Home automation using Alexa and Hive

Posted by under Electronics, on 20 January 2018 @ 3:10pm.

This is something I’ve wanted to do for a while, and for Christmas I was fortunate enough to get an Amazon Echo Dot and some smart Hive bulbs.

There are different combinations of systems out there including Google Home and Google Assistant to compete with Alexa, and Philips Hue to compete with Hive, and they all have their pros and cons (something I’m realising now). Alexa does a very good job at serving my needs so far, and Google Assistant which I can use on my phone supplements that.

At the moment I am able to control 2 lights in my flat using Alexa, an Android app and Google Assistant. I mostly use them on a timed schedule to turn on and off at set times, but I do have the option of controlling via Alexa and Google Assistant as well. It’s surprising how often you may want to turn your light on and off but never realise that you do it. You take it for granted when you flick the switch on the wall.

Something I find nice with the Hive bulbs is that you can dim them from 5-100% in 10% steps (5% for the first step). This is nice if you want to leave a light on overnight or late evening but dimmer so that you don’t hurt your eyes if you need to get up for the toilet. Personally I have my hallway light dim at 11pm to 50% and then again at midnight to 5% until 1am when it turns off. It also helps me to keep track of the time.

The bulbs don’t dim gradually, they just jump straight to that setting. Philips Hue bulbs on the other hand apparently don’t do this, but they’re also much more expensive (about twice the price). So you get what you pay for in that respect.

You can also get RGBW bulbs; these are multi colour with a separate white so that you get a true white not a mixed colour white. I don’t have any of those yet but I have seen examples where they can give some great results to the ambiance of the room. The cost of those is also quite high!

So besides bulbs what else can you control? Well, anything that can be internet connected in theory. That could be a toaster, microwave, kettle, washing machine, a roomba vacuum cleaner, anything really. Hive do some other sensors such as door and window sensors, cameras, motion sensors and moisture detectors which would be useful to those that are very security conscious. I was considering a door sensor in the future but not at the prices they are currently sold for. They’re just not worth that kind of money (£25+). A white only bulb alone is £16 from Hive at the moment.

Hopefully in time the prices will drop or I can get some good deals when they’re on offer.



Using my HP DL380 G6 and HP N54L together

Posted by under Servers, on 23 October 2017 @ 10:58pm.

Having now had time to set up and play with my new server, I have now given it proper tasks of running virtual machines rather than just sitting idle.

One of those tasks include running PFSense, a router operating system designed to handle the same tasks as your regular router but on a larger scale. It handles DHCP, routing, port forwarding, etc. This will give me more control over my internal network including the ability to monitor it better. My original router is still in the loop since it is also the VDSL modem, but it is fully DMZ to the PFSense so it acts like it’s not even there. PFSense does still get a local IP on the WAN port though.

Now that I am using the DL380 properly, this means I could retire the N45L from its original job as being the sole server. Since the DL380 only has 2.5″ drive bays this meant that I was unable to use my existing 3.5″ drives unless I found another solution. I was able to re-use the N54L as a NAS by using the FreeNAS OS. This turns the system into a fully fledged NAS to work in any way that I liked.

I had been dabbling with the use of iSCSI attached drives, but found Windows’ implementation poor as it required the use of a virtual hard drive container file to store everything. I didn’t like this because corruption of that file means anything contained within it is lost. For a virtual OS this is not so bad but for my regular data this was not an option. Thankfully, FreeNAS’s implementation allows you to just use a physical disk over iSCSI so that’s what I have done. This is then attached directly to the appropriate VM on the DL380.

The original N54L roles have now been switched to a VM on the DL380. This gives it more power to handle things like the CCTV, my web development setup, my Plex server that I am now able to run thanks to the additional power, and more should I ever need it.

