Building a Rechargeable LED Lamp

Connollacken · Nov 12, 2020

Okay, perfect thanks

Nigel Goodwin · Nov 12, 2020

Diver300 said:
Soldering to a magnet is very difficult or impossible. I suggest conductive glue or some sort of clamp. You could probably solder to a steel object and let the magnet attract that to the back face of the magnet.

Magnets are often made of steel, so quite solderable - the main issue is the iron been pulled to the magnet

Many decades ago I repaired a bass combo for a guy who worked next door to where I worked - all that was wrong was the wire had broken off the speaker. However, the speaker was a huge 18 inch one (it was a BIG combo), and had amassive magnet on it - it took a lot of time and effort to solder the wire on, because as soon as I got near the speaker terminal the soldering iron was pulled away by the magnet. Eventually I had to work out away of bracing myself (round the speaker) so I good resist the pull yet still maintain a degree of precision for soldering the terminal.

I like the suggestion in post #17 - and a small steel washer would be ideal to solder to, then let that attach itself to the magnet.

Connollacken · Nov 12, 2020

Okay perfect, thanks. I have everything ordered now, so I'll get back to ye in a week and a half hopefully with a progress report. Maybe even a fully functioning lamp. Who knows? Again, thanks a lot for the help

Connollacken · Nov 12, 2020

Nigel Goodwin said:
and a small steel washer would be ideal to solder to, then let that attach itself to the magnet.

That'd be sweet.

Connollacken · Nov 26, 2020

dougy83 said:
For each wedge, you could have:

To boost from 3.7V battery to 12V: **broken link removed**

For the switch, you could use a touch switch, configured for toggle mode: **broken link removed** The output of this switch can connect to pin 4 (MT3608 enable pin) of the IC on the boost converter.

To charge and protect the battery: https://www.ebay.com.au/itm/164271308971

The main wedge is the same as the others, except it has the charging socket exposed.

The 5V from the charger can be passed through the magnets, provided you're using those with a conductive coating, i.e. Ni coated neodymium types.

If you want to have charging only enabled when all four are connected together, you could have three loops (via the magnets) around assembled lamp, where one loop is the 0V connection, one is 5V in, and one is 5V charge. The 5V and 5V charge loops are connected in the main wedge, such that the 5V in is only connected to the 5V charge loop when all wedges are connected.

Alright, I'm having a bit of difficulty with the charging in a loop. First of all, would this be series or parallel? Series seems to be the only way to get it to work, but I'm not sure. Would it be possible for you to sketch how this loop might work. Just a simple one if possible, thanks

Edit:
Charging them is one thing, but keeping the rest of the circuit attached to the individual batteries is what I'm really asking about (the boost converter, on/off switch and LED)

dougy83 · Nov 26, 2020

Connollacken said:
Alright, I'm having a bit of difficulty with the charging in a loop. First of all, would this be series or parallel? Series seems to be the only way to get it to work, but I'm not sure. Would it be possible for you to sketch how this loop might work. Just a simple one if possible, thanks

The charging loop stuff (that only allows charging with all wedges connected is hopefully clear in the following drawing:

The yellow lines represent connections made by the magnets. The box with "L" in it is the rest of the lamp circuit (i.e. battery, charger, switch, boost converter, LED strip)

dougy83 · Nov 26, 2020

Connollacken said:
Edit:
Charging them is one thing, but keeping the rest of the circuit attached to the individual batteries is what I'm really asking about (the boost converter, on/off switch and LED)

The charger/battery/boost/switch/LED is in the "L" box in the above drawing, and should have the following stuff in it:

Pommie · Nov 26, 2020

Personally, I'd try to get 1 working and go from there.

Mike.

dougy83 · Nov 26, 2020

Pommie said:
Personally, I'd try to get 1 working and go from there.

I'd second that.

Connollacken · Nov 26, 2020

So will each wedge need it's own charger board?

Pommie · Nov 26, 2020

Get one wedge working and go from there. Baby steps.

Mike.

Connollacken · Nov 26, 2020

dougy83 said:
I'd second that.

Yea I second that second. I have the 'L' working. Still needs a bit of tinkering, but the light turns on, which is instant satisfaction. I can see why this line of work/hobbie could be addictive

Connollacken · Nov 26, 2020

I had the switch after the boost converter though. Is that bad?

dougy83 · Nov 26, 2020

Connollacken said:
I had the switch after the boost converter though. Is that bad?

Are you just using a normal mechanical switch?

A mechanical switch after the boost circuit will drain the battery slowly through the boost circuit when the light is off. If you connect the mechanical switch before the boost circuit, there is no current drain caused by the boost circuit. Depending on how much drain there is, you may or may not care about it.

Connollacken · Nov 26, 2020

It's not soldered yet, so I'll just put it before it. Better to stop the drain.

Connollacken · Nov 26, 2020

What's the middle line between the switch and the boost converter that you've drawn there? And will I need to get a charging board per each wedge? I agree with taking baby steps, but the difficult part is getting them all to charge together.

Also, thanks again for the help and the drawings. Extremely appreciate it

dougy83 · Nov 26, 2020

Connollacken said:
What's the middle line between the switch and the boost converter that you've drawn there? And will I need to get a charging board per each wedge? I agree with taking baby steps, but the difficult part is getting them all to charge together.

Also, thanks again for the help and the drawings. Extremely appreciate it

That was if you were using the touch-switch module. For a mechanical switch, just wire up as follows:

And yes, you need a charging board per wedge

Connollacken · Nov 26, 2020

Yea ideally I would be using that, but for the time that I have, I'll just go with the straight forward. It's already not straight forward atall. Down the line I could work more features into it possibly. On and off are good for now

Connollacken · Nov 26, 2020

How is that 3rd loop (the solo loop) connected to each of the 'L's?

dougy83 · Nov 26, 2020

Connollacken said:
How is that 3rd loop (the solo loop) connected to each of the 'L's?

By "solo loop" do you mean the uppermost one in the drawing?

Building a Rechargeable LED Lamp

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