Even with peak hold, you're limited by the sampling rate on the DMM. My DMM has a clamp. I set it up to peak hold voltage, and it showed no back EMF from my motor when I turned off power, so I thought it had an internal flyback diode and did not install one externally.
Then I used the clamp ammeter and peak hold, and I got wildly different peak current measurements. That got me to pull out the specifications and discover that the sampling rate was lower than I expected, so peak hold wasn't very meaningful regarding inrush current. That has made me suspect that I need to add a flyback diode too, even though I never detected any back EMF with peak hold voltage. On Wed, Apr 30, 2014 at 12:15 AM, David Nelson <gizm...@gmail.com> wrote: > My B&D CMM1000 24V 19" mower, IIRC, pulls just under 10A when not > cutting and something over 20A on initial surge on startup. I only > have a digital clamp meter that doesn't react fast enough to know the > peak current. Maybe I should look to see if it has a peak hold option. > > On Tue, Apr 29, 2014 at 2:56 PM, Michael Ross <michael.e.r...@gmail.com> > wrote: >> EVDL Dave R., >> >> Comparing on a weight basis $/lb (on the theory that weigh goes with Pb >> content which goes with quality of design and manufacture and looking at $/ >> Ah: >> >> *#1 13lb* $3.46/lb @ $45 17.2 Ah *$2.62/Ah* >> http://www.atbatt.com/genesis-np18-12-12v-172ah-sealed-lead-acid-battery-with-nb-terminal.asp?cr_brand=BB&cr_product=BP17-12#specifications >> *Is this the "Hawker Genesis" you were talking about?* >> >> *#2 14lb* $3.57/lb @ $50 21.6Ah *$2.31/Ah* >> this one weighs an additional pound for $5 more: >> http://www.atbatt.com/power-sonic-psh-12180nb-fr-sealed-lead-acid- >> battery.asp?cr_brand=BB&cr_product=BP17-12 >> >> *#3 14.1lb* $4.15/lb @ $58.5 22Ah *$2.63/Ah* >> http://www.atbatt.com/amstron-12v-22ah-electric-vehicle-agm-battery-nb-terminal.asp?cr_brand=BB&cr_product=BP17-12#specifications >> >> *#4 14.4lb* $4.38/lb @ $63 18Ah *$3.50/Ah* >> http://www.atbatt.com/bb-bp18-12-12v-18ah-agm-battery-w-nb-terminal.asp?cr_brand=BB&cr_product=BP17-12#specifications >> >> *#5 14.5lb* $4.96/lb @ $72 20Ah *$3.60/Ah* >> http://www.atbatt.com/bb-battery-hr22-12-sla-battery.asp?cr_brand=BB&cr_product=BP17-12 >> >> *#6 15lb *$6.60/lb @ $100 20Ah* $5.00/Ah* >> http://www.atbatt.com/bb-evp20-12-12v-20ah-agm-battery-w-nb-terminal.asp?cr_brand=BB&cr_product=BP17-12 >> >> Raises all sorts of questions... >> >> Is #3 lying about the Ah? Does the low weigh really me it is not as good >> as say #5 which weighs a 180 grams more for an additional $14 each? >> >> On a pure money for performance basis one of the lowest weigh, least >> expensive #2 seems like a good deal. Can 21.6Ah be believed? >> >> Is there any merit at all to buying #6? Its price point looks terrible, >> but on the weight theory is is best. >> >> This is a great way for me to learn here, if you all are willing to chime >> in... >> >> Mike >> >> >> On Tue, Apr 29, 2014 at 1:11 PM, EVDL Administrator <evp...@drmm.net> wrote: >> >>> On 29 Apr 2014 at 12:06, Lee Hart wrote: >>> >>> > I have Enersys, Hawker, and Concorde AGMs that are now over 10 years old >>> > and still delivering at least half of their original capacity. I also >>> have >>> > Gates, and Deka gels just as old that are still usable. >>> >>> I just recently retired the last of a batch of Hawker Genesis AGMs that >>> dated from about 1997. They were (well-) used when I got them. >>> >>> Of 24 equally old Deka Dominator gels, I'm still using 16 (and a couple >>> others sit around). Most have 60-90% of their rated capacity. >>> >>> One of the things I like about these batteries is how low their self >>> discharge is. They need only very infrequent charging when in storage. >>> >>> David Roden - Akron, Ohio, USA >>> EVDL Administrator >>> >>> = = = = = = = = = = = = = = = = = = = = = = = = = = = = = >>> EVDL Information: http://www.evdl.org/help/ >>> = = = = = = = = = = = = = = = = = = = = = = = = = = = = = >>> Note: mail sent to "evpost" and "etpost" addresses will not >>> reach me. To send a private message, please obtain my >>> email address from the webpage http://www.evdl.org/help/ . >>> = = = = = = = = = = = = = = = = = = = = = = = = = = = = = >>> >>> >>> _______________________________________________ >>> 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 >> >> michael.e.r...@gmail.com >> <michael.e.r...@gmail.com> >> -------------- next part -------------- >> An HTML attachment was scrubbed... >> URL: >> <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140429/444c4ae3/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) >> > > > > -- > David D. Nelson > http://evalbum.com/1328 > http://www.levforum.com > _______________________________________________ > 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) > _______________________________________________ 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)