At present the system has only 24GB of RAM with the main server VM using 8GB of that (up to 12GB dynamic). PFSense is allocated 2GB. That gives me plenty to start up more machines if I need it. A friend also passed to me another 48GB of RAM to add when I get the chance bringing the total to 72GB. That will be more than enough for me for the foreseeable future.

Eventually I will run other things on the server including a Steam cache (which I successfully trialled at the weekend and it works great). I just need some additional storage caddies so I can put in some more local drives. Without local drives I will be limited by the network connection to the NAS (1Gbps at present). Future plans include trying to team two NIC’s together for a 2Gbps NAS connection.

All in all it’s been a fun experience so far. One thing I did notice though is that my electricity bill has now doubled thanks to the server using a fair bit of power, but that aside it’s working just as I intended.

This is my setup at the moment. One of the N54L’s is a NAS and the DL380 on the bottom. At the top you can see my HP 1800-8G switch and BT Homehub 5 router/modem. In future I plan to get a rack to put these in but I just don’t have the space at the moment.



Server Virtualisation – A New Journey

Posted by under Servers, on 5 September 2017 @ 7:45pm.

Recently I managed to acquire myself an old HP DL380 G6 rack server. It’s the kind that you would find in a data center or business server rack. For just £125 it has 2x Intel Xeon processors and 24GB DDR3 ECC memory, a fully fledged RAID controller and redundant power supplies. It’s the kind of upgrade I needed for my ageing HP N54L micro servers.

Because of the amount of power that it holds processing wise, I decided it would be time to try out virtualisation. I decided to go with Microsoft Hyper-V because I’m familiar with Windows operating systems. I haven’t really had time to play with this server too much but I did get PFSense set up as my router as a virtualised operating system, and it’s working very well.

I gained a little experience from doing this and even more recently I decided to upgrade my web server (the one running this website) to a new one, allowing virtualisation. It has an Intel Core i7-7700, 32GB RAM and 2x500GB SSD’s. I currently run BetaArchive, this website and several others for friends from the server.

To separate BetaArchive from the rest I decided to virtualise the whole machine and install two operating systems and gave them both their own IP addresses. I had never done this before so I had to learn how to assign IP’s to each virtual machine as well as understand how the virtual hard disks worked (fixed sizes, dynamic sizes, etc). It’s all very complicated, and that’s the basic parts of it.

One thing that I did find when doing this on both my home server and web server is that SSD drives are an absolute must. Without them your system will run extremely slow because they just aren’t quick enough with standard mechanical drives. That quickly led me on to an issue that made me spend all day thinking there was a hardware issue with the new web server. I discovered that when I ran drive benchmarks that the SSD’s were not performing the way I expected. The reading was mostly OK but the writing was slow. I couldn’t understand it. I thought there was a disk issue so I asked for a replacement since the 2nd disk seemed to be OK.

The disk was replaced and I saw no change. I then theorised it might be a SATA cable issue so I asked for that to be changed. Again no difference. I then asked for the whole server to be swapped out except for the disks, and again, no difference! What?! That made no sense, so it had to be a software issue. For another 2 hours I was stumped, and then it clicked.

Kicking myself, I checked the drive cache settings. Write caching was disabled. Doh! Turning it on instantly gave the speed boost I was expecting. Why it was off by default I don’t know. Is it always off by default? I’ve honestly never noticed this on other systems that I have installed SSD’s into. I feel sorry for the tech that had to do all of those swaps for me!

Disk I/O problems isn’t something just caused by virtualising, but it is very noticeable when you try to run multiple machines at once and they fight for disk I/O. If one machine uses up all of the I/O, the other systems can lock up – not ideal! Thankfully you can restrict the maximum amount of I/O that each machine is allowed to use, as well as give each machine a minimum I/O that it is allowed to be restricted to if another machine is using a lot of I/O too. This stops one from using it all and starving the other.

So now that this is set up, everything is running just great. There are other considerations to make such as RAM and CPU allocation, but you can set up minimums and maximums for those as well.

