(Real) Intelligent NiMH Chargers? 58
Anti_Climax asks: "I, like many Slashdot readers, have a lot of battery powered devices. With the large number of cells that are in use at a given time, I have taken to using NiMH rechargeables (Ten 2.0Ah Cells for $10 at the local Fry's Electronics). My current charger is a timed unit that was made when 1.3Ah was the norm. I have accepted the fact that if I want my cells charged properly and quickly, I will need to invest in an intelligent charger. With the dozens of manufacturers in the market right now, the Google results are promising but far too broad. What have been your personal experiences in this area? How many of the supposed Smart Chargers are anything but? Who's offering the best deal for my dollar? While I don't need my cells to charge in 15 minutes, I would like to find an inexpensive Intelligent charger that can charge 4 or more high capacity cells (in pairs or individually) in an hour or less."
Kinda of a dupe (Score:5, Informative)
My advice is that you just buy whichever one that *clearly* states that is microchip (that is deltaV) controled rather than stopped by timer. Mine is a Hama and it works well.
For the batteries, check this comparison [imaging-resource.com]. To sum it up, the more mAh the better, brands are usually not that important.
Wal-mart Duracell charger (Score:4, Informative)
Rayovac (Score:2, Informative)
The model number is PS4. Info here. [rayovac.com]
I got mine at Walmart for under $30 with a couple batteries.
C. Crane QuickCharger (Score:3, Informative)
This one is excellent and well-reviewed in a number of publications: http://www.ccrane.com/quick_charger.asp [ccrane.com]. I have had mine for a while now and can attest it's excellent. It handles from four AAA through 4 D-cells. It has a slow-start (which prevents the batteries from getting hot), and for NiCd, it even discharges the batteries to 1.0V before recharging them. The spring clip is VERY strong, which helps assure good contact (at least I assume that's why they're so strong). You can leave the batteries in it, too, and it will keep them topped off.
It's not cheap (US$40) but it's been well worth it to me. I use rechargeables for everything and in every size except 9V. I get my batteries from http://www.batteryspace.com/ [batteryspace.com]. I like the AA 2250 mAh (currently 24 for US$30); they seem to last forever in my digital camera. My 11-year old daughter goes through batteries like crazy for her CD player, radio, clocks, toys, and flashlights, and going all-rechargeable was one of the best moves I ever made. I do keep a spare set of alkaline D-cells for my radio in case of extended power outage, but haven't had to use them yet (My 8 9500 mAh D-cells, like the A-cells, seem to last forever.
The C. Crane charger says it only does NiCd and NiMH, but I also recharge "rechargeable Alkalines" http://www.rayovac.com/products/recharge/rec_alk.s html [rayovac.com] in it with no problems.
Maha (Score:4, Informative)
All are good, the C401FS is their most intelligent charger and has a gentle charge time of 5 hours or a fast charge time of ~100 minutes. I own the C204F and it has been solid like a rock for two years. With the 204F you still have to recondition the batteries every 5 charges or so, the C401FS eliminates that need so I'd go with that if I were buying a new charger. Use the C204W if you want easy international power use.
Re:A related topic ... (Score:3, Informative)
Re:Check out your local hobby shop (Score:4, Informative)
You'll find that the vast majority of chargers put batteries in series for charging anyway. You'll have a hard time finding a charger that has four single cell chargers - it'll have one charger and either parallel four batteries into two sets of two series, or put all four in series. Either situation doesn't provide a great charge.
The trickle charge at the end of the full charge should equalize the individual cells in series.
So put them in parallel, set the capacity limit to the least discharged battery (ie, if one is still 3/4 full then set the limit to charge up to 500mAH) and then let it trickle charge for another few hours.
Either way, there is no consumer charger out there which will charge each cell individually - it doesn't make economic sense to sell high qaulity chargers because in the end the consumer isn't willing to pay 2-3 times the cost of a similar cheap charger - especially when you consider that they are buying rechargeables to save money.
Buy a good intelligent charger if you want your cells to last. If you want to be really anal about it, charge each cell individually. You won't find a cheap charger that will do that for you.
