Search found 6251 matches

by john61ct
May 11 2021 2:10am
Forum: EBike General Discussion
Topic: speed relationship between wheel and bike
Replies: 12
Views: 379

Re: speed relationship between wheel and bike

the number of wheels should make no difference at all, if they are all the same size. Nor does electric motor(s) matter as a factor, vs leg power or petrol or. . . RPM vs bike speed is what I thought you wanted help with. One of those being known obviously (to me) is required bike speed being unknow...
by john61ct
May 10 2021 9:56pm
Forum: Battery Technology
Topic: Bought a new battery - the range just does not make sense ( Chamrider)
Replies: 15
Views: 369

Re: Bought a new battery - the range just does not make sense ( Chamrider)

still hard to think that it is really a 43.2ah battery when it is the same footprint of my 28ah battery. The only difference being 18650 v.s 21700 cells which should only lead to a 30 percent increase maximum in capacity . Yes, it's def not, you got ripped off for sure, at least on energy capacity....
by john61ct
May 10 2021 9:49pm
Forum: Large EV General Discussion
Topic: Dynamically reconfiguring pack voltage for RV
Replies: 8
Views: 347

Re: Dynamically reconfiguring pack voltage for RV

I estimate that with that pack it should be capable of a good 40-50 miles per charge. I'm guessing under ten. > I know they need to be at a different voltage, I'm just curious as to whether it's feasible to tap that voltage off of the same battery in segments instead. No, you must draw from all seg...
by john61ct
May 10 2021 1:04pm
Forum: Motor Technology
Topic: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?
Replies: 109
Views: 3623

Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

But in fact Justin has documented the higher performance enabled by just a little of his fluid, the idea is proven effective.

This thread is about getting a bit more is all, exploring other fluid types.
by john61ct
May 10 2021 1:00pm
Forum: EBike General Discussion
Topic: speed relationship between wheel and bike
Replies: 12
Views: 379

Re: speed relationship between wheel and bike


tonylai wrote:And the speed while turning, how to calculate with the wheels' RPM?
There are literally hundreds of pages at the link I gave you that give you all the details

by john61ct
May 09 2021 11:59pm
Forum: Motor Technology
Topic: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?
Replies: 109
Views: 3623

Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

How about a **thermally conducting** (& obviously dielectric insulating) "potting" sealant that starts out in liquid form? Use that to coat all the (possibly reactive) components, seal up any (possibly leak prone) gaps let it thoroughly dry & cure. Then (if even needed) your perman...
by john61ct
May 09 2021 5:08am
Forum: Battery Technology
Topic: new larger lipo seems worse, is it?
Replies: 23
Views: 1164

Re: new larger lipo seems worse, is it?


jimmyhackers wrote: accucel does to the nearest 1mohm and the sdt to the nearest 0.1 mohm
Do they agree with each other when conditions are identical?

by john61ct
May 09 2021 5:07am
Forum: Battery Technology
Topic: Bought a new battery - the range just does not make sense ( Chamrider)
Replies: 15
Views: 369

Re: Bought a new battery - the range just does not make sense ( Chamrider)

And note there will always be a bit of drop from the stop charge setpoint even if the cells are isolated from all loads.

But do not keep the cells at high SoC% for long, store at midpoint and only charge up just before riding is best for longevity.
by john61ct
May 09 2021 5:04am
Forum: Battery Technology
Topic: Bought a new battery - the range just does not make sense ( Chamrider)
Replies: 15
Views: 369

Re: Bought a new battery - the range just does not make sense ( Chamrider)

I charged it to the point where it showed 59.0v on the battery indicator on my C8 display, but the supplied charger did not turn off at that point even though it only charges to 58.8v 14S means defining 100% SoC as "stop charging between 56.5V and 58.0V" Former better for longevity, latte...
by john61ct
May 09 2021 4:56am
Forum: Battery Technology
Topic: Bought a new battery - the range just does not make sense ( Chamrider)
Replies: 15
Views: 369

Re: Bought a new battery - the range just does not make sense ( Chamrider)

Ali is just a market platform, like a river with toll charges for boats carrying cargo, they make billions no matter how crappy the stuff flowing through. Unlike eBay they favour sellers rather than protecting buyers. They would likely not be so big and profitable trying to impose eBay style policie...
by john61ct
May 09 2021 4:52am
Forum: EBike Non-hub Motor Drives
Topic: Shimano STePS E5000 torque vs. not...
Replies: 2
Views: 202

Re: Shimano STePS E5000

Haven't seen DIY builds for that, are frames readily available that fit?
by john61ct
May 09 2021 4:51am
Forum: Battery Technology
Topic: bluetooth BMS?
Replies: 1662
Views: 224537

Re: bluetooth BMS?

Stupidly high precision, total waste of time and excessive wear on components.

