need you opinion on.
If i keep my small 20s6p battery for some more months and buy the 5T, i'd be happier for the moment than with a faster one i guess. (Also because i'll use it 90% of the time below 40 kph) And when i build a new battery and found out that i want more top speed i'll make 24 or more cells in serial to get a better high speed without needing a huge battery. What about that "last" thought ? :wink:

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minde28383   10 kW

10 kW
Posts: 600
Joined: Apr 02 2010 7:11am

Re: Again...3T, 4T, 5T, 6T difference

Post by minde28383 » Nov 30 2020 9:18am

Sparfuchs wrote:
Nov 29 2020 7:10pm
okay, i'm almost done and got thanks to you all the information that i need to make a decision.
just one last thought i need you opinion on.
If i keep my small 20s6p battery for some more months and buy the 5T, i'd be happier for the moment than with a faster one i guess. (Also because i'll use it 90% of the time below 40 kph) And when i build a new battery and found out that i want more top speed i'll make 24 or more cells in serial to get a better high speed without needing a huge battery. What about that "last" thought ? :wink:
It is 3kw motor you still need decent battery to make this motor perform as suppose. You current battery is a mach for up to ~1.5kw motor. Small battery = less distance, less performance, possible less speed. Slower motor needs less amps to have the same torque per amp but difference is not major.
Slower motor is just more controllable and energy saving on bad roads, bad road conditions, forest, slow trails. For good roads it does not matter so much if it is slow or fast version. Most important is to have enough amps to feed a motor and reach speeds you need, and also cover distance you plan to cover.
You aim for its top performance therefore to supply 3kw motor you need few hundred high discharge capable cells which ~10kg; better 300 cells or even more which is over ~15kg. Much depends on cells itself, higher discharge cells less heat, less sag. The rule is - big motor big battery if one aims for decent distance,speed,acceleration.
24s won't necessarily mean that battery gets smaller. Only cells are connected differently.
24s8p=192pcs
24s9p=216pcs
20s10p=200pcs
basically it's the same battery ~10kg. The same as with the motors. Faster motor needs less voltage to reach the same speed. Slower - needs more voltage to reach the same speed. You can change wheel size, voltage and other specs or components, till you get what you aim for.
You currently battery will definitely make your ebike ride with any motor, be it fast or slow version, but because it is small battery you will have less distance and less dynamic and less acceleration the faster motor you choose. But then again, any motor version will run.
24s and 5t would run near 80kmh (fully charged, less after discharge) with 19'' but 24s is too many in series for controller you chose. The controller is ok for 22s max. Even 22s might be too many if you use electric brake. With electric brake you push energy back to system and voltage raises. The controller is made in a such way that electric brake might not work (when fully charged) till voltage decreases, till battery discharges a little bit. So 21s is more suitable but now you know it and can run with 22s.

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