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Thread: What's the Best Battery Charger?

  1. #16
    Senior Member DougPaul's Avatar
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    I have several chargers, including the Maha MH-C401fs and the MH-C204. Both are good chargers, but I prefer the 401 because it has four independent charging circuits and the 204 has only two. (It can only charge batteries in matched pairs and batteries become mismatched over time. Or your headlamp uses three... Independent circuits are better because the charge is tailored for each battery individually.)

    I also have a Lacrosse BC-900 (the Maha MH-C9000 is similar). It is similar to the C401 with the additional capability of measuring the capacity of the cells. This can be useful after you have had some batteries for a while and wish to evaluate and sort out those that are getting weak. (I also label all my batteries so I can use them in matched groups and keep track of their health.)

    The MH-C401fs is a good basic charger. A good "starter' charger (and probably the one that I use most often).

    "Standard" AA cells have a capacity ~2600 mAh (AAA ~900 mAh) and low-discharge AA cells have a capacity ~2000 mAh (AAA ~800 mAh). I have some of each kind, but will probably be standardizing on the low-discharge cells in the future. (Standard cells will discharge significantly faster while sitting on the shelf than low-discharge cells. However, if you top off the charge shortly before using them, the standard cells work fine.)

    FWIW, I use Sanyo Eneloops for my low-discharge. They pretty much set the standard...

    Trickle charging is not a good way to charge or store NiMH cells. They charge best at a several hour charge rate using a "smart" charger. (A non-smart charger is likely to damage the cells.) Things that damage NiMH cells: overcharging, overheating when charging (typically by charging too fast), discharging to zero or reverse charging (by trying to get the last bit of use out of them). It is good to charge them frequently (there is no need to discharge them fully)--if charged properly using a good smart charger, they do not develop a memory effect. (Memory effect is primarily seen in NiCad cells.)

    Many of the chargers run on 12 volts and come with (or offer) a 12V automotive cord. Many also come with (or offer) international power supplies (120-240 V, 50-60 Hz).

    NiMH batteries are much better than alkaline batteries in digital cameras. Digital cameras tend to draw high currents for short periods of time--NiMH is good at this, alkaline is poor at best. (NiCads, lithium non-rechargeables, and Lion (lithium ion) rechargeables also work well in this kind of service.)

    I use NiMH batteries in my camera (at least the one that will take AA cells...), headlamps, GPS, bike lights, radios, etc. (Alkalines are better for smoke and CO2 detectors, clocks, and other indoor low-drain applications.)

    A good place to buy NiMH batteries and chargers:
    http://www.thomasdistributing.com

    Professional quality info on NiMH batteries:
    http://www.batteryuniversity.com/index.htm
    http://data.energizer.com/

    This general topic has been addressed a number of times in the past: just search on NiMH and lots of relevant threads will appear.

    Standard caveat: I have no connection with any of the companies mentioned above. Just a user or customer.

    Doug
    Last edited by DougPaul; 03-03-2010 at 10:36 AM.

  2. #17
    Senior Member DougPaul's Avatar
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    Quote Originally Posted by Kevin Rooney View Post
    On another note - a couple of years ago I got a great deal on solar-powered outdoor lights, and when they failed a year later I understand why Home Depot was dumping them - their NiMH battery was of poor quality, and only put out 600mAH IIRC. Over the course of about a week, all of them (some 20+) gradually failed to fire up at dusk. I replaced those batteries with aging Kodak NiMH rated at 1600mAH and have had no problems for many months now.
    Actually, NiCads work better in this kind of service--low drain (often to exhaustion) with trickle charging and widely varying temperatures (ie frequent abuse). NiCads are a lot more rugged than NiMHs, but the cadmium makes them hazardous waste. (Don't throw out NiCads--recycle them. Radio Shack and lots of hardware stores will take them for proper disposal.)

    Doug

  3. #18
    Banned Kevin Rooney's Avatar
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    Lots of good info (and a bit of humor )- thanks to all for creating this resource.

