The flatmate compliant charger

[Geebee]

Just one more safety warning Chinese switch mode PSU/ chargers sometimes have live heat sinks ie. lethal voltages on the heat sinks with no warnings, even approved ones, guess how I found out

 

[timidtom]

Has anybody mentioned the Darwen Awards yet?
;-(

 

[Old_Dave]

Just one more safety warning Chinese switch mode PSU/ chargers sometimes have live heat sinks ie. lethal voltages on the heat sinks with no warnings, even approved ones, guess how I found out

Hi Geebee

This is commonly caused by 1. incorrect connections from the iec socket to the pcb or 2. incorrect wired mains plug or 3. a poor earth / ground connection in the users mains supply where the device uses the ground as a return (Class 1 power supplys)

All of the above make a good argument for rcd protected socket outlets

 

[Geebee]

Nope, it was correctly wired, plugged into an electronics workshops power source.
It was a very high end piece of equipment as well, I was not impressed.
I have seen it done before but always with warnings on the heat sinks previously.

 

[Old_Dave]

electronics workshops power source.

Ahhhhh... for electrical safety that means 'isolated supply' which would indeed cause the problem with class 1 equipment.

 

[cwah]

You can get high impact polystyrene sheets from this supplier fairly cheaply. They also have a good range of electronics, heatshrink etc, and nice educational kits for the kids at Xmas.
High impact polystyrene sheet

D8veh, I just received sheet from them at 1mm, 1.5 and 2mm. And these sheet are really not... solid at all.

I was able to cut them easily with a pair of scissor!!! I think even cardboard is stronger than these sheets.


I think only the 2mm one is potentially usable and almost as strong as "heavy duty" cardboard. Acrylic seems way stronger than that (but I have a 5mm one)


Not sure if it can provide more protection than a cardboard? Maybe just water protection?


What's special about these sheets except the price? I think I'll use them to prototype ideas only before using stronger (and more expensive) material.

 

[cwah]

Thinking again, my wood and aluminium setup is way stronger than these High Impact Polystyrene sheets. I can't see how these sheets could end up with a stronger (or better) shell than what I have now.

I'm going to use these sheets to wrap my set up and protect it from dust, wet and inconscious fingers

 

[Tinker]

PPS My wife just saw this and her first response was who is paying the electric bill in the shared flat lol

Regards

Jerry

My wife thought it was one of my 'bodge-jobs'

 

[Deleted member 4366]

Acrylic is very heavy - specially 5mm.

I was thinking more about an enclose for your charger than your battery out of 2mm HIP.

You can make right-angle bends in HIP to make a nice box by heating it. Best is to make a line bender with hot nichrome resistance wire in a groove in some wood. Google "DIY line bender".

Alternatively, you can use a heat gun, but you have to be very gentle and gradual with the heat. Too much at once and it bubbles like acrylic. It;s a bit easier than acrylic because it's thinner.

To use the heat gun method, you need two blocks the same thickness. Lay the HIP on the first block with the line that you want bent along the edge of the block. Put the other block very close to the first one to support the sheet. Run the heat gun up and down the line where you want it bent (lowish setting). When the HIP is at bending temperature, remove the second block and use it to push down the HIP at the bend and push it against the other block to get the HIP at a right angle. Hold it until it cools. With a bit of practice, you can get nice folds. You can glue HIP with polystyrene cement like you use for Airfix kits.

 

[Old_Dave]

I'm going to use these sheets to wrap my set up and protect it from dust, wet and inconscious fingers

That's a major leap forward, another advance would be to consider some form of strain relief (nothing to do with piles) on the output cables.. Any method will be better than nothing, maybe even a knot in the cables before they pass out of the enclosure






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[cwah]

Thanks D8v3h, I have a heat gun so I'm going to try to do your method.

I've also found a DIY method from google:
[video=youtube;ZkjsPrWT0Ic]http://www.youtube.com/watch?v=ZkjsPrWT0Ic[/video]

It's quite interesting and professional, but also scary! He advise people to directly connect to the main plug with 2 wires to provide heat. He doesn't wear electric gloves neither. 1 mistake and it's lethal lol


Old Dave, I'm quite keen on stress relief on wires. I usually glue gun my output. I'll never do Knot on my wires, but I'm keen on knowing any other method to relief stress and insulate the output.

