Search found 3848 matches

by Punx0r
Jan 15, 2018 6:16 pm
Forum: General Discussion
Topic: Alternative current
Replies: 15
Views: 119

Re: Alternative current

Ya but smth is quite strange. When I rise the volume the amplifier there is a moment when the speakers do like a big "boom" and stop playing music. I believe that this is because they are receiving more than 12w. Have you got an explanation to this? Are you sure the 12V power supply for the amp isn...
by Punx0r
Jan 15, 2018 9:25 am
Forum: Motor Technology
Topic: Idiots guide to water cooled mid motor making
Replies: 89
Views: 3779

Re: Idiots guide to water cooled mid motor making

I believe this model of moped is a liquid-cooled 2-stroke
by Punx0r
Jan 15, 2018 5:36 am
Forum: Motor Technology
Topic: How can i control this 15kw motor
Replies: 10
Views: 330

Re: How can i control this 15kw motor

I'm afraid I have no experience using Sevcon controllers, but a few on this forum have, so you might want to search for "sevcon" and see what they say. The diagram above appears to show several methods for driving the motor, with regards to determining the rotor position for proper timing of the pha...
by Punx0r
Jan 15, 2018 5:27 am
Forum: Motor Technology
Topic: Idiots guide to water cooled mid motor making
Replies: 89
Views: 3779

Re: Idiots guide to water cooled mid motor making

These mopeds can be modded to do 100km/h with their inefficient petrol engines so the capacity of the cooler will be enough mated with an OK pump. That should be more than up to the job :) As a sanity check, for the rated output power of the moped, it will put at least as much heat into its engine ...
by Punx0r
Jan 15, 2018 5:17 am
Forum: General Discussion
Topic: Alternative current
Replies: 15
Views: 119

Re: Alternative current

The amplifier already has a potentiometer to limit the output - it's called the volume control... It's a myth that using a powerful amp you will end up unintentionally destroying your speakers - the reverse is more likely. As long as you don't use a powerful amp to deliberately drive your speakers i...
by Punx0r
Jan 13, 2018 1:58 pm
Forum: Motor Technology
Topic: Idiots guide to water cooled mid motor making
Replies: 89
Views: 3779

Re: Idiots guide to water cooled mid motor making

I wonder if they measure cpu die or coolant temperature? There is probably a significant difference (thermal resistance)! Yes, the specific heat capacity of water is very good (and convenient). Vehicles have radiator fans for when stationery, when moving, even at ~5mph, the fan is not required. As a...
by Punx0r
Jan 13, 2018 8:53 am
Forum: Electric Aircraft
Topic: Bell Helicopter electric flying taxi
Replies: 4
Views: 74

Re: Bell Helicopter electric flying taxi

If it's missing all the gubbins that make it function they might as well have claimed it's a time machine.
by Punx0r
Jan 13, 2018 8:47 am
Forum: Motor Technology
Topic: Idiots guide to water cooled mid motor making
Replies: 89
Views: 3779

Re: Idiots guide to water cooled mid motor making

That's bigger than I was expecting for a computer cooler. Something that size should do the job with a good fan or sufficient airflow from forward movement of the bike. Airflow through a cooler makes a huge difference to it's thermal performance and I think the problem with computer setups is being ...
by Punx0r
Jan 12, 2018 8:10 am
Forum: Motor Technology
Topic: Idiots guide to water cooled mid motor making
Replies: 89
Views: 3779

Re: Idiots guide to water cooled mid motor making

There was a lot of discussion a couple of years ago about a proprietary ebike system that used 5 phases. The manufacturer claimed all sorts of supposed benefits, many of which didn't stand up to scrutiny. My recollection is that after a lot discussion and analysis the conclusion was 5 phases over 3 ...
by Punx0r
Jan 12, 2018 4:10 am
Forum: Motor Technology
Topic: Idiots guide to water cooled mid motor making
Replies: 89
Views: 3779

Re: Idiots guide to water cooled mid motor making

I think comparison would be difficult as the motors are different in many other ways that will have effects on performance & efficiency. You'd need identical motors but just wound differently (and I can't think of any examples of this).
by Punx0r
Jan 12, 2018 4:07 am
Forum: Motor Technology
Topic: How can i control this 15kw motor
Replies: 10
Views: 330

Re: How can i control this 15kw motor

Ah, that's good you know it's a Sevcon - hopefully you can find a manual for the dragon8. Otherwise, maybe their other controllers use the same connector? Here's the pinout for the Gen4 model (page 3-11): http://www.thunderstruck-ev.com/Manuals ... l_V3.0.pdf
by Punx0r
Jan 11, 2018 6:12 pm
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 1364
Views: 27101

Re: Wind and Solar vs Coal, Gasoline, Nuclear

I'm talking about nationwide fluctuations in demand, so it seems you have to have a few coal plants idling alongside your inflexible baseload coal plants to take up the peaks (and presumably you still need to predict the peak well in advance to feed the boiler and raise sufficient steam). Doesn't th...
by Punx0r
Jan 11, 2018 3:24 pm
Forum: Motor Technology
Topic: Idiots guide to water cooled mid motor making
Replies: 89
Views: 3779