  4. #19
    Senior Member SAR-EMT40's Avatar
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    Oops. I should point out that the MH777 doesn't actually charge AA and AAA batteries directly. It is made mostly for power packs but I have been using AA and AAA battery packs that can be attached with alligator clips that come with the charger for so long I forgot that. So, it can be done with a 4 or 8 battery case from radio shack but doesn't actually come with it. It is an amazingly versatile charger.


    Sorry for any confusion on that,
    Keith
    "The real work of men was hunting meat. The invention of agriculture was a giant step in the wrong direction, leading to serfdom, cities, and empire. From a race of hunters, artists, warriors, and tamers of horses, we degraded ourselves to what we are now: clerks, functionaries, laborers, entertainers, processors of information."- Ed Abbey

  5. #20
    Senior Member DougPaul's Avatar
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    Quote Originally Posted by SAR-EMT40 View Post
    Oops. I should point out that the MH777 doesn't actually charge AA and AAA batteries directly. It is made mostly for power packs but I have been using AA and AAA battery packs that can be attached with alligator clips that come with the charger for so long I forgot that. So, it can be done with a 4 or 8 battery case from radio shack but doesn't actually come with it. It is an amazingly versatile charger.
    The MH-C777 looks fine for battery packs, but looks like it can charge only one item at a time. The ability to charge cells individually is desirable, so if you have a bunch of AA or AAA cells you are probably better off with a charger that simultaneously charges several cells individually (eg MH-C401 or MH-C801).

    I have several "lost" battery packs where one cell appears to be weak, but since the pack is sealed the entire pack must be replaced. If I could get at the cells individually, I might be able to fix (rejuvenate) or replace the weak cell... High quality battery packs (eg laptop batteries) often have external connections to each cell and internal temperature sensors to allow one to maximize the useful lifetime.

    Doug

  6. #21
    Senior Member SAR-EMT40's Avatar
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    Quote Originally Posted by DougPaul View Post
    The MH-C777 looks fine for battery packs, but looks like it can charge only one item at a time. The ability to charge cells individually is desirable, so if you have a bunch of AA or AAA cells you are probably better off with a charger that simultaneously charges several cells individually (eg MH-C401 or MH-C801).

    I have several "lost" battery packs where one cell appears to be weak, but since the pack is sealed the entire pack must be replaced. If I could get at the cells individually, I might be able to fix (rejuvenate) or replace the weak cell... High quality battery packs (eg laptop batteries) often have external connections to each cell and internal temperature sensors to allow one to maximize the useful lifetime.

    Doug
    Well actually like I was saying Doug. If you buy a 4 pack or 8 pack battery holders from radio shack.

    4 battery pack AA holder

    or like this

    8 battery pack AA holder

    You can charge anything you want including D, C or AAA cells or actually anything with the charger up to battery packs providing 25 Volts. Like I said it has a pair of alligator clips so you can just hook on and it does have the overtemp sensor as well. If you only ever need to do AA or AAA then I agree those others are a great choice. This is a really remarkably versatile system though if you ever need to do other types of odd batteries or battery packs. I have actually made a connector that re-charges/conditions many laptop batteries also. Like I said it will handle NiCd, NiMH and Lion batteries and battery packs.

    Regards,
    Keith
    Last edited by SAR-EMT40; 03-03-2010 at 04:42 PM.
    "The real work of men was hunting meat. The invention of agriculture was a giant step in the wrong direction, leading to serfdom, cities, and empire. From a race of hunters, artists, warriors, and tamers of horses, we degraded ourselves to what we are now: clerks, functionaries, laborers, entertainers, processors of information."- Ed Abbey

  7. #22
    Senior Member DougPaul's Avatar
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    Quote Originally Posted by SAR-EMT40 View Post
    Well actually like I was saying Doug. If you buy a 4 pack or 8 pack battery holders from radio shack.
    As I stated earlier, it is better for the NiMH cells to charge them individually if possible. Thus if you have a bunch of individual cells (eg AA or AAA) an MH-C401 (or similar) is a better choice than an MH-C777 (or similar) and a 4-cell battery holder. The MH-C777 looks like a fine charger for sealed packs.

