Range anxiety for Victorian drivers heading north using LPG may be worse than driving an Electric Vehicle.

A friend of mine owns a car that uses LPG. Until recently I never really thought about LPG as it doesn't affect me. However, recently I've come to understand that LPG is getting harder and harder to find and you can't be sure if a service station has supplies of LPG.

LPG usage peaked around 2013, so if you purchased a car that uses LPG around that time, the car could still be in good condition. Fast forward to 2024 and service stations with a reliable supply of LPG are becoming harder to find and that can create stress for owners of LPG cars.

It occurred to me yesterday that because of my interest in creating web sites based around petrol usage, I may have some knowledge that may be useful to others.

If you're driving up the coast in Victoria, I've been told, past Lakes Entrance and the supply of LPG is unreliable. That can be a concern. Using apps like PetrolSpy don't really help as they list service stations as having LPG facilities even when they no longer supply LPG. A hint is the LPG price isn't updated.

I suggested to my friend that they don't drive up the coast, but to drive up the main highway to NSW and then head to their favourite costal locations. The reason is NSW mandates that every service station reports their fuel prices, I believe every time the price is changed. That means you have more reliable information to let you know which service stations are currently providing LPG. That doesn't mean they haven't run out of supply when you need the LPG but knowing which service stations still supply LPG is a help.

The NSW government provides a website and an app which enables consumers to check the price for fuel in NSW. The site/service is called Fuel Check. Getting the location you want to see is a bit clumsy, but with a little bit of effort you can filter for just LPG and then bring up a map, to see where there are other service stations that provide LPG.

There may be a better way, but what I did is, I went to the home page (Fuel Check (nsw.gov.au)), selected LPG and clicked on Filter. I entered the location (say Batemans Bay), clicked Search and this provided a service station near Batemans Bay.

Hint: A location only comes up in the Enter suburb/postcode field if you type the correct spelling.

At this point you'll see in the top right corner an icon with the text MAP. Click on the icon and now you can see if there are other service stations further away that may be in the direction you're heading.

I have to admit I associate range anxiety with electric vehicles but had never thought about existing vehicles which use LPG.

It only took 11 years to go from the peak of LPG cars to the situation we're now in. I can only wonder if the same may be true with petrol and diesel vehicles in another 11 years.

In Australia we only think about our situation. We have to keep in mind cars aren't built for Australia, they're built for a world market. In Australia we often drive long distances, but in other countries the distances travelled are much shorter. For example, I was very surprised to see that in Rome there's a ring road and most people live inside the ring road which is 10km out from Rome. I live 22km out from Melbourne. Our 14 day Trafalgar bus tour that took us through eight countries, a distance of around 5,000km, which for us is a return trip from Melbourne to Brisbane.

When distances travelled are much shorter and fuel prices are higher, electric vehicles make sense. If electric vehicle become the main form of passenger transport overseas, we will have no choice.

Of course, if you turn your vehicle over every few years, you can simply change as the market changes. For those of us who keep our cars for longer, mine is 16 years old, we may also have range anxiety in the future.

Kelvin

Why you should check your car insurance every time you renew.

I've managed to become the go to person when people's insurance bills come up for renewal. Often people can save hundreds of dollars by shopping around. One thing I consider a trick used by insurance companies, is if you ask for a better price, they'll suggest increasing your excess to lower the price. They aren't offering any discount to you since you could have increased your excess anyway. The insurance company isn't reducing your price, just moving you to another option.

Three tips. One is if you take out a new policy with the same company online, you'll often get a discount. So don't renew. Take out a new policy to get a better price. The second is look at your excess. I've found for example if you increase your excess by say $150, the premium may drop by $50. In the first year you've saved $50 and each future year you'll save another $50. If you can afford the extra $100 if you have an accident, which isn't that much really, look at how much you can increase your excess before you feel the risk is too much. Finally, shop around. It's easy to do online and it could save you hundreds.

Here for example are the quotes for a Mazda CX5 I got last year for a person in their 80s. The policy was with Coles and the premium had increase considerably. The result was moving to AAMI with an excess of $1,300 for $1,074.74, with a saving of $765.16. Keep in mind these are last 2023 prices.

