There's a Harbor Freight forum on the front page and that's where you need to go.

 

Mine had two CR2330 batteries.
It was held together with 4 friction push pins in the corners and a label and glue along the lens edge.

 

Radio Shack has a good variety of batteries.

I bought the second battery for my HF big window helmet there (the now-discontinued helmet) - but it didn't solve that helmet's slow response problem.

 

I had the same issue. I repaired my helmet using AAA batteries instead of the coin cells. Here is the procedure:

http://www.pskl.us/wp/?p=648

Good luck!

 

That was a well executed repair.

 

Here's a Hong Kong website with the best prices on batteries that I have found. $3~5 for ten button cells. Everything they sell has free postage.

http://www.ledshoppe.com/battery.htm

They also sell camera memory USB readers etc. I have placed several orders, and all were as good as I hoped. Expect three weeks for the free mail delivery from Hong Kong.

 

I performed this fix on my HF AD helmet today. I had to cut the AD device apart using a utility knife. Then went to Radio hack and got a couple coin battery holders and two new batteries. (like yours Eric, only one was bad. Soldered in the new battery holders, then had to glue the assembly back together. Cost me 20 bucks for all the stuff I bought at Radio shack (don't buy coin batteries at RS expensive!!!) but I can replace the batteries now. The whole time I'm kicking myself knowing I could go down to HF and buy a brand new one for $39. My advice, if you put value on your time, just go buy another one whenever the batteries die. Mine worked fine when welding in daylight (solar cell must have been supplying enough current to make it work okay) But last evening I was welding and it was getting dark and I was getting a lot of flash. Haven't tried welding with it since I fixed it.

 

When reading reviews about 30-50 helmets.
I believe I saw a you tube video for it. Ah ha finally found it. https://www.youtube.com/watch?v=APkejMTWDe8
I personally didn't think I personally would arc weld much at all and that built in hard soldered batteries would just die over time then have to buy another $49-54 helmet.
I didn't want a flip style helmet just an auto darkening helmet I can simply pull off the shelf and use whenever I feel like it.
I really love my Kobalt auto darkening 1/20,000 comes with easy to remove 2CR2450 batteries ($6) 4 arc sensors cost me only $99 on sale it had very good reviews.
A CFL or halogen lamp, torch sparker works to test it easily.
Next on the list is a cheater lens.
Good luck and be safe let know how the repair goes.

 

I really love my Kobalt auto darkening 1/20,000 comes with easy to remove 2CR2450 batteries ($6) 4 arc sensors cost me only $99 on sale it had very good reviews.

I have one of those helmets too. One of the best deals around for a decent 4 sensor helmet, and you can buy it locally. Works well for tig when adjusted right.

 

8 years ago I bought a HF helmet and it lasted about 4 years before it did not darken at all. I took it apart and found the two soldered on batteries and one bad.
The manual clearly states they are rechargeable and to leave it in the sunlight for 4 hours before the first use.
Installing two external battery packs was not how I wanted to repair it so I bought another and put it aside.
The second one is now 4 years old and still working but for how long?
Today I searched and found some CR2032 cells listed as rechargeable. The rechargeable ones are Li-ion LiR2032 but some vendors listed them both ways??
The original batteries have on them CR2032 and Lithium both.
I found these that appear to be the exact ones with the correct solder tabs listed as CR3032 and also Lithium just like the originals including the yellow insulating cover at 2@ $6.49 and I ordered 2 sets.
http://www.ebay.com/itm/2-NEW-CR203...tery-with-Tabs-CMOS-backup-/181136728579?hash=item2a2c972203:g:FSUAAOxyW7tRiV8Z

JoBo

 

My HF helmet just died with more than three years of hard use. I took the plastic box apart and replaced the two batteries with 2 new ones and now the damn thing darkens when I'm not welding. Remove one battery and the viewer lightens up, put the battery back in and it darkens. LOL. Anyone no what's going on.

 

I did the battery replacement with the two AA battery holders to make the 3V on each side. I wanted to be able to replace them easy. I initially had the darkening problem kctgb had, but doing some testing looking at a light bulb, it started working fine. I haven't had any problems since. Of course, I have lost a little trust in the auto darkening, but so far so good.

 

I have read reviews that the fixed / hard soldered battery designs can or have flashed users when the batteries eventually die.
I called a big name brand technician (not HF) and he told me their helmets auto darkening will not work on solar power alone when the batteries die. There must be both solar and battery power.
After that I returned the $140 big brand welding helmet still in its plastic sealed.
For the reasons above I personally chose the following helmet below since I could buy it locally.
Kobalt auto darkening 1/20,000 comes with easy to remove 2CR2450 batteries ($6) 4 arc sensors.
Do easily test it with a CFL or halogen lamp, torch sparker works to test it easily.
Update. Hobart 150x magnifier fits 2" x 4" 1/4"