Editor's Note: I'm pleased to introduce Jim Hyman as a new writer for FilterJoe for the battery category. With my research and writing energy mostly devoted to baseball these days, it's great to have another knowledgeable battery enthusiast on board to research and write articles with even more depth and testing than I did. Expect more battery related articles and reviews in the future from Jim, and I will continue to provide the annual battery update — Joe Golton
We’re here today to look at three advanced compact budget smart battery chargers: the Panasonic BQ-CC17, the Fujitsu FCT344, and the Panasonic BQ-CC55.
To get the best performance and long life from your low self-discharge (LSD) NiMH batteries the three most important features are:
- independent charging bays so that each battery can be properly filled but not overcharged
- proper voltage termination for each battery to avoid under charging and over charging
- overheating detection to prevent damage to batteries and the charger
For more detailed information about these features see What Every Charger Needs and the Budget Models sections of this site’s Annual Battery Overview.
Note: Fujitsu sells four different budget battery chargers in the U.S. that are bundled with four or more Fujitsu low self-discharge (LSD) batteries but the FCT344 charger is the only Fujitsu charger that meets the requirements for an advanced smart charger. The Fujitsu FCT343-AUFX(CL), FCT345-AUFX(CL) and FCT345-AJ models are not smart battery chargers. Using dumb chargers will lead to under or overcharging your NiMH batteries more often than not. Overcharging is not good for the long-term health of your NiMH batteries, and extreme overcharging at a rapid rate can in some cases lead to safety issues such as batteries melting down or starting a fire. Undercharging will not damage your batteries, but it will cause lower run time performance.
The Panasonic Eneloop BQ-CC55 battery charger in North America is available as a stand-alone charger or it can be bundled with Japanese made Eneloop batteries from the FDK factory, but for best performance and long life make sure that any Eneloop bundles you buy indicate that the batteries were made in Japan (see Japan vs. China NiMH battery story).
Features
The BQ-CC17, FCT344 and BQ-CC55 chargers share the following features:
- all chargers are designed to be plugged in to a vertical wall outlet, preferably above a kitchen counter top
- 4 battery bays where each battery can accommodate standard and high capacity AA and AAA NiMH batteries
- each of the 4 battery bays has its own LED indicator which shows if each battery is charging, done charging or it is faulty
- The BQ-CC55 has additional LED functionality which seems much more advanced and helpful in theory but wasn’t too precise in practice—each individual LED starts red for nearly depleted batteries, switches to yellow if battery is between 20% to 80% full, and then green when close to full. It also claims the capability of indicating faulty or non-rechargeable batteries but we found this feature to have several false positives, where low quality, high self-discharge batteries were indicated as not rechargeable. Probably the most useful of the different colors was yellow, which did tend to reliably indicate when a battery was neither close to empty, nor close to fully charged. The “yellow” color is actually green with a thin yellow color below the main green color.
- you can charge different AA or AAA NiMH battery sizes and brands at the same time
- with the BQ-CC55 and FCT344 chargers the battery charging rate is set by the charger based on whether you are charging 1 – 2 batteries (faster charge rate) or if you are charging 3 – 4 batteries (slower, more moderate charge rate)
- the BQ-CC17 charger always uses the 300mA charging rate for AA batteries and it uses the 150mA rate for AAA batteries
- all chargers are made in China
- In North American, Japanese and European markets, bundled battery kits for all three chargers are made in Takasaki, Japan at the Fujitsu FDK battery factory. This is the same factory where Sanyo developed and manufactured the original Eneloop LSD NiMH batteries.
- In Australia and remaining Asian markets, the bundled battery kits for both Eneloop chargers (BQ-CC17 and BQ-CC55) will probably have the inferior, made in China Eneloop battery kits
Charger Dimensions
| Model | Height | Width | Depth |
| BQ-CC17 | 4.14” | 2.5” | 1.1” |
| FCT344 | 4.45” | 2.6” | 1.1” |
| BQ-CC55 | 4.75” | 2.75” | 1.1” |
Default Charge Rates
Charging times are the time it takes for completely depleted batteries to be fully charged.