Coles renewal
$1,839.90, Excess $1000

Coles online with 15% online discount
$1,953.40, Excess $800
$1,818.23, Excess $1,000
$1,429.82, Excess $1600

Changed age to 84 instead of 85 to see how age affected the premium.
$1,853.49, Excess $850
$1,889.98, Excess $800

Woolworths
$3,233.73, unlimited kilometres
$2,392.53, 8000km
Agreed value $21,000
Excess $800

$1,854.58 excess $1,500
$1,650.12 excess $2,000

AAMI
Up to 10,000km
$1,284.72, $900 excess
$50 online discount
Amount covered $21,100

$1,323,82, $845 excess
$1,074.74, $1,300 excess

RACV
$2,380.10, $825 excess
$2,004.31, $1,500 excess 

GIO
$1,304.83, $950 excess
$1,021.56 $1,750 excess

Budget Direct
$1,448.68, Excess $800
50+ age 

$1,371.70 less than 8,000km
$1,450.89, $18,800 agreed market value

A final thought is that Coles or Woolworths offer either discount or points for car insurance. You really should check if the value of the offer exceeds the difference with their higher premium. In our case the supermarket offer was less than the savings that could be had by moving to another insurance company.

Kelvin

Update: 29/09/2024
This year's (2024) renewal information. This year the easiest and what we considered the best option was to simply renew and existing AAMI policy. Unlike previous years, taking out a new policy was a couple of hundred dollars more expensive.

AAMI
$1,114.20, renewal

New policy
Save $50 first year
Image of car looks like GIO site
5,000-10,000km
$1,349.58

GIO
Up to 10,000km/year
Covered $17,100 can cover $12,825 and $22,230
$1,372.09, excess $950
$1,254.31, excess $1,150
$1,074.21, excess $1,750 

 Coles
$50 off your shop
15% off first year's premium
Tow bar/Tinted windows
10,000km
50+ age restriction
Low mileage
$1,519.17, $900 excess, market value
$1,622.36, Agreed value $16,725, excess $900
$1,413.06, $1,300 excess, Agreed value $16,725

South Australia/Adelaide mobile phone detection cameras now fining drivers.

The South Australian/Adelaide mobile phone detection cameras as of today are no longer in trial mode and people will start to be issued fines.

To find out where the cameras are located, you can visit www.SpeedLocations.com.au, select SA and then Mobile Phone/Seatbelt or go direct to the page www.speedcameralocations.com.au/mobilephoneseatbelt/?state=sa.

For those who wish to receive alerts whilst driving, try the new Speed Limit Alerts page which also provides alerts for fixed cameras and mobile cameras reported by others (www.speedcameralocations.com.au/speedlimitalerts/?state=sa).

Safe driving

Kelvin

Is a sodastream worth it? I decided to record my usage and share the results.

For a long time, I resisted getting a SodaStream and I'll explain why shortly. However, if someone gives you one for a present, that changes things. Who doesn't love a present?

My reasoning was fairly simple. First the SodaStream unit costs money. Then there's flavouring at $7 a bottle that makes 9 litres. That's 78 cents a litre just for flavouring. I'd estimated from online research people were getting around 20-30 litres from a SodaStream cylinder. Exchange cylinders at $19 which means 63-95 cents per litre. So, with just the cost of the cylinder and flavouring the cost per litre I'd estimated to be $1.41 to $1.73 and that's not taking into account the cost of the SodaStream itself.

I decided now having become the owner of a SodaStream this would enable me to do some testing. The first cylinder that came with the SodaStream I used to determine how much gas to add to my drinks. I tend to be a light fizzer. The second bottle I recorded each time I refilled the bottles. So how did it go?

I have 500ml and 1L bottles. For 500ml bottles I'd pump for one second three times. For 1L bottles I'd pump for one second five times. At the end I had to use triple the number of pumps for about three 1L bottles and then the cylinder was done. Yes, I didn't use twice the number of pumps for 1L compared to 500ml. That's just how it worked out for me, for my tastes.

500ml bottles - 33 refills of 3 one second pumps
1L bottles - 16 refills of 5 one second pumps
Plus, at end of cylinder life about 3 1L bottles so equivalent of 5 one second pumps.

That's a total of 194 one second pumps. In terms of litres if I'd just used 1L bottles that would be approximately 39 litres and for 500ml bottles, that would be 32 litres.

The cost per litre for my usage works out at 49-59 cents per litre, or an average of 55 cents per litre. People who prefer more fizz will find the cost per litre greater.

