On Feb 3, 8:42 am, Lucky <dave.lucky.po...@gmail.com> wrote: > On this subject do you think these are a good idea? > > http://www.all-battery.com/browseproducts/Protection-circuit-Module-%... > > I have a nixie clock circuit that uses a LiPo or Li-Ion as backup but > unsure of its charging capabilities > > Dave.
Hello Dave, Using a backup power source based on Lithium polymer technology is a good choice if you need a lot of power/energy contained in a small package, and you do not intend to commercially market the item. Some secondary cells include a "management module" that functions as a sort of rudimentary BMS, limiting the EOC (End of Charge) voltage. Others may include a LV (Low Voltage) cutoff to gate the output when the cell charge is nearly depleted. Depending on how elaborate you want to go, there are integrated products being offered by half a dozen US manufacturers to deliver a comprehensive histogram of the cell performance throughout it's service life. If you happen to choose a Cobalt doped LiPo chemistry, the peak EOC voltage is 4.2 @25 degrees C. The safe operation voltage is typically between 3.7 and 3.0, referenced to a 1c discharge. Manganese doping is scaled a little lower at 3.7v EOC, and operation between 3.3 and 2.8 volts. You'll a charge voltage source the same as the EOC, with current that does not exceed a 1c rate. Small switching wall warts for use as simple chargers are broadly offered at these termination voltages. Being a long time RC hobby flyer, the advancements in both cathode/ anode and electrolyte technology has been stunning over the last five years. Besides the cathode materials depositions, the separator thickness has shrank to micron scaling. Discharge rates of 50x the rated Ah capacity are commonplace now. Almost all of these cells and related support electronics are manufactured in China. Using this type of cell chemistry outside of the intended hobby RC market comes with a lot of responsibility. Cells rated for human-exposure applications are significantly more expensive than the Chinese made hobby market products, and the choices are limited for a reason. Manufacturers who have integrated these cells into their hand held (or wrist worn) products have considerable engineering hours conducted on volumes of cells to gauge their performance and safety within the intended application. Along with full traceability of the components and manufacturing process cycle. There are still a lot of trade secrets involved in this technology. You assume all risks by selling a product that includes Chinese hobby market LiPo cells integrated into the design. If you are a PE with an insurance policy, you'd need to check with your underwriter to see if your coverage spans this type of exposure. Regards, Jeff -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
