Every time I store my skis on the trailer, my normal routine is to unplug the 6 pin connector from the rear electrical box. If the battery stays in the ski, this is the quickest way to eliminate the MPEM from drawing power. Then you don't have any issue of having a dead battery in a few days or weeks. THIS INFORMATION ONLY APPLIES TO DESS-EQUIPPED SKIS. 1995 and prior skis do not have this battery drain problem.
Technical Information | ODYSSEY® Battery
Issue – This brand of watercraft experiences an electrical load on the battery during storage, caused by a control module monitoring the lanyard socket. If the lanyard is left installed the electrical drain is 18 ma after 10 minutes of shutting down the engine. If the lanyard is removed, the electrical drain is 7 ma. These electrical loads are continuous and can accumulate to be significant over time. At 18 milli amps, the battery will lose 1 amp/hour of capacity in 55.5 hours or 10 amp/hours (Ah) in 23 days. On a PC 625, 10 Ah is 59% of battery capacity.
Solution – For Sea-Doo watercraft always disconnect the lanyard from its socket when not riding the watercraft. Install a waterproof disconnect switch in the negative battery cable, so the battery can be disconnected after riding. Use switch P/N 32965 from Overton’s Marine Catalog or use the 12V, 6A Odyssey Battery charger suggested above.
Check your ODYSSEY battery voltage periodically for full charge, which is 12.84V. Recharge whenever below 12.65V.