Sadly, if you add the 55 cents to the 78 cents for the cost of flavouring ($1.33/L) that's more expensive than home brand drinks from Woolworths, Coles, or Aldi.

But wait, there's savings to be had.

First, I wait until the flavouring have been on half price specials and then stock up. That means the cost has been 39 cents/L, reducing the cost to 94 cents/L.

I've tried other brands of flavouring but haven't been a fan.

Cordial can make a good drink with the carbonated water. Aldi cordial is $2.69 a bottle and makes up 10 litres. That's 27 cents per litre for flavouring.

Getting creative with lemon and lime trees.

Yes, we all have someone we know that has a lemon tree, and sometimes a lime tree. Often people are happy to give away excess fruit.

I found dissolving a cup of sugar with a cup of lemon/line juice plus half a cup of water, produced a very nice syrup for flavouring. There are about 5 cups of sugar in a kg of sugar. A Coles 2kg bag of sugar costs $2.85 so the cost is 29 cents per litre. OK. Aldi cordial is cheaper than making your own. Didn't know that until now but isn't that the point of testing.

At say 30 cents per litre for cordial/syrup plus 55 cents per litre for gas, that's 85 cents per litre.  Keep in mind, that's not taking into account the cost of the SodaStream

Comparing that to Coles home brand fizzy drinks at $1.20/1.25L less 10 cents refund on the bottle, that gives us 1.10/1.25 = 88 cents per litre. Slightly cheaper in Aldi.

So, in summary, if you use full price SodaStream flavouring it simply costs more to use a SodaStream for drinks than buying home brand drinks. Yes, the flavouring from SodaStream are name brands like Pepsi/Pepsi Max, but to me they're not the same as the bottled versions, so in effect I'd put them on par with the home brands. That's just how I see it, you may not.

Add the cost of the SodaStream appliance spread over say three years at my usage (about 30 cents/L) and it's costing more than home brand drinks. Also, I purchased additional bottles which don't come cheap. SodaKing bottles are cheaper and also work.

There is one advantage that is worth noting. Your groceries are lighter each week if you don't buy the pre-bottled drinks.

The bottom line. Drinks made using the SodaStream, from my testing, are more expensive than home brand bottles of fizzy drink. That's just the way it is.

Kelvin

NOTE: The full SodaStream cylinder weighed 1,168g. Empty cylinder weighed 744g. Weight of gas/contents 424g.

Australian drivers using dashcams to dob in other drivers.

Today I read this article about Australians dobbing in their fellow Australians for breaking the road rules and using dashcam footage and reporting the footage to police.

Aussie road users hit with more fines as drivers use dash cam to dob others in (yahoo.com)

I find this quite perplexing as those dobbing in others are likely to also be breaking the road rules quite a bit of the time whether they realise it or not. The dobbers should realise that if the matter goes to court, they may be required to give evidence, and their personal details could become available. 

Common ways I see people every day breaking the road rules are: crossing single white lines, not stopping at a stop sign (rolling through it is not stopping), not stopping on amber when they could, driving over the white stop line, exceeding the speed limit whilst overtaking, etc., etc. We all see drivers every time we go out driving who break the road rules.

Don't get me wrong. I would dob in a driver if that driver caused harm to another person or their property. But it is easy to ramp people up, to get them angry at other drivers, to get them to dob in others. We need to remain tolerant and be considerate to others on the road. To have patience. Yes, others will drive in a manner that you're not happy with (those who cut in early when changing lanes, those who speed past at a zip merge making it dangerous), but you can only control what you do.

If everyone dobbed in everyone else who did something wrong on the road, it's only a matter of time before you get dobbed in. I'm thankful to those who have tolerated me when I've made mistakes.

For those interest Yahoo published the survey result and here's what it showed when I did the survey. Credit to Yahoo for the graphic.

It is interesting to see around a fifth of people answering the survey have dobbed in someone else. That's interesting and good to know about our fellow Australians.

www.SpeedCameraLocations.com.au

NSW to start trialing point-to-point cameras for cars/bikes using Heavy Vehicle cameras.

I often thought it was only a matter of time before the cameras used to monitor heaving vehicles would start to be used as point-to-point cameras to monitor speeding cars. The cynic would say it's a quick, cheap and easy way to increase fines and revenue for the state governments. The less cynically would say the more people that get fined the more people are likely to comply with the speed limits, thus increasing road safety.

