[Most of the "in-depth" La Crosse BC-900 threads here on FW have been 'Archived', so new information cannot be added to their 'Quick Summary'. ]
"Turak" said:There are at least 2 MAJOR reasons that you get about a 50-100mAh difference between an MH-C9000 and a BC900. I actually have 2 of each and love them both for different reasons.
1. Because of changes made to the firmware of the MH-C9000, the charger actually DOES NOT always charge an Eneloop (and others) to its maximum capacity.
The MH-C9000 charger uses -detaV, maxV, and a timer limit for its termination methods. In the early models (F models), the chargers maxV was set much higher and the batteries would actually hit -deltaV.....but the problem was they were getting just a bit too hot. Maha decided to lower the maxV point to 1.47V. THis had the effect of causing many batteries, especially Eneloops, to hit maxV before they hit -deltaV. This in turn causes the Eneloops to come off the charger slightly under maximum capaity. If you check the charts, the Eneloops typically seem to hit -detaV somewhere in the 1.50 to 1.55 range. So ultimately more batteries seem to terminate now by hitting maxV instead of -deltaV with this charger.
The BC900 charger uses the same termination methods and also suffers from the same problem except that it's maxV is set at approximately 1.52V. More batteries seem to terminate by hitting -deltaV than maxV when using this charger. This is also one of the reasons that batteries come off a BC900 a little 'warmer' (besides the fact they are jammed in a smaller space).... they are actually closer to maximum capacity when they hit -deltaV than maxV.
Most 1.5V NiMh AA batteries tend to hit -deltaV anywhere from about 1.45V-1.55V.
2. As stated by someone else, the MH-C9000 rests between the charge/discharge cycles and thus some of the surface charge bleeds away.Reference: CP Post #258
"SilverFox" said:...You got most of the way the C9000 functions correct, but you forgot to mention the top off charge...
After it terminates the main charge, it charges at 100 mA for 2 hours before droping to its 10 mA trickle charge. Depending on the capacity of the cell, this usually ends up with the cell voltage in the 1.5 - 1.55 volt range and it being fully charged.
A major difference between the BC900 and the C9000 is that the BC900 begins the discharge immediately after charging, and the C9000 incorporates a rest period before discharging...Reference: CP Post #259
On 06/19/09 ParatoOptimal said:Why do you prefer the Maha to the La Crosse?The Maha MH-C9000 has:
Break-In Mode (Industry-Standard Algorithm): Charge @ 0.1C for 16 hrs; Pause for 1 hr; Discharge @ 0.2C; Pause for 1 hr; Charge @ 0.1C for 16 hrs. Best way to activate ALL of the chemicals in a brand new cell and re-activate the ignored chemicals (i.e. when a camera shuts down while the cell still has remaining capacity and the user recharges it) in older cells. Maha recommends using it every ~30th charge, but since the majority of my cells are either 'Low Current Draw' (i.e. thermometers, clocks, remotes, Furbys when the grandchildren visit, etc..) or 'Storage Box Queens', I use it every ~90-180 days followed by 3 'Refresh & Analyze' cycles @ ~0.75C Charge (with C)apacity based on the results of the Break-In - NOT what's printed on the cell) and 100mA Discharge.
Lower Max Voltage with a 2 hour 100mA Top-Off: Avoids overheating when cells miss -DeltaV termination but still finishes the charge cycle with a gentle 100mA Top-Off to provide optimum capacity.
Better spacing between cells: Runs cooler, especially at higher charging currents.
Finer current control for charge and discharge (see below): Allows me to control the heat on older cells.
Separate charge and discharge controls (see below): I can charge at 0.5 - 1.0C and discharge at 0.2C; not limited to 50% of charge rate.
Discharge Mode: Measure cell capacity without immediately recharging. Useful for 'Self-Discharge' measurements or to see capacity remaining after camera circuit automatically shuts down.
Model: Maha MH-C9000
Input Voltage : 100-240VAC, 50/60HZ AC/DC Adapter; 12VDC - Cigarette Lighter Adapter
Channels : 4
Cells : 1-4 AA/AAA (NiMH, NiCD)
Charge Status : Alphanumeric LCD with Backlight (displays channels sequentially)
Shutoff Mechanism : -DeltaV, Max Voltage, Max Temp, Max Time
-DeltaV : 3mV
DT : N/A
Max Charge Voltage : 1.47V
Max Charge Temp : 135°F (4 sensors)
Max Charge Time : 20hr - 2hr (4000mAh/Charge Current)
Max Charge mAh : 4000mAh
Min Discharge Voltage: 0.9V
Charge Current : 200mA - 2000mA in 100mA steps
Discharge Current : 100mA - 1000mA in 100mA steps
Trickle Current : Topoff 100mA for 2 hrs; Maintenance 10mA
The Care and Feeding of NiCd Batteries - NiCd Only! - excerpts from NASA Reference Publication 1326, February 1994 Handbook for Handling and Storage of Nickel-Cadmium Batteries: Lessons Learned
"SilverFox" said:...The battery manufacturers recommend two charging rates. 0.1C for 16 hours, or charging in the range of 0.5 - 1.0C with proper charge termination. You will get the best life from your cells by following their recommendations.