    I think we are mostly in agreement on this tangent...

    FWIW, I think charging bunches of AA or AAA NiMH cells are the primary topic here.

    Doug

  8. #23
    Senior Member SAR-EMT40's Avatar
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    Quote Originally Posted by DougPaul View Post
    As I stated earlier, it is better for the NiMH cells to charge them individually if possible. Thus if you have a bunch of individual cells (eg AA or AAA) an MH-C401 (or similar) is a better choice than an MH-C777 (or similar) and a 4-cell battery holder. The MH-C777 looks like a fine charger for sealed packs.

    I think we are mostly in agreement on this tangent...

    FWIW, I think charging bunches of AA or AAA NiMH cells are the primary topic here.

    Doug
    OK, gotcha now. So you think that each cell on those units has it own charger or at least they are charged in parallel. I wasn't aware of that.

    I have been using mine in this fashion for quite a while but I do make sure they are worn down to (about) the same level and have had some good results over the years but I get what you are saying. Granted that is anecdotal but I have had good luck with it. I understand your point though.

    Regards,
    Keith
    Last edited by SAR-EMT40; 03-03-2010 at 09:44 PM.
    "The real work of men was hunting meat. The invention of agriculture was a giant step in the wrong direction, leading to serfdom, cities, and empire. From a race of hunters, artists, warriors, and tamers of horses, we degraded ourselves to what we are now: clerks, functionaries, laborers, entertainers, processors of information."- Ed Abbey

  9. #24
    Senior Member DougPaul's Avatar
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    Quote Originally Posted by SAR-EMT40 View Post
    OK, gotcha now. So you think that each cell on those units has it own charger or at least they are charged in parallel. I wasn't aware of that.
    Yes--chargers such as the CF-401 have four independent charging circuits so if the cells are mismatched or have different initial charge levels, each cell gets treated according to its individual needs.

    I have been using mine in this fashion for quite a while but I do make sure they are worn down to (about) the same level and have had some good results over the years but I get what you are saying. Granted that is anecdotal but I have had good luck with it. I understand your point though.
    Charging a group of cells connected in series (ie a battery) with a single circuit generally works, but is not the best for the cells. This forces the same amount of energy into all cells and as a result some may get overcharged and some undercharged. As you charge a cell, the energy first goes into desirable chemical changes (ie the charge) but once the cell is full, it must dissipate the energy in other ways. This excess energy can overheat the cell, generally damage the cell, cause gas formation, pressure build-up, and force the pressure seal to open and vent electrolyte. NiMH cells are pretty delicate with respect to overcharging--the max allowable overcharge current is ~.05C. (C is the capacity in amp-hours.) NiCads are more robust to overcharge current: the limit is ~.1C. (In fact, the standard trickle charge for NiCads is .1C for 14 hours.) A good smart charger charges at a good rate (2-3 hour (ie .5C to .3C charging current) is optimum for NiMH) and shuts down to a safe low trickle rate when the cell is fully charged or close to fully charged. (A smart charger can detect a fully charged cell because the its temp starts to rise and its voltage, which has been rising during the charge, levels off and begins to to drop.)

    The above is for NiMH cells. Lion (lithium ion rechargeable) cells are far more delicate and dangerous. If you discharge them to zero or overcharge them, they are destroyed. And if you overheat them or short circuit them, they are likely to catch fire and/or explode*. (Lion cells and equipment which uses them contain protective circuits to prevent such events...) There are several different chemistries of Lion cells with different safety factors. See http://www.batteryuniversity.com/partone-5B.htm for more info.

    * This is why higher quality Lion batteries bring out connections for all cells--so each cell can be watched individually.

    Doug
    Last edited by DougPaul; 03-03-2010 at 11:43 PM.

