replacing batteries in Norelco shaver
in [Repair]
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From: Darmok on 26 Aug 2005 18:07 On Thu, 25 Aug 2005 18:55:43 -0400, Darmok <cooncat.spam(a)gmail.com> wrote: >Hi, > >I've got an older Norelco electric shaver, which has some kind of >'fast charge' ni-cads in it (haven't looked, but that's pretty much >what they had when it was made). Normally, it will recharge in about >20 minutes or so. Well, after all these years, one or both batteries >is dying, and I need to replace them. I was thinking of just putting >in a couple of Ni-MH cells (these are 'AA' size), because I know that >they can handle a higher charge rate than standard ni-cads. I've got >some extras of both, but no 'high charge rate' ni-cads (although, I'm >pretty sure I could get some at Tower Hobbies, or similar R/C model >shop). > >Anyone ever replace batteries in a Norelco (or other brand) shaver? >Anything I should be aware of or watch out for? Seems like it should >be a pretty straight forward procedure. > >TIA Thanks for all the input .. very helpful indeed! Bill, KB8EB
From: H. Dziardziel on 26 Aug 2005 19:13 On Thu, 25 Aug 2005 18:55:43 -0400, Darmok <cooncat.spam(a)gmail.com> wrote: > Charging in only 20 minutes is a 3C charge rate ie, three times the cell mAh capacity. Shaver NiCads would be in the 500m-1000Ah range. NiMh 2000-2600mAh AAs can handle that 1500-2000mA charge rate but must not go over full charge or will be destroyed. The question is: is that a timed 20 minutes or a "smart" 20 minutes? If timed and one starts with fully discharged cells then all is well. NiMh have no memory effect so can be charged and dicharged from-to any level But, if a smart charger is used, it may not properly detect the NiMh charge state and keep charging past fully charged. For say, 1500mAh cells, that would take about one hour however so manul timing would suffice. Monitoring the cell temperature is a good idea. Some heating while charging is normal for NiMh but after full charge is reached it quickly ruins the cells.
From: Jim Yanik on 27 Aug 2005 01:04 H. Dziardziel <hdzi(a)zworg.nospamcom> wrote in news:s98vg193dgmvltgsvlsmqq90qcif0f7hhl(a)4ax.com: > On Thu, 25 Aug 2005 18:55:43 -0400, Darmok ><cooncat.spam(a)gmail.com> wrote: > >> > > Charging in only 20 minutes is a 3C charge rate ie, three times > the cell mAh capacity. Shaver NiCads would be in the 500m-1000Ah > range. NiMh 2000-2600mAh AAs can handle that 1500-2000mA charge > rate but must not go over full charge or will be destroyed. > > The question is: is that a timed 20 minutes or a "smart" 20 > minutes? If timed and one starts with fully discharged cells > then all is well. NiMh have no memory effect so can be charged > and dicharged from-to any level But, if a smart charger is used, > it may not properly detect the NiMh charge state and keep charging > past fully charged. > > For say, 1500mAh cells, that would take about one hour however so > manul timing would suffice. Monitoring the cell temperature is a > good idea. Some heating while charging is normal for NiMh but > after full charge is reached it quickly ruins the cells. > > According to what I've read here and there,cell temperature is NOT a good way to detect full charge for NiMH cells. For NiCd,its OK. By the time the temp changes the NiMH cell is overcharged. -- Jim Yanik jyanik at kua.net
From: gb on 27 Aug 2005 08:14 "mike" <spamme0(a)netscape.net> wrote in message news:430E9E21.3040601(a)netscape.net... > Darmok wrote: >> Hi, >> >> I've got an older Norelco electric shaver, which has some kind of >> 'fast charge' ni-cads in it (haven't looked, but that's pretty much >> what they had when it was made). Normally, it will recharge in about >> 20 minutes or so. Well, after all these years, one or both batteries >> is dying, and I need to replace them. I was thinking of just putting >> in a couple of Ni-MH cells (these are 'AA' size), because I know that >> they can handle a higher charge rate than standard ni-cads. I've got >> some extras of both, but no 'high charge rate' ni-cads (although, I'm >> pretty sure I could get some at Tower Hobbies, or similar R/C model >> shop). >> >> Anyone ever replace batteries in a Norelco (or other brand) shaver? >> Anything I should be aware of or watch out for? Seems like it should >> be a pretty straight forward procedure. >> >> TIA >> > > Call up a norelco shaver repair place. I don't remember the number, > but I do remember being amazed at how low their battery prices were. > I'd just been thru the hassle of replacing cells and would have just > bought > them from Norelco had I realized they were affordable. YMMV > mike I have one (Norelco repair facility) here locally -- still repair very old models and parts are very inexpensive (sometime cheaper than the department store batteries). gb
From: H. Dziardziel on 27 Aug 2005 13:05
On 27 Aug 2005 05:04:45 GMT, Jim Yanik <jyanik(a)abuse.gov.> wrote: >> For say, 1500mAh cells A typo, "1500mAh cells" should read "1500mA." >, that would take about one hour however so >> manul timing would suffice. Monitoring the cell temperature is a >> good idea. Some heating while charging is normal for NiMh but >> after full charge is reached it quickly ruins the cells. >> >> > >According to what I've read here and there,cell temperature is NOT a good >way to detect full charge for NiMH cells. For NiCd,its OK. >By the time the temp changes the NiMH cell is overcharged. My post was poorly worded thanks. My "monitoring the cell temperature" along with "some heating" was to imply hand sensing as a very simple check of what's going on in the cells if they have charged for more than 20 minutes or from an unknown charge state.. The assumption was the shaver does not use temperature sensing except for catastrophic shutoff and if a smart 20 minute charger it is of course designed for NiCad characteristics so may not ever shut off. Unlike NiCads, NiMh are exothermic while charging so will get warm, especially at this rather high charge rate.. Once fully charged however the temperature (T) rises sharply after the very small voltage drop that indicate full charge . The problem is this short delay and the electronics and packaging usually getting warm along with ambient variations. So, as you say, it's not usually used since difficult to detect reliably. NiCads, being endothermic are more reliably temperature end of charge detected since the T change is sharper. In either case, _hot_ cells indicate overcharging Regards.. |