Lithium-ion charging schemes, or modules?

Lithium-Ion is charged with scheme known as CCCV(i.e Constant Current Constant Voltage).Since the impedance of the battery is very low always it is required to control the current else it will cause gasing and result can be dangerous.

For your application there are many standard IC's available from TI,National,Maxim,Intersil etc.

http://focus.ti.com/paramsearch/docs/parametricsearch.tsp?&familyAliasId=1000411&familyId=411&uiTemplateId=NODE_STRY_PGE_T&techFamId=null&rootFamilyId=null&sectionId=null&tabId=null&appId=null&viewDeviceCallingPage=null&totalCount=262&showAdditionalParameters=no&lc=3000435&lc=3000430&lc=3000431&lc=3000432&lc=2001192&compare=yes&download=yes&sort=yes&customize=yes&paramResults=yes&paramCriteria=yes&familyTree=yes&military=no&baSystem=yes&paramTable=no&sortOption=PA_PARAMETER_2001636&sortMode=DESC&searchPaths=1000394&pageId=undefined&templateId=0&navigationId=0&family=analog&paramTable=no&military=no&compare=yes&download=yes&sort=yes&customize=yes&paramResults=yes&paramCriteria=yes&familyTree=yes&military=no&baSystem=yes&paramTable=no&sortOption=PA_PARAMETER_2001636&sortMode=DESC&searchPaths=1000394&pageId=undefined&uiTemplateId=NODE_STRY_PGE_T&techFamId=null&rootFamilyId=null&sectionId=null&tabId=null&appId=null&viewDeviceCallingPage=null

http://para.maxim-ic.com/en/search.mvp?fam=batt_chrg&tree=powersupplies

http://www.maxim-ic.com/appnotes10.cfm/ac_pk/5

Choosing a Li-ION battery charger is based on the efficieny requirement of your system.Thee are two types Linear and Switched.First one is less efficient but component count is less(also cost) and the 2nd one would be highly efficient(and cost ).

Also it is important to add a hysterysis at the switch which controls the supply switch over.

Regards,

Arun

Arun,

Welcome to Element 14. Thanks for the reply. It is in depth.

On the hysterysis point, any thoughts on how to implement a solution? I was thinking of adding a supercapacitor bank to rapidly store energy, and form there charge the batteries for longer term storage.

E

Eves,

I hope post by heath gives you a good understanding of the system and also about implementing the Hysterysis part.You can implement it using a widow(or a hysterysis) comparator or discrete circuitry based on transistors.But the discrete will not be a good solution since the switching between the supplies may not be ideal.

I agree using the super capacitor bank will yield a better charge capacity and extends the longetivity of the battery.I feel using a supercapacitor bank shall be quite costly because of the protection required to be provided(like inrush current limit).There are many standard products(Li-Ion chargers and battery gauges) which can make your system look less costly.

I am not sure if i understood your question correctly.Let me know.

Regards,

Arun

Eves,

I hope post by heath gives you a good understanding of the system and also about implementing the Hysterysis part.You can implement it using a widow(or a hysterysis) comparator or discrete circuitry based on transistors.But the discrete will not be a good solution since the switching between the supplies may not be ideal.

I agree using the super capacitor bank will yield a better charge capacity and extends the longetivity of the battery.I feel using a supercapacitor bank shall be quite costly because of the protection required to be provided(like inrush current limit).There are many standard products(Li-Ion chargers and battery gauges) which can make your system look less costly.

I am not sure if i understood your question correctly.Let me know.

Regards,

Arun