Is it advisable to use a little dielectric grease on the connector and then maybe even shrink wrap it to make a semi-permanent connection? Seems like that would solve the issue of it coming unhooked underwater and help reduce the possibility of if failing over time? Cutting the heat shrink is easy enough if you want to swap heads.
if you're doing that, why bother with the E/O in the first place? It's a very expensive "solution" to a problem that is almost non-existent in todays equipment.
@Wstern5
Some common reasons for having E/O's
Spare Light Heads-just grab a handheld that's about the same size and is actually a redundant piece of equipment. Dive Rite LX20+ or Halcyon aren't appreciably bigger than a spare light head and are truly redundant. New battery and LED technology has essentially eliminated the need to carry a spare light head in a pocket because we don't have bulbs that fail randomly and the smaller lights are nice to have for smaller dives.
Swapping light heads for different configurations-Most all of the heads on the market now are either upgradeable with new guts or the cost of sending the lid back for a new head is not going to be appreciably more than the E/O's but if you have to replace the E/O cord because it fails mid-cord then you're in for a much more painful repair bill as the E/O cords themselves are insanely expensive. For reference if you are halfway decent with a soldering iron you can replace a light cord in about 20 minutes with $3 of cable from Lowes/Home Depot. A new E/O cord is at minimum $60 for the cord itself. Same job to solder *you obviously only have to do one side*, but it's a $60 cord vs a $3 cord.
Using different batteries for different dives-this was a big deal back in the day with lead/NiMH batteries. With the density of lithium combined with the efficiency of LED's those days are IMO over. We don't need to carry monstrous battery packs anymore. Even for the massive 12-16hr expedition level dives that the KUR and WKPP are doing, you aren't needing your primary light for the vast majority of it and with lights that kick down to low, they will last the whole dive. LD40 with the big battery will go for about 5 hours on high. If you have a 4hr bottom time on high then kick it down to low it will go for another 4 hours. Once you're in the habitat you don't need the primary lights and a backup light on low will last for a million years.
Heat is where it can get complicated for big dives where you may need redundancy in heat for safety. I personally use a dedicated heat pack for my heated vest on big dives *with the stack caps from UWLD I can easily add it to my primary canister for the <6hr dives*, and then I have an older Halcyon pack with a battery from Batteryspace and an E/O on it that will plug into my vest. The UWLD's stay on my harness and the spare one stays with my O2 bottle/mp3 player on deco. For ocean diving I wouldn't bother with carrying multiple packs since the dives should be short.
Obviously my personal opinion which goes against a lot of the older school mentalities about the E/O cords, but I personally find them a bit of a nuisance, especially on light heads. I only have them on my heated vest instead of the vastly superior Seacons *actually designed to be wet-mateable* because they are the standard in the dive industry for heated vests *same issue I have with fischer cables*.