Introduction: Reviving an AutoDarkening Welding Helmet

Picture of Reviving an AutoDarkening Welding Helmet

Reviving an AutoDarkening Welding Helmet:
As an Instructables virgin, I decided to get started with sharing my experience with my Harbor Freight Auto-Darkening Helmet resurrection.

I use my mig welder all the time for quick fabrication of brackets etc. One day
I went out the the shop, fired up the welder, and donned my welding helmet. I then proceeded to start the weld and was surprised by the flash intensity. My auto-darkening helmet had always stepped in and attenuated the bright welding arc, but this time it didn't.

My quick test then was to go outside with the helmet, look at the sun indirectly through the welding lens, while waving my hand in front of lens to create a variation in light hitting the front and sure enough, the lens darkened, but faded back to clear in a second or two.

Items required:

- A welding helmet that needs fixing of this sort.

- A dremel tool with arbor and abrasive cutting disks( or diamond wheel types )

- Hot Glue gun and glue sticks

- A soldering iron and solder

- 4AAA or 4AA batteries.

- Qty2 2-Cell holders( =3VDC ) for the batteries selected above.

Step 1: Finding and Exposing the Battery

Picture of Finding and Exposing the Battery

On the front of the lens casing, at the top, there appears to be a solar cell.

Over the years I had assumed naively that the helmet recharged over time with ambient light. (Edit: as member::DerStu pointed out, It turns out it does trickle charge if left out in sunlight.)

From experimentation I found that there are 2 additional photo sensors( either photodiode or phototransistor based ) that sense and maintain the darkened state of the lens.

I decided then that there must be a battery or storage super-capacitor inside the lens that had died. Since the lens's plastic casing is approximately 3/8" thick, I guessed that it must use a coin cell type and looked for a reasonable location where they could have placed one.

I broke out my trusty dremel with my favorite attachment: A wheel arbor with a thin abrasive disk. This combination is very useful for all kings of fabrication and dissection of things. (Tip: look up images of "Riemann Sum" and you get the idea of one grinding technique to approximate shapes )

As seen in the picture, I was lucky to find a coin battery on the first try. Using the dremel tool with a pinky finger or two for support on the table, cut out a shallow ( at estimated plastic depth ) square shape approximately postage stamp-sized. Keep the square cutout piece of plastic to use later. The battery should be exposed. At this point make sure you identify and record the battery lead locations and polarity.

Take a small thin bladed screwdriver or precision nippers, carefully, as close to the battery 'weld's, pry the battery tabs upward to break them loose from the battery. Do not put so much stress on them that you break the tab leads at the location where they connect to the PCB. The underside of the battery is harder to work loose, but with patience and control the coin cell battery will cut loose.

Now go out and get qty:2 2xAA or 2xAAA battery holders and qty:4 AA batteries from RadioShack or similar. The emphasis on qty:2 of these holders will be explained later.

Step 2: Adding the External Batteries

Picture of Adding the External Batteries

Next solder the 2xAA battery holder leads. Red lead to the positive marked lead where the CR3023 battery was connected.

Then do the same procedure with the Black lead to the minus(gnd) marked lead where the CR3023 battery was connected. Cut a slot in the LCD case so that the holder leads can be routed outside the case. Hot glue the wire leads, slot, and glue cutout cover plastic you saved back into place. To break the suspense, I thought I was done at this point, but after tossing in batteries and welding, I found that the darkening attenuation at the dark-most setting of the lens was not what it used to be.

Short_tangent_rant: At this point I got on the internet and did a search to see if anyone else had tried this. I like to reason out and try things first before resorting to Google. This way I have to use my own creative muscles first, before using another person's brain power. This can be both good and bad in that often you can learn from others trial and error before doing a task, but if you always resort to others to tell you how to do things, you don't work through the "eureka" discovery process that can often lead to new and novel ways of doing things. End_Of Short_tangent_rant.

I found some links where people had found a 2nd battery on opposite side of the lens, but they couldn't explain its purpose or why it usually still had reasonable life in the battery. I can clear this up. The first battery powers the analog circuitry( op-amps etc ) that process the light levels an then control the drive to the LCD of the lens that darkens. The 2nd battery is the contrast voltage for the LCD and is responsible for how dark the lens can go. Contrast voltage to LCDs are extremely low current draw so this battery is often still usable.

Contrast voltages are sometimes negative with respect to the other circuitry and this is the case here. The two coin batteries are wired in series, with the first battery's negative connecting through the PCB to the 2nd battery's positive. This creates a bipolar supply +3vdc/-3vdc for both the analog processing and contrast circuits.

So after dremeling the case to expose and remove the 2nd battery, using the same procedure as the first battery revamp, I put in the 2nd set of AA's into the 2nd holder and mounted them inside the helmet above the lens.

