Julian Ilett

My name is Julian Ilett and I’ve been interested in electronics for as long as I can remember. These days I spend most of my time making electronics videos for my Youtube channel.

This WordPress website has evolved over the years from a web design consultancy (when 256.co.uk was first registered back in 1999) through PIC microcontroller design and sales to a design blog for the PWM5 Solar Charge Controller. The PWM5 was sold through this site from April 2010 to March 2014. A few more controllers will be manufactured and available for sale until 22nd July 2014 when sales will cease for good.

I’m a published author – I had a number of projects appear in the pages of Everyday Practical Electronics magazine back in the 1990s. These included the National Lottery Predictor, MIDI Analyser, EPE Fruit Machine and LED Matrix Message Display. I also wrote a piece called How to Use Intelligent LCDs which has made it onto the internet. Part one is here and part two is here. You can also get to it via Wikipedia.

This summer, 256.co.uk will become 256.uk when the new .uk domain becomes available for use.


If you want to contact me by email, simply put my first name in front of an @ symbol and follow that with 256.co.uk – I read all emails, but replying is much easier if your message is short (less than 100 words). Longer emails (with links to products or projects) will take longer to reply to. Please note that I may make public the content of emails sent to me (although not personal details).

My YouTube channel: https://www.youtube.com/user/julius256

My Twitter feed: https://twitter.com/julian256

Bespoke Projects

Generally speaking, I don’t get involved in consultancy, bespoke projects, ‘art’ installations or any other unsolicited one-to-one activities :-)

58 Comments on About/Contact

  1. Kerry says:

    Hi Julian,

    I’ve watched your very informative videos on youtube. I’m a little embarrassed that I know absolutely nothing about charging batteries with a solar panel, although I bought one because I would like to give it a try. The back of my solar panel reads ‘Max Power: 3.2W’, ‘Voltage at max power: 18.8 volts’, and ‘Current at max power 170 mA’. This panel was made by Volkswagen, and was supposedly used to charge the car battery using the sun. Would your charge controller work with this panel? I plan to use the solar panel, and hook it up to your charge controller, hook that up to a 425W power inverter, which then hooks up to 12v car battery (got this from your video). I look forward to seeing more of your videos. Mahalo.

    • Julian says:

      Yes the PWM5 charge controller will work with this panel, but it’s a very small panel and will take a long time to charge a vehicle battery (several days). In winter in the UK it would be next to useless. In Hawaii I would recommend a 20W solar panel to keep the battery topped up and to replace any power you may use at night.

  2. Hi,
    I want to ask a small question;
    With your charge controller I want to hook up a 5watt solar panel to my car permanantly, I saw a couple of writings about some systems can discharge the battery at night.Is this true?Or the controller cuts power transfer both ways at night? Surely I don’t want to end with a dead battery in the morning :)
    Thanks in advance

    • Julian says:

      The PWM5 charge controller has a diode (the bulge in the yellow wire) which prevents battery power draining back through the solar panel at night. Also, this controller has a very tiny power drain so the power that you put into the battery during the day isn’t used up by the controller electronics at night.

      A 5-watt panel is really too small. In the summer it will provide a small charge, but in winter it will be useless. I suggest at least 20-watts.

  3. Bryen says:

    What panel would you recommend be used with you device? Also what would happen when the altinator kicks in whilst driving?

    • Julian says:

      You can use any panel up to 100 Watts. Small panels (1 to 5 Watts) are pretty useless unless the load you’re driving is very tiny. When the alternator kicks in it won’t affect the charge controller or solar panel.

  4. Robin Hughes says:

    Hi Julian,

    I’ve purchased the PWM5 and have an 80 Watt Solar panel. I’m planning to use this to maintain a battery for purposes of running a water pump (to run water down a water ski jump when required).

    From you video it is clear how I should connect to the battery with the PWM5. I plan to connect the water pump to the battery which will be activated by a switch however when running the pump would you advise that I disconnect the solar panel and PMW5 incase of damage to the panel, or should I simply leave it connected to the battery whislt running the water pump? Any advice would be very welcome.
    Many thanks

    • Julian says:

      Hi Robin

      You can leave the solar panel and charge controller connected, no harm will come to either of them when you run the motor. The motor may run a bit faster when the solar panel is connected (and the sun is shining), but I can’t see a problem with that.