Charging Rates for the Eneloop BQ-CC17 Charger
| Battery Type | Number of Batteries | Charging Rate |
| AA | 1, 2, 3, or 4 | 300mA |
| AAA | 1, 2, 3, or 4 | 150mA |
Charging Rates for the Fujitsu FCT344 Quick Charger
| Battery Type | Number of Batteries | Charging Rate |
| AA | 3 – 4 (normal) | 550mA |
| AA | 1 – 2 (quick) | 1100mA |
| AAA | 3 – 4 (normal) | 280mA |
| AAA | 1 – 2 (quick) | 560mA |
Charging Rates for the Eneloop BQ-CC55 Charger
| Battery Type | Number of Batteries | Charging Rate |
| AA | 3 – 4 (normal) | 750mA |
| AA | 1 – 2 (quick) | ~1400mA |
| AAA | 3 – 4 (normal) | 275mA |
| AAA | 1 – 2 (quick) | 550mA |
What is a good, safe charge rate?
With battery chargers, lower charging rates usually generate less heat but this results in longer charging time to fully fill batteries. The following formula shows the relationship between charging rate, charging time and battery capacity:
charge rate X charging time = battery capacity
An example: 500mA X 4 hours = 2000mAh
In this example 500mA is five hundred milli-amps where amperage is the rate of current flow. Battery capacity is measured in mAh (milli-amp hours). A charging rate that is too low can cause a battery charger to miss the termination signal that signifies that the battery is full and that the charging process should stop. Using a charging rate that is too high puts more stress on the battery with higher charging temperatures and gradual degradation of the battery’s useful life. NiMH batteries do not tolerate being overcharged.
With proper care rechargeable batteries can be recharged many times and will maintain their rated capacity for many years. Charging NiMH batteries at higher rates often causes higher battery temperatures while the battery is being charged and if the temperatures are too high, battery capacity (how much energy it can store) and how many times a battery can be recharged will be significantly lower. A well designed battery charger has adequate thermal management protections that will prevent batteries from overheating.
Many battery chargers apply a small trickle charge to batteries when the charging process has completed. NiMH batteries can tolerate trickle charging for a short period of time. A few hours of additional trickle charging is OK, but I never let the trickle charge run overnight and certainly not for several days as this can lead to a shorter battery life. I prefer to use a charging rate that will fully recharge a fully depleted battery within a three to five hour range, but I recharge batteries when they begin to show signs that they are slowing down.
NiCD batteries are uncommon in recent years. They are susceptible to “memory” issues which reduce battery capacity if the NiCD batteries are not fully depleted before recharging. One of the main reasons they have been replaced by NiMH battery technology is that this is not an issue with NiMH batteries, which are not susceptible to this “memory effect.” This means that you can recharge NiMH batteries at any time and not have to worry that the “memory effect” could lead to lower capacity.
So back to the question, “What is a good, safe charging rate?” And specifically, how about the charging rates for the 3 budget chargers featured here? The BQ-CC17 has the lowest charging rates but clearly it is high enough as charging terminated properly with all of our tests. There does not seem to be many reports of this charger failing to terminate charging. The question remains as to whether the time-saving higher charging rates of the other two chargers generate too much heat. The next section answers this question.
Battery Temperatures While Charging
Compact battery chargers have the batteries very close together and this restricts airflow that can help to cool the batteries. It is normal for NiMH batteries to get lukewarm while they are being charged. Lightly touching a battery with your finger is good way to verify that battery temperatures are OK. Lukewarm is fine. Hot batteries, on the other hand, are a sign that something is going wrong.
-
using a “dumb” battery charger that charges batteries for a fixed length of time that is too long
-
using a smart battery charger with a charge rate that is too low to allow proper charger termination at the optimal time
-
using a charging rate that is too high
-
the ambient temperature is too high
-
using a battery charger that has faulty thermal management
-
charging an older battery where the battery’s internal resistance is too high
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improper battery storage such as leaving batteries in a parked car that receives a lot of direct sunlight during hot summer days
To prevent overheating, a properly designed battery charger has protective features that should stop the charging process if temperatures get too high. Better chargers will continue the charging process after the charger and batteries have cooled sufficiently to safely continue the charging process.