The Eneloop AA cells are 2000 mAh, so 0.1C = 200 mA, and the range of 0.5 - 1.0C = 1000 - 2000 mA. The Eneloop AAA cells are 800 mAh, so 0.1C = 80 mA, and the range of 0.5 - 1.0C = 400 - 800 mA.
If you only use cells of the same capacity, it is easier to pick a charger, however, if you have cells of a variety of capacities, you need a charger that allows you to set the charging rate.
Hobby chargers give you a lot of flexibility, but they are designed to work off of your vehicle battery. Bringing the charger inside usually requires the purchase of a power supply. Also, hobby chargers are more expensive.
The two consumer chargers that come up most often are the LaCrosse BC-900, and the Maha Wizard One C-9000...Reference: CP Post #137
Cycle Life Definition:
"MrAl" said:I see 1000 cycles on most of the NiMH cells i see on the web. The wording is 1000 cycles to 80 percent capacity... "SilverFox" said:Cycle life is defined as the number of cycles it takes to get to 80% of initial capacity utilizing a standard charge of 0.1 C for 16 hours followed by a 5 hour discharge. All of this is done at standard laboratory temperature conditions.
The Battery Handbook states that NiMh chemistry is good for roughly 500 cycles under these conditions.
Now, if you only do a partial discharge most of the time, your cycle life can exceed 1000 cycles. Duracell did some studies where they charged cells to 85% of full capacity and cycled the middle 60% of the cells capacity. They got excellent cycle life, in the laboratory...Reference: CP Post #25
On 05/02/09 MISURICK said:btw - eneloops advertises up to 1000 recharges - ! - what is with 500 recharges seen in a couple replies ?! IMHO, (aka, some 'WAG' numbers just off of the 'top-of-my-head'):
The 'Average' Rechargeable Battery Consumer, with a 'Smart or Dumb' Low Current Charger (under 0.5C), will be lucky to get ~100 cycles out of any battery due to:
Poor maintenance
Infrequent usage
'OVERCHARGING' since he charges at TOO LOW a current
'REVERSE CHARGING' since he 'doesn't know how / have the capability' to MATCH CELLS and will be irreversibly damaging them without even knowing it
The 'Semi-Technical' Rechargeable Battery Consumer, with a 'Smart' High Current Charger/Analyzer (0.5 - 1.0C), will be lucky to get ~200 cycles out of any battery due to:
Poor maintenance
Infrequent usage
'OVERCHARGING' since he probably charges at TOO LOW a current (trying to be 'gentle')
The 'Technical' Rechargeable Battery Consumer, with a 'Smart' High Current Charger/Analyzer, will probably get ~300+ cycles out of any battery due to:
Proper maintenance
Infrequent usage (Recharge your cell ONCE PER WEEK and that's 5.76 years! )
The 'Professional' Rechargeable Battery Consumer (Police, Fire, EMT, etc...), with a 'Smart' High Current Charger/Analyzer, will 'probably' get ~500+ cycles out of any battery due to:
Proper maintenance
CONSTANT (i.e. DAILY) USE!
Use the cell daily
Don't over-discharge it (below 0.9VDC under load)
Top it off each night (@ 0.5 - 1.0C)
And you might even break 1000 cycles. )
NOTE: 'Smart' High Current Charger/Analyzers (as of 05/04/09):
Maha Powerex MH-C9000
La Crosse BC-900 / BC-9009
'Geek' Rechargeable Battery Care Guidelines:
"Mr Happy" said:This is kind of theoretical, depending on how keen you want to be about the whole thing. But...
