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.

Specifications

  • 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

Features

  • 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

Gallery

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.

Challenges

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!

Code

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.

 

 

2 months with the Lexus CT200h

Posted by under Hybrid & EV Vehicles, on 7 September 2016 @ 10:49pm.

I’ve had my CT200h for just over 2 months now so I thought I’d write a quick update on how I was finding it.

clean_lexus_ct200h

To put it in short, I love it. For all the wrong reasons to some people mind you, but I love it.

Now I’m not a car guy at all, but I appreciate cars of all types, be it big petrol drinking V8’s, diesels, hybrids or electric. That is why I say I enjoy my car for the wrong reasons. It doesn’t make a pleasant noise when you put your foot down, or give hundreds of horse power worth of smiles, but I enjoy driving and cars in general.

Let me explain why I like the CT200h so much…

Driveability

First of all, it’s so incredibly easy to drive. This is my first automatic car, and not having to change gear anymore takes some of the unpleasantness out of daily driving. Since 99% of my driving is commuting, going to see friends, going shopping, etc, I have no interest in changing gear all the time. Going for a play however is a different ballpark. I’d love to have a manual. Unfortunately there is no semi-auto mode in this car because of how the gearbox works either. This said, I haven’t actually taken it on a ‘joy ride’ around some nice twisty roads or anything yet because I’ve not had the time. Despite this, the gearbox is silky smooth because it’s not physically changing gears since it’s an electronic CVT gearbox.

Ride and Handling

Next up is the ride. It’s by all means not a massively comfy ride. It’s pretty firm, but I actually find that I don’t mind that. I’ve driven on various road types in the last 2 months and I really don’t mind the firmness at all. It’s a common complaint with the CT200h but I honestly don’t see why. Because of the firm ride it feels like its sticking to the road very well (the huge tyres probably help too) and that’s a nice comfort some how. Steering input is also very sharp but the electronic power steering assist does take a little bit of feel away so it feels lighter than it should sometimes.

Economy

Now the one that no car guy would ever care about (remember, I’m not a car guy!). Economy. For a 1.8L petrol, it’s incredibly economical. On a recent 150mi run on the motorway I stuck to 70mph for the majority of the time and managed an astonishing 61.1mpg. I didn’t just use the car readout, I actually did it from a full tank and then filled up again to work it out. I won’t lie, I expected low 50’s from a motorway run so to get 61.1mpg was quite frankly amazing. The atkinson cycle engine coupled to the hybrid system clearly works far more efficiently than people realise. A lot of people I speak to are all “Oh it won’t be good on a motorway, it’ll only get good MPG around town!”. Clearly they’re wrong! Even shorter journeys to work which for me is 15 miles each way, I still manage a sensible 56-58mpg (at least during the summer months, it’s reported to be lower in winter).

One thing I have found is that if you do short journeys with a cold engine it still sucks for economy just like any other car would. Until the engine is up to temperature it has to run more often even when it’s not needed, wasting fuel. So for short runs to the shops all the time with no longer journeys don’t expect much in the way of economy. A trip to the local ASDA at around 1 mile each way with a cold engine I saw a horrible 36mpg or so on the display. You can’t use EV mode the whole way there and back either because it won’t last that long (it’s rated at about 1 mile from a full charge and that power has to come from somewhere when it runs out – your cold and inefficient engine!).

Power

Next up is power. Sure, there isn’t a lot of it, but 136HP combined engine and hybrid is plenty for overtaking when you put your foot down. On my motorway drive I never once found it lacking. It makes plenty of noise as you put your foot down and the RPM rises to 5000rpm and stays there as your speed increases (and yes it sounds really weird thanks to the e-CVT gearbox…), but the power delivery is very good. What you do have to watch out for though is if you’re doing lots of hard accelerations in a short time the hybrid battery can run down to the point where it can’t supply that extra power. It’s never going to happen under normal driving with the occasional overtake, but just be aware. Your 136HP can quickly fall off to 98HP! I’ll test that around some country roads some time and see if it really affects it, but I imagine only on a track would you see it happen often.

Space

What about space? It’s definitely much smaller than the VW Passat that’s for sure. But for my every day use it’s more than big enough. I’ll be attending an event in the near future which will require significant luggage being put into the car so I’ll see if it can handle that without a problem then. For going to camping for example I imagine it’ll be just fine with my own stuff, perhaps a 2nd persons supplementing, but definitely no more than that.