The following tests were run using Eneloop or Fujitsu low self-discharge batteries:
- four 2000mAh AA batteries
- four 950mAh high capacity AAA batteries
- two 2000mAh AA batteries in battery slots #1 and #4 (left to right)
- two 2000mAh AA batteries in battery slots #2 and #3
- two 2000mAh AA batteries in battery slots #1 and #2
| Eneloop BQ-CC17 smart charger | ||||||
| Battery Size | Battery | Charge | Battery Temperatures During Test | |||
| and Capacity | Slots Used | Rate | Low | Average | High | |
| 1 | AA 2000mAh | 1, 2, 3, 4 | 300mA | 31° (C) | 38° (C) | 39° (C) |
| 2 | AAA 950mAh | 1, 2, 3, 4 | 150mA | mid 30° (C) range | ||
| Fujitsu FCT344 smart charger | ||||||
| Battery Size | Battery | Charge | Battery Temperatures During Test | |||
| and Capacity | Slots Used | Rate | Low | Average | High | |
| 1 | AA 2000mAh | 1, 2, 3, 4 | 550mA | 30° (C) | 35° (C) | 39° (C) |
| 2 | AAA 950mAh | 1, 2, 3, 4 | 280mA | 3° – 4° (C) lower than test #1 | ||
| 3 | AA 2000mAh | 1 and 4 | 1100mA | 28° (C) | 32° (C) | 37° (C) |
| 4 | AA 2000mAh | 2 and 3 | 1100mA | 31° (C) | 35° (C) | 38° (C) |
| 5 | AA 2000mAh | 1 and 2 | 1100mA | 32° (C) | 36° (C) | 39° (C) |
| Eneloop BQ-CC55 smart charger | ||||||
| Battery Size | Battery | Charge | Battery Temperatures During Test | |||
| and Capacity | Slots Used | Rate | Low | Average | High | |
| 1 | AA 2000mAh | 1, 2, 3, 4 | 750mA | 35° (C) | 38° (C) | 41° (C) |
| 2 | AAA 950mAh | 1, 2, 3, 4 | 275mA | low to mid 30° (C) range | ||
| 3 | AA 2000mAh | 1 and 4 | 1400mA | 30° (C) | 35° (C) | 41° (C) |
| 4 | AA 2000mAh | 2 and 3 | 1400mA | 34° (C) | 41° (C) | 48° (C) |
| 5 | AA 2000mAh | 1 and 2 | 1400mA | 39° (C) | 45° (C) | 53° (C)* |
| *test halted, battery too hot to touch | ||||||
BQ-CC17 Charger Summary
- The BQ-CC17 has been around for several years and is still a popular option.
- There are four independent battery banks and each bank has its own LED indicator.
- Each LED light goes out after a battery has completed its charge and a blinking LED light means that there is a problem.
- It properly charged the batteries to their rated capacities. Battery temperatures were always below 40°(C).
- Charging times for batteries are long and require ~ 7 hours for depleted 2000mAh batteries and ~ 6 hours for depleted 800mAh batteries.
- Charging older NiMH batteries (even the high-discharge variety) is not a problem unless the battery is too far past its prime.
- You can download Panasonic Eneloop battery charger user manuals from: Panasonic Charger Manuals
FCT344 Charger Summary
- There are four independent battery banks and each bank has its own LED indicator.
- It properly charged the batteries to their rated capacities. Battery temperatures were always 39°(C) or lower.
- Battery charging times are:
- ~ 3.6 hours for three or four depleted AA 2000mAh batteries
- ~ 1.8 hours for one or two depleted AA 2000mAh batteries
- ~ 2.9 hours for three or four depleted AAA 800mAh batteries
- ~ 1.4 hours for one or two depleted AAA 800mAh batteries
- Charging with only 1 or 2 AA batteries automatically uses the higher 1100mA charging rate which is moderately high but the temperatures are well controlled.
- Charging with only 1 or 2 AAA batteries automatically uses the higher 550mA charging rate which is moderately high. My preference is to charge AAA batteries using a 300mA to 400mA charge rate.
- If you want to use the lower AA 550mA charging rate or AAA 280mA rate when charging only one or two batteries, insert additional NiMH batteries until at least 3 battery banks are populated, even if the extra batteries are already fully charged.
- Some older high self-discharge batteries get very hot, especially when only 2 batteries are inserted and the charge rate is even higher. The FCT344 has circuitry to prevent overheating which halts charging when the battery gets too hot. This is a good safety feature, but it does mean that batteries which start to get hot do not get fully charged.
BQ-CC55 Charger Summary
- There are four independent battery banks and each bank has its own colored LED indicator.
- With four AA or AAA LSD batteries, they were properly charged to their rated capacities. Battery temperatures were always below 41°(C).
- Battery charging times are:
- ~ 2.7 hours for three or four depleted AA 2000mAh batteries
- ~ 1.4 hours for one or two depleted AA 2000mAh batteries
- ~ 2.9 hours for three or four depleted AAA 800mAh batteries
- ~ 1.5 hours for one or two depleted AAA 800mAh batteries
- Charging with only 1 or 2 AA batteries uses the higher 1400mA charging rate which is moderately high and the temperatures are well controlled, but when charging two low self-discharge AA batteries, they must be inserted in the #1 and #4 slots to avoid over-heating the batteries.
- Charging with only 1 or 2 AAA batteries uses the 560mA charging rate which is moderately high. My preference is to charge AAA batteries using a 300mA to 400mA charge rate.
- Testing with four older high self-discharge AA batteries with high internal resistance caused the batteries to get too hot to touch but the BQ-CC55 charger did not pause or stop the charging process and temperatures kept rising. It was clear after 5 hours that the charging was unlikely to ever terminate and the temperature seemed dangerously hot so the test was halted.
- You can download Panasonic Eneloop battery charger user manuals from: Panasonic Charger Manuals
And the winner is …
The BQ-CC17 is an oldie but goodie that uses lower charging current and easily handles older and newer NiMH batteries. Battery temperatures were always below 39°(C) during all tests. The only drawback is that this charger will take two to four times longer to charge your NiMH batteries.
If you want noticeably faster charging times, the Fujitsu FCT344 charger easily passed all of the tests and even with its higher charging current, the battery temperatures were excellent and were always below 39°(C) during all tests. The only drawback with this charger is that it can stop charging some older high self-discharge batteries when temperatures get too high and the charging process is halted.
Panasonic’s BQ-CC55 was slightly warmer than the FCT344 and BQ-CC17 chargers when charging four NiMH batteries but it was still acceptable. When charging with two AA batteries, the battery temperatures were noticeably warmer and approached 50°(C) in one test and rose to 53°(C) before the test could complete. The battery temperature rose to 58°(C) immediately after the test was halted. Charging with older HSD (high self-discharge) batteries also resulted in excessively high battery temperatures where they too were too hot to touch and even after several hours, they were not fully charged.
The BQ-CC55 battery charger has poor (if any) thermal management features and is potentially dangerous where batteries might melt or it might catch on fire.
Do not use the BQ-CC55 battery charger!
Joe and I are thinking there’s a moral to this story: compact chargers and high charge rates do not easily mix. If you want to charge at a high rate, you’re better off using one of the larger, more expensive chargers reviewed elsewhere on this site, as these larger chargers simply do a better job of dissipating heat.
May I know is there any update about the newer one CC55C? It looks more advanced …
Ken, Based on a quick web search it looks like the “C” model is for Asian Markets. The Panasonic user manual that can be downloaded from their European site refers to the BQ-CC55E / BQ-CC55U models while my charger is the BQ-CC55A model.
Other than the flip out connector on the back of the charger for the wall plug, I’m not aware of any differences with the different models. All models should be compatible with 100 – 240 voltage input.
Great review. Would like to say thanks to the author for this and the Best Budget Charger articles, that’s how I found the Panasonic BQ-CC17 smart charger. I have recently bought it, and it’s indeed a great charger. It wasn’t cheap in my country, but was worth every cent spent on it. My batteries are grateful and will live longer, especially the ones which are not LSD type. The batteries do not get very warm, and I don’t care much about the charging current being low, as long as it keeps my NiMH batteries healthy. I put them into the charger in the morning before going to work, and when I get home in the evening, the batteries are fully charged. It seems to be a very reliable charger, and I highly recommend it.