Label each battery uniquely on purchase so you can identify it
Record each battery in a notebook with its purchase date and manufacturing date (if known)
When you buy new batteries, put them through a break-in cycle and in the notebook record the capacity for each cell
When you have a number of batteries of the same type and approximate manufacturing date, group them into sets according to similar capacities as recorded in 3
Every six months or so, repeat the break-in cycle on each battery and compare the capacity with the originally recorded capacity
When a cell's capacity has decreased to 80% of its original value, consider it recycle material
"jtr1962 on 11-28-2004 @ 11:21 PM" said:...I don't claim to be any kind of a battery expert, but I've recently been trying to garner as much info online as I can about nickel-based rechargeables. This combined with my electronics knowledge makes me feel I can address some of your concerns. Some of these overlap as you'll see. I have a few main points which I'll elaborate on later:
First, I've discovered both in the literature and from doing capacity tests recently that the term "quick full charge" is an oxymoron. Sure, you can get a cell fairly close to capacity in a short period of time, but in order to get that last bit of capacity you need a couple of hours. There's just no way around this regardless of the charger.
Second, I'll grant that some capacity claims are bloated for marketing purposes but for the most part I wouldn't be surprised if most of them were accurate. NiMH start life at about 85% of full capacity. They need anywhere from 50 to 150 cycles to come within a few percent of their ultimate capacity. Again, there's no way around this. You can buy cells which are factory cycled, but consider that you'll pay more, and you'll lose those cycles.
Third, charging rate can affect lifetime, although when to stop charging is much more important. You can easily destroy NiMH by leaving them on trickle charge for months even if there is little heating.
Fourth, one must seriously wonder at the logic behind even making a fifteen minute charger. Lawsuit city is the operative word here.
Let's start with capacity and charging rate. Nickel-based cells are very complex animals as far as charge characteristics go. Charging efficiency, meaning the percentage of energy put into cell which ends up as stored energy rather than heat, varies with charge rate, temperature, and how full the cell already is. NiMH and NiCad charge best at or near room temperature. Deviate too far in either direction, and charging efficiency drops. All nickel-based cells charge more efficiently at higher charge currents. For example, overall charge efficiency is 90% charging at 1C but only 70% charging at 0.1C. Of course, higher charge rates will cause cells to vent without some means of determining when the cell is full. This is why most cheap chargers use 0.1C or less. There is no danger of overheating. Finally, nickel-based cells have a nearly 100% charge efficiency up until they reach a SOC (state-of-charge) of 70%. Above that, the charging process becomes less and less efficient.
What does all this mean in practical terms? It means that you can dump a lot of current in a depleted cell and bring it to perhaps 75% capacity within minutes. This is what the 15 minute chargers take advantage of. The only mechanism for heating is the internal and contact resistance. Unfortunately, both, especially the internal resistance, place strict limits on how fast you can charge. NiCads have typical impedances of 10 to 15 milliohms while NiMH range from 15 to 25 milliohms. Practically speaking, in order to charge above 1C for sustained periods the cell must be designed for it. Consider charging a 2300 mAH cell at a current of 9A in order to gain a 15 minute charge cycle. There will be resistive heating of about 1.5W in each cell even if there is perfect charging efficiency. This will of course result in elevated temperatures which lead to less efficient charging which leads to still higher temperatures. Does any of this sound familiar? This is why no standard NiMH should be fast charged at 4C. 0.5C to 1C works best, 1.5C might be possible for at least the first 50% of cell capacity. Any more, and you need heavy external cooling and cells with very low internal resistance.
Once you get past 70% or 80% SOC you start to lose charge efficiency and the cells begin to heat up. Not severely at first, but if you're charging at 4C you need to back off the current by the time the cell reaches 70% or 75% SOC at best. You might then get by charging at 1C until the cells reach 85% to 90% SOC. After that, it's simply a timed trickle charge at maybe 0.1C to get that last 10% or 15%. Any higher current and the cells will overheat, even at 0.2C, before they reach full charge. Since charge efficiency is less because the current is lower and the cell is almost full figure that this "topping" charge will take at least another hour to two hours. You might need to charge at 0.01C overnight to get that last one on two percent. Therefore, you can reach maybe 85% SOC within fifteen minutes with a properly designed cell and charger, but that's all. Consider that the cells start life at 85% to begin with, so a 15 minute charger would probably only give you about 75% of the cells rated capacity with new cells. One hour chargers suffer from the same problems, although in one hour it is possible to bring a cell to perhaps 90% to 95% SOC if you use -dV/dt and dT/dt cutoffs (i.e. negative voltage drop and thermal cutoffs, respectively). Cell chemistry dictates this. The only way around it is to keep the higher charge rates for longer periods of time, and literally cook the cells. Sure, you might be able to reach 90% SOC in fifteen minutes but don't bet on your cells lasting more than a few dozen cycles. At 85% SOC you probably would get a couple of hundred cycles, especially with active cooling.
