Two is one, and one is none!
My body has never had a problem going into the Sauna either… Well I get a little wrinkled, but my skin always dries right out later on, 
.
Flashlights are not water proof (except diving lights - maybe), they are water resistant, but nothing is impervious to moisture being formed from the already present moisture level in the air that is in the light. Maybe we need to save all those moisture packets out of the pill bottles and stuff them into our lights.
Nurse!! More Pills Please!!!
The talk about moisture behind the lens reminded me of this old thread:
I guess humidity can be tough on flashlights.
Whoa wonder what I missed in this thread?
Anyway yesterday morning the light appeared better, less moisture behind the lens, and it worked mostly fine. Except the fact that strobe would activate sometimes when I would turn it off from one of the half press modes. I had sent a RMA request, and got a response from Fasttech- I’ll have no problem getting a new one. I was having second thoughts about sending it in until I got home last night and now it wouldn’t turn on. Alright so it’s gong back.
Yep!
Yes it was the Spark SG3. Contacted them a few times about it and never heard back.
Alright, no Spark headlamps for me then, if thats their attitude ;)!
SG5 looked ineresting…
Good dive lights, dive computers, and underwater cameras and housings are rated to a certain depth but even then need to have the seals cleaned and relubed whenever they are opened. Short of that though the pressure differential between hot and cold won’t equal the pressure of diving at 130’. The biggest issue is putting things together in a dry enough environment that condensation isn’t a problem under water. With a light it’s not usually a problem, when in use the light is warm inside and when not it’s opened up for a recharge. Cameras seem to have more issues with this because the lighting systems are generally remote and don’t heat the interior of the housing. Can’t go on a dive trip without hearing an earful about moisture. I don’t think I’d trust any light in the rain without testing it or checking afterwards to make sure it stayed dry and all the comments about moisture, humidity and pressure seem spot on.
Dumb question time. What about assembling the light after it had been in a frost free freezer? Our frost free freezer makes ice disappear or am I barking up the wrong tree.
I dont think thats a very good idea at all, (apart or together) because the minute you take it out, condensation is going to form on the parts, and then you get water along the edges of seals and if any gas gets sucked in…well there is water there first. Plus then you have a cold circuit board and condensation forming on it: I’m thinking you almost certainly would place moisture exactly where you dont want it.
I think heating it up a lot, then exposing it to cold air at the lens, opening and wiping any condensation that happens on the lens off and repeating would be a way to get rid of internal moisture. But none of that is too available in a tent, unless you want to stay up and wipe your lens in the dark 
I think NC really did design the EA4 with a one way valve to equalize pressure, it’s called the BRS system (ballooning rubber switch), in the instructions , they obviously failed to translate to English correctly.
Allow me to add the “incorrect” translation.
Features
· Novel ‘Unique Integrated Technology’ offers a more sturdy and lightweight body. · Utilizes a CREE XM-L U2 LED
· Maximum output of up to 860 lumens
· Integrated “Precision Digital Optics Technology” provides extreme reflector performance
· Boasts a peak beam intensity of 20,000cd and a throw distance of up to 283 meters
· Innovative single button two-stage switch offers a user-friendly interface , with pressure relieving valve system (patented)……… 0:)
Update on this: It’s being replaced with a D40A as soon as Fasttech gives me the credit for it (which should be in a day or so). No more Nitecore for me. Lets hope the D40s design holds up well to outdoor/camping use.
I would like to hear how the D40A survives!
Believe me, if it doesn’t hold up- I’ll be the first to post about it.
Well his problem had been resolved I’d thought, and it also sounded like his moisture problem in the tent was an exceptional amount of moisture, not just some lens condensation, possibly 100% humidity air being sucked into the light and condensing on the hot lens, enough to form a water droplet, air coming in also at 100% humidity so it couldnt re-evaporate readily. The ‘problem’ of lens condensation itself is simple: there is always moisture in air, and, when the light gets hot, and cold air runs past one side of a glass lens with warm air having moisture on the other, you will get some condensation as it cools due to the temperature difference (*and less water being able to stay in a gas at lower temp). If your light head is not completely sealed to air, it will always push air out when hot and suck more in when cooling, replenishing air and water in that air unless you toss the light in a desert environment or dessicant chamber while cooling. Anyways, this becomes a problem if the air you suck in has very high humidity already, not allowing the lens condensation to re-evaporate once you turn the light off.
Did you have to ship your EA4 back to FastTech and, if so, did they make you pay for it?
Sorry I forgot to answer this. They give you a store credit for the price of the shipping if you give them a tracking number and a scan of the receipt.
What a trip!!! I was scrolling through this because I have an EA4. I also have a TK-75 and WROTE THAT THREAD!!Notice the same picture with the username “Capolini”!
Long story short, the TK-75 IS NOT hermetically sealed. I used silica gel and it resolved the problem.
As far as the EA4,I only read a few posts before I came across this. There was also a thread on CPF regarding the issue of the switch on the EA4.
Was the switch in anyway melted or deformed? That was the problem they were having.
Nitecore improved/changed the material on the switch and that issue has been resolved!
If your serial number[ written small on bezel] begins with “307” then this is a new EA4.I am fortunate to have the new one.
If not, water may have gotten in there and did some damage.
FOOD FOR THOUGHT!!
Good luck!
This is for me, I never buy from dealers in China. I have several Fenix lights and they have 3 major distributors in this country that have been wonderful and taken care of me so I never have to deal with China.Fenix has a great warranty.
Nitecore does not! In that respect, after 2 weeks, which have past[!!] if my EA4 fails, I have to send it back to China!! It is the only Nitecore I have and will ever get! I will stick with Fenix!
I hope I did not make the op feel worse, I also hope the info. I gave can help!
Ciao,Roberto
Mhanlan, sorry to bother you again, but how long did you have this light before you sent it back to FastTech? Also, have you gotten a different light from them in the exchange? Thanks.
I told them I’d rather not have the same light, and asked if I could get a store credit instead of having another EA4 shipped to me. They did that and I decided to trade up for a D40A. The thing is, you need to do a “bulk order” request for a single item to pay a more reasonable price for a nicer light- since they raised their prices.
My order tracking page says I bought the light on March 22, returned on September 11th.
Thanks.