Keeping NiMh batteries charged without overcharging them

Discussion in 'Digital Photography' started by Daniel Prince, Jul 17, 2006.

  1. I know that this is off topic for this newsgroup but there is a lot
    of battery discussion here.

    My brother just bought a set of two FRS radios that came with NiMh
    rechargeable battery packs and a charging stand (Motorola Talkabout
    T5000R). The manual says that the battery packs are Nicad but they
    are NiMh. The manual says to charge the battery packs for 16 hours
    the first time and then after the first charge 14 hours. The manual
    also says that the battery packs should not be charged for more than
    16 hours.

    Can I keep these battery packs fully charged by putting the charger
    on a timer? If so, how many minutes per day should they be charged?
    Thank you in advance for all replies.
     
    Daniel Prince, Jul 17, 2006
    #1
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  2. Daniel Prince wrote:
    > I know that this is off topic for this newsgroup but there is a lot
    > of battery discussion here.
    >
    > My brother just bought a set of two FRS radios that came with NiMh
    > rechargeable battery packs and a charging stand (Motorola Talkabout
    > T5000R). The manual says that the battery packs are Nicad but they
    > are NiMh. The manual says to charge the battery packs for 16 hours
    > the first time and then after the first charge 14 hours. The manual
    > also says that the battery packs should not be charged for more than
    > 16 hours.
    >
    > Can I keep these battery packs fully charged by putting the charger
    > on a timer? If so, how many minutes per day should they be charged?
    > Thank you in advance for all replies.


    The answer to this conundrum is dependant on how much you have used the
    batteries each day plus a small amount of self-discharge. I wouls say it is
    not possible to use a timer effectively unless it is connected to a charger
    which switches off once the batteries are fully charged. There are many such
    chargers around.
     
    Dennis Pogson, Jul 17, 2006
    #2
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  3. In article <>, Daniel Prince
    wrote:
    > I know that this is off topic for this newsgroup but there is a lot
    > of battery discussion here.


    Here's a useful resource - http://www.batteryuniversity.com .


    Roger
     
    Roger Whitehead, Jul 17, 2006
    #3
  4. "Daniel Prince" <> wrote in message
    news:...
    >I know that this is off topic for this newsgroup but there is a lot
    > of battery discussion here.
    >
    > My brother just bought a set of two FRS radios that came with NiMh
    > rechargeable battery packs and a charging stand (Motorola Talkabout
    > T5000R). The manual says that the battery packs are Nicad but they
    > are NiMh. The manual says to charge the battery packs for 16 hours
    > the first time and then after the first charge 14 hours. The manual
    > also says that the battery packs should not be charged for more than
    > 16 hours.
    >
    > Can I keep these battery packs fully charged by putting the charger
    > on a timer? If so, how many minutes per day should they be charged?
    > Thank you in advance for all replies.


    Do you think it was a typo or do you think the instructions are actually for
    Nicads?
    Applying what I know about NiMh cells in a hybrid car, they are generally
    topped off to the 3/4 full capacity and generally not allowed to drain below
    1/4 remaining capacity. It's meant to extend the life of the cells.
    What we do know about your batteries is they will lose their charge. If we
    go by a guideline of 1% loss each day then maybe about 10 minutes on the
    charger will maintain the batteries at what ever level they may be at. In
    other words, if the batteries have 1/2 their power reserve, 10 minutes on
    the charger will keep them at 1/2 their power reserve. If we use 14 hours as
    the "going from dead to full charge state" then it would be about 8 minutes
    a day.
    If it were me I would just get a battery tester and go from there.
    mark_
     
    =?iso-8859-1?Q?mark=5Fdigital=A9?=, Jul 17, 2006
    #4
  5. "Dennis Pogson" <> wrote:

    >Daniel Prince wrote:
    >> I know that this is off topic for this newsgroup but there is a lot
    >> of battery discussion here.
    >>
    >> My brother just bought a set of two FRS radios that came with NiMh
    >> rechargeable battery packs and a charging stand (Motorola Talkabout
    >> T5000R). The manual says that the battery packs are Nicad but they
    >> are NiMh. The manual says to charge the battery packs for 16 hours
    >> the first time and then after the first charge 14 hours. The manual
    >> also says that the battery packs should not be charged for more than
    >> 16 hours.
    >>
    >> Can I keep these battery packs fully charged by putting the charger
    >> on a timer? If so, how many minutes per day should they be charged?
    >> Thank you in advance for all replies.