  10. #25
    Senior Member Paradox's Avatar
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    A touch off topic but Doug gave me the following reference Battery University. They state, and I have found out the hard way, that batteries (Alkaline, NiMH, and Lion) all tend to fail at about -20C (-4F) I have gotten around that with my GPS and camera by placing a handwarmer in the respective cases. On a long hike a few weeks ago to do the Twins and Galehead where the temps were as low as minus13F. my GPS worked fine and the camera's lens never fogged.
    WNH4K:48/48, SLAT50:50/50, NEHH:100/100, NE115:115/115,
    TW72:60/72, WADK46: 18/46, 52WAV:16/52, Cat35:9/35(39)

  11. #26
    Banned Kevin Rooney's Avatar
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    Yesterday I ordered one of the chargers recommended on this thread along with 4 low-discharge AA batteries. When it arrives I'm going to chuck my Energizer battery charger, aka "battery cooker".

    I'm no longer plugged into the tech-toy market (a good thing), and until this thread I hadn't heard of low-discharge batteries.

    Am going to wait on the rechargeable lion batteries ...

  12. #27
    Senior Member Quietman's Avatar
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    I was going to ask why rechargeable Lion AA batteries are not available, but instead did some quick research. According to the Greenbatteries.com site:

    Are Lithium Ion batteries available in standard sizes like AA , C or D cell size?

    No, Lithium-ion batteries are not available in standard sizes. We believe this is because it would be too easy for users to inadvertently put them in a charger not designed for Lithium-ion batteries creating a potentially dangerous situation. (If an alkaline battery is put into the wrong charger it might leak or even burst, but a lithium-ion battery put into a NiCd or NiMH charger not designed for lithium-ion, might ignite. Also, because Li-ion batteries operate at much higher voltage (typically 3.7V per cell) than the 1.2 to 1.5V of most cell batteries, designing a 1.5V lithium-ion cell would be expensive.


    I did find These batteries, but they do clearly state that they are not a direct replacement for 1.5v AA's.

  13. #28
    Senior Member DougPaul's Avatar
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    Quote Originally Posted by Paradox View Post
    A touch off topic but Doug gave me the following reference Battery University. They state, and I have found out the hard way, that batteries (Alkaline, NiMH, and Lion) all tend to fail at about -20C (-4F) I have gotten around that with my GPS and camera by placing a handwarmer in the respective cases. On a long hike a few weeks ago to do the Twins and Galehead where the temps were as low as minus13F. my GPS worked fine and the camera's lens never fogged.
    Lithium primary (non-rechargeable) cells work down to ~-40 (take your choice--F or C ). NiCads will also work to temps below the limits of NiMH, around -40, IIRC.

    Doug

  14. #29
    Senior Member DougPaul's Avatar
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    Quote Originally Posted by Kevin Rooney View Post
    Am going to wait on the rechargeable lion batteries ...
    You probably already have some--they are standard in laptops, cellphones, and many cameras...

    Doug

  15. #30
    Senior Member DougPaul's Avatar
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    Quote Originally Posted by Quietman View Post
    I was going to ask why rechargeable Lion AA batteries are not available,
    As you noted, the voltages are different and improper management of Lion cells can destroy them or cause fires/explosions.

    Are Lithium Ion batteries available in standard sizes like AA , C or D cell size?
    CR123 cells are a standard size that comes in Lithium primary (3V*) and Lion (3.3v rechargable) technologies.

    Lion (Or Li-Ion) cells seem to come in standard sizes that are different from the usual consumer sizes (AAA, AA, C, D, etc). http://www.batteryuniversity.com/ refers to the 18650 cylindrical size in a number of places and a search on "18650 lithium ion" brings up a number of suppliers including http://www.onlybatteries.com/cat_fea...d=162&uid=1106 which lists a number of sizes.

    Camera manufacturers, unfortunately, have steadfastly resisted the use of standard size Lion cells in their cameras. (And every other new camera seems to require a different size/form factor battery.) All the better to keep prices high...

    * There are two different chemistries for lithium primary cells--one produces 1.5v and the other 3V.

    Doug

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