  5. Dave says:

    Hi Julian,
    Is the charge controller you make temperature compensated.
    Normally lead acid chargers are but you make no mention of this

    • Julian says:

      No I didn’t include temperature compensation. The number of days during a typical year when there’s both cold weather and enough sun to fully charge a typical battery are few. The higher (temperature compensated) voltage is rarely ever reached.

      I opted for a different approach. I have a variable period for the boost charge (also a higher voltage) between 30 minutes and about 5 hours. In winter the boost charge voltage is applied for most (if not all) of the available daylight hours. However, once again, getting a battery to 14.5 volts in winter doesn’t happen very often.

      I think the latter method is just as effective as temperature compensation on the few days when it comes into play.


  6. Martin says:

    Hi Julian, If I connect up a 100W Panel to my caravan Battery via a PWM5 controller, Is that all I need to do? Caravan Batteries are usually charged via the mains elec hook up cable. Will connecting up the panel direct to the battery cause me problems? Would I need to disconnect the caravan from the battery while charging ? Any advice would be appreciated.

    • Julian says:

      You can do either one or both at the same time. Hook up your 100W solar panel via the PWM5 controller and/or connect up the mains powered charger.

  7. Trevor says:

    Hi Julyan, My name is Trevor. I’m currently reading your paper titled How to use Intelligent L.C.D’s. I cannot get experiment 1 to work correctly. I’m using a 16X2 LCD screen. I’ve set up my circuit exactly as you’ve described. The only positive things I’ve encountered are 1. the potentiometer contrast the screen accordingly, and 2. Every once in a while I can get some unidentifiable characters on the bottom row. I know there can be a plethora of problems, but I’ve spent a lot of time troubleshooting and nothing yet. Any thoughts for alternative ideas to make this work. I hooked the LCD to a microcontroller and it works fine. I want to learn about it using the manual switch method.

    Thanks for reading this and any input you can offer.

    • Julian says:

      You’re right, there could be any number of problems – what might work is if you take a photo of your setup and I’ll have a look if there’s anything that jumps out. Send it to my email address.

  8. Anthony says:

    This is an excellent piece of equipment to have. I ordered two and mounted each to the back of a 60 watt panel. The battery is up to a high, stable voltage in no time and I have a system that is fully customizable, thanks man!

  9. robert francis says:

    hi julian

    i would like to charge two seperate batteries 55ah eatch
    quickly at around 20amps do your controllers support 20amps
    from the same solar pannel array

  10. Ismail says:


    First of all I woud like to congratulate you on a wonderful controller. I ike the design and its features. Well done!

    Here is my problem. I have a 24W foldable solar panel. The thing is that it is a 24V 1A panel. I have 2 modes of storing energy. First I have a Powergorilla. Csn I connect the panels directly into the Powergorilla or would I need a regulator? If yes does the PWM5 work with 24V panels?

    My second storage mode is a 12V battery. I guess I would need to connect two of them in a series for my 24V panel? or is there another way?

    Please excuse my limited knowledge.

    I hope you can help me.

    Thank you

    • Julian says:

      I’m pretty sure you won’t be able to connect solar panels directly to the Power Gorilla. However, if the Power Gorilla has a vehicle charging cable (cigar lighter plug), then you can connect it to a lead-acid battery which is part of a system with solar panels and a charge controller. If the vehicle charging cable is compatible with 24 volt systems (used in lorries) you could use your 24v panel. However, my PWM5 controller is not compatible with 24v systems. It can only be used in 12v systems.

  11. Graham says:


    Would your controller be suitable for charging 12V leisure batteries with grid-tie panels? I have a couple of 200W and 250W panels (approx 40V) left over from jobs.



    • Julian says:

      No. My controller is only for systems with 12 volt batteries and 12 volt (nominal) solar panels (with an open circuit voltage of no more than 25 volts). I use a clamping diode across the solar panel inputs (yellow/black wires) which is a dead short at 30 volts, so rooftop panels (nominal 24 volts, 40 volts open circuit) are not suitable. Some MPPT controllers can do this.

  12. Guy says:

    Hi Julian
    I am in the process of setting up a 100w panel for my campervan which has 2x75ah leisure batteries.
    Right dumb questions time! Do I need to connect the PWM5 to either battery,I assume I treat the bank as 150ah battery as is connected in parallel.As at the moment the batteries are only charged by the alternator, will I need a switch between the PWM5 and the battery to disconnect solar when battery is low and I am driving so the alternator can do the hard work initially?
    Sorry for the long questions but I am unsure!