The following article appeared on the News.com.au site today.

https://www.news.com.au/technology/motoring/on-the-road/huge-change-coming-to-speed-cameras-in-new-south-wales/news-story/ac96220175163bca36612c5f5816e490

Across NSW there's quite a large number of routes where there's point-to-point cameras that by current legislation can only be used to monitor heavy vehicle traffic. It makes sense to extend this network of cameras to cover light vehicles. The hardware is already in place and only software needs to be changed, albeit at what would be a sizeable software contract.

The word trial is used and I have to say this misleads me. I think of a trial as meaning to test something out and if it doesn't achieve the results, to then cease the trail. I've come to understand that a trial when used by the government is more likely to mean, a testing phase followed by going live.

For example, if we use the stats provided in the article, we can instantly see the effect on the road toll will hardly be noticeable. Over a four-year period there were six deaths and 33 injuries on the two lengths of road nominated for the trial. Speed is considered a factor in 44% of road fatalities. That means each year, based on these figures we'd expect to see the road toll reduced by 6 deaths /4 year * 44% which is 0.66 of a person. We should keep in mind the injuries are also important and would equate to 3-4 per year. This is not a significant outcome in terms of road safety. In terms of revenue, that will be significant.

As this change permeates across Australia, as the heavy vehicle monitoring is Australia wide, I'll update the Speed Camera Locations site to also include the heavy vehicle point-to-point cameras as speed cameras.

When driving it is a good idea to use an app such as Waze (or my own Speed Limit Alerts web app) to help comply with the speed limit. It's easy to make a mistake, drive with the flow of the traffic, and get a fine for doing so. As cars are updated these features will be built into the cars, but for now, there's a few software tools that can help.

www.SpeedCameraLocations.com.au

Tolerance for fixed speed cameras and mobile speed cameras in Victoria

I often read people quoting there's a 10% tolerance before you'll get fined for speeding. This is a myth. The following is for the tolerance in fixed and mobile speed cameras which can be found in the following regulations document. The information here is for Victorians, but hopefully it also relates to the situation in other states.

https://content.legislation.vic.gov.au/sites/default/files/2023-06/19-88sra016-authorised.pdf

Division 3—Fixed digital road safety cameras 

35 Testing of fixed digital RSC

(b) is satisfied that the speed calculation unit is 
properly calibrated so that it indicates speed 
readings within a limit of error not greater 
than or less than 2 kilometres per hour or 
2 per cent (whichever is greater) of the true 
speeds.

Division 4—Mobile digital road safety cameras 

38 Testing of mobile digital RSC 

(b) is satisfied that the speed calculation unit is 
properly calibrated so that it indicates speed 
readings within a limit of error not greater 
than or less than 3 kilometres per hour or 
3 per cent (whichever is greater) of the true 
speeds. 

Division 5—Speed detectors

42 Testing of speed detectors 

(b) is satisfied that the device is properly 
calibrated so that it indicates the speed 
readings within a limit of error not greater or 
less than 2 km per hour of the true speeds.  

We need to keep in mind, this is the tolerance the government allows in their own equipment. If the government's equipment is accurate, then for a fixed camera that means we'd get a tolerance of 2 km/h for roads with a speed limit up to 100km/h, and 2% for roads above 100km/h.

However, if their equipment is not accurate, then their equipment could record you as going up to 2km/h (or 2% for roads above 100km/h) faster than you're actually going or record you as going slower than you're actually going.

What's important to note is the legislation is for their equipment, not your equipment or the speed you're going. 

For example, let's say the speed limit is 60km/h and you're travelling at 60km/h, but their equipment can read you as going anywhere between 58km/h to 62km/h.  Let's say you were actually doing 61km/h. The detected speed could be 63km/h and your alleged speed would then be 61km/h. In theory you could get fined for driving at 61km/h. I've read if you took this to court you could lose. Whilst at this stage I have no evidence for Victoria, I'd suspect the government would not take you to court for such a low infraction. It doesn't look good for the government and it could cause the community to lose faith in the system. Both outcomes the government wouldn't want. 