I recommend to use Velcro with really good adhesive that wont slide off over time. Liquid Nails item called "Perfect Glue" in a tube is one of the best clear adhesives around. It's not Vinyl bases, but like stiffer silicone on steroids. I used coated Romex wire in a pinch to wrap them in place.

Step 3: Conclusion and Test:

Picture of Conclusion and Test:

Using the "sun" test mentioned above, I found the helmet worked perfectly and has been in use
for 2 years now without issue.

Good luck, Be Safe, and Have fun Hack-Making

-Lee Studley 20141210 Merry Christmas and holidays to all

I'd like to thank author: HollyMann and others for their inspiring Instructables and creative sharing.

Disclaimer: This instructable involves the use of power hand-tools, electricity, and soldering. If you are not comfortable using these items, then refrain from doing so. I'm not responsible for what and how do after reading this instructable. If you disagree with this instructable or any items therein, please feel free write an instructable reflecting your experiences.


DerStu (author)2014-12-12

I have the same hood which I let sit for about 5 years and mine does charge via the solar cell, but it's a trickle charge, and takes quite a while to recharge I wonder if your photo sensors were blocked from the fumes as I was having a similar problem while tig welding and charging the hood under a light fixed it for me either way rewiring it with replaceable batteries is awesome

studleylee (author)DerStu2015-01-04

Agreed. I did clean the sensors while I was doing the modification. They were dusty.

I did leave the helmet in the dark shop most of the time, so that was partly the cause too.

The coin batteries would take a charge at a slow/low rate so that makes good sense.

Cool, I hope it goes well.

Coin batteries aren't actually designed to take a charge, so you got lucky there...

Most coin batteries are throwaway and not rechargeable. (Dispose of properly!)

twitting (author)2014-12-12

An easy way to test an auto darkening shield is with a cheap (e.g., bic) lighter. The sparks from the flint striking the thumb wheel should make the shield go dark momentarily. You don't light the lighter...just flick the thumb wheel a few times.

Thanks for the write up...I'm sure I'll need to do this at some point.

I assume the spark from an oxy-actelene rig lighter would do the same as a "Bic" or better.

studleylee (author)twitting2014-12-12

Great idea. I will test that out. Thanks.

simonrafferty (author)2015-05-01

Thanks for the Instructable! I have a (expensive) ESAB helmet which has stopped working. I couldn't bear to put it in the trash and had planned to investigate. At least I know what to expect now!

studleylee (author)simonrafferty2015-05-01

That's great! If you have time take some pictures and post them in the replies.

I'm adding a 2nd instructable to add a minimum filter and an LED headlamp for the users concerned about the fractional milliseconds of flash before the lens darken.

Wise idea sir, radiation exposure is cumulative, and sooner or later, the retina will be permanently scarred.

John T MacF Mood (author)2017-02-03

i am honestly thinking the solar cells are part of the flash detection and NOT used not for recharging. I'd love to get the annotated schematics to learn more.

SteveMann (author)2016-02-12

External batteries is an excellent idea.

I've got a bunch of welding helmets that take strange batteries that I can't find in stock at many different stores.

Send me an old broken one, I'd love to test my theories on the button cell vs he "AA" or "AAA" replacements... And come out with a really cheap fix - I'd HAPPILY share any data gathered! I'm on Facebook as "John T. MacF Mood" (I'd be glad to pay shipping if it isn't crazy expensive. And the additionj of as fixd dark lens to supplant the shiort rise time in the darkening stage is a very wise idea,

studleylee (author)SteveMann2016-02-12

I just use my fixed up one the other day.

CharlesL6 (author)2016-12-20

Why franstine your helmet when you could get anther battery to put back in?

studleylee (author)CharlesL62016-12-20

This older brand of helmet had non-replaceable batteries. No access to them. So using external cells makes it easy to replace as needed. Newer helmets are trending to make the batteries replaceable.

John T MacF Mood (author)2017-02-02

Great hack! One doesn't want to take chances with vision, that blindness would kind of end any kind of project building for me...

This one I'm filing way for future reference. I may modify a new welding helmet from Harbor Freight. Yes, I do buy there, but only select items, a lot they sell isn't worth the money, even at their "bargain" prices.

The battery hack is applicable to computers, read on...

I have little to no confidence in the common CR-20132 and similar which I HAVE to use in my computer. In watches, they always fail at the most inopportune moments, one of Murphy's Laws sub corollaries, no doubt. A set of alkalines replaced every 6 month or so dust cleaning cycle would definitely do the trick for my computer. Once my motherboard is out of warranty, I'm changing over. Some of the earliest computers I worked on had a four cell "AA" pack rather than the CR-2032. I've been a computer tech for almost 40 years. Some Altair builders used this as a "mod" to the original kit/plans. If you never heard of an Altair, you're too young.