    • Julian says:

      Yes, if the batteries are connected in parallel, you can treat them as a single battery and you’ll need just one charge controller. No, you don’t need to disconnect the PWM5 charge controller when you start up the vehicle engine.

  13. Geoff Fox says:

    I have a 12v 140ah leisure battery that i use to power an electric outboard which i use in france fishing. I’m usually fishing for up to 10 days so i need a solar setup to charge a battery as quickly as possible. Now, I know nothing about this field and require your expertise to help me. What Panel would i need at what sort of price? What Controller? I like the quick wire connections you use too. (ie the ones you use in your video to connect the crocodile clips)Are you able to make these to buy!
    Hope to hear from you soon.

  14. Vic Richards says:

    Hi Julian
    Is it OK to connect one of your PWM5 charge controller to a SEALED LED ACID BATTERY?

  15. Tony says:

    Hello Julian
    First of all congratulations on first class product that does what it says on the tin.
    I use the PWM5 with a 20w panel on my small sailing boat to help a small gel battery for my autopilot.
    I also have a small outboard with about 2amps at 22v max available when it’s running is it possible that the PWM5 could handle this output as an alternative to the panel???
    Many Thanks

  16. Kevin Brown says:

    Hi Julian, I have the PWM5 controller set up charging a 12v battery from a 10-Watt 12-Volt ES Polycrystalline PV Solar Panel which lights a small light for several hours each day. Seems to be working fine. However I have a question. On the controller, after I initially hooked up the solar panel, controller and light, the controller blue light went on for a couple of seconds, flashed once or twice and then the controller light went out. Does this mean that the 12v battery is fully charged and the controller suspends charging until needed? Thanks. Kevin

    • Julian says:

      The blue LED should always tell you something: either flashing (count the flashes to tell the voltage) or constantly on (but pulsing) to indicate the battery is full. If there is no LED activity, the PWM5 has gone into LED disabled mode – disconnect both battery connections and solar panel connections (or disconnect just the battery connections when it’s dark) to restore the LED activity.

  17. Kevin Brown says:

    Thanks Julian for the quick reply. I have it now to where the LED is flashing twice (12 volts) and more quickly about 4 – 5 times.


  18. Bill Whiteside says:

    G’day Julian,

    I received the controler safely today thank you.
    I read in the instructions I should fit a 8amp fuse before the battery. Can I use a 5amp or a 7.5amp fuse in place of the 8amp?
    8amp fuses are like Hens teeth in this neck of the woods.

    Thanking you in advance for your advice.

    Bill Whiteside

    • Julian says:

      A 7.5A auto fuse (standard or mini blade type) would work just fine. The fuse is almost unnecessary as the controller is protected against short circuit at the yellow/black end by the diode (lump in the yellow wire). As long as the solar panel is 100W or less the controller won’t be overloaded. The fuse is more a precaution than a necessity.

  19. Bill says:

    Thanks Julian, I’ll use a 7.5 mini blade fuse, the panel is only 10W, if the 10W is not big enough, I’ll add another one or two 10W panels.

    Thanks again.


  20. Lily says:

    Dear Manager,This is Lily from Precision-lightings. Chinese led light manufacturer. Many interesting products can be found in our website,www.precision-lightings.com. If you are interested, please feel free to contact.Sincerely,Lily

  21. Rodrigo Cordero says:

    Hello Julian

    I need information about a personal project:

    My project is a coffee vans.

    What I require help to connect a coffee machine + inverter DC / AC + Battery + Solar Panel.

    The characteristics of the coffee machine are:
    Voltage: 120 / 220-240 60HZ
    Power: 3200W

    This project I’m doing in Colombia South America.

    Thanks for your help

    • Julian says:

      3.2kW is a lot of power! Rooftop solar systems are typically around this size and I doubt the coffee van will have a roof as large as a house. I can’t see this working I’m afraid.

  22. whitney graves says:

    I enjoy your videos on u tube. Lots of information
    and content. I did buy one of your chargers last week
    and hooked it up to a 100 watt solar panel. LED and charging
    was functioning first day. Day two had nothing. disconnected solar panel and tried several batteries. Blue light turns on for
    a few seconds and then turns off. Based on your instructions, light should be flickering as the charging process in ongoing.
    any ideas? Ill keep reading .
    whitney graves
    Kansas city.

