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by Punx0r
Jan 25 2020 5:17am
Forum: E-Bike Technical
Topic: Doesn't make sense.. does my battery broken?33mΩ too much ir??
Replies: 23
Views: 644

Re: Doesn't make sense.. does my battery broken?33mΩ too much ir??

It's not "my method" - it's Georg Ohm's method. I've repeatedly stated you must account for SoC and temperature, so your argument above is moot. Please post details of the method YOU use to determine a more accurate measurement of DC IR. The one that doesn't use Ohm's Law. Because you haven't sugges...
by Punx0r
Jan 24 2020 4:50am
Forum: E-Bike Technical
Topic: Doesn't make sense.. does my battery broken?33mΩ too much ir??
Replies: 23
Views: 644

Re: Doesn't make sense.. does my battery broken?33mΩ too much ir??

I left this thread alone hoping it would just quietly go away, but since you're bring it back up: "The two-tier DC load method offers an alternative method by applying two sequential discharge loads of different currents and time duration. The battery first discharges at a low current for 10 seconds...
by Punx0r
Jan 23 2020 3:25am
Forum: Battery Technology
Topic: Help me build a quality, datalogging, charging/discharge bank @ home, DIY.
Replies: 46
Views: 767

Re: Help me build a quality, datalogging, charging/discharge bank @ home, DIY.

They are expensive but so is a five grand bench PSU and the OP says he's got money to spend. The crestchic units are widely used in private industry, not just government projects. There may be cheaper alternative manufacturers.
by Punx0r
Jan 22 2020 3:44am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 5500
Views: 271122

Re: Wind and Solar vs Coal, Gasoline, Nuclear

Pls quote the part of the article that says AGW is/will accelerate plate tectonics. kthxbye
by Punx0r
Jan 21 2020 10:06am
Forum: Battery Technology
Topic: Practical advice on achieving the 10min full charge LTO(Titanate) cells are meant to deliver
Replies: 63
Views: 1200

Re: Practical advice on achieving the 10min full charge LTO(Titanate) cells are meant to deliver

Ride a folding bike long distance? Nope! ... and Street AC/DC recharging in 40mins ... As to 25kg+ battery it's not a deal breaker on its own ... 25kg (by the time it's built into a sturdy pack you're looking at ~30kg) on a bike frame is a lot. Before commiting to something like that I really would...
by Punx0r
Jan 21 2020 9:59am
Forum: Battery Technology
Topic: Practical advice on achieving the 10min full charge LTO(Titanate) cells are meant to deliver
Replies: 63
Views: 1200

Re: Practical advice on achieving the 10min full charge LTO(Titanate) cells are meant to deliver

10min charge (6C) can be achieved on LiCO cells - just look at the RC world. Not very safely at dozens of kW Nor conducive to cell longevity You don't have to buy RC cells - they're just the cheapest and most readily available. TBH the price of 6C-capable cells is not the most serious drawback in t...
by Punx0r
Jan 21 2020 3:41am
Forum: Battery Technology
Topic: Practical advice on achieving the 10min full charge LTO(Titanate) cells are meant to deliver
Replies: 63
Views: 1200

Re: Practical advice on achieving the 10min full charge LTO(Titanate) cells are meant to deliver

Ride a folding bike with a 25kg+ battery? Nope!
Ride a folding bike long distance? Nope!

10min charge (6C) can be achieved on LiCO cells - just look at the RC world.
by Punx0r
Jan 21 2020 3:30am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 5500
Views: 271122

Re: Wind and Solar vs Coal, Gasoline, Nuclear

No, that article absolutely does not support the argument presented by ZeroEM.
by Punx0r
Jan 17 2020 3:38am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 5500
Views: 271122

Re: Wind and Solar vs Coal, Gasoline, Nuclear

The Australian government unfortunately appears to be in the pocket of it's coal industry. Renewable energy and EV use are way below average for OECD countries.
by Punx0r
Jan 15 2020 6:41am
Forum: Motor Technology
Topic: ESC, 14S 300A $700, waterproofed
Replies: 1
Views: 452

Re: ESC, 14S 300A $700, waterproofed

Would love to see one torture tested on a dyno 8)
by Punx0r
Jan 14 2020 10:31am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 5500
Views: 271122

Re: Wind and Solar vs Coal, Gasoline, Nuclear

One thing that would help, regardless of any prediliction for climate change denialism, is to stop cutting down the forests that transport water from the coast inland.
by Punx0r
Jan 14 2020 5:42am
Forum: Motor Technology
Topic: Why more KV = more power, the Maximum Power Transfer Theorem
Replies: 51
Views: 2713

Re: Why more KV = more power, the Maximum Power Transfer Theorem

This is true. I think a lot of information out there is more relevant/true to battery-fed DC brushed motors with simple switched control.
by Punx0r
Jan 14 2020 4:16am
Forum: E-Vehicles General Discussion
Topic: Can EVs survive without subsidies ?
Replies: 59
Views: 3762

Re: Can EVs survive without subsidies ?

Hillhater wrote:
Jan 13 2020 6:00am
True, but you still have to lubricate the cylinder walls somehow.
Most of those large marine “diesels” run on fuel that is closer to sump oil than it is diesel :shock:
Yes, you do it the conventional way: from below the piston and use oil control rings.

