Allan, I use my gps with a waterproof bag with a transparent window. That works fine, but sometimes it's hard to read the gps screen through the window. That's why I thought I'd try the silicone grease, so I can use the gps without a bag. (BTW, the unit floats, so there's no danger of losing it if it falls in the water.) Recently I tried sealing the edge of the battery cover of my gps, but a few drops of water did get in, and must have produced some kind of short, because all of a sudden the gps lost all power. When I got home I dried the compartment, put new batteries in, and the unit was fine, except it had lost all stored waypoints and other data. The reason why I think FILLING the compartment with grease might work is that then no water can get in at all. Of course, changing the batteries would be messy, but that's a price I'm willing to pay for using the gps without a bag. Jack Fu 47 37 39 N, 122 07 57 W -----Original Message----- From: Allan McLane [mailto:amcl_at_sover.net] Sent: Friday, September 01, 2000 9:36 AM To: Jack Fu Subject: RE: [Paddlewise] Filling battery compartment with vaseline? Jack, I'm not sure that I'd go and wholesale fill up a battery compartment... yikes, what a mess that will make! A little grease on seals usually will do the job. If there's misalaignment on the cover and gaps that water can get in then maybe try some vinyl electrical tape or some of that silicone splicing tape. Just some thoughts as I've never actually tried any of this myself ;] FWIW, My Garmin GPS 12XL battery cover is designed so that a lot of water could get in quite easily... I'd prefer some sort of waterproof bag with a window... --allan On Fri, 1 Sep 2000 09:17:37 -0700, Jack Fu wrote: >>> A much better choice would be silicone grease, available from industrial >supply houses. > >Good point, thank you! I'll go look for some silicone grease. > >Jack Fu >47 37 39 N, 122 07 57 W > *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced/forwarded outside PaddleWise without author's permission Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Jack Fu wrote: > I use my gps with a waterproof bag with a transparent window. > That works fine, but sometimes it's hard to read the gps screen > through the window. That's why I thought I'd try the silicone > grease, so I can use the gps without a bag. [snip] > The reason why I think FILLING the compartment with grease might > work is that then no water can get in at all. Of course, changing > the batteries would be messy, but that's a price I'm willing to > pay for using the gps without a bag. I have no direct experience with greasin' battery compartments, but I am skeptical that it would work to keep water out. Reason: as the unit warms and cools, the grease will expand and contract. Silicone grease expands quite a bit with temp, for some reason. When the grease expands, most likely it will ooze out through the "seal" (note oxymoron), and get transferred to something else. Then, when the GPS cools, perhaps as a result of going under water, the grease will contract, creating a void for water to enter. After a couple cycles of this sort, you will still have water in your battery compartment, albeit not much. 'Course, it does not take "much" salt water to short out a battery! If you are serious about preventing water intrusion, perhaps a tight-fitting, elastic rubber enclosure that slips over the end and up far enough to cover the battery compartment but leaves the screen unobscured will work. 'Bout the only thing that comes to mind in that department is the ubiquitous condom. And, actually, one of those might be clear enough that even if it did go over the screen, you could still read the screen. When you go shopping for that, make sure there are no videocams to record the "Candid Camera" conversation ... Professor Inverbon, where are you? -- Dave Kruger Astoria, OR *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced/forwarded outside PaddleWise without author's permission Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
>> If you are serious about preventing water intrusion, perhaps a tight-fitting, >> elastic rubber enclosure that slips over the end and up far enough to cover the >> battery compartment but leaves the screen unobscured will work. 'Bout the only >> thing that comes to mind in that department is the ubiquitous condom. And, >> actually, one of those might be clear enough that even if it did go over the >> screen, you could still read the screen. Dave, TransLUCENT condoms I have seen (and have), but trasPARENT ones? Never seen one. ;-) Jack Fu 47 37 39 N, 122 07 57 W *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced/forwarded outside PaddleWise without author's permission Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
There seems to be a bit of confusion on this list regarding the function of "leaking" battery compartments, both in GPS receivers and in VHF alkaline battery trays. It is not difficult to design a AA battery compartment that is completely watertight. I have a $10 diving flashlight that uses AA batteries and is watertight to 2000 feet. Why, then, are there so many examples of electronic gear that are designed to have leaking AA battery compartments? On reason is to avoid explosion. As alkaline batteries are used, the corrosion of the electrode in the electrolyte causes hygrogen gas to be released. To quote from the NIOSH factsheet on "Exploding Flashlights", many battery compartments "are constructed to allow leakage" of hydrogen gas. This is not the only way to deal with the problem. Instead, "some manufacturers of equipment with air- and water-tight battery compartments have incorporated safeguards to prevent H2 accumulation. For example, one-way relief valves may be incorporated in battery compartments to allow H2 to escape. Or, chemicals may be used to absorb or recombine H2." (It is this latter design that my diving flashlight uses.) It is an easy matter to modify a battery compartment to make it watertight. But before you do so, make sure that you consider why the compartment was designed to leak in the first place (to vent hydrogen gas), and be sure to include a gas-absorbing chip, one-way relief valve, or other design modification so that you do not transform your GPS receiver into an exploding GPS receiver. The NIOSH factsheet can be found at the following URLs: http://www.usfa.fema.gov/alerts/flashlgt.htm http://www.cdc.gov/niosh/fact0002.html Dan Hagen *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced/forwarded outside PaddleWise without author's permission Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
It's bad enough having a gps die on you on a long trip, but to have one explode is even worse! Guess I'll just stick with the waterproof bag. *SIGH!!* Jack Fu 47 37 39 N, 122 07 57 W *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced/forwarded outside PaddleWise without author's permission Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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