Hopefully this is something that I can get into more and work with at home when I find the time to do it. The biggest issue I have at home is that my disks are 3.5″ disks but the new server only takes 2.5″, so I will need to use the old one as a storage array. I’ll get around to it. Eventually…



Hybrids in hot and cold weather – 1 year with the Lexus CT200h

Posted by under Hybrid & EV Vehicles, on 2 July 2017 @ 8:06pm.

I’ve had my Lexus CT200h for 1 year now, and in that time I have been logging my fuel economy on a spreadsheet so that I can get an idea of how it performs over the year with different driving types and different temperatures.

Here are some notes to add before we look at the data:

  • Most of my driving is commuting 15 miles per direction, and I tried to average around 60mph for the majority of this 1 year period for the sake of this test.
  • Long journeys, which I do a few times a year, were done at 70mph.
  • Short journeys to the supermarket once or twice per week.
  • In March 2017 I did barely any driving, but this shouldn’t have impacted the data.
  • I was using “pulse and glide” after I discovered it, for the majority of the year.


Hopefully most this table should be self explanatory. Discrepancy is the difference between what MPG the car said it got and what was worked out on a fill up.


The graph looks complicated but is quite simple.

  • The green bars represent the real MPG as calculated by filling the tank
  • The red bars represent the MPG the car said it was getting.
  • The blue line is a representation of outdoor temperature calculated by taking 2 values, the minimum and maximum temperatures during that tank of fuel, and averaging them. It’s not an accurate representation of outdoor temperature (I would have to log it all the time to do that) but an average representation so you can see a trend.
  • The dark orange line is the average discrepancy in MPG between the actual MPG and what the car said it was getting.
  • The purple line is the discrepancy for that tank of fuel.
  • The black line is a running average MPG calculated over the last 3 tanks, to make it easier to compare with temperature.


OK, how you’ve had a second to digest the data on the graph, lets talk about it.

What is the first thing we can tell from this data?

Plain and simply, hybrids work better when it’s warmer. Why? Because the engine gets up to working temperature quicker and which means it can shut off the engine earlier so the electric part of the hybrid system can do what it is designed to do. You can apply this rule to pretty much any vehicle.

Why is there a discrepancy between the displayed and actual MPG?

This can be caused by a few things, with the most likely being speedo calibration. The vehicle reads about 4mph too high at 66mph (so it’s reading 70mph at this point) as checked by GPS, which is a 5.8% difference. Tyres can cause this but I just got new tyres and it looks to be the same (though I haven’t checked it accurately, only via the speed limit symbol on the GPS turning red when you speed). Most cars in the UK over read very slightly.

This 5.8% is mostly accounted for in the 5-9% discrepancy that we see in the data (I’ll share the full Excel document at the end of this blog which contains more data). The remaining could be put down to tyre pattern and pressures, weight in the vehicle, etc.

Once you know roughly how far out your vehicle is, it’s easy to take the reading and subtract a few MPG to get the real MPG.

What economy do I get at XX mph?

As a rough estimate based on my observations:

  • <35mpg in town on a short journey from cold
  • >50mpg in town if engine is warm
  • ~53mpg at 60mph on a 15mi journey
  • ~53mpg at 70mph on a long journey


These figures will change based on your driving style, how much you demand from the heating or A/C, weight, tyre pressures, your driving route, etc.

What average economy do I get?

According to all of the data that I have collected, which is every fuel-up for 1 year, and with a mix of driving types and speeds, I saw an average of 52.2mpg over the 12 month period. This is 30% below the rated 74.3mpg combined rating, which was expected because these ratings are recorded under artificial conditions.

The highest I saw was 61.1mpg on a long journey at 70mph, where I barely had to change speed for 150 miles and it was pretty warm. I don’t know if this was fluke or real, but I have never managed an MPG this high since. Temperature has only just reached similar conditions recently so this is likely why.

