| Electronics > Beginners |
| Dropping voltage from a Li-ion battery |
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| Cricri:
FYI, I didn't do my conversion on the shaver. My wife is not an engineer and has this boring "if it ain't broken don't fix it" attitude. Granted, I "fixed" an Android box few months ago that was working alright, and by the time I finished improving it, it was dead. I'll just wait until the NiCd dies and swap them for the Li-ion + 2 x 1N4001 as planned. I was under the impression that NiMH need more gentle care than NiCd, so even if you were "upgrading" from crappy NiCd to a-wee-bit-less-crap NiMH, wouldn't you need to redesign/swap the charging circuit anyway? My first pair of NiMH I ever bought were charged in my NiCd charger, and when I got them out they were piping hot. The fact that they never worked properly was a hint that they didn't appreciate the treatment! @psi: >Any lithium + switchmode system you add will need to be disconnected to prevent the switchmode draining the battery all the time. I'm not sure if that is a problem with my charging boards, I did check the batteries months after recharging them, with the board still connected, and they were still charged. >And if you don't do it properly there's a risk it will burn your house down in the middle of the night Yes, I never leave the batteries charging when I'm not in the house. I'm even more careful when it's a battery salvaged from the bin! |
| Psi:
For low current devices you can swap between using NiCa and NiMh without any problems. NiCa can usually handle higher discharge current so if the device draws 5+Amps from a single cell then changing to NiMh may not be the best plan. That said, you can get special NiMh cells intended for high discharge. |
| 6PTsocket:
Later, they offered NiMh for longer run time and eventually dropped the NiCd's. Now you can get generic 2000 mah. NiMh Versapak batteries. Since I owned a smart charger and several Versapak trickle chargers, I gutted one of the trickle chargers so it is just a charge stand for the smart charger. I can charge them in an hr. or so at 1.9 amps and it shuts off like a good charger should. With a set of generics a few spare filters and the brush and crevice tool there is no end in sight LOL!! --- Quote from: james_s on December 27, 2018, 05:56:05 am --- --- Quote from: 6PTsocket on December 26, 2018, 06:49:29 am ---In defence of NiCd's, I have them in a number of devices like an old 4.8 volt carpet sweeper, 7.2volt B&D dust buster, a 14.4 volt drill, an electric tooth brush and a beard trimmer. I may be stuck in the past but they all work and a few are on their second set of batteries. They are still used in many non critical, inexpensive applications. According to Battery University, the educational site devoted to all things battery, the NiCd memory effect was a problem solved in the very early days of NiCd production and the real cause of the problem is something else entirely. NiCd's on trickle chargers are continuously over charged and loose capacity. Then again all rechargeable batteries loose capacity over time. There is a new generation of low self discharge AA and AAA NiMh batteries with high capaity and high discharge rate ability that give lithiums a run for their money. I woukd use those for replacement of similar size NiCd's. They will work on the old NiCd/NiMh charger. One of the manufacturers is Tenergy, the other brand eludes me. Sent from my SM-G900V using Tapatalk --- End quote --- There is a Dust Buster at our family cabin that was installed back in the 80s when they were a new thing. It has sat on the charging cradle ever since and I was surprised to find recently that it still actually works. Doesn't run very long, but it has 30+ year old NiCd batteries in it. --- End quote --- Sent from my SM-G900V using Tapatalk |
| 6PTsocket:
The eneloop pros can handle a pretty high discharge rate --- Quote from: Psi on December 27, 2018, 10:22:21 pm ---For low current devices you can swap between using NiCa and NiMh without any problems. NiCa can usually handle higher discharge current so if the device draws 5+Amps from a single cell then changing to NiMh may not be the best plan. That said, you can get special NiMh cells intended for high discharge. --- End quote --- Sent from my SM-G900V using Tapatalk |
| james_s:
--- Quote from: 6PTsocket on December 27, 2018, 10:38:41 pm ---Later, they offered NiMh for longer run time and eventually dropped the NiCd's. Now you can get generic 2000 mah. NiMh Versapak batteries. Since I owned a smart charger and several Versapak trickle chargers, I gutted one of the trickle chargers so it is just a charge stand for the smart charger. I can charge them in an hr. or so at 1.9 amps and it shuts off like a good charger should. With a set of generics a few spare filters and the brush and crevice tool there is no end in sight LOL!! --- Quote from: james_s link=topic=159349.msg2070625#msg2070625 [/quote --- Yeah I'm sure the newer ones are better, I just find it remarkable that this crusty old original model from the 80s still works. I actually hadn't even tried it out until recently, it's so old I just assumed the batteries would have been shot years ago. --- End quote --- --- End quote --- |
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