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Charging NiMh batteries when not completely discharged

Started by AK June 13, 2019
The aaa alkaline batteries went out on my tv remote.

I decided to use my NiMh UBL aaa batteries. 1100 mAh.

They are currently showing 1.31 volts.

And they work ok in the remote as is.

My charger is the manual type.

It charges that type at 150 mA.

I want them fully charged since they are 1.2 volts versus 1.50 for the alkaline.

I would like to know how much longer to charge them.

Thanks,
Andy
AK wrote:
> > > The aaa alkaline batteries went out on my tv remote. > > I decided to use my NiMh UBL aaa batteries. 1100 mAh. > > They are currently showing 1.31 volts. > > And they work ok in the remote as is. > > My charger is the manual type. > > It charges that type at 150 mA. > > I want them fully charged since they are 1.2 volts versus 1.50 for the alkaline. > > I would like to know how much longer to charge them. > > >
** The correct procedure is to discharge the cells fully and then apply a full recharge cycle - 8 hours in your case. If you must recharge partly discharged cells, then it takes whatever time needed until their temperate just starts to rise. Constant monitoring by you is needed. ... Phil
On Thursday, June 13, 2019 at 7:28:44 PM UTC-5, Phil Allison wrote:
> AK wrote: > > > > > > The aaa alkaline batteries went out on my tv remote. > > > > I decided to use my NiMh UBL aaa batteries. 1100 mAh. > > > > They are currently showing 1.31 volts. > > > > And they work ok in the remote as is. > > > > My charger is the manual type. > > > > It charges that type at 150 mA. > > > > I want them fully charged since they are 1.2 volts versus 1.50 for the alkaline. > > > > I would like to know how much longer to charge them. > > > > > > > > ** The correct procedure is to discharge the cells fully and then apply a full recharge cycle - 8 hours in your case. > > If you must recharge partly discharged cells, then it takes whatever time needed until their temperate just starts to rise. Constant monitoring by you is needed. > > > > ... Phil
I have no way of monitoring temp. How do I fully discharge the cells manually? Andy
On Thu, 13 Jun 2019 19:08:20 -0700 (PDT), AK
<scientist77017@gmail.com> wrote:

>On Thursday, June 13, 2019 at 7:28:44 PM UTC-5, Phil Allison wrote: >> AK wrote: >> > >> > >> > The aaa alkaline batteries went out on my tv remote. >> > >> > I decided to use my NiMh UBL aaa batteries. 1100 mAh. >> > >> > They are currently showing 1.31 volts. >> > >> > And they work ok in the remote as is. >> > >> > My charger is the manual type. >> > >> > It charges that type at 150 mA. >> > >> > I want them fully charged since they are 1.2 volts versus 1.50 for the alkaline. >> > >> > I would like to know how much longer to charge them. >> > >> > >> > >> >> ** The correct procedure is to discharge the cells fully and then apply a full recharge cycle - 8 hours in your case. >> >> If you must recharge partly discharged cells, then it takes whatever time needed until their temperate just starts to rise. Constant monitoring by you is needed. >> >> >> >> ... Phil > >I have no way of monitoring temp. > >How do I fully discharge the cells manually? > >Andy
If they are unused, it is best to charge low self-discharge NiMH every nine to twelve months. Do NiMH batteries need to be completely discharged before charging? No, NiMH batteries do not have a memory. They can be charged without adverse effect at any point regardless of their state of charge. https://www.thomasdistributing.com/Battery-and-Charger-FAQs_ep_46-1.html Get a quality charger that monitors each battery under charge individually with an indicator for each cell to tell you when it is recharged. Monitoring temperature is over-kill IMO and not the best method. It is too dependent on ambient temperatures, air flow, etc.. By all means get the batteries that are low self-discharge types. (sold as "pre-charged") Old Nickel Cadmium cells required discharging to get the full capacity out of them.
On Friday, June 14, 2019 at 4:52:06 AM UTC-5, default wrote:
> On Thu, 13 Jun 2019 19:08:20 -0700 (PDT), AK > <scientist77017@gmail.com> wrote: > > >On Thursday, June 13, 2019 at 7:28:44 PM UTC-5, Phil Allison wrote: > >> AK wrote: > >> > > >> > > >> > The aaa alkaline batteries went out on my tv remote. > >> > > >> > I decided to use my NiMh UBL aaa batteries. 1100 mAh. > >> > > >> > They are currently showing 1.31 volts. > >> > > >> > And they work ok in the remote as is. > >> > > >> > My charger is the manual type. > >> > > >> > It charges that type at 150 mA. > >> > > >> > I want them fully charged since they are 1.2 volts versus 1.50 for the alkaline. > >> > > >> > I would like to know how much longer to charge them. > >> > > >> > > >> > > >> > >> ** The correct procedure is to discharge the cells fully and then apply a full recharge cycle - 8 hours in your case. > >> > >> If you must recharge partly discharged cells, then it takes whatever time needed until their temperate just starts to rise. Constant monitoring by you is needed. > >> > >> > >> > >> ... Phil > > > >I have no way of monitoring temp. > > > >How do I fully discharge the cells manually? > > > >Andy > > If they are unused, it is best to charge low self-discharge NiMH every > nine to twelve months. Do NiMH batteries need to be completely > discharged before charging? No, NiMH batteries do not have a memory. > They can be charged without adverse effect at any point regardless of > their state of charge. > > https://www.thomasdistributing.com/Battery-and-Charger-FAQs_ep_46-1.html > > Get a quality charger that monitors each battery under charge > individually with an indicator for each cell to tell you when it is > recharged. > > Monitoring temperature is over-kill IMO and not the best method. It > is too dependent on ambient temperatures, air flow, etc.. > > By all means get the batteries that are low self-discharge types. > (sold as "pre-charged") > > Old Nickel Cadmium cells required discharging to get the full capacity > out of them.
Thanks default. My EBLs were low self discharge. Andy
default wrote:
>
> > Phil Allison wrote: > > >> > > >> > The aaa alkaline batteries went out on my tv remote. > >> > > >> > I decided to use my NiMh UBL aaa batteries. 1100 mAh. > >> > > >> > They are currently showing 1.31 volts. > >> > > >> > And they work ok in the remote as is. > >> > > >> > My charger is the manual type. > >> > > >> > It charges that type at 150 mA. > >> > > >> > I want them fully charged since they are 1.2 volts versus 1.50 for the alkaline. > >> > > >> > I would like to know how much longer to charge them. > >> > > >> > > >> > > >> > >> ** The correct procedure is to discharge the cells fully and then apply a full recharge cycle - 8 hours in your case. > >> > >> If you must recharge partly discharged cells, then it takes whatever time needed until their temperate just starts to rise. Constant monitoring by you is needed. > >> > >> > >> > >> ... Phil > > > >I have no way of monitoring temp. > > > >How do I fully discharge the cells manually? > > > >Andy > >
..................................
> > > If they are unused, it is best to charge low self-discharge NiMH every > nine to twelve months. Do NiMH batteries need to be completely > discharged before charging? No, NiMH batteries do not have a memory. > They can be charged without adverse effect at any point regardless of > their state of charge. >
** Fraid you did not read the question, the OP wanted to know HOW LONG to charge his cells with his existing charger. There is NO way to know that without first discharging them.
> > Get a quality charger that monitors each battery under charge
** An expensive and unnecessary option. IOW - a wank.
> > Monitoring temperature is over-kill IMO and not the best method. It > is too dependent on ambient temperatures, air flow, etc.. >
** Utter bullshit. Long as one has fingers on the ends of one's hand, a user can easily monitor a small temp rise that takes hours to happen. Ambient and air flow have SFA to do with it.
> Old Nickel Cadmium cells required discharging to get the full capacity > out of them.
** A well worn myth that applies only to cells made in the 1960s. Bet not too many of them are still working... ... Phil
On Fri, 14 Jun 2019 23:30:12 -0700 (PDT), Phil Allison
<pallison49@gmail.com> wrote:

>default wrote: >> > >> >> Phil Allison wrote: >> >> >> > >> >> > The aaa alkaline batteries went out on my tv remote. >> >> > >> >> > I decided to use my NiMh UBL aaa batteries. 1100 mAh. >> >> > >> >> > They are currently showing 1.31 volts. >> >> > >> >> > And they work ok in the remote as is. >> >> > >> >> > My charger is the manual type. >> >> > >> >> > It charges that type at 150 mA. >> >> > >> >> > I want them fully charged since they are 1.2 volts versus 1.50 for the alkaline. >> >> > >> >> > I would like to know how much longer to charge them. >> >> > >> >> > >> >> > >> >> >> >> ** The correct procedure is to discharge the cells fully and then apply a full recharge cycle - 8 hours in your case. >> >> >> >> If you must recharge partly discharged cells, then it takes whatever time needed until their temperate just starts to rise. Constant monitoring by you is needed. >> >> >> >> >> >> >> >> ... Phil >> > >> >I have no way of monitoring temp. >> > >> >How do I fully discharge the cells manually? >> > >> >Andy >> >> >.................................. >> >> >> If they are unused, it is best to charge low self-discharge NiMH every >> nine to twelve months. Do NiMH batteries need to be completely >> discharged before charging? No, NiMH batteries do not have a memory. >> They can be charged without adverse effect at any point regardless of >> their state of charge. >> > > >** Fraid you did not read the question, the OP wanted to know HOW LONG to charge his cells with his existing charger. > >There is NO way to know that without first discharging them.
Mmm, and then he might use the recommended recharge time and get an even charge in each, assuming of course, the batteries he's using are the same capacity that was available when the charger was purchased, and the batteries still retain their label capacity. Not having a wealth of information on his charger I'd go with an intelligent charger. Those things with a transformer, diode, resistor for their "technology" just don't cut it IMO; batteries cost too much and I depend on them too much to skimp when it comes to a charger that will far outlast the batteries and keep all my toys working.
> >> >> Get a quality charger that monitors each battery under charge > > >** An expensive and unnecessary option.
Yup a smart chargers for (AAA-AA X4) costs about $10-20, while a cheap one through a surplus or close-out outlet can be had for $2. But given the cost of batteries, or how "mission critical" the application is, or how much hassle one is willing to put up with to save a buck or two, the relatively small difference in price overwhelmingly favors the expense IMO.
> > IOW - a wank. > > >> >> Monitoring temperature is over-kill IMO and not the best method. It >> is too dependent on ambient temperatures, air flow, etc.. >> > >** Utter bullshit. > >Long as one has fingers on the ends of one's hand, a user can easily monitor a small temp rise that takes hours to happen. > >Ambient and air flow have SFA to do with it.
I'd tend to agree with you. Or would if I hadn't just finished a long and careful study (observation) of some LED grow lights I'm using for an "aero-garden" knock-off. The evidence I was seeing suggests the mere orientation of the lights (vertical/horizontal), proximity to things impeding air-flow, and ambient T, had a great deal to do with peak temperatures. Turning on my whole-house fan, with no difference in ambient and a "breeze" that was undetectable to me would result in a 5 C change in temperature at the heatsink, ditto tilting the light bars, moving them away from the housings etc.. I used a calibrated digital thermometer, not my fingers. (after my fingers told me I might have a problem...) I dunno about you, but I never argue with empirical results, no matter what the theory, or my bias says.
> > >> Old Nickel Cadmium cells required discharging to get the full capacity >> out of them. > > >** A well worn myth that applies only to cells made in the 1960s. > > Bet not too many of them are still working...
"About 22% of portable rechargeable batteries sold in Japan in 2010 were NiMH" Wikipedia. So, with the exception of some small SLA batteries that would imply that NiCads were still going strong. Also from Wikipedia: Work on NiMH batteries began at the Battelle-Geneva Research Center following the technology's invention in 1967 Interest grew in the 1970s with the commercialisation of the nickel&#2013266070;hydrogen battery for satellite applications. In 1987, Willems and Buschow demonstrated a successful battery based on this approach (using a mixture of La0.8Nd0.2Ni2.5Co2.4Si0.1), which kept 84% of its charge capacity after 4000 charge&#2013266070;discharge cycles. The first consumer-grade NiMH cells became commercially available in 1989. In 1998, Ovonic Battery Co. improved the Ti&#2013266070;Ni alloy structure and composition and patented its innovations. "For 50 years, portable devices relied almost exclusively on nickel-cadmium (NiCd). This generated a large amount of data, but in the 1990s, nickel-metal-hydride (NiMH) took over the reign to solve the toxicity problem of the otherwise robust NiCd. Many of the characteristics of NiCd were transferred to the NiMH camp, offering a quasi-replacement as these two systems are similar. Because of environmental regulations, NiCd is limited to specialty applications today." (from "battery university") Actually the Chinese are still unloading some NiCads in things like solar powered lights and such - I took some apart that I just bought. You're a rude insufferable bastard most of the time, and (infuriatingly) right most of the time; but this time you are WRONG.
> > > > >... Phil
On Fri, 14 Jun 2019 20:02:22 -0700 (PDT), AK
<scientist77017@gmail.com> wrote:

>On Friday, June 14, 2019 at 4:52:06 AM UTC-5, default wrote: >> On Thu, 13 Jun 2019 19:08:20 -0700 (PDT), AK >> <scientist77017@gmail.com> wrote: >> >> >On Thursday, June 13, 2019 at 7:28:44 PM UTC-5, Phil Allison wrote: >> >> AK wrote: >> >> > >> >> > >> >> > The aaa alkaline batteries went out on my tv remote. >> >> > >> >> > I decided to use my NiMh UBL aaa batteries. 1100 mAh. >> >> > >> >> > They are currently showing 1.31 volts. >> >> > >> >> > And they work ok in the remote as is. >> >> > >> >> > My charger is the manual type. >> >> > >> >> > It charges that type at 150 mA. >> >> > >> >> > I want them fully charged since they are 1.2 volts versus 1.50 for the alkaline. >> >> > >> >> > I would like to know how much longer to charge them. >> >> > >> >> > >> >> > >> >> >> >> ** The correct procedure is to discharge the cells fully and then apply a full recharge cycle - 8 hours in your case. >> >> >> >> If you must recharge partly discharged cells, then it takes whatever time needed until their temperate just starts to rise. Constant monitoring by you is needed. >> >> >> >> >> >> >> >> ... Phil >> > >> >I have no way of monitoring temp. >> > >> >How do I fully discharge the cells manually? >> > >> >Andy >> >> If they are unused, it is best to charge low self-discharge NiMH every >> nine to twelve months. Do NiMH batteries need to be completely >> discharged before charging? No, NiMH batteries do not have a memory. >> They can be charged without adverse effect at any point regardless of >> their state of charge. >> >> https://www.thomasdistributing.com/Battery-and-Charger-FAQs_ep_46-1.html >> >> Get a quality charger that monitors each battery under charge >> individually with an indicator for each cell to tell you when it is >> recharged. >> >> Monitoring temperature is over-kill IMO and not the best method. It >> is too dependent on ambient temperatures, air flow, etc.. >> >> By all means get the batteries that are low self-discharge types. >> (sold as "pre-charged") >> >> Old Nickel Cadmium cells required discharging to get the full capacity >> out of them. > >Thanks default. > >My EBLs were low self discharge. > >Andy
EBL is what I've been buying and get good results with them. Eneloop are excellent too but cost more. I just bought some Amazon branded batteries to see if they are any good (but the price wasn't that much better than EBL). Awhile back, after getting frustrated with rechargeable AA performance, I rigged a dummy load across a battery holder and bought a few cheap quartz clocks to see which of the odd collection of batteries I had on hand still could hold a decent charge. The clocks stop working when the voltage gets down to ~.7V and records the hours takes to get there.
On Saturday, June 15, 2019 at 5:42:07 AM UTC-5, default wrote:
> On Fri, 14 Jun 2019 20:02:22 -0700 (PDT), AK > <scientist77017@gmail.com> wrote: > > >On Friday, June 14, 2019 at 4:52:06 AM UTC-5, default wrote: > >> On Thu, 13 Jun 2019 19:08:20 -0700 (PDT), AK > >> <scientist77017@gmail.com> wrote: > >> > >> >On Thursday, June 13, 2019 at 7:28:44 PM UTC-5, Phil Allison wrote: > >> >> AK wrote: > >> >> > > >> >> > > >> >> > The aaa alkaline batteries went out on my tv remote. > >> >> > > >> >> > I decided to use my NiMh UBL aaa batteries. 1100 mAh. > >> >> > > >> >> > They are currently showing 1.31 volts. > >> >> > > >> >> > And they work ok in the remote as is. > >> >> > > >> >> > My charger is the manual type. > >> >> > > >> >> > It charges that type at 150 mA. > >> >> > > >> >> > I want them fully charged since they are 1.2 volts versus 1.50 for the alkaline. > >> >> > > >> >> > I would like to know how much longer to charge them. > >> >> > > >> >> > > >> >> > > >> >> > >> >> ** The correct procedure is to discharge the cells fully and then apply a full recharge cycle - 8 hours in your case. > >> >> > >> >> If you must recharge partly discharged cells, then it takes whatever time needed until their temperate just starts to rise. Constant monitoring by you is needed. > >> >> > >> >> > >> >> > >> >> ... Phil > >> > > >> >I have no way of monitoring temp. > >> > > >> >How do I fully discharge the cells manually? > >> > > >> >Andy > >> > >> If they are unused, it is best to charge low self-discharge NiMH every > >> nine to twelve months. Do NiMH batteries need to be completely > >> discharged before charging? No, NiMH batteries do not have a memory. > >> They can be charged without adverse effect at any point regardless of > >> their state of