In terms of evidence for an additional tolerance however, we can see for South Australia, from the data they release for their SAPOL Expiations (think fines), for fixed and mobile speed cameras for a 60km/h speed zone, the alleged speed starts at 68km/h for fines. This indicates the South Australian government does have an additional tolerance and I suspect this would be true of other states as well. Although my instinct is that some states will have a tighter tolerance than SA. However, for speeding fines other than fixed or mobile speed cameras, (categorised as "other", which I suspect would be by police) the data does show the alleged speed can be as low as 64km/h.

Kelvin

Free Parking Melbourne

Free Parking Melbourne: Free Parking Melbourne has now been added to the Mapz site.

I had an idea a while ago and wondered if there was much street parking riding distance from the Melbourne CBD. Turns out there is. Recently I drove my car to Port Melbourne and then rode my escooter to South Bank to meet a friend for lunch.

Whilst the roads can be a bit scary, it doesn't take long to reach the bike paths where it's a pleasant and safer ride. Good to get out in the beautiful weather.

I'll share the drive and escooter ride on my YouTube channels in the near future.

Drives

360 4K videos

Kelvin

Liter to Gallon / Litre to Gallon Calculator - Australia, United States, United Kingdom, Liters to Gallons, Litres to Gallons

Liter to Gallon / Litre to Gallon Calculator - Australia, United States, United Kingdom, Liters to Gallons, Litres to Gallons has now been added to the Gallon to Liter Calculator.

4K dashcam video of 17 new red light speed cameras around Melbourne

The Victorian government has installed over 30 new red light speed cameras around Melbourne over the past 18 months or so. In this video are 17 of the new red light speed cameras.

Melbourne Driving Tour - City of Melbourne and the Docklands - YouTube

To make it easier to go to a particular section of the Melbourne Driving Tour, I've now added Chapters.

Melbourne Driving Tour - City of Melbourne and the Docklands - YouTube

To see and go to a chapter move the mouse over the video to see the timeline, then move over the timeline to get to the section that interests you. You can also go to the description for the video and click on any of the timestamps.

When your viewers are on YouTube first appeared today (previously Not enough viewer data to show this report).

Various things happen on YouTube once some unknown point is reached. In YouTube there's a graph like the following, which shows when your viewers are on YouTube.

Until yesterday all I had in this section was a message that I think was "Not enough viewer data to show this report". The above graph appeared today (3rd January 2024) for the first time and I wanted to share my statistics in case it helps other determine when this might happen for them.

I started my 360 4K video channel on the 4th of October 2023, which is 91 days ago.

Since starting the channel my stats for the period 4 Oct 2023 to 1 Jan 23 are:

Views: 79,608 (Shorts: 75,425, Videos: 4,191)
Watch time: 367.0 hours
Subscribers: 117

The difference between the individual figures in brackets is because they are until the 3rd of January, whereas the other figures are for the period up until two days ago, the 1st of January 2024.

Looking at the last 48 hours of views there's only one hour where there were no views.

It may be the graph appears after 90 days, but I think this is unlikely, although I can't be sure. If you hover your mouse over the different shaded bars on the graph you get further information which states: "Very few of your viewers are on YouTube", "Few of your viewers are on YouTube", "Some of your viewers are on YouTube", "Many of your viewers are on YouTube" and "Very many of your viewers are on YouTube".

There is no "None of your viewers are on YouTube" at a particular hour, which I find interesting. If I were to guess, it may be this graph only appears once there are one or more viewers in each hourly bucket for the 24 hours for the 7 days. Keep in mind this graph is for the most recent 28 day period, so each hour on each day is the sum of 4 days from each of the weeks.

I don't know why or when the "When your viewers are on YouTube" graph appears, but hopefully by sharing my information it will provide clues to others should a pattern appear.

I should add my first channel is very different from my 360 4K channel as to when viewers are on YouTube. The main reason I think is when I started my first channel it is based on content largely from Australia and published based on the time in Australia. Currently 70% of my viewers are from Australia. For my 360 4K channel which this graph is from, the content started based on a recent trip to Europe and the viewers came mostly from Europe. I've focused on using Shorts to build the audience and currently the top viewers for All Viewers come from Russia, United States, India, Germany, Uzbekistan, whereas if just looking at long form video the top viewers are from: Fance, India, Australia, Brazil, Italy. Sometimes I wonder if the graph is for all viewers, or just long form videos. Again, I don't know the answer, but I thought I'd put the thought out there.