  23. paul coyston says:

    hi i was looking at this device with a slightly differant use and wanted your advice.
    i have a motorhome with a leasure battery which is charged via mains hookup,the vehicle battery is only charged by the altenator,could i use your device to trickle charge the vehicle battery when the motorhome is standing and plugged into the mains ,this seems to me to be replacing the solar panel source with a battery and electric charger paul

    • Julian says:

      Hi. No, this won’t work and could damage the PWM5 controller. The 100W limit on solar panel size ensures that current through the controller is within an acceptable range. Using it to connect one battery to another could very easily overload it. In any case, it wouldn’t do anything more than act like a piece of wire. The PWM5 can only have a solar panel (up to 100W) connected to its input.

  24. Anthonygee68@hotmail.co.uk says:

    Hi Julian
    I have a motorcycle which uses a Gel battery, can I connect the controller to this?


  25. Jojo zeng says:

    Dear Julian ,

    Nice day!
    Greeting from lepu lighting –Jojo.

    Here i want to share a new updated Sharp cob spotlight with you!
    After 8 months market testing and improving. we have updated our Sharp cob –Sunflower.

    1, 0-100% dimming, No stroboflash can compare with the Philips
    2, Sharp new updated BMC level leds. 2700k CRI>85 , same as the halogen lamp.
    3, 45deg same as the halogen lamp, can create a nice lighting environment.
    5,CE ROHS passed, 3 years warranty, during the period, free replacement any defect item.

    Look forward to your reply!

  26. Tony Zhou says:

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    Would you mind to visit our website for more information,

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    skype:ke.zhou4 W:www.alpcb.com.cn E:tony@xnjpcb.com
    SZ Office Add: Room636,Fude building,Cuigang west road,Fuyong Town,Shenzhen,Guangdong,China
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  27. alex says:

    Hello I have been watching ur videos for months now and I just see where u have completed ur project. Is it possible I could get a copy on ur first design that used the 555 ics even that circuit would be good for me . if u sell the finish product please tell me also how to purchase one . thank u and keep up the good work

  28. Dylan says:

    Hey Julian,

    Great work, I was wondering where did you buy the demo board for your acs hall effect sensor?


  29. Steve Atwell says:

    Hello Julian,I am a fellow electronics enthusiast and I follow all of your videos with great interest in particular you have got me interested in solar.I would love to build your MPPT charge Controller ,would it be possible to obtain or buy a copy of the circuit details from you? Please keep up the good work. And thanks for all the knowledge you have passed on.
    Steve Atwell

  30. Pavel says:

    Hi Julian,

    Thank you for your videos, I watched about a dozen and used for figuring out the pinout for ftdi USBaurduino board :) It’s very convenient to watch your new videos

    I can’t find a detailed description of your PWM5 mppt charging controller in terms of what it’s suitable for. I’ll be searching better, but please let me ask my question.

    I need a solar/battery “balancer” for FPV. I want to glue solar panels on top of the wings of my bixler 2 radio controlled aircraft and power up the whole airborne electric circuit. Power suppliers: one 3s lipo battery 2200 mAh 11.1v and solar panels. Constant power consumers total to 600mAh at 11.1V: radio receiver, autopilot, telemetry transmitter all at 5V; camera and 200mW radio transmitter both at 8V through e-bay avia modelling step-down switching buck voltage regulator. Variable power consumers are brushless motor and 6 servos, with consumption of 0…12A at 11.1V = 0…133W. I plan to plant on my plane ~26 solar panels, each 0.63W, connected in series to add up the voltage, theoretically totalling to 0.5V*26 = 13V and 0.63W*26 = 16.38W.

    During the cruise flight I assume I’ll need ~4..8A at 11.1V. I want the solar panels to supply as much as they can and the battery to supply all the rest (battery = total consumption – solar supply). So basically I need a luminosity-adaptive buck converter with Maximized Power Point Tracking being able to supply 1.47A at 11.1V (16.38W = 11.1V / 1.47A) with the “tap” for battery power at full motor thrust.