Interestingly, the much maligned negative pulse or "burp" charging technique really does seem to allow you to charge at higher rates for a little longer. I cobbled together my own negative pulse charger two days ago. Prior to doing so I could only charge my cells at 0.8C for an hour before they felt hot to the touch (maybe 45° to 50° C). In technical terms, I could input 80% capacity at an 0.8C rate. With the negative pulse charge I can input about 90% capacity at 0.8C before the cells get anything above mildly warm. At about 93% I go to trickle charge, and even then the cells are still cooler than they were without negative pulse charging. The downside? I've heard that negative pulse charging might cause loss of capacity after 500 cycles. Who really cares? I doubt my cells will see half as many, and the loss of capacity is at most a few percent.
Anyway, what I'm getting at in the last few paragraphs is that the manufacturers are misleading the consumers into thinking they'll get the full capacity in fifteen minutes with brand new cells. They may come close, say 75% or even 80% with a well designed system, but that's about the best these things will perform out of the box. After the cells have run a hundred or so cycles you might be able to reach perhaps 90% capacity (more likely 85%) in fifteen minutes, but that's about it. The laws of physics and cell chemistry prevent you from doing any better unless you use some serious liquid cooling. Furthermore, if the cell is not specifically designed for 4C charging forget it. Fans or not, the cell will likely get so hot that it will either vent or the charger will detect the overheating, and cut the rate back to 1C or less. And since the cell will be hot and charge less efficiently than one designed to, you will get much less of the cell's full capacity in fifteen minutes. This all leads nicely into the next part of the discussion-capacity ratings.
Capacity ratings for NiMH are different than for NiCads. Both are usually based on the same 0.2C discharge rate until the cell falls to 1.000V, but NiCad ratings are usually a minimum whereas NiMH are an average. Thanks to manufacturing tolerances, these two values can differ by as much as 10%. Of course, marketing goes for the higher numbers of average capacity. Also, it is not incumbent upon the manufacturer to rate the cell at the beginning of its life. Rather, they can use the average maximum value of a bunch of cells which are cycled as many times as necessary under optimal conditions in order to reach whatever ultimate maximum capacity they'll reach before they start to degrade. The consumer may never realize such numbers in actual practice, but the manufacturer's behind is covered because all they need to do is pull out the tests and then claim that consumers are not charging the cells "optimally". It's all a numbers game really. My new 2300 mAH cells averaged about 85% capacity on the first charge. If they had been rated the way NiCads are, the might have been rated at perhaps 1900 mAH, which is a little below the smallest capacity I saw on the first run. If so, then I would have thought I was getting "extra" capacity for free. However, 2300 sounds better than 1900, and most users would be clueless how to check capacity anyway. To put this into perpective, overrated or not, these are still over 3 times better out of the box than the 600 mAH NiCads most people used five or ten years ago, and they cost less than those cells did in terms of adjusted dollars. I'm happy, and I know after a hundred or so cycles I'll probably be coming pretty close to rated capacity anyway. If the ratings are averages under optimal usage patterns so be it. It's good to know what the cell is ultimately capable of anyway. As an aside, every time I've done capacity tests on NiCads, they're usually 5% to 10% more than rated capacity after about five to ten cycles. Now I know why.
Lifetime can be another complex issue. More than anything else it is heat and/or overcharge which destroys rechargeables of all types. For nickel-based chemistries charge rate shouldn't affect lifetime if the cell is kept cool. This obviously means knowing when to stop the high current charge and go to an intermediate charge or a trickle charge. It also means making sure that the trickle charge doesn't continue for more than a set time because overcharge can weaken NiMH cells long term even if there is no overheating. All of these problems can be solved by using the right charger. A good test of how many cycles you can get from a cell is to measure the peak charging temperature in a given charger. If it's 50°C or more, you will get at best 300 cycles, and less if temperatures stay above 45°C for a prolonged period. If the charger can accurately determine when the cell is full and reduce current before it gets too hot, then the cell should last 500 cycles or more. Tens of thousands of cycles are possible under ideal conditions. Part of the secret besides not overheating is to not fully discharge the cells (except once every month or so to prevent the dreaded "memory" effect), and also to not charge them beyond about 80% to 85% of capacity. That last 15% or so in capacity gain comes at a steep price. You reduce the cell's life from thousands of cycles to perhaps 500 to 1000 (still plenty for consumer devices). In fact, the usual 500 cycle NiMH rating assumes some rough treatment by consumer. Manufacturers would likely have more problems if they rated lifetime rather than capacity optimistically. Therefore, 500 might be realistic for these 15 minute chargers. So long as the cells are kept under about 45°C they should last at least that long.