Being honest, I don’t think the BQ-CC17 I bought was that expensive. It came packaged with 4 Eneloop BK-3MCCA AA batteries, made in Japan, making a perfect combo.
Cássio – thank you for your kind words. As you have found out, the BQ-CC17 charger does an excellent job taking care of batteries and it doesn’t have any shortcomings. Our goal is to provide accurate and useful information that helps readers make informed decisions.
Great review. I have the BQ-CC17 charger. It and the eight BK-3HCCE batteries I have are only two months old. The batteries were made in Japan and came with the charger. All went well for a while but now the charger shuts down after about ten min, which I believe is due to the overheating issue. The batteries get quite hot. I can’t seem to get them charged because of this problem. I use them for photography ( flash ) and am afraid that I can’t rely on them. I thought about getting another charger but I don’t know if that will help. All eight batteries do this. I’m not sure what I should do. I don’t want to throw good money after bad if this will continue to occur. Does anyone else have this same problem Any comments or suggestions?
Hi John,
I have never heard of anything like this happening with BQ-CC17 so my best guess (without having your charger in hand to test) is that you have a faulty charger. If it were just 1 or 2 batteries I would guess faulty batteries but it’s just about impossible that 8 batteries would all fail in the same way at the same time. My guess is that the charger is charging at a rate much higher than the intended design, triggering the safety cutoff mechanisms.
You should be able to get the charger replaced for free from where you purchased it or from Panasonic.
John,
I agree with Joe’s analysis that your charger is faulty and that the charging rate is too high. My concern is that your batteries might now have reduced capacity where they might not be able to be charged to their full capacity or that their designed number of charge/discharge cycles might be reduced. See if you can exchange your eight nearly new high capacity batteries with new batteries when you get a new charger.
Let us know how you make out with your replacements. Good luck.
I am using BQ-CC16 battery charger and I am having blinking lights issue with eneloop batteries.
My clock is using 3x AAA batteries and there is always 1 battery that have blinking issues and refuse to charge it. And I will need to use an Energizer battery charger to charge it.
Does BQ-CC17 exhibit the same behaviour? Even new AAA eneloop pro batteries have the same behaviour. Annoying to find batteries uncharged.
Hansen – It sounds like there might be a defective AAA battery slot with your BQ-CC16 charger. Does the blinking charger light always happen with the same battery slot? Have you tried to charge the blinking battery by itself in a different battery slot? Have you labeled each battery with a unique identifier, such as E01, E02, …?
The BQ-CC16 user manual states “For AAA battery, insert from (-) terminal, then place (+) terminal into (+) contact place.” This is different from the AA battery installation procedure.
With compact battery chargers, I have found that installing AAA batteries can sometimes be somewhat tricky and it helps to spin or rotate each battery in its slot to ensure that it is making full contact. Make sure that the battery and charger contacts are clean before you insert batteries.
The BQ-CC16 is a fast charger that uses higher charging rates when charging 1 or 2 batteries and a lower charge rate when charging 3 or 4 batteries. The BQ-CC17 is a slow charger that uses a low charge rate no matter how many batteries are installed.
@Jim Hyman At which BQ-CC55 model do you get folded (flip-out) AC pins? There were in my older BQ-CC16 charger (recommended!!), but I see long bulky protruding AC pins in my ordered BQ-55CCE (still in plastic blister, as I consider returning the product due to its bulkiness). BQ-CC16 seems much better option when in travel (smaller dimensions, folded AC pins).
BQ-CC16 is perfect for my Sanyo and Panasonic Eneloops (both classic white and black XXs/Pros), but refuses to charge any other NiMH battery (LEDs got blinking).
Jacek – (this reply is actually from Jim):
The BQ-CC55A model has the folding/flip out 2-pin USA setup. It looks like Europe has two BQ-CC55 models; E and a U models. I found references to BQ-CC55 C models in Asia. Check out HKJ’s review of the BQ-CC16 model that comes with a removable European adapter that is installed over the USA flip out plug. In his conclusion, HKJ says:
Check out the discussion in the Eneloops: what charger do I need? (info and discussion thead) at the CPF forum.
