Leaks and other problems arise in the battery compartment of strobes such as the Inon and Sea&Sea UW strobes.
Inon Strobes have a double cap, an external female cap that seals out the water and an internal one with spring contacts and a screw nut to secure the batteries. Leaks arise when the edge of the cap as it is being screwed down twists part of the O-ring and allows water into the battery compartment.
The solution is to keep the O ring lightly lubricated, in a pinch even saliva will do. To prevent leaks, it is very important that one look all around the O-ring each and every time the cap is screwed on.
The inner Inon battery cap (and Sea&Sea cap) has metal spring terminals to interconnect the batteries. To prevent corrosion, after diving in salt water they need to be rinsed in fresh water, dried and lubricated.
The screw nut for the inner cap is a nuisance to screw on, and is easy to misplace or drop. Packing a spare screw nut is not a bad idea, and if lost, it can be replaced with a wad of paper or a short length of plastic tube, say cut from a ball point pen or Tygon tubing, so the outer cap compresses the inner cap to contact the batteries firmly.
As this three part Inon battery cap is trouble prone let us hope Inon soon replaces it with a secure one piece cap.
Sea&Sea strobes use a plug style cap with the O ring mounted on it in a groove. The cap plug has a twist seal with three prongs that lock it to the battery compartment. As long as the O ring is intact and the surfaces are clean, this cap provides a secure water proof seal, and is easy to use.
The cap's O-ring requires minimal silicone lubrication. However, the caps electrodes which connect the batteries two by two can bend out of alignment, as shown here by the bent lower right contact.
Sea&Sea has improved the design of their cap over the years, and fortunately the old and new styles are interchangeable.
Photo of old and new Sea&Sea strobe battery caps, Sub-50 TTL on left, YS-110 middle and YS-D2 on right.
The battery compartment itself is quite similar in both strobe makes. Troubles such as poor contact, strobe not turning on or intermittent power failure arise from corroded battery contacts at the compartment's bottom where there are three battery contacts; the one shown below links two of the four batteries.
If it corrodes, it can be removed to be polished; the screws do not go through the plastic case.
The two other contacts are sunk into the compartments body and cannot be removed; when corroded, they can be polished by attaching a piece of fine steel wool to the end of a thin rod, pencil or a pen, and rotating it.
The hexagonal head screws at the bottom connect to the electronic compartment. As they are not sealed, once water enters the battery compartment it can flood the electronic compartment by leaking around these screws. It is most desirable for the strobe manufacturers to seal these screws, such as with O-rings, so they are water proof.
The Sea&Sea and Inon battery contacts that connect to the electronics are recessed and have small gaps around them, visible here at each of six corners, which allow water to enter the electronic compartment.
To prevent battery problems, such as leakage and corrosion, it is a good idea to use top of the line batteries, such as Duracell and Eneloop. A small digital battery tester, say from eBay, is quite useful. Also, be sure to remove the batteries at the end of each dive trip or season.
O-Rings: Inon and Sea&Sea use different types of O-rings. Even though both makes of O-rings are surprisingly tough and durable, it is wise to carry spares. They should be removed and inspected on a regular basis, say before and after each dive season. The Inon yellow O-ring is 4x42mm and Sea&Sea blue O-ring is 3x34mm.
Sync Cord Plug (Bulkhead): Those us who only use fiber optic cables tend to forget that strobes have a capped sync cord connector (bulkhead). Its cap should be unscrewed and the connector, cap and O ring inspected and cleaned at least once a year, or at the beginning and end of each dive trip or season.
The battery compartment is the strobe's Achilles heel, giving it attention and loving care is a wise investment.
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Edited by Kraken de Mabini, 16 June 2019 - 02:45 PM.