This brings us to the last part-why bother to make these fifteen minute chargers at all? Yes, there are probably going to be spectacular failures and/or people burning themselves. These may or may not lead to costly settlements. What I'm most concerned about though is that a few failures will give a bad name to rechargeable cells in general in much the same way that early fluorescents gave a bad name to fluorescent lighting in general. We don't need people getting a bad taste in their mouth and then going back to alkalines. We finally have a cell in NiMH that is as good as or better than alkaline for anything other than very low-drain applications. This is why I think marketing anything faster than a one hour charger is a very bad idea. Besides the potential for disaster, you're providing yet another device to enable the already impulsive, disorganized lives that much of the general public leads. While I'll agree overnight charging can be an inconvenience that requires advance planning, 1 or 2 hour charging should be sufficiently fast for almost everyone. What is it to pop a cell in the charger while you shower, shave, eat breakfast, and get ready to go? That might take an hour or more anyway to do all those things. So now people want something which will charge their cells while they take an extended bathroom break? I tend to think maybe we shouldn't always be so quick to cater to a very rushed lifestyle, especially if it means potentially giving a great technology a bad name.Reference: CP Post #4
NOTEs:
I found the above 2004 CPF explanation of the relationship between SOC (State-of-Charge), Charge Rate and Temperature very interesting.
BOLD formatting added by me for emphasis on SOC / CR / T.
Message edited by: TakeTheActive on 2008-12-27 15:58:26 CST
(This appears to be a very common question, so since I researched it for my reply in a recent "Eneloops On Sale" thread, I also placed it here for future reference purposes.)
Battery University said:Charging nickel-metal-hydride
Nickel-metal-hydride chargers require more complex electronics than nickel-cadmium systems. To begin with, nickel-metal-hydride produces a very small voltage drop at full charge and the NDV is almost non-existent at charge rates below 0.5C and elevated temperatures. Aging and degenerating cell match diminish the already minute voltage Delta further. This makes full charge detection difficult.
A nickel-metal-hydride charger must respond to a voltage drop of 8-16mV per cell. Making the charger too sensitive may terminate the fast charge halfway through the charge due to voltage fluctuations and electrical noise. Most of today's nickel-metal-hydride chargers use a combination of NDV, rate-of-temperature-increase (dT/dt), temperature sensing and timeout timers. The charger utilizes whatever comes first to terminate the fast-charge.
Nickel-metal-hydride should be rapid charged rather than slow charged. Because of poor overcharge absorption, the trickle charge must be lower than that of nickel-cadmium and is usually around 0.05C. This explains why the original nickel-cadmium charger cannot be used nickel-metal-hydride.
It is difficult, if not impossible, to slow-charge a nickel-metal-hydride. At a C?rate of 0.1-0.3C, the voltage and temperature profiles fail to exhibit defined characteristics to measure the full charge state accurately and the charger must rely on a timer. Harmful overcharge can occur if a partially or fully charged battery is charged with a fixed timer. The same occurs if the battery has aged and can only hold 50 instead of 100% charge. Overcharge could occur even though the battery feels cool to the touch.
Lower-priced chargers may not apply a fully saturated charge. Some will indicate full-charge immediately after a voltage or temperature peak is reached. These chargers are commonly sold on the merit of short charge time and moderate price.
Simple Guidelines:
Avoid high temperature during charging. Discontinue the use of chargers that cook batteries.
A charger for nickel-metal-hydride can also accommodate nickel-cadmium, but not the other way around. A charger designed for nickel-cadmium would overcharge the nickel-metal-hydride battery.
nickel- and lithium-based batteries require different charge algorithms. The two chemistries can normally not be interchanged in the same charger.
If not used immediately, remove the battery from the charger and apply a topping-charge before use. Do not leave nickel-based battery in the charger for more than a few days, even if on trickle charge.
A well-designed charger is a reasonably complex device. Taking short cuts will cost the user in the long run. Choosing a well-engineered charger will return the investment in longer lasting and better performing batteries.Reference: Battery University: Charging Nickel-Based Batteries
SilverFox said:“What is a good rate to charge my NiMh cells?” and “Is this charger good?” are frequent questions that come up around here. Slow charging has been around forever, and it is used in determining cycle life. However, there is a provision in the testing standard for “Accelerated Test Procedures,” when testing for cycle life. The accelerated procedure involves charging and discharging at 1C. The goal is to achieve more than 500 cycles. The accelerated test procedures have a footnote that states that 1C charging should be done for 1 hour, or with appropriate charge termination, as recommended by the manufacturer.
The next step is to review what the battery manufacturers have to say about “appropriate charge termination.”