I don’t know if your BQ-CC55E model has a similar removable A.C. adapter. The BQ-CC16’s flip out adapter is located near the top edge of the charger. The BQ-CC55’s A.C. plug looks like has a different setup that does not have a removable A.C. plug, check out this picture.
Your earlier post in the FilterJoe 2016 AA battery update blog did not mention if the other battery brands were older High Self Discharge types. A fair number of newer model, higher powered, faster budget chargers have problems with charging older HSD batteries. With non-eneloop batteries, after you started charging, did you wait for one or two minutes to see if the blinking green lights would stop blinking?
do these chargers discharge batteries to a certain level before charging them? I am from the philippines and i saw a charger online with a refresh button
Newstar Smart Switching Charger w/ LCD Display
https://www.lazada.com.ph/newstar-smart-switching-charger-w-lcd-display-and-4pcs-2800-ni-mh-aa-batteries-cec-3fa-57015951.html?spm=a2o4l.cart.0.0.4f5764dfU5f3ot&mp=1
let me quote
“Has Refresh Function:
Discharges the battery to 1.0V before recharging to eliminate “memory effect or voltage depression” also known as “Battery Conditioning Function.”
Is this a useless function considering panasonic doesnt have this feature? Or maybe its built-in already?
Hi Raymer,
Refresh is a function available on most “premium” chargers. All it does is discharge a battery down to around 1.0V at a slow, controlled rate, and then recharge to maximum. This can be useful in two scenarios:
1) You have brand new low self-discharge batteries (LSD batteries) and you want to bring them up to maximum capacity before using them. I don’t know the chemical explanation for it, but typically LSD batteries don’t go up to max capacity the first time you recharge them. It takes about 3 or 4 discharge/recharge cycles before capacity stops going up.
2) If you do many partial discharge and recharges, then over the course of years, or maybe even months, the batteries maximum capacity decreases. In some cases, doing a refresh will increase the maximum capacity, though probably not all the way back up to the capacity they were when you first got them and did 3 or 4 discharge/recharge cycles.
Note that I have personally observed scenario 1 many times. I have not observed scenario 2 to be true for any of my batteries, but on the other hand I haven’t done much experimenting with it.
Raymer Tan,
The three compact battery chargers in this review do NOT discharge batteries. The refresh function would help reduce “memory capacity” problems with NiCD batteries and would provide little or no benefit with NiMH batteries.
Discharging batteries down to 1.0 or 0.9 volts is a useful feature when using full featured analyzing chargers and will display how much battery capacity the battery has or the maximum mAh capacity that a battery can store. Watching several NiMH analyzing charger youtube videos will explain the different features that they provide. From personal experience, I’m impressed with the Opus BT-C2000 and BT-C2400 analyzing chargers and it looks like the Opus BT-C700 should also be a very good charger.
There are several features features of the charger that you linked to that are not good:
1) The charging rate is 1000 mA, which is too high for AAA batteries, a 150 – 400 mA charge rate would be better.
2) The 1000 mA charge rate is OK for newer, high quality AA batteries, but it will probably be too high when these batteries are several years old.
3) To prevent overheating, the cover of the charger must never be used while charging batteries.
4) It isn’t clear what information is displayed by the LCD screen.
5) It looks like the included 2800 mAh batteries are the Fujicell brand, and these are probably lower priced, high self-discharge (HSD) batteries which will not last as long as more expensive low self-discharge (LSD) batteries.
6) Fujicell batteries are Chinese batteries that are not related to the high quality batteries made by Fujitsu in their FDK battery factory.
This is actually a great read. I’m a little sad I only found this after I bought the BQ-CC55E, should’ve gone for the BQ-CC17. I wouldn’t mind longer charge time as long as the battery themselves are good over the years. I don’t think I would buy a different charger for a couple years at least (as long as this one keeps working) but I’m guessing as long as I buy Eneloop LSD batteries and charge them all at the same time or charge 2 at a time at slot #1 and #4, I probably wouldn’t see any issues right?
Charging all 4 at a time should be fine. Yes, if you’re going to charge only 2, using slots #1 and #4 is the coolest and therefore best way to do it. But if I were using the CC55E personally on a regular basis, I would always charge at least 3 batteries.
