Background information

Hartenberger Unterwassertechnische Geräte GmbH - Handleuchte professional / Handleuchte compact

Traditionelle Akku-Tecnology


Nickel-Cadmium- (NC) und Nickel Metall-Hydrid- (NMH) Akkumulatoren are generally described as being gas and acid sealed cells. The position of the cells during the charging process is therefore irrelevant as no electrolyte can escape. There is however no supplier of cells that will guarantee this feature for the entire life of the cells! During the charging or discharging process, the cells may produce an over pressure inside, opening the integrated over pressure relief valve.
Should this occur, the electrolyte, or Hydrogen can escape from the cells.
Because the electrolyte is a very aggressive acid, and additionally conducts electricity, this may lead to the galvanic corrosion of the cells, and a destruction as a result of the contact with the acid. The escaping hydrogen can combine with oxygen in the air and form a highly explosive gas. A single cell the size of a standard D cell battery can produce up to 25 litres,
(1 cu ft) of gas!
It is for this reason that Nickel-Cadmium cells and Nicke- Metall-Hydride Cells should always be removed from a housing before they are recharged. Only then is the safe use and longest possible life of the cells guaranteed.

Since the company's founding in 1983, we have manufactured powerful underwater lamps using nickel cadmium re-chargeable cells. These cells are extremely resilient to high power consumption. The cells are sturdy and with the proper care and attention it is not unusual to reach over 10 years of reliable service with these cells.
Efforts are presently being undertaken to ban these cells for environmental reasons (probably taking effect in 2008, the imminent introduction of these regulations and the negative environmental implications of nickel cadmium cells have driven us over the past 10 years to search for safe and reliable power alternatives.


Hartenberger Unterwassertechnische Geräte GmbH - Handleuchte professional / Handleuchte compact




Since 1998, we have been using type-A nickel metal hydride re-chargeable cells.

Although the high power drain resistance properties of these cells particularly in cold operating conditions is not as good as the nickel cadmium cells.
The life expectancy is usually 4-6 years,but the cells offer weight and price advantages and make an ideal alternative for small lightweight underwater lamps for the travelling sport diver.



Dangerous cells for use in


Keeping pace with modern technological developments, particularly in the area of re-chargeable cells, we are constantly testing new products.
The lithium ionen cells offer apparent advantages in power and capacity but also present certain problems and potential risks that have become apparent during our research and development work.
After testing these cells for approx. 3 years, we have come to the following conclusions:
The high power/time requirements of an underwater lamp (approx 1 hour discharge) exceed the capabilities of lithium ionen cells.
The life expectancy of lithium ionen cells is drastically reduced (to approx 2-3 years) in high operating temperatures.
The balance of the individual cells within a cell pack must be monitored and controlled by complicated electronics. If this fails and individual cells fall out of line, then the reaction between the lithium and the stored cobalt (so called metallic burn) is extremely dangerous and is drastically accelerated by the presence of water.
If a lithium ionen cell is damaged mechanically (such as dropping the lamp, or if the lamp is subject to a sudden blow in baggage) the cell may, even after some time, react and explode.
Such accidents have been documented on many occasions in laptop and mobile telephone applications.
For safety reasons, we will never use such
re-chargeable lithium ionen cells in our underwater lamps.
Considering these risks, we cannot understand other manufacturers who use such lithium ionen cells with these disadvantages and the potential dangers, especially in sealed housing lamps.



Safety cells for use in


Since 2003 we took receipt of a newly developed
re-chargeable cell for test purposes, a Lithium-Manganese-Cell.
The electrode material is manganese sealed in a so called spinell rather than the traditional cobalt electrode.
The cells have proven themselves to be the "wonder cells" with the following properties:
  • Excellent power properties and resilience
  • Low self discharge, less than 3-8% per Month
  • At temperatures as low as -15°C (+5°F), the cells retain 95% capacity.
  • A missing (defective) protection switch within the cell will reduce the capacity of the cell but will not produce an explosive reaction such as those previously mentioned in lithium ionen cells.
  • Mechanical damage such as a blow or squeezing, or even a puncture of the wall of the cell such as with a nail will not produce a critical chemical reaction within the cell.
  • For fully charged cells at high ambient temperatures, the aging process of these cells is considerably less than that in lithium ionen cells.

    Another feature that must be mentioned is that aged lithium manganese cells do not produce dangerous hydrogen gas and therefore make re-charging in a sealed housing much safer and in our opinion only now possible.

    The only disadvantage of the lithium manganese cells is that the energy density is approx 10% less than lithium ionen cells. Compared to the nickel metal hydride cells, the lithium manganese cells have 30% higher energy density.
    These positive properties of the lithium manganese cells have provided us with the opportunity to develop new underwater lamps with benchmark features using modern materials combined with Hartenberger technology.
    nano compact
    mini compact LCD
    maxi compact LCD

Hartenberger, leading the way in underwater lighting




Für viele unserer Leuchten ist dieser Lithium-Mangan-Akkumulator optional erhältlich.
Der steckbare Wechselakku besitzt eine spezielle Überwachungselektronik. Diese ermöglicht das automatische Laden mit demselben Ladegerät, welches wir für das Laden von Nickel-Cadmium oder Nickel-Metall-Hydrid-Akkumulatoren verwenden.

Der spätere Wechsel zu diesem modernen, leistungsstärkeren Lithium-Mangan-Akkumulator ist daher nicht mit zusätzlichen Anschaffungskosten für ein spezielles Lithium-Ladegerät verbunden.

Der Lithium-Mangan-Akkumulator (LiMn) ist zur Zeit der sicherste und einer der leistungsstärksten Akkumulatoren.