Everything else aside, 52.2mpg is impressive for a vehicle running a petrol engine, and outperforms many diesel vehicles too.

My previous car, a VW Passat 2.0 TDI was managing around 44-46mpg. I have friends with diesel vehicles such as a Ford Mondeo 2.0 TDCI which averages around 45mpg.

Whilst there are cars out there that will do more than 52.2mpg, chances are they aren’t doing it whilst abiding by emissions laws (remember the whole dieselgate scandal from VW).

The average economy of the CT200h on Fuelly.com shows as being around 49mpg, which means that I was driving a little above the average economy wise, probably due to going most places at 60mph for this test.

2013 Lexus CT200h average fuel economy. Source: Fuelly.com


So, do hybrids really work? Yes, they do, at least in my personal experience. But there are still conditions under which they’ll perform no better than any other car, with the biggest being in cold weather and short journeys. If you have a particularly heavy right foot all the time you may also not see much benefit, but I can’t testify to that.


Lexus CT200h – 1 year of economy data – 50KB



Arduino PWM Charge Controller V3

Posted by under Electronics, on 4 June 2017 @ 12:49pm.

This project has been a relatively long time in the making, but here it is, the next iteration of the controller.


  • 3x P-Channel FQP27P06 in parallel for lower total resistance
  • Low quiescent current 5v regulator for minimal power consumption
  • 2x40A diodes in parallel for lower total resistance
  • 30A hall effect current sensor
  • Modular design to enable upgrading of the power board
  • Current design limit 10A (may be capable of more but untested)
  • Power consumption: 7mA (no solar input) to 35mA


  • Voltage reading (accurate to +/- 0.02v) for battery and solar panel
    • Translates into a percentage reading with hysteresis
    • Software over-voltage protection
  • Current reading (accurate to +/- 0.1A)
    • Continuous polling
    • Records power flow in Ah and Wh
    • 2 sets of records for running and total records
    • Readings stored in EEPROM in case of CPU reset
  • 255 step PWM controlled output
    • Adjusted up to 700 times per second
  • 3 charging modes
    • Bulk
    • Absorb
    • Float
  • Night detection to lower power consumption
    • Lower CPU frequency
    • Turns off current sensor
    • Lowers backlight brightness
  • Button for additional functions
    • Changes screens
    • Resets power flow totals
  • Over temperature cut-off
    • Protects diodes and MOSFETs from damage
    • Override available in case of temperature probe failure
  • Firmware upgradable
  • RGB status LED
    • Red = Bulk
    • Orange = Absorb
    • Green = Float
    • Blue = Night / No solar input
    • White = Power up sequence
  • Multiple screens available
    • Full information screen
    • Volts, Watts, Amps
    • Volts, Wh, Ah
    • Rotating screen
      • Volts, Watts, Amps
      • Battery %, Wh, Ah
    • Graphical screen
      • Battery bar
      • Volts
      • Battery %
      • Amps
      • Watts
      • Ah
      • Wh
    • Power
      • Hold button on this screen to reset values
    • Total Power
      • Hold button on this screen to reset values
    • Temperature override
      • Hold button on this screen to enable/disable temperature override


Flaws in the design

As with anything I make, not everything always goes according to plan. There is one flaw with the project that I found whilst I was writing the software. The ambient temperature probe picks up heat from the voltage regulator through the copper tracks, making it slightly inaccurate (it reads high). If I had to re-make the control board I would move it further away from the regulator and put a large copper pad around it to take away any heat that is transmitted.


There were several challenges in this version of the controller.

Initially I wanted to use N-Channel MOSFETs because they have lower resistance and are easier to drive. However I quickly found that this wouldn’t work without some complex drive circuitry. For loads N-Channel is easy, but for power shunting from a solar panel it requires complex drive circuitry in the form of a charge pump or a MOSFET driver. Needless to say I wasn’t prepared for that set back so I decided to go with P-Channel once again.