 

So overall, I love the car. Its really well built with no rattles (I should hope so too for a 3 year old car), it drives amazingly, it’s super quiet especially at lower speeds, and it’s fun to drive. Yes, hybrids can be fun to drive! Yes, yes, I’m not a car guy, I’ll shush. But seriously, don’t knock it till you try it for yourself. You might be pleasantly surprised…

 

 

The Passat is no more! Bring on the Lexus CT200h

Posted by under Hybrid & EV Vehicles, on 14 July 2016 @ 8:37pm.

I finally did it! Just over 4 years since buying the piece of crap that was my VW Passat, I finally got rid of it. I’ve replaced it with a Lexus CT200h petrol hybrid hatchback. Yes, that’s the one I mentioned in a previous blog about test driving. I’ve been loving every minute of it and actually look forward to my next drive!

 

IMAG0236

lexus-ct200h-mpg

It’s a 2013 model with just under 20,000mi on the clock. It has a 1.8L Atkinson cycle engine producing 98BHP (73kW), coupled with an 80HP (60kW) hybrid electric system which can boost the total output to 136BHP (it doesn’t do 178HP as you might think given the numbers because the battery can’t supply all 80HP to the motor, the engine supplements some of this power to give extra pulling torque). 0-62 is in around 10.4 seconds which isn’t too shabby. The Passat did it in 9.6 seconds but it had double the torque too. Due to it being an automatic it feels like it gets there quicker (it probably does as well!).

MPG

OK so of course this was going to be one of the biggies that I talked about. Why else would you buy a hybrid other than to boast about your great MPG’s? Well so far all I’ve done is mostly trips to work and a few other things like shopping and the odd trip to friends houses, but despite these relatively short journeys (under 15 miles) I am still managing an average of around 58mpg. Though I’m often seeing higher on single trips to work and back (like the 67.2mpg below), the average is obviously reduced by some shorter journeys that I do. The rated MPG is 78mpg (yeah right, maybe if you do 30mph everywhere!) but you never get what they rate it at. You’d be lucky to get 75-80% of what they say. I still need to see what I get on a long journey on the motorway too.

It will be interesting to see what the actual mpg is when I fill up the tank this weekend as I am still using my first tank of fuel. I’m hopeful it will be close to what the display says. The real average in the Passat was usually around 43-46mpg (the display would read 7mpg too high) and that was whilst being gentle with it. It looks like not even being gentle on the throttle with the CT200h still yields great MPG in comparison. If it gets a real 55mpg average or more, I’ll be more than happy.

lexus-ct200h-mpg-trip

Drivability

It’s a brilliant car to drive, period. It’s very smooth and relaxing, with no gears to change (it’s a e-CVT transmission – you can learn about how it works here). The transition from electric to engine sometimes results in a small jerk or lurch which as a driver you notice but soon learn to ignore it. My passengers say they couldn’t feel a thing. Understanding how the e-CVT works helps you understand why it happens by the way, so give the link above a read and play with the interactive diagram.

Sticking the car into sport mode definitely makes it punchier. A lot of people say this is a slow car, but it’s really not. It’s just as quick as the Passat was but it does lose some top end due to the lower torque. This hasn’t bothered me so far though.

In electric mode, it’s silent. The engine doesn’t run unless it needs to, and it switches to electric whenever it can below 40mph. Being in electric mode is where you save the most fuel and boost your MPG’s, so if you’re below 30mph you’ll find yourself in electric mode a fair bit unless the battery is low. It’ll give you about 1 mile of electric driving at 30mph which isn’t too bad. It’s rare I’ve seen it deplete all the way that it requires the engine to come on. It’s definitely giving me a somewhat smug feeling whenever it is using electric, but I’m sure that’ll wear off, right?!

So what are my overall impressions so far? Well it’s certainly smaller than the Passat, by a long way in fact. But I knew this when buying it. I don’t need a large car for the majority of the year bar trips camping and epic.LAN, so I saw no need to buy one so large. Even with a car this size I can still get away with those trips without a problem. I also knew when buying a new car that I wanted an automatic. I’m bored of changing gears all the time except when I want to have a play, and I don’t do that often, so a manual wasn’t on my list of requirements. That said, if you want a hybrid you have no choice but to get an automatic as the fundamentals of a hybrid just don’t work with a manual.