charge. > >> > >> https://www.thomasdistributing.com/Battery-and-Charger-FAQs_ep_46-1.html > >> > >> Get a quality charger that monitors each battery under charge > >> individually with an indicator for each cell to tell you when it is > >> recharged. > >> > >> Monitoring temperature is over-kill IMO and not the best method. It > >> is too dependent on ambient temperatures, air flow, etc.. > >> > >> By all means get the batteries that are low self-discharge types. > >> (sold as "pre-charged") > >> > >> Old Nickel Cadmium cells required discharging to get the full capacity > >> out of them. > > > >Thanks default. > > > >My EBLs were low self discharge. > > > >Andy > > EBL is what I've been buying and get good results with them. Eneloop > are excellent too but cost more. I just bought some Amazon branded > batteries to see if they are any good (but the price wasn't that much > better than EBL). > > Awhile back, after getting frustrated with rechargeable AA > performance, I rigged a dummy load across a battery holder and bought > a few cheap quartz clocks to see which of the odd collection of > batteries I had on hand still could hold a decent charge. The clocks > stop working when the voltage gets down to ~.7V and records the hours > takes to get there.
Interesting results. Andy
On 15/06/19 11:42, default wrote:
> On Fri, 14 Jun 2019 20:02:22 -0700 (PDT), AK > <scientist77017@gmail.com> wrote: > >> On Friday, June 14, 2019 at 4:52:06 AM UTC-5, default wrote: >>> On Thu, 13 Jun 2019 19:08:20 -0700 (PDT), AK >>> <scientist77017@gmail.com> wrote: >>> >>>> On Thursday, June 13, 2019 at 7:28:44 PM UTC-5, Phil Allison wrote: >>>>> AK wrote: >>>>>> >>>>>> >>>>>> The aaa alkaline batteries went out on my tv remote. >>>>>> >>>>>> I decided to use my NiMh UBL aaa batteries. 1100 mAh. >>>>>> >>>>>> They are currently showing 1.31 volts. >>>>>> >>>>>> And they work ok in the remote as is. >>>>>> >>>>>> My charger is the manual type. >>>>>> >>>>>> It charges that type at 150 mA. >>>>>> >>>>>> I want them fully charged since they are 1.2 volts versus 1.50 for the alkaline. >>>>>> >>>>>> I would like to know how much longer to charge them. >>>>>> >>>>>> >>>>>> >>>>> >>>>> ** The correct procedure is to discharge the cells fully and then apply a full recharge cycle - 8 hours in your case. >>>>> >>>>> If you must recharge partly discharged cells, then it takes whatever time needed until their temperate just starts to rise. Constant monitoring by you is needed. >>>>> >>>>> >>>>> >>>>> ... Phil >>>> >>>> I have no way of monitoring temp. >>>> >>>> How do I fully discharge the cells manually? >>>> >>>> Andy >>> >>> If they are unused, it is best to charge low self-discharge NiMH every >>> nine to twelve months. Do NiMH batteries need to be completely >>> discharged before charging? No, NiMH batteries do not have a memory. >>> They can be charged without adverse effect at any point regardless of >>> their state of charge. >>> >>> https://www.thomasdistributing.com/Battery-and-Charger-FAQs_ep_46-1.html >>> >>> Get a quality charger that monitors each battery under charge >>> individually with an indicator for each cell to tell you when it is >>> recharged. >>> >>> Monitoring temperature is over-kill IMO and not the best method. It >>> is too dependent on ambient temperatures, air flow, etc.. >>> >>> By all means get the batteries that are low self-discharge types. >>> (sold as "pre-charged") >>> >>> Old Nickel Cadmium cells required discharging to get the full capacity >>> out of them. >> >> Thanks default. >> >> My EBLs were low self discharge. >> >> Andy > > EBL is what I've been buying and get good results with them. Eneloop > are excellent too but cost more. I just bought some Amazon branded > batteries to see if they are any good (but the price wasn't that much > better than EBL). > > Awhile back, after getting frustrated with rechargeable AA > performance, I rigged a dummy load across a battery holder and bought > a few cheap quartz clocks to see which of the odd collection of > batteries I had on hand still could hold a decent charge. The clocks > stop working when the voltage gets down to ~.7V and records the hours > takes to get there.
I thought the subject was batteries, not cells. When considering discharging, there is a very significant difference between cells and batteries. Fully discharging a cell with a resistor is relatively safe, whereas fully discharging a battery that way *will* cause the weakest cell to be reverse charged - and damaged.