Another challenge was the software. In order to get the best possible voltage control the software has to run as quickly as possible. This means making it as efficient as possible because of the limited CPU speed. I quickly found that using timers was the best way to get around this. The main control loop runs unrestricted but non-essential code runs less frequently. The screen updates every 500ms, and everything else runs every 1 second.

Circuit Layout

I realise that many of the components are not labelled, sorry!


Version_3.00 (12KB) – 04/06/2017



Fitbit Blaze: A quick review

Posted by under Technology, on 17 March 2017 @ 5:39pm.

After a recent health issue I decided it was time to get myself a Fitbit to help me get into shape. I decided on the Fitbit Blaze which combines a smart watch and a fitness watch into one tiny device. I have to say for £140 it’s a very capable device and seems to work very well.

Its main feature is a heartrate monitor and step counter, but it also includes a pressure sensor so it can tell when you have gone up and down stairs for example.

It tracks heart rate 24 hours a day and uploads this via your phone to Fitbit. It does this at 5 second intervals except when you’re exercising. Using this it is able to estimate how many calories you have been burning during your activities.

It can also monitor your sleep to determine how well you slept and for how long. I can say that it does work with some degree of accuracy as I do occasionally get up to use the toilet and it at least records this reliably.

Although I have not yet put it through its paces with any proper exercise, I hope to do so soon. One of the features which I bought it for was reminders to move regularly which will come in handy given I have a desk job. This should prevent me from sitting down for long periods of time (at least that’s the theory!).

Battery life is quoted to be about 5 days. Having had it for just a few days and only charged it once, I can say this is a likely length of time if not a day less than quoted.

Smartphone notifications are I would say adequate but nothing special. If you receive a message it displays on the screen a snippet of the message. This applies to e-mails, instant messengers, etc. too. Each can be turned on and off in the app settings. Phone calls also come through but are delayed a little if you turn off ‘always on’ connectivity, which I have because it drains my phone battery like crazy.

The Fitbit uses Bluetooth 4.0 LE (low energy) to minimise battery consumption. This is good but reduces the range of the bluetooth signal to about 10ft. Perfect if you carry your phone but otherwise you will definitely miss notifications from the other side of the room. That’s not a big thing for me since my phone is usually with me anyway.

I’ll probably write a more detailed review as I use it more, but so far I’m enjoying the data it’s giving me.



Hybrid vehicle economy in warmer weather

Posted by under Hybrid & EV Vehicles, on 6 March 2017 @ 4:15pm.

I wrote a post in the past about how cold temperature affects hybrid vehicle economy. Now that it’s turning to spring and the temperature is beginning to increase, there has been a noticeable change in direction on my MPG vs temperature graphs.

Though it’s not a lot, the change is there, and it’s felt noticeably warmer too. I’ll continue to keep this data recorded and continue to update here.

I suppose the takeaway from this so far is that colder weather does negatively affect the MPG due to the engine needing to run more often, and that combined with running richer when colder means that more fuel is used overall.

I guess the solution to this problem could come in many forms (if we’re talking about keeping the ICE alive and not going EV):-

Additional engine heating – The engine is very thermally efficient, which means it takes longer to heat up. This efficiency is only good however when the engine is already warm, otherwise the engine has to run rich (use more fuel) until it is warmed up. It would be interesting to see if adding electrical heating that runs from the hybrid system to heat up the oil and coolant would significantly improve efficiency for shorter journeys, by getting those fluids and the engine up to temperature quicker. While it would of course use more energy, would this be offset by getting it up to its efficient operating range quicker? In winter it might well do, but at the expense of additional hardware. It might not pay for itself over the lifetime of the vehicle.

