Search found 6136 matches

by john61ct
May 13 2021 7:53am
Forum: Motor Technology
Topic: Hubmonster teardown
Replies: 164
Views: 9528

Re: Hubmonster teardown

The precise failure point will be different between the motor and controller.

In theory you could wreck lots of small motors with a robust enough controller designed for big ones
by john61ct
May 13 2021 7:47am
Forum: Battery Technology
Topic: LiFePo4 15s Charger?
Replies: 17
Views: 220

Re: LiFePo4 15s Charger?

High voltage cutoff, just a circuit that controls a relay / solenoid / contact switch when the specified voltage is reached. Most BMS types could be rigged to work, Arduino etc, some OTS adjustable units out there, "battery protect" "DIY UPS" circuits. Results in CC only charging...
by john61ct
May 13 2021 3:57am
Forum: Battery Technology
Topic: LiFePo4 15s Charger?
Replies: 17
Views: 220

Re: LiFePo4 15s Charger?

That is a a good unit, and yes that V range will cover both 15S & 16S ranges, decent flexibility. Note there is another step up in the HLG series for power, 600W iirc. But the HLG is a power supply, not a charger as such, no automated stop-charge best to look for an adjustable HVC to cut its AC ...
by john61ct
May 13 2021 1:15am
Forum: Battery Technology
Topic: "Copper/nickel sandwich" buses for series connections
Replies: 53
Views: 4295

Re: "Copper/nickel sandwich" buses for series connections

Cool!

key issue is, if the plating is thick enough to increase the copper's resistance enough

Please let us know!

Are you using Kweld with caps or lipo or? Optimizing the joules output might be critical
by john61ct
May 13 2021 12:47am
Forum: EScooters/EMotorcycles
Topic: More low end torque for up hill climbing power
Replies: 19
Views: 356

Re: More low end torque for up hill climbing power

Of course hub motors get hot when overloaded.

Hot enough to get destroyed if the controller has no overtemp protection.

Adding a CA v3 will also work well.

Doesn't even take a big hill, just increasing the load on a hot day can do it.
by john61ct
May 13 2021 12:43am
Forum: Battery Technology
Topic: Spot Welding Copper Strips to 18650 Battery Cells
Replies: 536
Views: 88016

Re: Spot Welding Copper Strips to 18650 Battery Cells

3> There is no 3 There are dozens of threads with discussion on all that. The third option is mechanical pressure, as with magnets, poron foam "springs" etc For this specific thread only one strategy is on topic. Start your own thread for general discussion comparing others if you aren't ...
by john61ct
May 13 2021 12:34am
Forum: Battery Technology
Topic: LiFePo4 15s Charger?
Replies: 17
Views: 220

Re: LiFePo4 15s Charger?

No, just easier to find cheap chargers.

Highly reco Satiator, very flexible for future proofing

model# 4808 labeled "24V-52V", I believe output range is 24-63V @8A (manual states 12-63V)
by john61ct
May 11 2021 1:07pm
Forum: Battery Technology
Topic: LiFePo4 15s Charger?
Replies: 17
Views: 220

Re: LiFePo4 15s Charger?

I would not go above 52V unless current at 0.5C or a bit higher, 54.0V max at say above 0.1C, CC-only is fine. Or for occasional cap testing to judge SoH%, 54.0V even if below 0.5C holding CV then, a high current rate doesn't matter, hold until amps trail to 0.2C. So adjustability is important. If g...
by john61ct
May 11 2021 7:53am
Forum: Large EV General Discussion
Topic: Dynamically reconfiguring pack voltage for RV
Replies: 8
Views: 207

Re: Dynamically reconfiguring pack voltage for RV

Skoolies have a high carrying capacity

not that they can't get dangerously overloaded, imbalanced.

Of course actual range is reduced with every extra kg carried
by john61ct
May 11 2021 2:10am
Forum: EBike General Discussion
Topic: speed relationship between wheel and bike
Replies: 12
Views: 291

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: 291

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: 207

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: 3292

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: 291

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: 3292

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: 1067

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: 291

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: 291

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: 291

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: 126

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: 1655
Views: 221431

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: 1695
Views: 227967

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: 536
Views: 88016

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: 291

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.