All of the battery manufacturers recommend charging at either 0.1C for 16 hours, or in the range of 0.5 – 1.0C with proper charge termination. They list peak voltage, change in temperature with respect to time, and total temperature rise as the preferred termination signals, but also recognize that –dV can also be used...
...When picking out a charger for NiMh cells, the first thing you need to know is how does it determine charge termination. Once you know that, you can then check to see if the charging rate of the charger is suitable to produce a strong end of charge signal. In the case of chargers that utilize –dV termination, the suitable charge rate is in the range of 0.5 – 1.0C.
The next thing to look at is the trickle charge rate at the end of the charge. If this rate is too high, and you leave your cells on the charger, you will cook your cells and greatly reduce your cycle life. The optimum is to have the charger trickle for awhile, then shut off...
...A Swedish study looked at the affects of a 30% overcharge. It found that charging at 0.3C with a 30% overcharge yielded around 225 charge/discharge cycles before the cell capacity dropped to below 80% of its initial capacity. Charging at 1.0C with proper termination (actually they were using a –dV of 10 mV which I think is high. They would have obtained better results using a –dV of 2 mV, but this study was done a few years ago) yielded around 500 cycles before the capacity dropped to below 80%. The study goes on to illustrate that overcharging at 1.0C is more detrimental than overcharging at 0.3C, but the point is well made that overcharging, even at lower charge rates, is bad for the health of the cell.
OK, let’s throw some numbers out… If you have a 2000 mAh cell, a 0.3C charge rate would be 600 mA. If your charger misses the end of charge termination, it will continue to charge until the safety timer shuts off. If your safety timer is set to 3000 - 3300 mAh (BC-900) or 4000 mAh (C-9000), or 8050 mAh (Vanson BC1HU), you will end up with an overcharged cell. A 30% overcharge on a 2000 mAh cell is roughly 2600 mAh...
...Slow charging produces large crystals, and large crystals produce voltage depression. Once again, ultra slow charging may not give you the best performance. Now we are in an area that is application dependent. I have often heard that you should charge at about the same rate that your application uses the cells. There may be a lot of truth in this... Reference: CandlePowerForum: A Look at Slow Charging
Message edited by: TakeTheActive on 2009-05-03 16:00:39 CDT
Lurker1999 said:Any thoughts on the Tenergy Speedy Box BC1HU?Before your post, none.
After several hours of reading over at CPF and following some LINKs I found:
"SilverFox" said:I have added the results from testing the AccuManager 20 charger...
...Previously the Vanson BC-1HU (after 24 hours on charge) held the record for putting the most charge into my Titanium 2400 mAh test cells.
Move over Vanson, AccuPower has demonstrated that its advanced charging algorithm allows charging to more capacity in a shorter amount of time without overheating. I am very impressed.
The other claim that AccuPower has made good on is the AccuManager 20 will charge all capacity cells in one sitting. I had no problems charging a 12000 mAh D cell. It still takes a lot of time, but when the light stops blinking, they are ready to go.
If you are looking for a high capacity independent channel charger that will do AAA, AA, C, D, and 9V cells, this is the charger for you.Reference: CP Post #94
Keep in mind that BOTH of these chargers are 2005 Technology (or older)!
Current Thoughts:
Why did you pick the BC1HU (available under SEVERAL names besides Tenergy)?
Do you need to charge C/D/9V besides AA/AAA?
Do you currently have another charger?
Personally, I think FIXED Charge (700 & 350) / Discharge (350 & 125) Rates and NO DISPLAY are major disadvantages (BC1HU Operating Instructions). The industry recommended 0.5C (to positively trigger the negative Delta V circuits) for a 2000mAh AA is 1000ma. For a 5000mAh D (conservative!), it's 2500ma. 700ma MAX is like buying the 'crippled' La Crosse BC-700.
I haven't researched C/D charging options, but I DID buy a RadioShack 23-428 (On Sale!) a few years ago (for my 'fake' Cs & Ds) SPECIFICALLY for it's 2.5A C/D output (and a FREE pair of RS NiMh Ds and the $10 off $40 RadioShack coupon in the Entertainment Book ).
For anyone with a substantial AA/AAA investment, I think the La Crosse BC-900 is the best "Bang-for-Your-Buck". For more $$$ (~$20, IIRC), the Maha MH-C9000 looks 'interesting'. If you need C/D/9V capability, I recommend buying TWO chargers - the BC-900 and "something-with-AT-LEAST-a-couple-of-AMPS".
Message edited by: TakeTheActive on 2008-12-14 18:34:48 CST
Thanks for the time investment in your reply. I really appreciate it.