Yep, bunker fuel
by Punx0r
Jan 14 2020 4:10am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 5500
Views: 271122

Re: Wind and Solar vs Coal, Gasoline, Nuclear

Increasing temperatures mean bad fire years happen more frequently and the extreme years get more extreme.
by Punx0r
Jan 13 2020 4:23am
Forum: E-Vehicles General Discussion
Topic: Can EVs survive without subsidies ?
Replies: 59
Views: 3762

Re: Can EVs survive without subsidies ?

There are plenty of large indutrial/marine 2-stroke engines about (including diesels) that use regular sump oil lubrication and don't burn any of it. If you have a turbo or supercharger you don't need to use the crank to pressurise the cylinder(s) and consequently force the lubricating oil into the ...
by Punx0r
Jan 11 2020 6:37am
Forum: Motor Technology
Topic: Why more KV = more power, the Maximum Power Transfer Theorem
Replies: 51
Views: 2713

Re: Why more KV = more power, the Maximum Power Transfer Theorem

When you tell someone that an electric motor makes the most power when it's loaded to 50% efficiency, they tend to balk at the idea as it's counter intuitive. Agreed. The similar case mentioned above with peak battery power being at 50% voltage also takes some thinking about. In both cases I think ...
by Punx0r
Jan 10 2020 2:51pm
Forum: Motor Technology
Topic: Chinese motor ratings :)
Replies: 3
Views: 316

Re: Chinese motor ratings (or ratings in general)

Real motors are always rated for output power. RC motors and general shysters may differ :wink:
by Punx0r
Jan 10 2020 9:48am
Forum: Motor Technology
Topic: Why more KV = more power, the Maximum Power Transfer Theorem
Replies: 51
Views: 2713

Re: Why more KV = more power, the Maximum Power Transfer Theorem

Punx0r, what conflict do you see in my example trying to show the relationship between KV and MPTT? I have no problem with the concept of impedance matching a motor to a battery/controller/PSU for maximum power transfer Similarly, I think it's very relevant to select motor Kv and system voltage suc...
by Punx0r
Jan 10 2020 4:29am
Forum: E-Bike Technical
Topic: Doesn't make sense.. does my battery broken?33mΩ too much ir??
Replies: 23
Views: 644

Re: Doesn't make sense.. does my battery broken?33mΩ too much ir??

For one thing, that cell has the power to overcome most meters in speed and capability... You could use an oscilliscope if you wanted more accuracy. These specs have been published for years. 1) You think the OP should be buying a 'scope to troubleshoot his battery? 2) How is response speed of the ...
by Punx0r
Jan 09 2020 1:17pm
Forum: E-Bike Technical
Topic: Doesn't make sense.. does my battery broken?33mΩ too much ir??
Replies: 23
Views: 644

Re: Doesn't make sense.. does my battery broken?33mΩ too much ir??

Congratulations on being technically correct, with no consideration of context. The scenario is the OP wants a simple test he can perform at home on his battery to discriminate between two very distinct states: 1) "condition = OK" 2) "condition = garbage". R = V/I works just fine and will likely be ...
by Punx0r
Jan 09 2020 4:16am
Forum: Motor Technology
Topic: Why more KV = more power, the Maximum Power Transfer Theorem
Replies: 51
Views: 2713

Re: Why more KV = more power, the Maximum Power Transfer Theorem

Punx0r or anyone, could you write a quick explanation of how BEMF works from your understanding? Keep it simple, use an ideal motor (no loss) and treat it as an impedance. We have a miscommunication happening and I'm not quite sure where it's at. How does BEMF limit input power? Where do the voltag...
by Punx0r
Jan 09 2020 3:44am
Forum: E-Bike Technical
Topic: Doesn't make sense.. does my battery broken?33mΩ too much ir??
Replies: 23
Views: 644

Re: Doesn't make sense.. does my battery broken?33mΩ too much ir??

Cell DC IR can be calculated from sag via V = IR just fine! It's not complicated - quite simple :) Yes, you can reverse a cell in a battery, but this is not really sag. Maximum sag possible on a single cell cannot exceed the cell's open-circuit voltage. So you cannot have 5V of sag on a 4.2V cell. T...
by Punx0r
Jan 08 2020 6:24am
Forum: Motor Technology
Topic: Why more KV = more power, the Maximum Power Transfer Theorem
Replies: 51
Views: 2713

Re: Why more KV = more power, the Maximum Power Transfer Theorem

I specified output power as shaft output power to make it more clear that it is mechanical in nature. I'm trying to separate the mechanical/electrical because a motor needs to be viewed as both a motor and a generator. It is, but I'm not sure you need it beyond appreciating where BEMF comes from. I...
by Punx0r
Jan 07 2020 4:26am
Forum: Motor Technology
Topic: Why more KV = more power, the Maximum Power Transfer Theorem
Replies: 51
Views: 2713

Re: Why more KV = more power, the Maximum Power Transfer Theorem

I don't think I referred to BEMF as motor output anywhere, but if I did please point it out so I can change the wording. When I'm speaking of motor output, I'm talking about shaft power. Here: If we take a 2000KV motor and..Using our 20V power supply with infinite current supply capability, we brin...