Underwater Scooters (DPVs)

Dive Gear Express is an authorized dealer for Submerge Underwater Scooters (Diver Propulsion Vehicles), upgrades/Accessories and replacement Parts. Their Minnus line of Diver Propulsion Vehicles (aka DPV, aka 'scooter') with LiPo NMC batteries, brushless DC motors, and electronic speed controls represents the latest generation of technology.

DPV Battery Technology Tradeoffs

Lead Acid Nickel Metal Hydride Lithium Polymer
Lead acid batteries are a very mature technology, having a low cost. NiMH batteries are modern technology and more expensive than lead acid. LiPO batteries are newest and most expensive technology, but with best characteristics.
As lead acid batteries discharge, particularly as they near full discharge, the scooter becomes gradually and progressively slower. NiMH batteries maintain full power throughout discharge but will cut-off suddenly when they have been fully discharged. If used with an Electronic Speed Control (ESC) LiPO batteries can discharge with graceful degradation, similar to lead acid.
Modern high quality lead acid scooter batteries can have a life of up to 500 cycles but typically less, and in DPV applications can only deliver about 60% of nominal rated capacity. NiMH batteries have a life of over 500 cycles, and in DPV applications can deliver about 80% of nominal rated capacity. LiPO batteries have a life up to 1000 cycles and can deliver 100% of nominal rated capacity.
Lead acid batteries are double the weight of similar capacity NiMH batteries. NiMH batteries are much smaller and lighter than lead acid batteries of similar capacity. Lithium Polymer batteries are the lightest batteries currently available.
Lead acid batteries recover well from over discharge, if re-charged as soon as possible. NiMH batteries can suffer from reverse charging if over discharged, causing permanent damage and reduced burntimes. LiPO batteries incorporate electronics to protect cells from over discharge.
Lead acid batteries have an low rate of self discharge. The higher the ambient temperature, the higher the rate of self discharge. Idle NiMH batteries must be 'topped off' periodically. Lithium Polymer batteries have almost zero self discharge. LiPO should not be stored with a full charge.
No transport restrictions. No transport restrictions. Lithium chemistry batteries are not approved for transport in passenger aircraft.

There is still some demand for scooters using lead acid batteries, they are simple and inexpensive with the main objection being size and weight. Although Nickel Metal Hydride technology in DPV applications is not as ideal as lithium, NiMH offers huge weight savings over lead acid and also has no transport restrictions. Keep in mind that regardless of the battery chemistry, you should not expect more than 3 to 4 years of service life from any DPV battery.

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