On Fri, 30 Nov 2018 at 04:18, Neil wrote: > I chose these batteries based on size, and voltage is just specified as > the nominal 3.7V... > > > > https://www.amazon.com/gp/product/B0746JGS4T/ref=3Doh_aui_detailpage_o04_= s00?ie=3DUTF8&psc=3D1 > > > Since their charger gets the battery to only 4.1V, is it safe to assume > that that is the voltage I should be charging to? I generally don't > trust the accuracy/tolerance of these really low-cost & cheaply made > products, but I have a few of these chargers and they all charge to the > same voltage. And each one has 4 individual charging circuits, so I can > say that the 4.1V is pretty consistent over a sample size of 12. > > 4.1V CV is wholly acceptable - and results in longer cycle life than th= e more usual 4.2V. As that is below the lowest IC programmed Vreg and as the terminate lights never light it's not obvious what is happening. The charger IC requires a minimum 0.3v headroom. [ *Datasheet page 3 section 1.0, supply voltage =3D *VREG(Typical)+0.3V ] What supply voltage are you using? "Trickle" is acceptable at Vmax of < to << of Vmax (nominally 4.2V). At 4.1V I'd want to be sure that temperature excursions would be accounted for and at 4.0V you are probably safe to apply voltage constantly. Constantly applied 4.2V is liable to lead to rapid cell degradation. It does not sound as if this applies, but: If you are loading the battery while charging and if Ichg is also supplying this load then if Iload >> Iterminate_programmed then charging will never terminate. Russell --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .