T12 battery portable iron

[capwizard]

T12 iron tips + two 18650 + MT3608 2A Max DC-DC Step Up = battery portable T12 iron......................

PS: 10 sec to heated up the iron, voltage adjust to 24V.

[budm]

Re: T12 battery portable iron

So the load IS (T12) at 24V @2A OR MORE? which is about 48W @2A of power (t12 is rated at 70W).
So How much current are you drawing from those two 18650 connected in series to provide about 8V to the boost converter?
I estimate at 6A or more, I hope you have good protection circuit not to allow over current and not allowing the batteries to discharge to unsafe level before being recharged, and battery can handle high current.
It remind me those E-Cig that people modify to get more heat but ending blowing in their face.

[capwizard]

Re: T12 battery portable iron

You are right when I push the on button it drop to 12v, will test more and give feedback, I think use 4 x 18650 will be better.

PS: Will try 2 x 18650 without boost converter. voltage is not that important because I did not use the Thermocouple , it depends on current.

[budm]

Re: T12 battery portable iron

Lucky it did not blow up on you.
Make sure you understand the relationship between input power and output power first.
BTW, that micro switch has the load current or input current flowing through it? I hope it can handle the current as well if you use it that way instead of using as on/off control signal to turn off the Boost converter circuit through the control signal pin.
So the iron is 70W? your boost converter is rated at 2A max output? No head room?
What is the actual spec of that board?

https://cdn.badcaps-static.com/pdfs/...3da13e3c4d.pdf

spec of the IC:
FEATURES
• Integrated 80mΩ Power MOSFET
• 2V to 24V Input Voltage
• 1.2MHz Fixed Switching Frequency
• Internal 4A Switch Current Limit
• Adjustable Output Voltage
• Internal Compensation
• Up to 28V Output Voltage
• Automatic Pulse Frequency Modulation
Mode at Light Loads
• up to 97% Efficiency
• Available in a 6-Pin SOT23-6 Package

[budm]

Re: T12 battery portable iron

You are right when I push the on button it drop to 12v, will test more and give feedback, I think use 4 x 18650 will be better.

PS: Will try 2 x 18650 without boost converter. voltage is not that important because I did not use the Thermocouple , it depends on current.

Check the resistance of the iron, check the current draw and the batteries Voltage when load is connected when it settles down so you have some idea what you dealing with. It is basically dumb iron with no control.
At least put fuse for protection.

[capwizard]

Re: T12 battery portable iron

"micro switch has the load current or input current flowing through it"
YES it was a 3A 250v switch, the load current did flow through it, change to MT3608 PIN 4 (EN) will be better.


MT3608 2v-24v 2A DC-DC Step Up Power Apply Module Booster Power Module Max



1.Electrical characteristics
1). The maximum output current: 2 a
2). The input voltage: 2 v ~ 24 v
3). The maximum output voltage: 28 v
4). Efficiency: ≤93%

[budm]

Re: T12 battery portable iron

So you are drawing more than 2A with that load since the iron is rated 24V 70W = 2.91A @24V, since you know what the load will try to draw form your supply at 24V, you can then estimate what the input current will be.
So it has 2A fuse on the input side of the module.

[capwizard]

Re: T12 battery portable iron

I just read bad reviews about this MT3608 2A Max DC-DC Step Up board will catch fire!

I will change to 4 x 18560 and a fuse to protect the iron.

[budm]

Re: T12 battery portable iron

Well, you should do some testing:
1) Put Volt meter to monitor DCV of the batteries when without load and with load.
2) Put DCA meter to monitor load current, you need to use heavy gauge wires to reduce series resistance introduce to the load when Amp meter is in place.
You are lucky the batteries did not blow up on you.

"I will change to 4 x 18560 and a fuse to protect the iron." the fuse is to protect the source in case the load shorted out or draw too much current above the source can safely supply. Fuse is connected in series with the load.
Also should have thermal cutoff fuse in case the batteries over heated.

[petehall347]

Re: T12 battery portable iron

this is coming on fast .
can i suggest a later add on ?
a charging circuit that can run the iron and charge the battery at the same time . this way it could be kept fully charged on the bench and will last ok in the field .
doing this should make the batteries last longer . well in theory it should do

[capwizard]

Re: T12 battery portable iron

petehall347: "a charging circuit that can run the iron and charge the battery at the same time "

Really! I thought about the same idea......... that is use $0.99, solar calculator's tiny solar panel, add to the battery iron, but I do not know how to transfer this small mount of current to battery? needs boost circuit?

[capwizard]

Re: T12 battery portable iron

budm Thank you for safety issue and safety current calculations. Sorry, the dc module Ive used has on fire problem will change different one, with the one has current adj and voltage adj ....with adjustable current to fit with different type of batteries..... might be avid some safety issues......pic 1

High Drain Batteries for Sub-Ohm Vaping
http://ecigarettereviewed.com/best-h...hm-vaping-2015

Maximum current on non protected 18650's
http://www.candlepowerforums.com/vb/...tected-18650-s
2.1Ah 18650 cell can safely deliver 3A because its below "2 times Capacity" which is 4.2A

5 common lithium-ion battery myths explained
https://batterybro.com/blogs/18650-w...yths-explained

Panasonic NCR18650B 3400mah Amp Limit & 18650 Battery Datasheet
http://www.batteries18650.com/2015/0...0-battery.html

[capwizard]

Re: T12 battery portable iron

4 x 18650 works good!.........10 seconds to melt solder.......................

T12
http://www.hakko.com/english/product...x951_tips.html

[capwizard]

Re: T12 battery portable iron

Better safety calculator.......Thank you .....budm........with Joules..........

[capwizard]

Re: T12 battery portable iron

Add Celsius heat unit, and Calories for fun.............

PS: KWh = $8 here, How much it will cost you, In this case is battery, so not 100% correct, it needs to count energy lost.

PS: How many Joules need to heat up iron tips to 280F?

Solving specific heat problems
https://www.youtube.com/watch?v=FyNFXN5i-j0

Heat and phase changes
https://www.youtube.com/watch?v=w5DZtABqfCA

Advanced Specific Heat Example Problems
https://www.youtube.com/watch?v=hSX5B1-1-Vc

Specific Heat Example Problems
https://www.youtube.com/watch?v=c2NaAHEusm4