After Every Dive
Rinse in fresh water. Soak your computer in fresh water for 15–30 minutes after every saltwater dive. Press buttons while submerged to flush salt from around the button seals. Salt crystals that dry in place corrode contacts and stiffen buttons over time.
Dry naturally. Air dry out of direct sunlight. Never use a hair dryer or compressed air — heat can damage LCD screens and O-ring seals, while compressed air can force water past seals.
Inspect the sensor port. The pressure sensor port on the underside of the case should be clear of debris, sand, and salt buildup. A blocked port can cause inaccurate depth readings.
Battery Types and Replacement
User-Replaceable Coin Cells
Computers like the Suunto Zoop Novo, Cressi Leonardo 2.0, and Mares Puck 4 use standard coin cell batteries (typically CR2430, CR2450, or similar). These last 100–300 dives depending on backlight use. Replacement involves opening a battery hatch on the back of the computer, swapping the cell, and re-sealing with a fresh O-ring (included in battery kits). Always replace the O-ring — a reused O-ring is the most common cause of flooding.
When to replace: Replace when the low battery indicator appears, or proactively before a dive trip if you have not replaced it in over a year. Do not wait until the battery dies mid-dive.
Rechargeable Lithium Batteries
The Shearwater Peregrine, Garmin Descent series, Suunto D5, and most watch-style computers use internal rechargeable lithium batteries. Charge before every dive trip. These batteries do not need to be fully drained before charging — partial charges are fine. Over time (3–5 years), lithium cells lose capacity. Most manufacturers offer battery replacement as a service.
Charging tips: Charge in a cool, dry environment. Do not charge in direct sunlight or in an enclosed hot car. Most computers reach full charge in 2–3 hours via USB or magnetic charging.
Long-Term Storage
If you will not dive for several months, rinse the computer thoroughly, dry it completely, and store it in a cool, dry place out of direct sunlight. For user-replaceable battery models, consider removing the battery to prevent slow drain or corrosion — but only if your computer retains dive log data in non-volatile memory (most modern computers do). For rechargeable models, store at roughly 50% charge and top off every 3–4 months to prevent deep discharge.
When to Get Professional Service
Condensation under the glass: This indicates a seal failure. Stop using the computer immediately and send it to the manufacturer.
Erratic depth readings: If the computer shows depth on the surface or reads significantly different from a buddy's gauge at the same depth, the pressure sensor may be compromised.
Corroded contacts or stuck buttons: Usually caused by inadequate rinsing. Minor corrosion can sometimes be cleaned with a soft brush and isopropyl alcohol, but persistent issues warrant manufacturer inspection.
After any flooding: Even a small amount of water inside the case can damage electronics. Send it in for inspection.