Re: Idiots guide to water cooled mid motor making

In my case it's best improvement seems to be the possibility to use two controllers and double the available controller power. My understanding is this is only practical advantage. AFAIK there is no real inherent efficiency or performance benefit, maybe slightly reduced torque ripple. "John in CR" ...
by Punx0r
Jan 11, 2018 5:30 am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 1364
Views: 27101

Re: Wind and Solar vs Coal, Gasoline, Nuclear

For sure, RE has required more grid links than would otherwise have been required, but some would have existed anyway. Cross-country links in Europe are more common than I realised and that's between many countries with low RE. As you say, fossil & nuclear are stable with continuous output. Sadly, d...
by Punx0r
Jan 11, 2018 3:53 am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 1364
Views: 27101

Re: Wind and Solar vs Coal, Gasoline, Nuclear

The whole point of renewables is to save the environment and Germany has done the opposite they are quite literally cutting down forests to install solar farms. Evidence for this claim, please. Wind generators in Germany are "guaranteed" a feed in tarrif of 8€ct/kWh for 5 years, and a lower rate fo...
by Punx0r
Jan 10, 2018 10:25 am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 1364
Views: 27101

Re: Wind and Solar vs Coal, Gasoline, Nuclear

CO2 emissions are predicted to increase every year and be 16% higher in 2040 than 2017. The latest framing of what's required to meet the Paris Climate Accord targets (<2°C warming) are halving of CO2 emissions every 10 years and a doubling of green energy every 5 years (continuing the trend that s...
by Punx0r
Jan 10, 2018 9:57 am
Forum: Battery Technology
Topic: 700 mile charge in 1 minute
Replies: 13
Views: 305

Re: 700 mile charge in 1 minute

You hear of people recharging high performance RC lipo in under 10mins, so assuming 5-10x better performance with a speculative, probably solid-state future battery isn't too far fetched. However, charging your RC toy battery in 60 seconds may be practical, but there's a bit of a scaling issue with ...
by Punx0r
Jan 10, 2018 3:52 am
Forum: Battery Technology
Topic: 700 mile charge in 1 minute
Replies: 13
Views: 305

Re: 700 mile charge in 1 minute

The battery might be capable of it, but the wiring, connector and local supply probably won't be.

700miles x 450Wh/mi = 315kWh / (1/60) = 18,900kW = ~19MW

At 400V that's around 47,250A
by Punx0r
Jan 09, 2018 4:30 pm
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 1364
Views: 27101

Re: Wind and Solar vs Coal, Gasoline, Nuclear

New York is the 7th highest state for population density and is cold. Mileage for many other areas is likely to vary...
by Punx0r
Jan 09, 2018 4:25 pm
Forum: Motor Technology
Topic: Mid drive vs Hub Motor for 10000 watt project
Replies: 57
Views: 1088

Re: Mid drive vs Hub Motor for 10000 watt project

It's not something I've done, just read about on this forum, so it's not something I have experience of. However, if you follow the phase leads inside the motor, they are soldered to the ends of the winding bundles. How the bundles are joined to each other and the phase leads determines the star/del...
by Punx0r
Jan 09, 2018 3:56 pm
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 1364
Views: 27101

Re: Wind and Solar vs Coal, Gasoline, Nuclear

Right. So as I said, you may triple the contribution of German solar and wind toward total energy consumption which will place it up into the realm of 10% now. It is a good start. Indeed. It is early days. It's only in the last few years the technology has become mature and cheap enough to really b...
by Punx0r
Jan 09, 2018 3:52 pm
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 1364
Views: 27101

Re: Wind and Solar vs Coal, Gasoline, Nuclear

Wind turbine spacing to prevent dominoe cascading damage upon blade breakage requires at least 2.5 diameters between turbines. Vortex shadowing cuts power up to 50% at 2.5D in successive rows so that 7D spacing in the prevailing wind direction is recommended. ... NY state uses 33 GW Summer and 25GW...
by Punx0r
Jan 09, 2018 3:50 am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 1364
Views: 27101

Re: Wind and Solar vs Coal, Gasoline, Nuclear

I didn't realise you disliked gas plants in preference to coal, I thought it was just fossil fuel over RE... It was a very simple question, intended to see if your preference for coal was based on not having to personally suffer its immediate externality of air pollution. You obfuscated rather than ...
by Punx0r
Jan 08, 2018 5:39 pm
Forum: Motor Technology
Topic: What limits the no-load speed of a motor.
Replies: 6
Views: 108

Re: What limits the no-load speed of a motor.

I somehow never damaged a car starter motor testing them with jump leads and a starter battery. I had no idea what I was potentially doing to them! :D
by Punx0r
Jan 08, 2018 5:34 pm
Forum: Motor Technology
Topic: Mid drive vs Hub Motor for 10000 watt project
Replies: 57
Views: 1088

Re: Mid drive vs Hub Motor for 10000 watt project

eRPM is pole pairs (13 for your motor) x mechanical RPM. Thinking about it, with your hubmotor you're unlikely to be at the limit for even a low speed controller. The star-delta thing is how the windings are terminated and can usually be changed without rewinding the motor. If you motor is wired in ...