Submerge scooters, the first DPV company in the USA to stock and deliver NiMH underwater scooters to divers around the world, is continuing it's commitment to offer the best power solutions for your underwater vehicles. In early 2004 we developed a custom NiMH power pack which was used by Gilberto Menezes of Brazil to complete the survey of one of the longest underwater caves in the world, where the end of the line is currently at 21,000 feet. (see latest news page) Even more impressive, during his dive, 1 single scooter was used to scooter 9000 meters or 30,000 feet, possibly doubling any any distance covered by a single scooter before. Based upon this experience, and 5 years of providing scooters highly regarded for performance, reliability and service, we have chosen SAFT NiMH technology. SAFT batteries are THE premium NiMH "F" cell producers in the world. We took some time out to dive the production SAFT UV-18 NiMH scooters, with positive reviews. These packs endurance compares to the Genesis 26 amp packs, but with a much more manoeuvrable package that also saves nearly 25 pounds of above water weight. Although we rate the UV-18 NiMH at 90 to 100 minutes run time, we easily cruised for over 130 minutes, covered about 4.2Km / 14,000 feet, with video camera attached, and still had almost 30% reserve! Feel free to view the video of one of the UV-18 NiMH dives at Jackson Blue cave, Florida! Cameraman: Rodney Nairne. Divers: Suzie Dudas and Rob Steffen. Download 20 MB UV-18 NiMH cave diving video here copyright Rodney Nairne 2005 Comparison standard UV-18 and NiMH version. Completely interchangeable, same hull and nose cone. Mascot 32 volt power supply. Charging electronics are built specifically for these SAFT packs, and are internal to the pack. Advantages of the SAFT NiMH pack: In the UV-18 size scooter, the NiMH batteries double the burn time. (SEE TABLE BELOW) Outperforms lead acid chemistry in cold temperatures. Possibility of more charge cycles (yet to be determined in the field). Disadvantages: To protect the batteries from cell reversal, the pack cuts off completely at 21 volts. This means you have no "limp home" option if you over extend your dive. Consistency and repeatability of capacity is no match for the Lead Acid Genesis: We burn test ALL batteries so we have a lot of experience with NiMH vs Lead Acid batteries. The Genesis lead acid packs will give full capacity time after time. The NiMH packs will give inconsistent results from 1 test to the next. For example, expect the NiMH to give between 70 to 100% of capacity when the ambient temperature is relatively high (75-85 degrees F). For example, on 20 cell Chinese F cell packs we have tested, the capacity can be anywhere from 33 to 45 minutes from one test to the next. The SAFT packs we use can be between 70 and 103 minutes for the 40 F cell pack. (on average 10% more than the Chinese cells) Whereas the UV-26 Genesis will give 90 minutes every time, and the UV-18 will give 50 minutes every time. I would expect batteries need to be replaced every 3 years, so the 500 or 1000 cycle life of NiMH batteries is irrelevant unless you scooter dive EVERY DAY! (Besides, the Genesis batteries have 400 cycle life @ 80% depth of discharge.) At least 40 more connections in the scooter, although the cells are spot welded which is possibly as reliable as the 6 "cells" in each 12 volt lead acid battery. Not as "water-proof" as the Genesis which claim to be sealed to 100 feet of pressure. Control electronics increases complexity of the electrics, extra failure points, and not waterproof. Prices: Battery pack conversion $1450, Includes batteries, charger, bulkheads and wires. UV-18 NiMH $4500. Weight 70 pounds, same as UV-18 sealed lead acid. Lastly, you can switch between the NiMH and lead acid at any time. Completely interchangeable between the 2 chemistries. Particularly useful if you need to re-sell your scooter but don't want to pay $1000 for a new set of NiMH batteries, or if you want cheaper batteries as you no longer need the extended run times. WARRANTY: Submerge does NOT warranty the packs, for any reason, including flooding due to ANY reason. Good news: Our scooters don't flood unless you forget to do up a latch, or other user error which is the same with any other piece of underwater equipment. 2nd Good news: these packs are covered by a SAFT warranty for 12 months. Charge indication: Very accurate. Adjusts to the aging of the pack. NOT simple voltage indicator. As pack ages and capacity decreases, a full discharge/charge cycle adjusts the electronics to give the true capacity reading. Very useful for cave dives, as you can check the remaining reserve capacity. If you have less than 20 -40% in reserve after a cave dive, time to review your dive planning! OUR RECOMMENDATIONS: The Genesis lead acid battery is still the superior option. This is when charge complexity, cost, ease of replacement worldwide, and proven reliability is taken into account. For ocean dives, the UV-18 Genesis lead acid. For cave dives, the UV-26 Genesis lead acid. If you boat/ocean dive and cave dive, the UV-18 with the UV-26 conversion. Use NiMH only if you can not accept the extra weight of the UV-26 but need to scooter for more than 60 minutes provided by the UV-18 Genesis. If you are boat diving and need 2x 60 minute dives, remember you can buy the UV-18 with an extra battery pack and switch it between dives. For most divers, 2 boat dives can easily be completed on a single Genesis UV-18 battery pack, and we suggest you try this first and only buy the second battery pack only if required. Note lead ballast weight. Purpose of ballast: 1) maintain same weight as lead acid batteries/maintain interchangeability 2) maximise the propeller torque offset, needed for longer, effortless scooter dives. Without torque offset, scooter dives over 30 minutes make the diver expend more arm effort. This is very important consideration for longer dives, especially as this pack will run over 150 minutes on cruise speed.
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