Bigger battery and electric cabin heating – If the battery were higher in capacity then it would be possible to use electric for cabin heating, either through resistive heating or a heat pump (more efficient than resistive in many cases), thus allowing the engine to stop when it’s viable to do so. I believe this can happen at above 50*c coolant and oil temperature. This means that all heating could go into the engine coolant and oil, it will work a little harder to generate electricity for the cabin heating, which also adds heat into the engine for the additional load. Perhaps this is all a little excessive for the gain? I’m sure Toyota/Lexus did the math on that one! However I do know that heat pump heating on EV’s is significantly more efficient than resistive in a lot of climates, so it probably wouldn’t hurt to add that to hybrid vehicles to supplement the cabin heating in cold weather. After all it’s just a modification to the A/C system…

No doubt my ideas were thought of and dismissed for cost reasons by Toyota but I’ve not read anything about either anywhere to date, so who knows!



Goodbye BT, hello Plusnet

Posted by under Technology, on 3 January 2017 @ 10:49pm.

I recently got my latest BT bill and noticed that my monthly fee had gone back up to normal. I had been enjoying a £10/month discount over the past 12 months as I felt the cost was far too high, complained, and got that offered to me. Well, it had gone back up to £46/month and I am not prepared to pay that much for broadband. BT have put up their prices significantly in the last 2 years and it’s now what I would consider to be unreasonable, so I decided to look at the deals available elsewhere.

I quickly came across Plusnet, who interestingly are owned by BT themselves. They offer the exact same package I am on now for just £30/month, minus a few things that I never used to use anyway (cloud storage, BT Wifi, free security, etc). I used to use the BT Wifi on occasion, but not nearly enough to warrant the additional £16/month. Comparing with BT for customer satisfaction on Thinkbroadband the scores are better for Plusnet (marginally).

I contacted BT via phone and asked if they were able to do anything about it. Would they match or even reduce the fee to approach that of Plusnet? No. What about any kind of discount? No, “nothing available” I was told. OK, fair enough, the guy at the other end can only offer what he’s been told he can. I was disappointed and let them know as much via Twitter. I was a loyal customer of about 5 years and they wouldn’t do anything to keep me. Their loss in the end!

So on to Plusnet – being owned by BT means that I will get the same level of support if there is an issue. The router I’m being sent is basically a re-badged BT Home Hub, so I know that will work just fine. The line speed should not change at all, though this remains to be seen. Best of all, if I want a static IP address, it’s a one off fee of just £5 – something BT were unable to offer at all.

All in all, I think I am getting a good deal, but the quality of the connection will be the determining factor. After all, they should use the same back-haul as BT, but it might be segmented and limits put in place. Here’s hoping they don’t.

In terms of cost, I’m going to be saving nearly £200 a year with this switch. In this day and age the cost of broadband should not be as high as this as it’s become almost a human right. Sure, you can go with cheaper suppliers such as TalkTalk, but their quality speaks for itself. If you want a connection that actually works, do some research and go with one at an average or higher price. As they say, you get what you pay for.



Save Fuel with Hybrid Vehicle Pulse & Glide

Posted by under Hybrid & EV Vehicles, on 18 December 2016 @ 1:09am.

What is pulse and glide?

Pulse and glide is a fuel saving technique used primarily by hybrid vehicle hyper-milers, but after driving a hybrid for a while you can make it normal driving habit and its completely safe too (unlike other techniques used by non-hybrid vehicle hyper-milers).

How does it work?

It works by keeping the engine on only whilst it is doing useful work in its efficiency range. Outside of this, such as minimal acceleration to maintain a set speed, is wasteful because it is operating in an inefficient power range. Put simply, the engine is using more fuel to keep itself running and overcome internal friction and compression than fuel used producing useful propulsion.

Here is how it works in bullet points:

  • Use the engine at its efficient RPM (in my case 2000-2500rpm) to produce useful propulsion.
  • Get up to just above your desired speed, then let off the accelerator so that the engine can stop.
  • Accelerate just enough to overcome regenerative braking, but don’t use the electric portion of propulsion. Keep it as close to zero acceleration and zero braking, as if you were in neutral.
  • When your speed drops too low, accelerate again up to just above your desired speed, and repeat.