    I guess it’s cheaper to use ebay boost / buck converter to feed constant power consumers from solar panels. But these components are vital in terms of aircraft control and video transmission, so I want to get a single power source for all the consumers, consisting of two suppliers: solar panels and lipo battery. Ideally, the controller should be able to charge the battery according to lipo-assumed charging cycle (in case when the plane is lifted up in a thermal air stream and the motor is off)

    Can I use your PWM5 for this application?

    If I can’t use your PWM5 for this application then:
    1) what is the limitation,
    2) when I will experience it and
    3) where in my description above it fails to provide the functionality needed?

    Here is the closest solution I found (I don’t mind buying one or soldering from a DIY kit but they don’t sell it saying “it’s open source”):

    Here is a costly ($115) and heavy (400 gram?) solution:

    And here is the general discussion thread where the two above are mentioned (I’m sure there are more potential buyers):

    Solar panel spec:
    52x78mm (poly)
    Average Current (Amps): 1.26 Imax
    Average Voltage (Volts): 0.5 Vmax
    Average Power (Watts): 0.63Wp

    Kind regards,

  31. Kevin Meier says:

    Hi Julian,

    Been watching your Nokia LCD videos and as a result I am moving my project away from the standard 16×2 LCD to the Nokia. In video 1, you have an 8-pin wire hardness to connect the LCD to the Arduino. I have been trying to find one of these, but with no success. Sparkfun has a 6-pin, but need an 8-pin so hoping you can provide me with the name of your source.


  32. Stuart McConnachie says:

    Julian, Here’s why your Arduino project is limited to displaying +/-32 or 0-64.

    All integer maths is done in 16 bits on your Arduino (word size of machine), unless you specify some other data type (e.g. you found forcing float fixed the problem). When the expression is calculated the multiply on the left happens first, but is limited to a 16 bits because this is what the compiler deduces as the default type in use. The largest number in 16 bits is 65535, which then raps back round to zero. 65535 / 99 = 661.969, so the largest number you can have as a result of your A/D conversion without problem is 661. After this the multiply will overflow and wrap back round to zero. For example 662×99=65538 but this is too big for 16 bits so the 17th bit get lost and is wraps back round past 0 to 2 (65538-65536=2).

    As you know, the top bit is the sign bit, so actually any value over half of this, i.e. 330, gives an incorrect result because it forces the sign bit on in the result of the multiply when it shouldn’t be. Note that WORD() is actually forcing the multiply to have an unsigned result, which is why you get 0-63 in this case instead of +/-32. But the problem is the same – the multiply result is limited to 16 bits.

    Now you need to consider what happens when you divide the maximum range of truncated values that can be returned by the multiply, either +32767/-32768 (in the case of a signed result) or 0-65535 (in the case of unsigned), by 1023. Well that is either +31/-32 or 0-63, which is what you observe.

    The best way to fix your problem is to make the multiply use long type of 32 bits (or better yet probably unsigned long since we will assume in this case the Arduino A/D result can never be negative). Something like:
    long(analogRead(A0)) x long(99) / 1023.0
    Sorry, I’m used to C, not Arduino – but I hope you get the drift.

    It is always best on a low end microprocessor to use integer math wherever possible, because floating point calculations are expensive without any hardware assist being available. So, as you aren’t using any digits of the float result on the display, you would be even better to stick with integer maths entirely here and not use any float types at all. It will be faster and use less RAM (no need for floating point library). So:
    long(analogRead(A0)) x long(99) / 1023

    Also, if say you require a value in watts, but with decimal places, it is sometimes better to calculate in mW and simply imply the decimal so the values can remain an integer. Then do integer divide and mod by 1000 to get the parts to display before and after the decimal.

    HTH Stuart.

  33. joseph jonatas says:



  34. chris smith says:

    hi Julian
    fantastic you tube clips can you please advise me what size panel I will need to charge my 110amp hr deep cycle batts .
    I recenty bought a 50w panel and had problems with it so starting a fresh wood a 50w be ok along with one of your controlers? send me details I will take one even if its a old prototype or cosmetic second thanks in advance chris (solar retard)…….

  35. Vitor Valente says:

    Hello Julian,

    I bought this power
    ( http://www.ebay.com/itm/131172.....1497.l2649 )

    and this led
    ( http://www.ebay.com/itm/360916.....1497.l2649)

    I need to know what I have to buy to connect these LEDs, I want to connect 6 leds is the power,if I could say what I need to buy to connect the LEDs, i will be very grateful

    excellent work
    Vitor Valente

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