    >
    >The answer to this conundrum is dependant on how much you have used the
    >batteries each day plus a small amount of self-discharge. I wouls say it is
    >not possible to use a timer effectively unless it is connected to a charger
    >which switches off once the batteries are fully charged. There are many such
    >chargers around.


    Most of the time the batteries will not be used at all.

    Here are some pictures of one of the battery packs:

    http://img242.imageshack.us/my.php?image=pict0354gt2.jpg

    http://img119.imageshack.us/my.php?image=pict0352up0.jpg

    Are there automatic chargers that will work with these battery
    packs?
     
    Daniel Prince, Jul 17, 2006
    #5
  6. mark_digital© <> wrote:

    >
    >"Daniel Prince" <> wrote in message
    >news:...
    >>I know that this is off topic for this newsgroup but there is a lot
    >> of battery discussion here.
    >>
    >> My brother just bought a set of two FRS radios that came with NiMh
    >> rechargeable battery packs and a charging stand (Motorola Talkabout
    >> T5000R). The manual says that the battery packs are Nicad but they
    >> are NiMh. The manual says to charge the battery packs for 16 hours
    >> the first time and then after the first charge 14 hours. The manual
    >> also says that the battery packs should not be charged for more than
    >> 16 hours.
    >>
    >> Can I keep these battery packs fully charged by putting the charger
    >> on a timer? If so, how many minutes per day should they be charged?
    >> Thank you in advance for all replies.

    >
    >Do you think it was a typo or do you think the instructions are actually for
    >Nicads?


    The instructions and table of contents say "NiCd" several times and
    never mention NiMh. The battery packs are clearly marked NiMh. I
    think the manual was written when they used NiCd battery packs and
    not updated when they switched to NiMh technology.

    >If it were me I would just get a battery tester and go from there.


    What kind of tester would I need for the battery packs in the
    pictures below?

    http://img242.imageshack.us/my.php?image=pict0354gt2.jpg

    http://img119.imageshack.us/my.php?image=pict0352up0.jpg
     
    Daniel Prince, Jul 17, 2006
    #6
  7. Daniel Prince

    ASAAR Guest

    On Mon, 17 Jul 2006 11:35:54 -0700, Daniel Prince wrote:

    > What kind of tester would I need for the battery packs in the
    > pictures below?
    >
    > http://img242.imageshack.us/my.php?image=pict0354gt2.jpg
    >
    > http://img119.imageshack.us/my.php?image=pict0352up0.jpg


    It wouldn't be very practical to try to test those battery packs.
    Relatively inexpensive testers can be had, but they're usually
    designed to test individual cells. From the images, it appears that
    those battery packs contain 3 AAA NiMH cells. Perhaps AAA was used
    to minimize the size, but Motorola also makes several very small FRS
    radios that use 3 AA batteries, so if you ever plan to get
    additional FRS radios, look for them. As NiMH batteries can now be
    easily found with capacities in the 2,500 to 2,700 mah range, that
    would give them 4 times the capacity of the rather anemic battery
    packs used by your Motorola FRS radios.


    > Can I keep these battery packs fully charged by putting the charger
    > on a timer? If so, how many minutes per day should they be charged?


    The best way to keep the batteries charged depends to a great
    extent on how often you use the radios. What complicates the matter
    is that your charger doesn't appear to be a "smart" charger that
    knows when to stop charging. You should have at least on more
    battery pack than you have radios. From your battery's standpoint,
    it would be best for them if you use the radios frequently enough so
    that any battery pack in the radio would be fully depleted in
    anywhere from one day to several weeks. Whenever the battery pack
    goes dead, pop in the spare battery pack that's fully charged, and
    put the dead battery pack back in the charger for another 14 hours
    of charging. The spare battery (like most rechargeable batteries)
    will slowly lose charge while sitting unused, but if it's eventually
    used in one of the radios within several weeks of its last session
    in the charger, it will be close enough to being fully charged so
    that whatever charge it lost won't be a significant amount.

