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View Full Version : RMR in a hot trunk



Chris Upchurch
07-19-2011, 03:24 PM
My carry gun is an RMRed Glock 17, but when I'm teaching I prefer to use an iron sighted Glock. Most of my students are using iron sights and I want to emphasize that the things I'm demonstrating are a product of training and practice, not the nifty sight on top of my slide.

Alex Nieuwland and I were teaching a class this weekend and it was HOT. I'd slipped the Searaphim with the RMRed Glock off my belt and into the trunk Sunday morning and left it there for most of the day. As we were wrapping up, I wanted to show the students my RMRed G17 and give them a chance to shoot it. I got it out of the trunk and was in the process of swapping out my carry ammo for practice loads when I noticed, no dot. I wondered what the heck was going on, but class was still going and I didn't have time to do much diagnosis, so I just put it back in the trunk and the students shot Alex's RMRed G19 instead.

As I thought about it, I figured that maybe the temperature in the trunk was outside of the RMR's operating limits. Sure enough, once it cooled down the dot came right back. According to Trijicon's web page, the RMR is rated to function up to 120 degrees. I don't doubt that it was hotter than that in my trunk on Sunday.

120 degrees is pretty hot; most of us probably don't encounter temps that high on a regular basis outside of an oven. However, one place where we can run across them is inside a car on a hot day. If you need to leave your RMRed gun in the car on a regular basis (while you're at work in an NPE, for instance) this is something to keep in mind.

While I was able to notice this in a training environment, I was still really glad that my Glock was done by TSD with the BUIS. This means that if I need to make a precision shot I can transition from the dot right to the irons just by dropping my head another half an inch. The RMR's pretty reliable, but it's always good to know that a backup is right there if you need it. The TSD package is definitely the way to go.

paranoid
07-19-2011, 03:53 PM
Thanks for the update Chris.
I going to put a thermometer in my vehicle to check the temp out of curiosity.

Bill Lindsay
07-19-2011, 04:10 PM
We did some checking on this at the department. Here in Michigan we recorded temps at 130 degrees +. After that we stored no ammo in the patrol car trunks.

chad newton
07-19-2011, 04:40 PM
I will make sure I keep mine on me not in my trunk.:)

ZMB HNTR
07-19-2011, 06:16 PM
Hmm, not very practical for a Vegas application. In construction we have lasers fail quite often due to the extreme temps. Good to know, thanks for the post.

Michael Swisher
07-19-2011, 06:44 PM
Hmm, not very practical for a Vegas application. In construction we have lasers fail quite often due to the extreme temps. Good to know, thanks for the post.

Even in Vegas I would think that if you have it on your person, you would be okay. If its so hot that the RMR fails, you probably will to. Just don't get in any car trunks.:scared1:

ZMB HNTR
07-19-2011, 06:55 PM
Even in Vegas I would think that if you have it on your person, you would be okay. If its so hot that the RMR fails, you probably will to. Just don't get in any car trunks.:scared1:

Yeah, I suppose I shouldn't keep playing trunk monkey in the summer :). But realistically the ambient temperatures routinely get to 115, and anything metal or black (like a holster/etc) will only absorb the heat. I know Gabe being in Arizona deals with very similar conditions, guess it hasn't been much of an issue for him so far?

chad newton
07-19-2011, 07:50 PM
Prescott isn't phoenix bro.

ZMB HNTR
07-19-2011, 08:45 PM
Prescott isn't phoenix bro.

Yeah, fair enough. I am used to having to make adjustments with equipment, never really with optics/etc; but our surveying lasers and the like are prone to shut down in the summer - or worse they go out of calibration, you just hope you catch it!

chad newton
07-19-2011, 08:58 PM
I freaking hate the heat, I'm crying when it 100 here. :)

JustMe
07-19-2011, 10:23 PM
If batteries cared that much about temp then cars would not start do to being stored in the "front" trunk.

Electronic components typically come in "commercial" (0C to 70C) and "industrial" (-40C to +85C, and -55C to +125C in some cases) versions, industrial having expanded temp range such as for cars and their more demanding needs. Added expense is usually not huge. For a properly designed device plastics in the packaging will melt before the electronics will have any problems.

Anybody that has 2 identical RMRs:

Put brand new batteries into both. This has to do with batteries not liking COLD temp, the internal elecrolyte ion diffusion slows dramatically thus causing a current limit. Which is why car batteries die (start showing their age) in winter. The diffusion rate goes up in the heat, but "poisoning" of the chemistry occurs faster at higher temps, which is why you shorten the life of you cordless drill when you stress it beyond reasons and thus the batteries heat.

Set both to the same setting and verify the brightness is the same for both. Place one in a hot area such that the dot seems to work fine. Stick the other in the freezer for a few hours.