I bought the BC1HU as it appeared to be the "best" charger at the time that I bought it although I'm far from a diehard and don't read CPF. When I bought bicycle lights a couple of years ago I needed something that could charge a set of 4 AA batteries in a relatively short amount of time. Basically get home, take the batteries out of the holder, dump them in the charger, have them done in a couple of hours.
I don't have any C/D/9V rechargables so the answer there would be no although that might change some time in the future.
I did just spring for a La Crosse BC-900 and have that charging some batteries but I find the 200 mA charging rate maddeningly slow, particularly in the charge/refresh cycling. I think to make it practical I'd either need to buy another one which seems wasteful or just up the charging rate to something higher. Any particular recommendations on what charging rate? I also have a bunch of All-Battery Tenergy AAs which apparently aren't great but will get me to/from work on a daily basis without the lights dying (nightly recharge).
Lurker1999 said:Thanks for the time investment in your reply. I really appreciate it.
I bought the BC1HU as it appeared to be the "best" charger at the time that I bought it although I'm far from a diehard and don't read CPF. When I bought bicycle lights a couple of years ago I needed something that could charge a set of 4 AA batteries in a relatively short amount of time. Basically get home, take the batteries out of the holder, dump them in the charger, have them done in a couple of hours.
I don't have any C/D/9V rechargables so the answer there would be no although that might change some time in the future.
I did just spring for a La Crosse BC-900 and have that charging some batteries but I find the 200 mA charging rate maddeningly slow, particularly in the charge/refresh cycling. I think to make it practical I'd either need to buy another one which seems wasteful or just up the charging rate to something higher. Any particular recommendations on what charging rate? I also have a bunch of All-Battery Tenergy AAs which apparently aren't great but will get me to/from work on a daily basis without the lights dying (nightly recharge).
Mawashi said:I've tried the Full Refresh but after more than 36 hours the display wasn't showing FUll yet, is it supposed to take that long to refresh 4 AA 2300mah?... Mawashi,
At such a SLOW charge rate (2300mah @ 200ma = 0.087C), figure on:
Charge: (2300 / 200) * 1.6 = 18.4hrs (some charge turns into heat)
- notice, if the BC-700 / BC-900 could provide 230ma (Industry Recommended Standard 0.1C,
based on 16hrs timed), it would be:
Unless the largest cell you plan to recharge is 1400mAh, SKIP THE BC-700!
[/OPINION]Even at the BC-700s maximum charge rate of 700ma, you'd only be at (700ma / 2300mah = ) 0.304C, where you now risk charging at too slow a rate to produce a clear "-Delta v" detection while still high enough to allow the cell to continue to OVERCHARGE until it reaches either THERMAL detection or TIMER expiration.
NOTEs:
1.4 multiplier for the recommended charge rate of 0.5C is my guess, based on my 'rough' interpolation.
Stated cell capacity is an average, based on a 0.2C discharge rate. For above and below, I'm just guessing at 80%. If I find new numbers, I'll update.
milkandcookies said:TakeTheActive said:^BUMP^ to prevent automatic 90-day archiving...I'll second that bump. Thanks (although one ^BUMP^ every 89 days is all that's really necessary).
GREEN on the OP, (Original / first Post in the thread) is also greatly appreciated for whatever influence it may have on the 'Score / Rating' field (aka SORTing) returned in FW SEARCHes so that more folks are aware of the information available here.
Message edited by: TakeTheActive on 2009-05-03 16:29:18 CDT
Don't be lulled into the false security that 200mA is always 'safe' and/or 'best'. As cells age, they need more current to insure a positive -DeltaV termination but not too much current to cause excessive heating due to rising internal resistance.
Try this experiment, ESPECIALLY on older non-LSD cells (skip Step #4 on AAA cells). Instead of REFRESH, or TEST (which only display Discharge capacity):
Do a DISCHARGE @ 200/100 and note the final 'Accumulated Capacity'.
Do a DISCHARGE @ 500/250 and note the final 'Accumulated Capacity'.
Do a DISCHARGE @ 700/350 and note the final 'Accumulated Capacity'.
Do a DISCHARGE @ 1000/500 and note the final 'Accumulated Capacity' (watch for overheating).
Compare the results. If the result from #1 is way higher than the others, it missed the -DeltaV termination and overcharged (usually without overheating).
Here are some examples. The missed -DeltaV terminations are obvious.