If we are talking about different areas of battery technology then it's probably because you don't understand battery technology. I can see why you're asking slashdot for battery charger recomendations - you don't understand battery charging so you hope to purchase a device that will do all the work for you. But then you state you have all these 'special needs.' Until you understand how batteries and packs work and how charging works then you won't be able to determine what a good charger is, or how to correctly use one if you happened to buy the right one for your needs. We can't help you any more than you can because you haven't really defined your needs.
For this reason I suspect you'll be best served by a simple intelligent charger such as one sold by radio shack, sam's club, or batteries plus. You don't have to understand how the cells work, how charging works, or anything more difficult than plug-n-chug.
If you want the batteries to get a full charge, if you want them to be conditioned so you can use the full capacity, if you want them to last through hundreds of charges, if you want them to be well matched, if you want them to charge quickly, and if you want to charge them without observation and not worry about leaving them on for 'too long' - learn more about how an intelligent charger works, and then buy a good intelligent charger. Those higher end models made for radio controlled cars are good for this because they follow one of the 'ideal' charging algorithm and are fairly configurable and feature complete.
But that's kind of like setting up a Linux firewall when what you really want is to buy a linksys router with built in sort of decent firewall. In the end you need to decide whether your time and energy in going over the learning curve is worth the benefit. If you aren't going to learn, then you'll not only find the linux solution more confusing, you also risk doing it wrong and making the situation worse than it is.
-Adam
If you need a serious charger, get one ... (Score:3, Informative)
My current favorite is the Great Planes Triton charger [towerhobbies.com] -- I like it so much that I've got two of them. It'll charge anything. If you need it to run off of 110v AC current, this page [marcee.org] will probably help set you up cheaply. You'll need to make a battery holder to hold the cells, but you could easily charge 10 at once, or possibly even charge them inside whatever you're using them in.
(And this [google.com] tells how to find the best price on it right now.)
Note that most NiMH cells will only tolerate being charged at up to 1 C -- so don't charge your 2 Ahr cells at more than 2 A if you want them to last (and one amp, 1/2 C, would be better.) I don't know what they do to the 15 minute cells to let them be charged at 4 C, but whatever it is, most NiMH cells do not have it. No charger, no matter how smart, is going to remove this limitation for you.Of course, chargers like the Triton are probably overkill for what you need, especially at $130, but I certainly love mine ...
Re:Maha (Score:3, Informative)
I was very pleasantly surprised to find that the charger restored the Kodak batteries as well (up to ~100 shots instead of ~10).
I later saw this review of the charger:
http://www.imaging-resource.com/ACCS/C4
One nice thing is that each cell is independently charged. This is a very nice feature when you have things like the Motorola FRS radios that use 3 cells. Chargers that only charge pairs of batteries are a real pain. Avoid them.
Unfortunately I then bought a new camera that uses a proprietary lithium battery.
Oh well, I now have extra sets of cells for the GPS, MP3 player, camera flash, etc.
Re:A related topic ... (Score:3, Informative)
I have. It's called a Q-Tip travel pack. Go to your local drugstore and look for a $1 package of 30 Q-Tips in a plastic box with a flip up lid. Open box, discard Q-Tips, insert 6 AA batteries. They'll rattle around a little but it's as good a fit as you're going to find for the money.
Don't use rechargeables for all needs (Score:5, Informative)
Rechargeables are not the best idea for low(est) power devices. A common TV remote control operates on two, sometimes three Alkaline cells for two or three years, sometimes even longer. Most, if not all, remote control chips are optimized for this operation mode. True, if you press a button on a remote, it draws a lot of power for the infrared LEDs. One ampere is not unusual. But it sends very short pulses (or else the LEDs would literally burn), and the real power does not come from the battery, but from an electrolyte capacitor contacted in parallel, via a very small resistor, to the battery. It is rapidly discharged by the LEDs, and then charged again by the battery. The battery just has to provide a very small current to recharge the capacitor after each pulse, and an even smaller, permanent current for the controller chip. Alkaline cells have a very low self-discharge factor, so they can work like this for years. The remote control continues to work even if the alkaline cell is nearly dead (1.3 V), but with a reduced range (because of the lower available energy due to the lower voltage) and with a noticeable recovery time. When the voltage is so low that the chip does not work properly, it starts to send nonsense to the TV (and may under certain circumstances crash the microprocessor inside the TV - nobody is perfect).
