ROBERT
* lithium cobalt formulations have never burst into flame because of contact with air
* the risks are:
- impact damage causing internal shorts - can cause fire
- over charging can cause fire
- over discharge - too high a rate can cause fire - but taking to a ultra low charge state wrecks the cells
- using cells which are too cold can result in massive overheating and fire
- USERS ignoring obvious signs of damage such as impact marks, puffing and overheating
- makers over specifying cells and users refusing to accept that this was the case
These are risks in ultra high discharge situations eg near maximum cell discharge rates
People who have fires in cell charging have either failed to use a balancing charger or ignored the signs of damage to cells
As presented the battery system in question should be very safe
* they have impact resistant cases
* good connections system
* full time battery management
The scaremongering over the dangers of lipo has been legendary and associated with misuse of cells, inappropriate cells and refusal of users to accept repsonsibility for their own actions.
Having used Lithium cobalt for the last 10 years in ultra high out put systems, my experience suggest used appropriately used Lithium cobalt is increasing stable safe and very very powerful.
Andrew Gilchrist
----- Original Message -----
From: rschwirz [mailto:rschwirz@sbcglobal.net]
To: electricboats@yahoogroups.com
Sent: Fri, 27 Jan 2012 01:09:03 -0000
Subject: [Electric Boats] Re: Marine Li-Po Batteries 51.8Vdc 100-200 Ah
Interesting info
I have been using Lithium Polymer Batteries for years with my the remote control model airplanes and I like them.
They are very good.
Model airplane enthusiast also know there comes a danger with Li-Poly batteries.
I several cases the airplanes burst into flames while the batteries are been charged. Not only out there in the field but also in peoples basements.
The chemicals of the Li-Poly batteries used in airplanes are only in a light weight pouch. If that pouch gets punctured and the Lithium gets exposed to air
It will ignite into high temp flames just by coming in contact with air. That's why all the suppliers of those batteries recommend charging them outside the house in a flame retardant container. Again, those pouches are light weight and can be damaged easily in a small crash.
I know youtube has some videos about Li-Poly fires http://www.youtube.com/results?search_query=li-poly+battery+fire&oq=Li-Poly&aq=0&aqi=g6g-C1g-sC1&aql=&gs_sm=c&gs_upl=4092l7410l0l13422l7l7l0l0l0l0l377l1822l0.1.1.4l6l0.
There is no danger with LiFEPO4 batteries as far as I know.
Robert
--- In electricboats@yahoogroups.com, Bill Heintz <bheintz@...> wrote:
>
> Perhaps af interest: from LinkedIn Green Yachts Design & Tech Group
>
>
>
>
> Marine Lithium-Polymer Batteries Developed by ESTechnologies BV -
> Netherlands
> Monday, January 23, 2012
>
>
> ESTechnologies has designed the first Lithium-Polymer battery with
> Lloyds Certificate in the world. This battery is specially designed
> and certified for Marine applications and large Energy storage systems
> in the most harsh environment.
> Energy storage
> With a Lithium Polymer Battery you can create energy storage in a cost
> effective manner, reducing fuel and therefore making a contribution
> to a better environment. Reduction of CO2 emissions, and energy which
> normally gets lost, will now be saved and stored by means of optimized
> power management.
> This makes the use of energy more efficiently. This is due to the
> special qualities of the lithium polymer cells. Firstly, the chemical
> composition of the battery, using non corrosive chemicals which
> guarantees long lifetime and little wear.
> Secondly, the use of polymer technology allows to make batteries with
> extremely high efficiency and low impedance(lowest on the market).
> The polymer technology and the chemical composition makes it possible
> to realize an extremely high number of charge / discharge cycles, over
> 5000 cycles, with a long lifetime.
> With these cells ESTechnologies produces high voltage and high power
> battery systems. For this purpose, 51.8 Vdc battery blocks have been
> developed with a capacity of 100Ah or 200Ah.
> The battery blocks are built with only 14 large single cells instead
> of (most common), hundreds of small cells. This contributes to the
> already high reliability of the battery systems.
> Battery Management System
> To guarantee the extensive lifetime of this battery, ESTechnologies
> has also designed a unique Battery Management System with constantly
> active balancing. Unlike any other system available on the market
> today, this Battery Management System has superb specifications. It
> can balance energy between cells within one battery unit and even
> between cells of different battery units connected in one system. This
> is all achieved with minimal losses. Special care has been taken to
> ensure safety at all times. High DC voltage is present at large energy
> storage systems and additional safety measures are built into the
> battery module itself.
> The batteries communicate with other modules and system controllers
> like NMEA2000 devices. The 50V battery modules are constructed for
> durability with just 14 large LiPo cells in series and a reduced
> amount of parts.
> Each cell has its own chemical process. Therefore a balanced system is
> needed. EST uses an in-house developed, state of the art, active
> balancing and monitoring board for each module. If there is an
> imbalance in the system, a part of the energy will be transported from
> the highest cell to the lowest cell. Result: The EST modules are
> always 100% balanced.
> The required voltage is realized by connecting batteries in series,
> the required power can be obtained by connection these battery series
> in parallel. ESTechnologies is responsible for the complete supply and
> installation of the complete system including battery, total battery
> management and safety features.
> Because of working with a high DC voltage, safety has top priority and
> is included in the overall design philosophy. The housing and
> connectors are fully protected and have IP65 rating.
> Further Development
> ESTechnologies is still improving their batteries and have now made a
> very important step forward. They have found positive improvements
> regarding the weight of the batteries.
> ESTechnologies has succeeded to reduce the weight of their batteries
> with 12% from 85 kg to 75 kg. This by using a new cell which is
> lighter and by improving the mounting frame on the inside.
> Other Specifications of ESTechnologies batteries are:
> . Lloyd's Certified with Lloyd's Certified power connections
> . Certified for high DC voltage systems
> . Have a charge and discharge efficiency of more than 95%
> . Configurable for Mega-Watt applications
> . Very light weighted and ultra-compact in size
> . Designed for large energy storage systems
> . Maintenance free
> . Environmental friendly (100% recyclable)
> . 10 years limited warranty
>
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