Note, I preceed the recorded capacity with a '+' to denote 'Accumulated Capacity' (Charge IN) vs 'Available Capacity' (Discharge OUT):
I've begun moving my old, non-LSD cells REFRESH cycles from my 'old' La Crosse BC-900 to my 'new' Maha MH-C9000 due to the independent (i.e not tied to 2-to-1) and more varied (4 vs 19) Charge/Discharge rates. When 'Refreshing / Cycling Multiple Times', I discharge @ 100mA to attempt to discharge as much as possible but I charge at as high a rate as I can without generating excessive heat. When 'Charging / Cycling Once', I discharge @ 0.2C to have a standard reference to compare to (ala 'Break-In').
Also note that WARM is not HOT and both are relative. My older, non-LSD cells do get warmer than my new LSD cells but an old RadioShack Indoor/Outdoor Thermometer confirms they're not exceeding 120°F. (You can also unplug the BC-900 and get the thermistor readings during boot up.)
I imagine many folks don't completely understand how their chargers operate. The La Crosse BC-700/BC-900 and the Maha MH-C9000 have FOUR 'Shutoff Mechanisms' (aka Termination Methods):
-DeltaV
Max Voltage
Max Temp
Max Time
If the charger misses one, there are three more 'Backups'.
Reviewing this example:
Sears DieHard 1300mAh AA NiMH | #1 #2 #3 #4
---------------------------------+---------------------------
06/16/09 BC900 Discharge: 350 |+1204 +1289 +1234 +1180 mAh
06/15/09 BC900 Test: 200/ 100 | 1100 1061 1165 1120 mAh
06/15/09 BC900 Discharge: 350 |+1212 +1153 +1260 +1156 mAh
06/14/09 BC900 Discharge: 250 |+1243 +1176 +1264 +1172 mAh
06/14/09 BC900 Discharge: 100 |+1722 +1384 +2130 +3380 mAh
note the OVERCHARGE of cells #3 and 4 during the 06/14 200/100mA DISCHARGE cycle. If I had done a 200/100mA REFRESH or TEST, I would have only seen results similar to the 06/15 200/100mA TEST cycle and been unaware of the damage being done. With 3380mA put back into a 1300mAh cell with an ACTUAL Discharge Capacity of 1120mAh, it appears that 'Shutdown Mechanism' #4 was the ONLY termination that worked. With the La Crosse chargers, it's important to understand WHICH capacity the charger is displaying - CHARGE (IN) or DISCHARGE (OUT).
See the problem? (aka "Ignorance is Bliss" )
Another point to note in the data presented is the difference in 'Discharge Capacity' reported by the Maha MH-C9000 vs the La Crosse BC-900. The MH-C9000 rests 2 hours between the Charge and Discharge portions of the Cycle (La Crosse Refresh), allowing the 'Surface Charge' to bleed off. Unless you're using your cells IMMEDIATELY off the charger, your TRUE DISCHARGE CAPACITY is what's actually left after the 'Surface Charge' dissipates, NOT what the La Crosse displays.
Example:
TakeTheActive said:SLOW Charge Rate Is Not Always BEST Charge Rate!
To: La Crosse BC-700/BC-900 Owners (Primarily!)
Don't be lulled into the false security that 200mA is always 'safe' and/or 'best'. As cells age, they need more current to insure a positive -DeltaV termination but not too much current to cause excessive heating due to rising internal resistance.
Try this experiment... 37 days and not one taker...
Has anyone reading this thread changed their 'Rechargeable Battery' habits due to the information presented?
TakeTheActive said:SLOW Charge Rate Is Not Always BEST Charge Rate!
To: La Crosse BC-700/BC-900 Owners (Primarily!)
Don't be lulled into the false security that 200mA is always 'safe' and/or 'best'. As cells age, they need more current to insure a positive -DeltaV termination but not too much current to cause excessive heating due to rising internal resistance.
No wonder some of the batteries doesn't show up as full yet after taking it out and put it back in the charger, then it shows up as full. Thanks for all the info you have presented. i will set the charge current to 500ma on my older batteries and maybe save up for a C9000
deuxsoul said:No wonder some of the batteries doesn't show up as full yet after taking it out and put it back in the charger, then it shows up as full...Re-starting a CHARGE cycle after one just ended is SURE WAY to damage a cell. These 'SMART' Chargers just aren't that smart. And, if the Charge Current is too low, they may just try to JAM another couple thousand mAh back into a FULL or almost full cell.
deuxsoul said:...Thanks for all the info you have presented...You're welcome!
deuxsoul said:...i will set the charge current to 500ma on my older batteries and maybe save up for a C9000 Do "The Experiment" - it will be OBVIOUS if your charger is terminating properly (or NOT!).
If a BC-700 is STILL not terminating properly @ 700mA, set a TIMER and manually remove the cells after the appropriate amount of time.
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