Kelvin

My first channel
Ride, Drive, Walk by Kelvin

My 360 4K channel
360 4K UHD videos

Victoria Container Deposit Scheme, Vic Container Deposit Scheme

Victoria Container Deposit Scheme, Vic Container Deposit Scheme is now live so I've produced a map showing the location of container collection points. Most of the collection points around me are OTC (Over The Counter) collection points. A local milk bar for example. It will be interesting to ask them a few questions such as, how many containers are considerable a reasonable number for OTC returns.

I'm looking forward to trying out one of the automatic vending machines, but unfortunately, they're location too far away.

It's important to keep in mind making a special trip to even your closest collection point may not be viable for dropping off a smaller number of contains. For example, our nearest collection point is a 5km return trip, which is over a dollar of petrol usage at current prices. That's 10 containers before you start getting your money back.

Another thing to note is vending machine don't give you cash, whereas OTC points cash is an option.

I hope others find the map and the above information useful.

Kelvin

Contrary to recent media reports, Queensland is not fining drivers speeding close to speed sign zone changes.

I recently read people in Queensland were now getting fined when speeding very close to the speed signs when the speed limit zone changes. This concerned me as it appeared to be an easy way to increase revenue. Yes, people shouldn't speed. Being a good driver also means obeying the road laws. None of us obey the letter of the law, all the time. I decided to do some research.

After finding a few articles with photos showing the same location, things didn't make sense to me. The road markings did not match where the speed signs were located. The following is the article on Yahoo News, but I think I also saw headline from the Courier Mail.

Aussie driver caught twice by 'sneaky' placement of speed camera on highway (yahoo.com)

It turns out the driver was mistaken (along with many others), who believed the sign in their picture was a speed limit sign. It isn't a speed limit sign. It is an informational sign for a camping area and the road name.

The following video is from my travels and starts just before the sign shown in the speeding fines and then continues on to the speed limit change, about 220m further on. 

Driving Queensland, Agnes Water to Gladstone - Tour #3 - YouTube

People are speeding up before reaching the sign and from the other direction, not slowing down to the speed limit as they reach the sign. This is normal driving behaviour, but it isn't legal behaviour. You have to at or below the signed speed limit for the section of road you are travelling on. If you're approaching a 60km/h sign from a faster section of road, you need to be at or below 60km/h when you reach the sign. If you're approaching a 100km/h sign from a lower speed limit zone, you can't speed up before you reach the speed limit sign. Not what we all do, but something we should be doing.

So in this case the media reports are based on incorrect information, and unfortunately, lack of fact checking.

Kelvin
www.SpeedCameraLocations.com.au

Edinburgh, Scotland, High Street to Edinburgh Castle

Edinburgh, Scotland, High Street, The Royal Mile

Edinburgh, Scotland, High Street

Edinburgh, Scotland, Victoria Street, Diagon Alley

Edinburgh, Scotland, Grassmarket Market Square

Aldimobile Auto Recharge leaves users open to bill shock.

In February I moved to Aldimobile. Overall it's been a good service, but then recently something unexpected happened.

It was after midnight and I received an SMS, "Hi, Your ALDImobile PAYG credit is fully depleted. Please go online or use your mobile app to recharge."

My first reaction was to go and top up the account.

My next reaction was what the? I'm on Auto Recharge. Shouldn't I be covered?

Turns out at the end of the month the Auto Recharge can take up to a day to be applied. So for hours and up to a day, anything you use is taken out of your PAYG balance. Luckily there was only a $4.88 balance which was cleared out by Aldimobile. Never knew where that 12 cents went, but my guess now is data use during the time Auto Recharge hadn't been applied in the past. A second service also had money taken out.

To me the worst-case scenario is you have a large PAYG balance and you're watching a movie online and your balance is cleared out.

Of course, all of this can be found online, as long as you make the effort to read further than the first screens. ALDImobile also states "No bill shock", but isn't an unexpected and an unknown amount being charged what bill shock is?

I didn't know ALDImobile's Auto Recharge meant you weren't fully covered with your monthly payment. Perhaps others don't know as well, which is why I'm sharing this story.

I don't think ALDImobile's Auto Recharge is good enough and as a result, have moved to another provider so this is not an issue.

Kelvin