Lexus themselves

My impressions of Lexus themselves were fairly great too. I bought the car just 2 days after it came in from the previous owner finished their PCP contract and got their new car, so they didn’t have time to fully refurbish things like the alloy wheels, which were a little worse for wear on the edges. Presumably the last owner liked to scrape kerbs whilst parking. In any case, Lexus arranged for a week later to take the car back and have that sorted. They look like brand new, and it didn’t cost me a penny extra. They even took me to work and collected me again whilst it was with them. I could have had a courtesy car if I needed one, but I work in an office so there was no need.

And the guy I dealt with the whole time was friendly too (probably because he just sold a car!) but he seemed pretty genuine. I hope I can continue to get that sort of service during my whole ownership.

I’ll be using Lexus for servicing so I can keep both the warranty intact as well as the full service history. It’ll help the resale value when I come to get a new car years down the line (especially if I stay with Lexus). Also since the car is incredibly technology complex, if anything goes wrong they can’t blame it on any 3rd party work and have any excuse to reject any warranty claims (not that they’ll likely be needed since it’s an incredibly reliable system).

 

That’s all I have for now, but no doubt I’ll make another blog in the future about the car and how it works.

 

 

WEC 2016, Camping, Power Box

Posted by under Electronics, on 26 June 2016 @ 9:40pm.

This blog is going to cover a number of things on my mind given I haven’t written a blog for a while. It’ll probably be a mish mash of all three since they’re all related in some way, so here goes…

So far this year I’ve been to 3 FIA WEC events, the first 3 in the season as it happens. It started in here in the UK at Silverstone for the first round. The second round took us to Spa in Belgium, and the third to Le Mans in France. I feel privileged to be able to attend so many of these events because I enjoy them so much. I live in an ideal area of the world that gives me access to 4 events – the places listed above plus the Nürburgring event added a few years ago.

spa_francorchamps_2016

All 3 of these events have been their own personal missions in some way or another. Silverstone I’ve done lots of times, but Spa was my first time this year. I have to say it’s a very difficult trip. Why? Well we travel there, watch the race, and travel home all in the same day. That means we’re awake for about 36-48 hours with little if no time to sleep. We could quite easily stay somewhere if we wanted to but if you can do it in a day then why not? It saves money and avoids needing time off work too. It’s definitely not something I would do every other weekend though – once a year tops! It really does take it out of you.

Le Mans. Now we’re talking. This has been my primary holiday of the year for a couple of years now as it’s a great way to spend time with friends whilst camping and enjoying racing, and on top of that getting to photograph them too. Not many people can say that their holidays let them enjoy 4 of their favourite activities in one go.

This year felt a little different though as we were one person short for the majority of the holiday. One of our friends wasn’t able to get the time off work so he only came up for one night, the night the race was on. As soon as it was over he was on his way back home again. It definitely felt odd with him not being there. He almost wasn’t the only person who wasn’t able to go either. One of our other friends almost couldn’t go because his holiday was rejected last minute by his work. Thankfully he managed to sort it out 2 days before we were due to go! Talk about cutting it close… He won’t make the same mistake last year so he’s booking it as soon as he can!

power_box_june_2016

Now then, power box… I’m still planning upgrades to the power box because of what I’m about to talk about. I should add that it has been upgraded since my last post through the addition of 2 speakers and an amplifier in the front. We’ve wanted this ability for quite a while since music is something we all enjoy whilst camping, and speakers on mobile phones really don’t cut it. I got the speakers for free off a friend and the amplifier cost about £5 online. A little modification to attach it to the box and it was good to go. Definitely worth the effort.

We tried the speakers out for the first time properly at Le Mans, though we tried them in Silverstone successfully too. We kept it quiet though and because we weren’t near the track we couldn’t tell if the volume it was capable of would be enough to get over the top of the noise of the cars. We wanted this ability so we could put the radio broadcast through it. As it turns out, it was plenty loud enough for this at Le Mans.

camping_solar_2016

Power consumption is quite high from this amplifier, and you can tell it’s not very efficient because it gets quite hot. I did some initial tests before I put it in the box and it uses up to 2A depending on volume and the audio being played. That could very easily kill the power box in just 24 hours if uses loudly without solar input. This is something we found out during the week at Le Mans this year. Come Friday we were at an unbelievably low 20% (11.00v) charge with just a couple of phones charging. I quickly made sure everyone was aware and we only charged phones if it was absolutely needed. I had a full 22,400mAh power bank available for my phone so I was in no desperate need of it.

