Lee, I am not trying to design a product, just having fun. All I know I learned from Forrest Mims so if it gets too complicated or doesn't work easily - I quit. But, really, I usually learn a lot by floundering around on just this sort of thing. Failure is always an option. I have a lot of misplaced patience.
I will probably be implementing a DC battery system for lighting and so on so I can get op amp power from there. Or there is already a converter to 12V on it. I would not use TTL if I can get around it - because it is noise vulnerable. I would likely resort to some optos if noise gets difficult. >From a "do this task" POV, an op amp comparator is exactly the right function. If the difference between the two halves is too great then it warns. if the difference is intermittent then the indication stops. I think I may li ke this better than a slowly increasing brightness, but I could get one of your Batt-Bridges and put them side by side for personal interest. On Fri, Apr 18, 2014 at 12:33 PM, Lee Hart <[email protected]> wrote: > Michael Ross wrote: > >> I was thinking of an op amp comparator. >> > > You could use an IC, but then you will have to power it. That means > something to convert pack voltage to 5v or so for the comparator. An EV's > propulsion system is noisy, so you'll need filters. The customer might hook > it up wrong; you'll need parts to protect against that. It doesn't take > long before you have a dozen parts. > > Complex electronics are the fashionable and obvious solution; but they > really aren't needed or desirable for such a simple function. > > You don't have to monitor every single cell unless it's necessary to know > *which one* is high or low. Often, the pack is a monolithic block; you > can't change a single cell anyway (the manufacturer wants you to replace > the whole thing). > > I try to start not by picking the parts; but instead by defining the > problem *without* assuming the solution. In this case, the Batt-Bridge just > tells you that *some* cell is high or low. That's all you really need to > know to stop charging or driving before you damage it. > > -- > Customer: I want a switch to turn on a light. > Engineer: OK; first we have to pick the operating system. Windows or > Linux? And what CPU do we use; how many GHz and Mbytes? Then > the interface; wifi or bluetooth? > > -- > Lee Hart's EV projects are at http://www.sunrise-ev.com/LeesEVs.htm > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/ > group/NEDRA) > > -- Put this question to yourself: should I use everyone else to attain happiness, or should I help others gain happiness? *Dalai Lama * Tell me what it is you plan to do With your one wild and precious life? Mary Oliver, "The summer day." To invent, you need a good imagination and a pile of junk. Thomas A. Edison<http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> A public-opinion poll is no substitute for thought. *Warren Buffet* Michael E. Ross (919) 550-2430 Land (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones> Google Phone (919) 631-1451 Cell (919) 513-0418 Desk [email protected] <[email protected]> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140418/9ddabe08/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