I run a fairly "hot" processor, and it will force a shutdown if you reach 80°C (Athlon 4100 series 3.6 gigahertz.) I keep a temperature monitor on screen, and clean the dust whenever the temp starts to climb and clean and replace the heat sink compound. I'm at 37°C right now (98.6°F) so it's relatively cool. (Yes, I build my own PC's) I haven't bought a retail desktop since 1982. Laptops just don't seem to come in kit form. Intel chips will also throttle back and stop running in a similar fashion, to prevent "core meltdown".

DonL55 (author)2016-10-31

Here's an update to my(DonL55) hack. There is only one Panasonic battery to replace. The Tenergy 3v RCR123a battery I used, is a lithium ion battery that can charge to 4.2v and has circuitry, which activates at initial load, that limits voltage to 3v. If charged to 4.2v(battery circuit limited) the batteries internal circuitry to adjust to 3v is quick, but not quick enough to not damage some circuits so be careful if your battery comes charged to 4.2v. My battery came charged and I discharged it to 3.2v so you wouldn't need to buy the charger for this. This type of battery needs to charge at .2C which for this 600mAh battery is a special charger is needed for charging. I placed a work led lamp which is super bright about 1ft away and left it there for 2hrs and then checked the voltage on the battery and it just barely increased the voltage, so I doubt the 4.2v limit will ever be reached while using...Oh, did I mention it works great so far and I'll try and report back 1yr from now with another update.

studleylee (author)DonL552016-11-03

@DonL55 That's awesome info!! I will try to get an RCR123a and try it out. -Lee

der_fisherman (author)2015-07-13

Anyone is allowed to disagree here if they wish, but it is far more useful to specify with what you disagree and exactly why........that brings some point to your post!!

If you are the original Author, you appear to think that I "stole your Thunder" in some manner. Actually, I added to it!!! Now its right!!!

Its nothing new, but many people misunderstand Batteries generally, sadly and have weird ideas on how they work, also sad!!

I design and build battery chargers for different battery types. In tests for some battery types, I am exceeding 11 years of life in daily usage.....and no sign of an end in sight!!

Waiting on an exact reply, point by point please.

Thanks in advance.


der_fisherman (author)2015-07-13

Firstly, as I said before, a great Instructable, many thanks. Sorely needed here.Good work.

But some points may not be clear enough for any Solar welding Helmet repair. So here I go, adding a few points!

1. Using non rechargeable batteries in such a repair is probably a "NO-NO" for most helmets as the solar cell, will try and recharge them, this can lead to problems, even leakage. But the addition of a "blocking" diode ((almost any small signal diode "1n4001" should work just fine) will stop them being recharged and the helmet will work till the batteries need replacing, with no problems. Alkaline batteries will give the longest life in such cases. Here is a short video on using Blocking Diodes:-

But you need to use it reversed as shown, as you will need it to STOP the battery being charged. Also a far smaller one will do the job, a 1 amp 1n4001 for example....

2. Its better to use rechargeable batteries in two battery holders, then no blocking diode is needed, but do charge them fully before inserting. Leaving the helmet when not in use facing the light, should keep them charged for years to come....I would use AAA size as they are physically relatively small, but hold a greater charge than 2032 cells.

3. Assuming that you have only got space for the CR2032 batteries, normal ones, not rechargeable, then you need the blocking diodes again, properly orientated. But there are also CR2032 batteries that are rechargeable, they cost a little bit more, and can also be used with a CR2032 battery holder, for example.

These are really small and flat. But you might have problems charging them before usage, other than placing the helmet in the sunlight!! Li-Ion Rechargeable Button Cell LR2032 CR2032 3.6v. Naturally no blocking diodes needed!


Leaving (any!) rechargeable batteries with no charge will will eventually damage them. So if using them, leave the Helmet facing sunlight when not in use.

If you install correctly, no matter what battery types or holder you use, make sure that a) you can easily measure the voltages of both units if you get problems and b) that you can replace them when needed, or even give the rechargeable AAA ones a quick boost charge.....

I hope this helps you to obtain further life from your helmet!!



graydog111 (author)2015-06-19

Thanks for posting this,studleylee. I bought an expensive Miller Jackson helmet several years ago. It quit working after about 6 months. The dealer gave me a new lens reluctantly. It quit again after about a year. I wired in a battery holder, but it didn't help, so I bought a Chinese one off eBay. It's really nice and is still working fine. So much for Miller Jackson's reliability.


