This matches what I saw. SOME nimh cells can take continuous trickle. In = the data sheet, the word "Tolerate" is used a lot.=20 I wouldn't advise trickle for any NIMH. -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of= RussellMc Sent: Tuesday, June 6, 2017 2:44 AM To: Microcontroller discussion list - Public. Subject: Re: [EE} Pulse charging batteries. Partial comment: You MUST NOT tricklle charge modern high capacity NimH ce= lls. The boundary is around 1800 mAh for AA cells. Below that it is (or was) typically acceptable. Older lower capacity cells had a mechanism/chemicals to allow reecombinati= on of the H2/O2 generated at end of charge. As energy capacityrose this was= removed to make more room for active material. A modern NimH MIGHT survive= C/100 trickle according to a few manufacturers, but MOST say DO NO TRICKLE= CXHARGE. (I looked at many such specs a few years back). My too many times given advice on this my Stack Exchange maybe related answers Including https://electronics.stackexchange.com/a/56843/3288 https://electronics.stackexchange.com/a/123750/3288 https://electronics.stackexchange.com/a/300627/3288 https://electronics.stackexchange.com/a/41648/3288 https://electronics.stackexchange.com/a/207003/3288 _____________________ After spending too much time and effort trying to treat NimH AAs well in po= rtable solar charged equipment I decided that LiIon is a much nicer chemist= ry to manage (without any comment on its dangers). Moderrn NimH and LiIopn are of ABOUT the same energy densities in AA cells = .. LiFePO4 wrt NimH: superior charging managability, better whole of life cost per en= ergy stored. wrt LiIon: much better safety and whole of life cost per energy stored and cycle life somewhat lower terminal voltage, lower mass and volume ene= rgy density, I'd use LiIon or LiFePO4 rather than NimH if possible. Russell Unrelated : Yee ha Starts at 3m 45s for will-be-obvious reasons. Watch from start in due course. I MUST go there !!! https://www.youtube.com/watch?v=3DrB4HVn6Rnmk&feature=3Dyoutu.be&t=3D345 On 6 June 2017 at 08:27, David C Brown wrote: > I am building a simple charger for NiMH batteries. It will have a fixed > rate constant current source and I intend to vary the charge rate=20 > between different cells and standard/trickle rates by pulsing the=20 > charger.. A web search suggests that this is a well accepted technique b= ut the one piece of > information I am struggling to find is the pulse rate. My gut feeling i= s > that something between 1Hz an 100mHz would be about right. can anyone=20 > confirm this? > __________________________________________ > David C Brown > 43 Bings Road > Whaley Bridge > High Peak Phone: 01663 733236 > Derbyshire eMail: dcb.home@gmail.com > SK23 7ND web: www.bings-knowle.co.uk/dcb > > > > > *Sent from my etch-a-sketch* > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive=20 > View/change your membership options at=20 > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/chang= e your membership options at http://mailman.mit.edu/mailman/listinfo/piclis= t --=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 .