And bad for cells to sit at high SoC% that long

Really best to forget top balancing completely, do it at the bottom, or mid point as they are delivered.
by john61ct
May 09 2021 4:45am
Forum: EBike General Discussion
Topic: 2 Speed Xiongda hubmotor
Replies: 1701
Views: 229341

Re: 2 Speed Xiongda hubmotor

everyone making hubs for bicycle wheels, essentially is making them for more or less the same size of wheel The point is, if more torque is needed than what the designer intended to deliver going to smaller wheels is a relatively easy way to get that without going to a stronger motor which may not ...
by john61ct
May 09 2021 4:41am
Forum: Battery Technology
Topic: Spot Welding Copper Strips to 18650 Battery Cells
Replies: 539
Views: 90197

Re: Spot Welding Copper Strips to 18650 Battery Cells

Depends on the environment and degree of exposure. Tin plating, "tinning" copper is certainly required for long term integrity in coastal areas with salt fog atmospheres unless the case is very well sealed. Of course rising resistance may not be a big problem over just a few years, if the ...
by john61ct
May 09 2021 4:34am
Forum: EBike General Discussion
Topic: speed relationship between wheel and bike
Replies: 12
Views: 379

Re: speed relationship between wheel and bike

https://www.google.com/search?q=rpm+speed+wheel+size

Obviously the two wheels will have the same RPM

unless they are different outermost circumference, even very different tire pressure wojld be significant.
by john61ct
May 09 2021 4:24am
Forum: EBike Non-hub Motor Drives
Topic: Cheapest prices for Cyclone 3000w/4000w?
Replies: 8
Views: 392

Re: Cheapest prices for Cyclone 3000w/4000w?

Maybe set up a group buy with other members on the same continent as you?
by john61ct
May 08 2021 8:48pm
Forum: EBike Non-hub Motor Drives
Topic: Cheapest prices for Cyclone 3000w/4000w?
Replies: 8
Views: 392

Re: Cheapest prices for Cyclone 3000w/4000w?

Just you, I think very reasonable, especially if it arrives within four months.
by john61ct
May 08 2021 8:33pm
Forum: Battery Technology
Topic: Bought a new battery - the range just does not make sense ( Chamrider)
Replies: 15
Views: 369

Re: Bought a new battery - the range just does not make sense ( Chamrider)

With Ali sellers you have to assume they are lying scammers.

Getting recommendations from trusted fellow members here can increase the odds of finding one just not quite as egregious as most of them.
by john61ct
May 08 2021 8:30pm
Forum: EScooters/EMotorcycles
Topic: More low end torque for up hill climbing power
Replies: 27
Views: 731

Re: More low end torque for up hill climbing power

Go to a smaller wheel

Also upgrading the controller, FOC being more efficient, maybe high as possible voltage to get more power within the same current/heat limitations.

That last is your "hard & fast" limit unless you can improve cooling, after that need to upgrade the motor
by john61ct
May 08 2021 2:23am
Forum: Battery Technology
Topic: bluetooth BMS?
Replies: 1662
Views: 224537

Re: bluetooth BMS?

Yes those are all within 0.03V aren't they

You can try for a lower delta but likely will hit the accuracy limits and just cause unnecessary wear to little benefit.
by john61ct
May 08 2021 1:52am
Forum: Battery Technology
Topic: charges only 53.2 volts, it is meant to charge 54.4
Replies: 5
Views: 224

Re: charges only 53.2 volts, it is meant to charge 54.4

How many cells in series? 13s What cells? Li-ion Assuming well balanced, within say 0.02V overall then a stop-charge of even 52.7V is plenty, ideal for longevity 54V is the maximum I'd use if the use case needed every mAh of range, capacity utilization but then you are losing some cycle longevity. ...
by john61ct
May 08 2021 1:45am
Forum: Items for Sale - New
Topic: Prismatic lifePo4 cells 50ah Sale
Replies: 19
Views: 855

Re: Prismatic lifePo4 cells 50ah Sale

Don't let them sit at high V like that for long!

For longevity, when not actively being cycled, keep at the midpoint or lower

and ideally cool.

Only charge hours before loads need feeding
by john61ct
May 08 2021 12:49am
Forum: EBike General Discussion
Topic: 2 Speed Xiongda hubmotor
Replies: 1701
Views: 229341

Re: 2 Speed Xiongda hubmotor

the central point is, the easiest way to get more power / torque

from a light / weak motor

is to use smaller wheels.

Think like Archimedes' levers, long end vs short
by john61ct
May 06 2021 10:15pm
Forum: Battery Technology
Topic: WTB Battery Relay Controller 100V 20S
Replies: 8
Views: 240

Re: WTB Battery Relay Controller 100V 20S

Yes prejudice against an arbitrary label just shows a closed mind and limited experience. There are BMS costing thousands that are more robust than most industrial scale contactors. And any decent BMS even cheap ones have adjustable setpoints and the ability to disable those functions you are handli...
by john61ct
May 06 2021 10:03pm
Forum: Large EV General Discussion
Topic: Dynamically reconfiguring pack voltage for RV
Replies: 8
Views: 347

Re: Dynamically reconfiguring pack voltage for RV

Unless your needs for actual trip distances are bizarrely minimal, an electric skoolie will just not be a practical project. Maybe a millionaire seeking a Green virtue signalling PR stunt And even if you wanted to spend 30K+ to just go a few miles per day that tiny bank and its House circuits should...