Phil B (author)2015-06-18

I did an Instructable about my Lincoln auto darkening helmet with single grade #10 shade. First, it uses two AAA batteries, all fully replaceable by the user. Second, when the batteries fail, the lens remains at its darkest and does not lighten, this is the opposite of your Harbor Freight helmet, these two things reinforce for me the wisdom of paying a little more to get a better helmet that protects one's eyes. I have since purchased a Miller adjustable shade helmet and its batteries are also replaceable by the user, I do not have enough experience with it yet to know what happens when the batteries fail.

CharlesM15 (author)2015-05-09

I just disassembled the same model to check the batteries, it's possible to gently pry the whole assembly apart without cutting. I found the batteries holding about 2.1 volts each which I guess is not enough as it doesn't respond to the bic test. I will be adding a plug connector to the battery on one side in order to charge it with a 500ma 5.5v phone charger, or usb cable. Will comment again after to share results. This is the first method I'll try as I would prefer to use the plug to 'top up' the batteries, while leaving the self charging function alone. I have some concerns about solar charging alkaline (non-rechargeable) batteries while they are next to my face.....

studleylee (author)CharlesM152015-05-09

Cool! I'd like to see a picture of that. -Lee

brennerb23 (author)2014-12-12

Good job on the first instructable.
The one thing I have always learned welding is take care of your eyes! I personally would never Jimmy rig a welding hood it's not safe or conducive to your health I would not recommend this project to other people. I am an aerospace tig welder. I would instead go the route of putting a fixed shade lense in place of the auto dark element.

studleylee (author)brennerb232014-12-12

Thanks brennerb23. I'm a professional EE so I'm comfortable with my work. It's really just replacing the batteries in an item as you would a flashlight. It's up to the reader to test if its functional again or not hence the disclaimer.

brennerb23 (author)studleylee2014-12-13

I guess you could look at it like a flashlight. The disclaimer just states "warning you will be using power tools". The harbor freight welding hood doesn't allow you to change the batteries for a reason that's why there is no battery tray unlike on my miller digital eliet that has battery trays for replacing batteries. My whole comment was about "hacking" something that is designed to save your eyes it was nothing to do with a auto dark hood. like I stated above I have a auto dark hood as well as a fixed shade huntsman hood.

studleylee (author)brennerb232015-01-04

Hi Brennerb23, I think I owe you an apology. The more Iive thought about your suggestion of adding a fixed filter, I like the idea of having a minimum backup filter, and adding a headlight for the helmet. I still like the auto-darkening feature, but I tried using it with an added a pair of welder glasses while using the helmet and it was usable, but I think an LED headlamp would make it right on. Of course adding a minimum filter to the LCD area would achieve the same effect.

studleylee (author)studleylee2014-12-12

Otherwise you could be potentially tossing a perfectly good $50 helmet.

neo71665 (author)brennerb232014-12-12

Do you throw away your truck when the battery dies?

brennerb23 (author)neo716652014-12-13

No that's not what this is about a battery for a truck isn't designed to protect your eyes. would you hack and rewire the ABS sensors in your truck?

neo71665 (author)brennerb232014-12-13

Batteries die, you replace them. I replaced the batteries in my jackson hood the other day. Nobody is replacing the hood or lens with tissue paper.

As for abs my 78 nova rally has a LS engine, dash gauges, and abs system from the engines donor. It has passed every safety inspection its been to since I built it so ill let you answer your own question.

3of5 (author)neo716652014-12-12

Nope, not even my tractors.

3of5 (author)brennerb232014-12-12

the helmet does auto darken enough to keep your eyes safe, but there is enough time between the actual flash and completed darkening of the helmet. After enough continuous welding it could become an issue. I agree.

studleylee (author)2014-12-17

Thanks for all the great feedback on this.

djfoz (author)2014-12-13

I did the same with mine but I managed to find the button cells with the solder tabs on Ebay (intended for Game Boy) and they worked significantly better than the AA batteries I initially tried.

More Cowbell (author)2014-12-12

Good call. I have the same helmet. I always thought the solar cells were for charging. I'll keep an eye out for dying button batteries....I do however always test mine before use. Great write up.

atweedlie (author)2014-12-12

nice bit of hacking!

seamster (author)2014-12-12

Excellent work!

Nice to see you jump in and post your first project, too. I liked your tangential rant; I do the exact same thing regarding waiting to google something till I've tried to work through it myself, and it's fun to see that I'm not alone in that approach!

Hope you'll post more projects soon!

studleylee (author)seamster2014-12-12

Thanks Seamster!!! You are my first ever 'commenter'!!! I have tons of things I need to share. Thanks! -Lee

About This Instructable




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More by studleylee:Storage Idea: A System of Buckets -or- how to retrievably pack more stuff in a semi-trailer etc.Reviving an AutoDarkening Welding Helmet
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