    The problem for the batteries would occur if you don't use the
    radio very frequently. Then you'd often be in the position of
    needing to recharge battery packs that still have a good amount of
    charge left in them, and it would be best for the batteries if they
    were charged only long enough to be fully charged. Whether this
    would be 2, 5, 7 or 11 hours, you'd have no way to tell, and could
    only guess based on experience. At least your charger is a very
    slow one, so overcharging probably wouldn't overheat the batteries
    very much, which is very hard on them. What's even worse for
    batteries is non-use. If you get tired of using the radios at the
    end of this summer and pack them away for next year's use, this can
    greatly reduce the battery's performance. Unlike some rechargeable
    battery types (ie, some lithium formulations) that can be totally
    ruined if they go a year or more between charges, NiMH probably
    wouldn't be ruined, but they might lose a substantial amount of
    their capacity.

    It would be good to be able to estimate (roughly) when the
    batteries need to be recharged. Check your manual. It might show
    how long batteries last for both receiving (affected by audio
    volume) and transmitting. Then if you think that the radio has used
    up at least 3/4 of its charge, swap it with the spare battery if
    you're near the charger. If you're away from home and using the
    radio, continue using it until you see a battery warning (assuming
    that the Motorola shows one) and then swap battery packs.
     
    ASAAR, Jul 17, 2006
    #7
  8. "Daniel Prince" <> wrote in message
    news:...
    > mark_digital© <> wrote:
    >
    >>
    >>"Daniel Prince" <> wrote in message
    >>news:...
    >>>I know that this is off topic for this newsgroup but there is a lot
    >>> of battery discussion here.
    >>>
    >>> My brother just bought a set of two FRS radios that came with NiMh
    >>> rechargeable battery packs and a charging stand (Motorola Talkabout
    >>> T5000R). The manual says that the battery packs are Nicad but they
    >>> are NiMh. The manual says to charge the battery packs for 16 hours
    >>> the first time and then after the first charge 14 hours. The manual
    >>> also says that the battery packs should not be charged for more than
    >>> 16 hours.
    >>>
    >>> Can I keep these battery packs fully charged by putting the charger
    >>> on a timer? If so, how many minutes per day should they be charged?
    >>> Thank you in advance for all replies.

    >>
    >>Do you think it was a typo or do you think the instructions are actually
    >>for
    >>Nicads?

    >
    > The instructions and table of contents say "NiCd" several times and
    > never mention NiMh. The battery packs are clearly marked NiMh. I
    > think the manual was written when they used NiCd battery packs and
    > not updated when they switched to NiMh technology.
    >
    >>If it were me I would just get a battery tester and go from there.

    >
    > What kind of tester would I need for the battery packs in the
    > pictures below?
    >
    > http://img242.imageshack.us/my.php?image=pict0354gt2.jpg
    >
    > http://img119.imageshack.us/my.php?image=pict0352up0.jpg
    >


    I have NiCad's their charger wouldn't charge anymore, and at $90 per battery
    pack it turned my stomach to discard them. I gave them to my son-in-law and
    cycled them thru a "mindless" charger (a charger with the same
    characteristics as yours). I got them back and when it came time to
    recharge them my charger did just that. So, there's pros and cons to
    dedicated automatic chargers.
    Bring the battery pack to Radio Shack (or similar outfit) and they'll show
    you a simple multi-tester with probes.
    You say you or your brother won't be using the batteries most of the time.
    Is it because you'll be using an adapter or you won't be using the radios
    often? I'm not familiar with those radios and whether or not they can be
    powered by an ac to dc power supply or from a vehicle's electrical system.

    mark_
     
    =?iso-8859-1?Q?mark=5Fdigital=A9?=, Jul 18, 2006
    #8
  9. mark_digital© <> wrote:

    >Bring the battery pack to Radio Shack (or similar outfit) and they'll show
    >you a simple multi-tester with probes.


    I have several digital multimeters but from what I have read it is
    not possible to determine the state of charge of NiCd or NiMh
    batteries just by measuring the voltage of the cells or packs. If
    it is possible, what voltage would correspond to what state of
    charge?

    For example what would the voltage of this pack be when it was 50
    percent charged?

    What would the voltage of this pack be when it was 25 percent
    charged?

    What would the voltage of this pack be when it was ten percent
    charged?

    >You say you or your brother won't be using the batteries most of the time.
    >Is it because you'll be using an adapter or you won't be using the radios
    >often?


