BamaBuzz4UA Posted August 30, 2009 Report Share Posted August 30, 2009 I am building charging system for 12v tool batters ( drills, lights, etc. ). I found a 12v a/c adapter and I cut the end off the but bullet connectors that hook up to a wire with a shielded female spade connector. The shade fits the 12v battery. My question is - is there a way to design a circuit that will let me know when its charged, like with a red and green light. Any help or schematic would me greatly appreciated Quote Link to comment Share on other sites More sharing options...
www.electronworks.co.uk Posted August 30, 2009 Report Share Posted August 30, 2009 It depends on what type of battery you have. To charge batteries you need a constant current source, but the method of charge termination varies from chemistry to chemistry. Lead acid batteries charge with a constant current then need a float voltage top off. NiCads and NiMH need a change in voltage with time charge (or temperature). Lithiums need an extremely accurate charge termination (to 100mV accuracy).Look at the MAX712/713 datasheet from Maxim for NiMH and NiCads. Quote Link to comment Share on other sites More sharing options...
Herman the German Posted September 2, 2009 Report Share Posted September 2, 2009 It depends on what type of battery you have. To charge batteries you need a constant current source, but the method of charge termination varies from chemistry to chemistry. Lead acid batteries charge with a constant current then need a float voltage top off. NiCads and NiMH need a change in voltage with time charge (or temperature). Lithiums need an extremely accurate charge termination (to 100mV accuracy).Look at the MAX712/713 datasheet from Maxim for NiMH and NiCads. Lead-acid-batteries are charged with constant voltage e.g. 13.8V. Their charging current decreases while they approach full charging voltage.NiCads are charged with constant current. Quote Link to comment Share on other sites More sharing options...
Hero999 Posted September 2, 2009 Report Share Posted September 2, 2009 A lead acid battery will charge very slowly if charged to 13.8V.If it's charged to 14.5V and reduced to 13.8V when the current drops below a certain level, it will charge much quicker. Quote Link to comment Share on other sites More sharing options...
Herman the German Posted September 23, 2009 Report Share Posted September 23, 2009 A lead acid battery will charge very slowly if charged to 13.8V.If it's charged to 14.5V and reduced to 13.8V when the current drops below a certain level, it will charge much quicker.OK! Partially agreed. :DSubtract 0.1V for a final charge voltage of 14.4V to make it safe! ;) Beyond 14.4V any lead-acid battery starts gasing (Hoffman's electrolytic gas production facility) ??? ???H + O mixed make a beautiful firework if touched off by the spark of a switch. ;DHtG Quote Link to comment Share on other sites More sharing options...
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