Oddly, by Sunday we had managed to reach full charge again. I don’t know how though since only 18Ah of power had been put into it (unless it’s not been reported correctly on the display, but my testing did show it was relatively accurate), and some of that had been used charging phones and running the tent LED light. With a 50Ah battery that surely doesn’t add up. But hey ho, it showed 100% again and 12.8v under load which is indicative of a full charge. The green LED came on near the end of Sunday as well which indicates it hit 14.5v for at least 2 hours, again indicating a full charge.

In any case, I think a new solar panel next year is going to be needed. With mobile phones sucking more power, and us plugging in more things than ever before (charging power banks, charging up our hand held walkie talkies, and more), power is being drained more excessively than it was 2 years ago.

folding_80w_solar_panel

I plan on buying an 80w folding solar panel. This will be 2.6x more solar power that we currently have (30w at present). That should almost certainly be enough. It may even be more than we need, which is good in any case. Taking a lead acid battery below 50% doesn’t do it any good, and nobody likes it when power is low and you have to restrict your usage.

In order to use the 80w solar panel though I will need a new charge controller as well as the existing one is only capable of working up to 3A (36w) without getting far too hot. I am designing a new one which can cope with about 10A (120w) as a minimum which should allow for the 80w panel upgrade plus a bit more in the future.

It’s going to be an interesting project as I’m planning on making it into a monitoring controller as well. It’ll measure power going in and out of the battery as well as incoming solar power so we can see power consumption. At the moment it only measures the incoming power and not how much we have used. Because of this I can’t see what our typical power usage is so I can tailor the solar power to our needs. If I had that I could properly size the right solar panel instead of guessing. I’ve already ordered a fair number of the components for this so I can start work on it as soon as they arrive in the coming weeks.

Anyway, that’s all I’ve got for now. Watch this space for the next version of the charge controller, and maybe even a new power box front panel too.

 

 

Solution to slow FTP Server speeds (Filezilla and others)

Posted by under Servers, on 23 March 2016 @ 10:50pm.

I recently found that despite having a 70Mbps (8.75MB/s) internet connection and a 1Gbps (125MB/s) dedicated server to download from, I could only seem to download from the FTP server at about 16.8Mbps (2.1MB/s) on a single thread. However over HTTP I could easily manage about 65.6Mbps (8.2MB/s) on a single thread. This confused me, as there should be no reason why the speeds should differ so wildly. I’d expect a little difference, but not that much.

After some forum discussions on Beta Archive regarding this (I looked into things after a user complained about slow speeds), a user told me that he uses IIS FTP Server with no such speed issues. This instantly told me that something wasn’t implemented or optimised properly on Filezilla and Gene6 FTP Server (the two servers I use). I started looking at the possibilities and quickly found the solution.

Solution!

The “internal transfer buffer size” and the “socket buffer size” values were set quite small on the server at just 32KB and 64KB. There is a notice that says too low or too high can affect transfer speeds. So I did what anyone would do… I bumped it up about 10 notches to 512KB on both of them! Instantly my transfer speeds hit 65.6Mbps (8.2MB/s), the same as I was getting over HTTP. Perfect!

filezilla_ftp_socket_and_buffer_size_options

More tests

I did a few more tests to make sure that I didn’t set it too high or too low, but it seemed OK. Going from 64KB to 128KB made the speed hit about 46.4Mbps (5.8MB/s). Better, but not good enough. 256KB buffer allowed me to hit 65.6Mbps (8.2MB/s), which is the maximum I’m likely to get due to protocol overheads.

Assuming that the buffer size doubling also doubles the speed, a buffer of 512KB should allow up to about 192Mbps (24MB/s) which really is more than enough for the things I need it to do. Given my connection is much slower than this, and broadband in the UK doesn’t really hit those speeds either, it should be plenty for now.

Filezilla only allows a maximum buffer size of 999,999 (almost 1024KB or 1MB) so the maximum it should allow (again assuming that the buffer doubling = speed doubling) is about 384Mbps (48MB/s). Other software might allow higher so by all means use it if you need to.

 

 

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