But it seems that the only difference between LA and Lithium Ion in what you are saying is which piece of equipment requires that the charge current be limited. Even for lead acid, it may well be that it is not safe (or good for the life of the battery) to allow it to charge at the highest current it will accept at the CV point. All of the battery books I have read, as well as all of the charger documentation I've seen, refers to typical lead acid charge profile as CC-CV (they sometimes talk about CC-CV-CC to describe putting in a fixed fraction of a C at the end to make the tail of the charge curve more deterministic, to protect against thermal runaway, and to ensure a controlled amount of overcharge). Sean On Sat, Apr 30, 2011 at 10:54 PM, RussellMc wrote: >> I think we're saying the same thing. > > If that's what you originally meant then it's quite different from > what is neant by CC in a typical LiIon call, which was the point I was > originally dealing with. > > Common or garden [tm] LiIon have a 1C max charge current. Exceeding > this rate substantially tends to lead to a JLLB (Jerry Lee Lewis > Battery) situation. (Great balls of fire). > Lead Acid tends to just die at greater or lesser rates depending on > how the high rate affects the cell. LiFePO4 aretypically rates at 10C > charge and som newer Lithium chemistry variants are claiming around 1 > minute charge times. (60*C) > >> My point is that a fully-depleted >> lead acid battery usually will be able to draw more current than the >> charger can apply, therefore the beginning of the charge is a constant >> current charge at the max that the charger can supply. > > Yes. So its a AC-CV mode (Available current, constant-Voltage) unlike > the CC-CV mode fr LiIon where battery characteritics set both limits. > >> Even chargers >> that can supply 100s of amps usually would not cause a >> fully-discharged LA battery to reach the CV voltage right away. Either >> the charger or the wires or the interconnects inside the battery are >> usually the limiting factor for charge current at low SOC, but that >> still results in a CC charge as the fastest way to charge the battery >> within this region. > > Not wanting to be picky , but that's really just saying that th > fastest way to charge the battery prior to it reaching a present > voltage is 'the fastest way you can manage'. > > R > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .