Product category: Batteries and Chargers
News Release from: Saft Lithium Battery Division | Subject: VL 25500-125 and LSH 20-150
Edited by the Electronicstalk Editorial Team on 27 November 2007
Lithium-ion cell claims temperature record
Robust Li-ion cell is capable of charging and discharging at extreme temperatures up to +125C, while being able to safely withstand temperatures up to +135C
Saft has launched the world's first Li-ion (lithium-ion) cell capable of operating at temperatures up to +125C - an innovation that opens up exciting new possibilities for the design of MWD (measurement while drilling) tools. At the same time, Saft has also launched a new D-size primary lithium cell.
This article was originally published on Electronicstalk on 27 November 2007 at 8.00am (UK)
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The launch of the new VL 25500-125 Li-ion cell and the new LSH 20-150 primary cell is a major development in the design of reliable, cost-effective power sources for electronic equipment operating under the high levels of shock, vibration and pressure and extreme temperatures experienced by MWD tools in the oil and gas exploration industry.
To complement its growing range of lithium cells for MWD tools, Saft operates a dedicated battery design, development, testing and volume production facility at its factory in Poitiers, France.
Here, the lithium cells are integrated into bespoke, ruggedised cylindrical MWD battery systems, known as 'staves'.
As well as ensuring that the lithium cells have reliable electrical connections, a key element in the stave design is to provide complete mechanical integrity, even under extreme temperatures, vibrations and pressures.
This involves careful selection of the construction materials and specialised manufacturing techniques, such as the cross-ply tape wrapping process.
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The staves also incorporate electronic controls, such as diodes to protect primary cells or balancing circuits to manage rechargeable cells.
MWD tools incorporate a variety of electronic sensors, such as accelerometers and magnetometers.
These provide the operator on the surface with real-time information about the tilt and position of the wellbore, especially in directional drilling, as well as detailed information about the conditions at the drill bit, such as: rotational speed; torque and weight on the bit; vibration; temperature and type of rock formation.
As there is no possibility for a direct cable link from the surface to the drill bit, the electronics are powered by onboard battery systems, and the data is transmitted most commonly by a technique known as mud pulse telemetry.
MWD is a highly demanding application that creates a challenging environment for the batteries.
They must operate over a wide temperature range - from well below 0C at the surface in Arctic oil and gas exploration projects to well over 100C during drilling - while enduring very high vibrations (20g RMS) and provide complete reliability for long periods (typically from a few hours to over 20 hours).
This is especially important as time is money in the exploration industry.
Each time the bottom hole assembly has to return to the surface it costs tens of thousands of dollars in downtime, so premature withdrawal to replace a failed MWD battery would add very significant costs to the operation.
Saft has achieved a world first by creating a robust Li-ion cell capable of charging and discharging at extreme temperatures up to +125C, while being able to safely withstand temperatures up to +135C.
This major leap in operating temperature, from the current maximum of +65C, opens up new horizons for MWD tool developers and manufacturers as, for the very first time, they will be able to incorporate a high performance rechargeable battery in their design.
In some future applications this could eliminate completely the need to withdraw an MWD tool for replacement of a spent battery, with the benefit of improved continuity for the drilling operation.
The new VL 25500-125 C-size and VL32600-125 D-size cells are intended for use in the construction of batteries to be integrated within sophisticated MWD tools that incorporate onboard alternator technology, driven by the mud flow, to power their electronic systems.
When the mud is flowing the battery will be charged.
When the flow stops, such as when drilling is halted, the battery will be discharged to provide power for the MWD electronics.
When the flow restarts the battery will recharge itself.
The fast-charging, deep-discharge and high cycling capability of the Li-ion electrochemistry will effectively enable the MWD tool to remain in continuous downhole operation.
At the same time, Saft has also launched the LSH 20-150, a new D-size primary lithium cell capable of operating at temperatures up to +150C.
Currently, the optimum primary battery solution for MWD tools utilises lithium-thionyl chloride (Li-SOCl2) cells such as Saft's super robust LSH 20 HTS D-size cell, which is a mechanically enhanced version of a design developed originally for space probes.
With the new LSH 20-150, Saft has extended the maximum operational temperature to +150C (from the previous maximum of +120C).
The new cell enables Saft to address the battery needs of the mid-temperature applications (+125 to +150C) that are the most substantial part of the MWD market. Request a free brochure from Saft Lithium Battery Division....
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