    We use the radios when we go out together to large stores, swap
    meets, parks and amusement parks etc. Sometimes we use the radios
    two or three days a month and sometimes we go a couple of months
    without using them.
    --
    Never ever let your brain explode. It's VERY bad for you and
    it leaves a terrible mess for someone to clean up.
     
    Daniel Prince, Jul 19, 2006
    #9
  10. Daniel Prince

    EDM Guest

    "Daniel Prince" <> wrote in message news:...
    > mark_digital© <> wrote:
    >
    > >Bring the battery pack to Radio Shack (or similar outfit) and they'll show
    > >you a simple multi-tester with probes.

    >
    > I have several digital multimeters but from what I have read it is
    > not possible to determine the state of charge of NiCd or NiMh
    > batteries just by measuring the voltage of the cells or packs. If
    > it is possible, what voltage would correspond to what state of
    > charge?


    Chargers don't measure charge state by voltage. They do it by
    resistance. When cells are at or near their capacity, resistance
    skyrockets.
     
    EDM, Jul 19, 2006
    #10
  11. "Daniel Prince" <> wrote in message
    news:...
    > mark_digital© <> wrote:
    >
    >>Bring the battery pack to Radio Shack (or similar outfit) and they'll show
    >>you a simple multi-tester with probes.

    >
    > I have several digital multimeters but from what I have read it is
    > not possible to determine the state of charge of NiCd or NiMh
    > batteries just by measuring the voltage of the cells or packs. If
    > it is possible, what voltage would correspond to what state of
    > charge?


    I have a Liberty Plus Mosquito Magnet. It runs off a 4.8 NiMh battery pack
    only enough to start, and then the appliance makes enough electricity on
    it's own. Last night I was getting bit like crazy and found the Magnet shut
    down and blinking error lights. I took the appropriate action and then there
    was a different set of error lights when I tried to restart the machine. I
    looked up the error code. "Low voltage". I'm keeping my fingers crossed the
    low voltage situation was caused by the first error code and not from the
    100 degree weather and over heating the unit and battery pack. I'll know
    more this morning when I remove the charger and try to start the machine. I
    have no idea without calling tech support what or how much lower than 4.8
    the pack has to be before the circuitry decides it's low voltage.
    One side note: The Magnet is capable of taking care of way more than just my
    backyard. I joked with my wife the neighbors probably wondered why there was
    a on-slaught of mosquitoes last night. Normally everyone's out having a good
    time. Not last night. Dead silence ;)

    mark_
     
    =?iso-8859-1?Q?mark=5Fdigital=A9?=, Jul 19, 2006
    #11
  12. "mark_digital©" <> wrote in message
    news:...
    >
    > "Daniel Prince" <> wrote in message
    > news:...
    >> mark_digital© <> wrote:
    >>
    >>>Bring the battery pack to Radio Shack (or similar outfit) and they'll
    >>>show
    >>>you a simple multi-tester with probes.

    >>
    >> I have several digital multimeters but from what I have read it is
    >> not possible to determine the state of charge of NiCd or NiMh
    >> batteries just by measuring the voltage of the cells or packs. If
    >> it is possible, what voltage would correspond to what state of
    >> charge?

    >
    > I have a Liberty Plus Mosquito Magnet. It runs off a 4.8 NiMh battery pack
    > only enough to start, and then the appliance makes enough electricity on
    > it's own. Last night I was getting bit like crazy and found the Magnet
    > shut down and blinking error lights. I took the appropriate action and
    > then there was a different set of error lights when I tried to restart the
    > machine. I looked up the error code. "Low voltage". I'm keeping my fingers
    > crossed the low voltage situation was caused by the first error code and
    > not from the 100 degree weather and over heating the unit and battery
    > pack. I'll know more this morning when I remove the charger and try to
    > start the machine. I have no idea without calling tech support what or how
    > much lower than 4.8 the pack has to be before the circuitry decides it's
    > low voltage.
    > One side note: The Magnet is capable of taking care of way more than just
    > my backyard. I joked with my wife the neighbors probably wondered why
    > there was a on-slaught of mosquitoes last night. Normally everyone's out
    > having a good time. Not last night. Dead silence ;)
    >
    > mark_


    Success! It's running!! I put an umbrella close by to shade it just in case.

    mark_
     
    =?iso-8859-1?Q?mark=5Fdigital=A9?=, Jul 19, 2006
    #12
  13. Daniel Prince

    EDM Guest

    EDM, Jul 19, 2006
    #13
  14. "EDM" <> wrote in message
    news:Daqvg.1926$...
    > "mark_digital©" <> wrote in message
    > news:...
    >> > I have a Liberty Plus Mosquito Magnet.