If the one in the freezer is brighter than the one in the heat then their internal circuit has a temperature compensation issue and THAT is why it's dying at high temp. According to Trijicon's site the battery is one single CR2032. This presents a nasty issue regarding temp. LEDs typically run at a voltage close to or just above 2 volts which leaves less than a volt to "play with" regarding the brightness control circuit and temperature compensation (if any). This is made worse by the fact that the battery voltage is not constant over it's useful life so the control circuit must do its job just in the range of well under 1 volt. When I say "nasty" I don't mean it's a hard problem to solve, it just mean it's gets complicated (= money and more room for parts).

If sticking a brand new battery into the RMR at the high temp (to make sure the circuit has "spare" voltage range in which to do it's job) results in the dot being displayed then again it is a temp compensation issue. You just gave the circuit more voltage to use to control the LED. If not, then there is "no information". Go back to the freezer test.

YARP
07-20-2011, 07:28 AM
We did some checking on this at the department. Here in Michigan we recorded temps at 130 degrees +. After that we stored no ammo in the patrol car trunks.

I can't imagine what it would be like the past couple weeks.....it hit 101 out at my folks place! HOT, DAMN HOT!

WinstonSmith
07-20-2011, 12:40 PM
Does this also affect the tritium (non-battery) RMRs?

YARP
07-20-2011, 01:06 PM
I guess I still wouldn't store mine on the dashboard (or the trunk) in hell... err I mean Phoenix.
:haha:

Priceless!

Mickey Rourke
07-20-2011, 01:38 PM
My G26/Jpoint has been staying in the passenger compartment of my Cherokee during work. It has been inside an OD laptop bag with my S2K. No problems this year or last.

We've had several near-100 days here with heat index over 100 in Alabama.

Housertl
07-20-2011, 01:51 PM
This makes me wonder....didn't Trijicon make these with the intent that they could go on weapons going to the Sandbox? I know when I was in HOA, the temps routinely hit 135-145F for at least half the year. From what I hear, Kuwait/Iraq is almost as hot.

Mickey Rourke
07-20-2011, 02:01 PM
This makes me wonder....didn't Trijicon make these with the intent that they could go on weapons going to the Sandbox? I know when I was in HOA, the temps routinely hit 135-145F for at least half the year. From what I hear, Kuwait/Iraq is almost as hot.Maybe being enclosed inside has a worse effect than being out in the open with temps being similar????

Housertl
07-20-2011, 02:05 PM
Maybe being enclosed inside has a worse effect than being out in the open with temps being similar????

I can't imagine that the trunk being closed would do more than raise the temp, since the air can't circulate.

JustMe
07-20-2011, 02:41 PM
This makes me wonder....didn't Trijicon make these with the intent that they could go on weapons going to the Sandbox? I know when I was in HOA, the temps routinely hit 135-145F for at least half the year. From what I hear, Kuwait/Iraq is almost as hot.

Maybe they did.

Sometimes manufacturers will change a part's spec on you and your product specs then drift. Or someone might change the potting material, or PCB manufacturer, to reduce costs, and cause unexpected leakage currents which affect the circuit behavior.

Thus someone at the manufacturer needs to go to the floor once in a while and grab an article before it goes out the door and verify it's specs top to bottom.

It's all mental masturbation until someone can run a sanity check as I suggested above.

Poohgyrr
07-25-2011, 08:48 AM
This makes me wonder....didn't Trijicon make these with the intent that they could go on weapons going to the Sandbox?

We have temp problems with our car laptops that were supposed to work fine over there, and our summer temps only reach 95 to 115 here.

JustMe
07-25-2011, 02:24 PM
I'd hold it in front of the AC for a minute and it would begin functioning again.

Thermal cycling is also something "consumer" devices are not designed to handle, espically like that.

This results in added stress to the surface mount components. This is why you may still find high reliability devices constructed using more expensive "through hole" methods as the pin stress bend each solder connection versus causing shear forces. Vibration and impacts make this worse.

To prolong device life I'd avoid using the AC this way. I'd expect a red dot to be designed to handle this, but not consumer electronics.

The Shadow
07-25-2011, 07:35 PM
Temps inside a car/truck cab can reach 140 degrees in short order I've kept a thermometer inserted into one of the air conditioning vents on my vehicles for the last 18 or so years, and I religiously use a sunscreen to cover the dash.

Within 30 minutes it can go from approx 60-70 degrees inside a car to 120-130 and I've even seen it higher if in the sun or longer time in shade.

I've used the thermometer to check the air temp in summer everything working OK vent temp is at 40 degrees, in winter temp can get up to 79-80+ depending on where the controls are set.

People often exclaim about how it was only 15-20 minutes the baby/child was in the vehicle, I just ran into the store for a minute and the child died due to heat complications, it doesn't take long for a child or animal to die if left in a vehicle.

gunplumber
07-26-2011, 09:26 AM
Prescott isn't phoenix bro.

Yes, a few weeks ago it was 116 here in Surprise (NW Phoenix metro). So GF & I drove to Prescott and then Jerome, because it was a cool 100 up there.