Silicone glue is for now the best choice, but as it's a bit expensive I tend to only use glue gun. I don't like doing that because the glue has some yellowish colour and the result looks so unprofessional.

 

[cwah]

For a complete isolated enclosure, I'd need to extend the voltage and amperage trim pots on the cover. Any idea what I can use to do that?

 

[banbury frank]

Hi The Video shows the mains in the USA witch is 110 volts if you try this with UK mains 230volts it is LETHAL we use 110 volts in the UK for site work via yellow step down transformers Much safer also A legal requirement

Frank

 

[Old_Dave]

Hi cwah

for stress / strain relief on the output wires, have a look at this kinda thing..

Strain Relief Grommets : Spacers & Grommets : Maplin Electronics

Re the trim pots, then drill a small hole in the case that aligns with the pot so an insulated trim tool like this can be inserted.

Goot Zirconia Cross Screwdriver for Electronics DIY [E3709] : Electronic Gadgets, Home Gifts & Unusual Novelty Gifts - BestOfferBuy

Then pop these into the hole for a nice finish

Hole Plug : Spacers & Grommets : Maplin Electronics

 

[shemozzle999]

Here is a safe PS for you Cwah, if your quick only 2 hours left:

FUSION ADJUSTABLE POWER SUPPLY 600 WATT 0-FS-PS600ADJ ((NEW IN BOX) UK WARRANTY | eBay

Together with this Lipo charger:

http://www.commonsenserc.com/product_info.php?cPath=38_84&products_id=617

 

[cwah]

Thanks Frank for the warning, I'm going to do it with my heat gun then

Old_Dave, your suggestion are really helpful and I'm going to get few mini-screwdriver and stress relief grommets

Too sad there isn't anything that could waterproof and be at the same time "removable"


Shemozzle, I have a 20s lifepo4 with BMS to charge. The charger is never going to work because it's 12s only. And the power supply is probably less safe than mine. I'm using a laptop power supply, these things are double insulated and quite bullet proof.

 

[Old_Dave]

There are ready made cases available in different sizes and different materials which would be very water resistant.. Not with a high IP rating but good enough for the task

I think that Maplins may do them


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[Old_Dave]

Couldn't edit my post cos I'm on the mobile, but they are called Project Boxes and may be cheaper / better than making your own





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[cwah]

Thanks Old_Dave, I've seen these on Maplin:
Project Boxes : Plastic Enclosures : Maplin Electronics

But I talking about the wire output rather than the box. I already have the material for it (thanks to D8veh). With the grommets or strain relief grommets it's not waterproof or dust proof at all.

These box have potentially their use if the charger happen to be the right size. But most of the time it isn't.


Will try to play with the HIPS and see how it goes

 

[cwah]

Ok, I had a play with these High impact polystyrene sheet and did my first enclosure!!


As you can see... it's really ugly:

It makes me think about these bodge jobs on cars:
Hilarious DIY car repair bodge jobs carried out by amateur mechanics | Mail Online

I didn't really plan for it and litterally wrapped the sheet to the charger. Obviously, it's not very clean and I definitely need to plan properly how I want to shell this charger.


Haha, the bolts really don't look nice on it! Maybe spray the bolt on white?

Just left enough space to keep it the extinguisher safe

What I like about these HIPS:
- Very very easy to work with
- I can cut them with a pair of scissor or a cutter
- I can thermo form them so easily. Just get the heat gun on the area I want it to bent and that's it. No bubbles like acrylic or polycarbonate!


What I still need to do:
- Add the mini-screwdriver to change the voltage and amperage manually.
- Make better rectangular holes. I started with my drill and finished with the small needle file but I think I still don't have the skills
- Add the stress release grommets.. but not sure how it would fit rectangular holes
- Dust proof it
- Add the ground wire
- Make it look more pretty. May have to sand it and paint the bolt?


I'm not very proud of my first enclosure, and will probably recreate a new once I've finished my todo list because this one is shameful lol