    >
    > You have my sympathies:
    > http://www.amazon.com/gp/product/B000140B6I/104-9109701-4636743?v=glance&n=228013
    >
    >


    I know those complaints are real. If the guy and his friends are all buying
    their propane from the same place and the propane is lousy, it'll clog. If
    they move their Mosquito Magnets without shutting them off first it can
    cause contaminants in the tank to clog the line. If the new type of valve on
    the tank is opened too quick the safety shut off will be triggered. If the
    unit is placed too close to where everyone is the mosquitoes will head
    straight for them instead. The one thing it doesn't mimic is our heartbeat.
    I'm having good luck with my unit. It does an excellent job attracting
    ticks.
    This is my third summer season with it. Without a doubt, it's not for every
    backyard situation. It took me awhile to find the right place in the yard to
    run it.
    mark_
     
    =?iso-8859-1?Q?mark=5Fdigital=A9?=, Jul 20, 2006
    #14
  15. Daniel Prince

    EDM Guest

    "mark_digital©" <> wrote in message news:...
    >
    > "EDM" <> wrote in message
    > news:Daqvg.1926$...
    > > "mark_digital©" <> wrote in message
    > > news:...
    > >> > I have a Liberty Plus Mosquito Magnet.

    > >
    > > You have my sympathies:
    > > http://www.amazon.com/gp/product/B000140B6I/104-9109701-4636743?v=glance&n=228013
    > >
    > >

    >
    > I know those complaints are real. If the guy and his friends are all buying
    > their propane from the same place and the propane is lousy, it'll clog. If
    > they move their Mosquito Magnets without shutting them off first it can
    > cause contaminants in the tank to clog the line. If the new type of valve on
    > the tank is opened too quick the safety shut off will be triggered. If the
    > unit is placed too close to where everyone is the mosquitoes will head
    > straight for them instead. The one thing it doesn't mimic is our heartbeat.
    > I'm having good luck with my unit. It does an excellent job attracting
    > ticks.
    > This is my third summer season with it. Without a doubt, it's not for every
    > backyard situation. It took me awhile to find the right place in the yard to
    > run it.


    Operational issue aside, the customer support complaints
    are what struck me. Downright abysmal customer support.
     
    EDM, Jul 21, 2006
    #15
  16. "EDM" <> wrote in message
    news:rX_vg.2689$...

    > Operational issue aside, the customer support complaints
    > are what struck me. Downright abysmal customer support.
    >
    >

    I called cs and asked for some help because mine was making a low howling
    sound early mornings and I was concerned it would wake my neighbors. "Is it
    really that loud?", I was asked. "Yes", I replied, "It sounds spooky"
    Well, it was definitely within the one year warrantee, so they shipped a new
    head and I shipped the old one back. I recall I had the new head in three
    days.

    The main difference between the old and the new was a subtle change in the
    "throat" where the air goes down and then back up. Cool morning air and
    subsequentially a slightly slower flow created an audible sound much like a
    musical instrument. I still hear howling when it ramps up to speed when I
    restart it. But it only lasts for a few minutes and then goes away.

    Umm, trust your instinct. If you have a gut feeling about something, by all
    means, stay away from it.

    mark_
     
    =?iso-8859-1?Q?mark=5Fdigital=A9?=, Jul 21, 2006
    #16
  17. Daniel Prince

    Neil Maxwell Guest

    On Mon, 17 Jul 2006 08:43:47 GMT, Roger Whitehead
    <> wrote:

    >In article <>, Daniel Prince
    >wrote:
    >> I know that this is off topic for this newsgroup but there is a lot
    >> of battery discussion here.

    >
    >Here's a useful resource - http://www.batteryuniversity.com .
    >

    Excellent link - thanks!



    --
    Neil Maxwell - I don't speak for my employer
     
    Neil Maxwell, Jul 21, 2006
    #17
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