If you replace the alkaine cells with NiCD or NiMH, this lowers the available voltage by 0.3 volts per cell (NiCD=1.2 V, alkaline=1.5 V), thus reducing the available engergy for the LEDs, thus reducing the range of the remote control. Those rechargable cells discharge themselves, so you need to recharge them often. But at that time, you want to use your remote control as well, so you need two pairs of rechargeable cells, and you need a charger. Probably a good one, so it does not kill your cells while loading them. And after some time, your rechargeables are dead because they had nothing "to do". So you need two new pairs of cells, probably after two years. Just about after the same time that you would have bought the first new pair of alkalines (the first one is usually included).
Just calculate for yourself: Using rechargeables in remote control is nonsense. And if you are concerned about the environmental impact: At least here in Germany, there is a well-working return system for alkaline (and zinc carbon) cells (in fact, you have to return your used cells).
The same is also true for other low(est) power devices, like clocks and calculators with liquid crystal displays (LCDs), and most analog quartz clocks. Radio controlled analog clocks need a little bit more power and a "high" voltage for the receiver, so they can not drain alkaline cells as much as clocks without receiver and remote controls.
My "BRAUN" electical toothbrush uses a single NiCd cell which is permanently charged when it sits in its "docking station". After about one year of permanent "keep alive" charging, the cell is now nearly dead. It still can hold enough energy to work for five minutes, but when it is disconnected from the wall outlet for more than a few hours, it simply does not work and needs two days to recharge. The cell is sealed into the toothbrush, having a predetermined breaking point in the case to take out the cell for disposal, so I can not replace the cell without permanently damaging the toothbrush. A trick I've seen too late on TV: Do not permanently charge the toothbrush, discharge it while using, and connect it only to mains when it is empty. It will need round about a day to charge. This will avoid the memory effect.
About batteries and cells:
A cell consists of two electrodes (the positive anode and the negative cathode), the electrolyte, and a case. Depending on the materials used, a single cell has 1.2V (NiCd and NiMH), 1.4V (zinc air button cells), 1.5V (alkaline and zinc carbon), 1.55V (Silver / Quicksilver button cells), 2V (Pb=lead acid), 3V (Lithium), o
Re:no CPU involved (Score:4, Informative)
Re:Why not more popular? (Score:4, Informative)
1. Voltage.
2. Discharge.
The voltage of rechargeable batteries is only 1.2V, which means you are undervolting anything you are using them in. They work fine in things like portable CD Players where they were designed for rechargables, the voltage is mostly irrelevant for all their electronics in the device, and they only use 2 batteries anyhow.
If we are talking about most other electronic devices, a 0.3v drop makes the batteries last a much shorter ammount of time. Or, in something like a flashlight, it makes the bulb dimer, like the batteries are nearly dead, even when they've just been fully charged. The more batteries you use in a device, the most serious the undervolting is... If you put around 4 batteries in a single device, the voltage is so low with rechargables, it's like one whole battery is missing. That means the device goes dead very quickly, and it may not be opperating well while it is able to work.
The second problem is discharge. Alkaline batteries hold their charge for years and years if they aren't used. NiCad and NiMH batteries don't. Most battery-powered devices are not ones that use up massive ammounts of power every day, they're more like flashlights, portable CD players, etc, where you want to leave the batteries in there for months before you actually want to use them. Waiting for them to charge when you need them is not an option, and constantly re-charging a rotating set of dozens of batteries is so cumbersome that it's not worth the effort.
Now, the second issue isn't one that's easy to solve, but the first one is. Somebody should smack around the battery manufacturers and ask why they aren't making higher voltage rechargable batteries. There is no technological reason why they can't make batteries as high voltage as Alkalines, but they just don't do it.
Re:Check out your local hobby shop (Score:3, Informative)
Hmm... No, that's not true. In the past, most charged in parallel, but not serial. Today, most charge individually, and cheap ones charge only in sets of 2.
No, not even slightly. I know my Energizer 1hr NiMH charges each of the 4 cells individually, and I suspect so to do the Duracell chargers. They aren't very expensive, and are found just about everywhere now. Besides this one, I know that most, if not all "smart" chargers these days handle batteries individually... Having twice the circuitry is really no big deal (ie Charging 4 individual, vs 2 in pairs).
No. There are lots, and they've been around for a long time.