Why does it work?

Here are some reasons why it works:

  • Manual and automatic transmission vehicles have engine drag or use fuel to idle when you come off the accelerator or put it into neutral.
  • In a hybrid the engine can stop because it can decouple the transmission from the engine so that there is zero engine drag and zero fuel use when it turns off.
  • In a hybrid, the battery power must come from somewhere, and that somewhere is the engine. You want the engine to only charge the battery whilst you’re using it for useful propulsion at the same time, keeping it in its efficiency range. Pulse and glide allows this because you avoid using excessive battery power, plus you can still recapture some energy used during the glide through regenerative braking as well as engine recharging during your next pulse.

What sort of results should you expect?

It will vary depending on the speed, your driving style, the terrain and a few other factors such as whether your engine is warm (so it is able to turn off, and when it is on is operating as efficiently as possible).

Lets assume for my example that its a sensible 30mph with a smooth driving style, relatively flat roads and a fully up to temperature engine:

I found that when not using pulse and glide I was depleting my hybrid battery from full to almost zero in the 1.5 miles where I am able to use electric power on my last leg of my journey home. I was using the engine to get to 30mph (as the electric acceleration is wasteful of battery and is very slow) and then using electric to maintain that speed. By the end of the 1.5 miles my battery was depleted.

With pulse and glide, my hybrid battery stayed almost completely full by the end of the 1.5 miles, and the engine was on for only another few seconds each time I was pulsing up to around 35mph. This offsets the several minutes the engine would need to run to re-charge the battery (whether under useful propulsion or not).

With pulse and glide my displayed MPG was not affected so much, mostly because the way the car calculates MPG doesn’t change between electric use and gliding (it assumes 99.9+MPG). But it will definitely increase it in the long term because you’re not having to use extra fuel to recharge the battery because you didn’t deplete it in the first place.

My use of pulse and glide is limited most days because of my engine being cold and because most of my driving is on motorways where pulse and glide doesn’t really work. However during around town driving the more you can use it the better the effects on your MPG.

It takes a little practice and definitely requires patience, but once you have mastered it you’ll see the benefits quite quickly. I imagine it will work best in summer though when the engine can get up to temperature quicker (and stay there longer). Using the engine for heat is the biggest downside to most hybrids as when the engine cools it must run to reheat itself regardless of your use of its power!



Lexus CT200h: How the cold affects MPG

Posted by under Hybrid & EV Vehicles, on 12 November 2016 @ 11:48pm.

I have a slight obsession with my MPG and I’ve been tracking it regularly using Fuelly.com. What I have noticed is now that the weather is beginning to get cooler the average MPG is getting lower. I expected this would be the case when I got the car so it’s not a shock to me. However since I was tracking the MPG anyway I decided to also track temperature too.

*Graph updated 22/02/2017

As you can see clearly, the average temperature (blue) has been dropping as we enter autumn/winter, and the average MPG (black) has also begun to drop as well.

So why does this happen? A couple of reasons actually…

  1. The engine runs less efficiently when cold and it takes longer to heat up, so extended warm-up times means it runs less efficiently and for longer.
  2. The engine must run even when its not moving the vehicle to generate enough heat for the climate control, so the vehicle occupants can stay warm.
  3. The hybrid battery is less able to provide power when cold, so it doesn’t help as much.


However it is surprising that on a short 15mi journeys, which is what 90% of my journeys are to work during the week, that I am still managing over 50mpg. Not bad for a 1.8L petrol! Some diesels would be lucky to see that, and a non-hybrid petrol wouldn’t come close.

I’ll continue to log this as we go into winter and it gets colder, and I’ll make a further blog post in the future. I do suspect that I will see a dip below 50mpg at some point when it gets colder, but for now it’s still impressive. The Passat, even for a diesel, was lucky to average 46mpg during summer and got even less in winter.



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