NiCd cells with 4 year life for emergency lighting

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treez

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Hello,

We are making a 5W LED light which comes on when the mains falls, to illuminate an emergency exit sign.

Our boss insists that we are sure that the NiCd cells that we use can definetely manage this duration (4 years) ....and wants to know the price difference for cells which can give a 7 year life.

How can we find this out?, i only know the SAFT website, and they give no price information.

Do you know the name of any battery manufacturers where i can find this information?

(we use NiCd as its the cheapest)
 

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If you want a fully charged battery for intermittent use I am not sure that NiCds are the best choice. For them to retain their ampere hour capacity they need to be cycled frequently. I think that if you keep your battery fully charged its capacity will diminish. Try Li ion cells, this site seems to have a lot of gen. :- https://www.batteryspace.com/howtochoosebattery.aspx
Frank
 
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NiCd batteries have the memory effect problem... So it is risky to keep them for auto-recharge for such a long period... As per chuckey, Li ion are good. For non-rechargeable batteries, Lithium thionyle batteries are good...
 
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Though SAFT actually have the VNT range of NiCd batteries, which they say is specifically for emergency lighting, so NiCd must be good for emergency lighting.
 

treez said:
Though SAFT actually have the VNT range of NiCd batteries, which they say is specifically for emergency lighting, so NiCd must be good for emergency lighting.
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If Saft can guarantee their batteries for your sort of service, get it in writing and go for them. Else they would be very good for Saft as they would need replacing every year or two.
Frank
 
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NiCd can have around 5-6 years lifetime if there is a quality of product. My opinion that is bad choice. This kind of batteries are very toxic! You must use some kind of condition checker and periodic jogging-cycling circuit. Lithium based batteries are becoming cheaper and cheaper on markets. NiMh have lifetime range around 3 years, that means for now that lithium based batteries are right choice, if price is adequate.


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"Nickel Cadmium (NiCd) — mature and well understood but relatively low in energy density. The NiCd is used where long life, high discharge rate and economical price are important. Main applications are two-way radios, biomedical equipment, professional video cameras and power tools. The NiCd contains toxic metals and is environmentally unfriendly."




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