Oh, you mean charge 3 batteries so that the charge rate would be lower ? That’s a neat idea as well. But, since I’m planning on using 2 batteries at a time and have 2 charged batteries ready for swap, it might not work for me at the moment. If I find myself needing to buy more batteries, maybe I’ll do just that.
Thanks for the advice!
Thanks for all the information. I have 2 questions: based on your review, I bought the Panasonic BQ-CC17 charger. Is it safe to charge batteries overnight in this charger?
Secondly, have you ever reviewed the XTAR VC4 charger? I’ve used mine frequently for the past 10 months without a problem. I’d like to know your opinion of it.
Thanks
Doug
Hi Doug,
Yes, it is safe to charge batteries overnight in BQ-CC17. It is a “smart charger” which is able to detect when each battery is full independently of every other battery being charged. When battery is full, it stops applying any charge. Many high quality chargers then start to apply a very small “trickle charge” after they stop applying full charge, but the BQ-CC17 does not. It stops applying any charge at all, and is therefore totally safe to leave overnight. Even if it were applying a tiny trickle charge, it would still be safe.
I have never tested the XTAR VC4 so I can’t offer you an opinion on that one.
I just upgraded to the CC-55 (have been using the CC-17 before) and some of my batteries reach close to 56c (133f) ! To me that is crazy hot. I actually couldn’t hold the battery in my hand for long. You need tiny fan next to it, or its just going to destroy your batteries. Total waste of cash. Shame on you Panasonic!
Hi,
First of all I want to thank you for the article, since while the title only says about chargers comparison, in reality you wrote huge amount of useful information about charging in such a compact text. Excellent!
I have 2 questions.
1) I saw in other reviews that (unlike BQ-CC17) BQ-CC16, BQ-CC55and BQ-CC65 make top-off charge at a low current for 1-2h after main charge phase is finished. BQ-CC65 shows ‘Full’ after 15m of top-off charge and continues charging for 45m. But what about BQ-CC55 – does it indicate the start of the top-off charge?
2) I decided to calculate capacity, that chargers put into the batteries in your test:
BQ-CC17: 300*7=2100, 150*6=900
FC: 550*3.6=1980, 280*2.9=812, 1100*1.8=1980, 560*1.4=784
BQ-CC55: 750*2.7=2025, 275*2.9=798, 1400*1.4=1960, 550*1.4=770
Base on this data, can you say that BQ-CC17 overcharges the batteries, or other chargers undercharges them? Or the difference exists due to different ‘chemistry’ for different currents?
Alex – The BQ-CC55 does not indicate whether it has started the top-off charge in any obvious way. Really, no charger does, though many will have a light that shows when it charging, and that that light turns off when it goes into trickle charge mode. I’m pretty sure BQ-CC55 is in that category but it’s been so long since I used it that I’m not longer 100% sure.
As for calculating capacity – I don’t think the amount of current supplied is a good way to determine whether overcharging occurred for a couple reasons:
1) Some of the current supplied is lost to heat. The faster the rate, the more will be lost to heat.
2) I do not understand the chemistry involved, but in addition heat inefficiencies, there may be other inefficiency rates caused by the chemical reactions, that vary depending on charge rate.
3) Batteries lose charge doing nothing. Granted, this is a very low rate normally, but when a battery is really close to full, that rate is faster. This is likely the least important of the reasons.
4) And yes – it’s also possible that some are being overcharged or undercharged because of when the delta V cutoff gets triggered. I remember reading somewhere that if your current supplied is low enough, than delta V trigger gets delayed or in some cases never triggered. From what I’ve read among battery enthusiasts, BQ-CC17 is not too low. But it does seem possible that the much higher charging rates are triggering the delta V cutoff a little earlier, and therefore slightly undercharging relative to the batteries’ full potential.
The CC55 is horrible with older cells, they get really warm to the touch. I pointed my temp gun and it said one of the batteries were around 58c … Yikes! I stopped my charge right there. With newer cells however, it works just fine. Luckily I also have the CC17 so I use that one for older cells (or when time doesn’t really matter).
One thing I don’t like about the CC55 though is the 1 hour trickle charge. Maybe they thought it was necessary in a fast charger? As far as I know though, NiMH batteries don’t need it. However it is nice to see the colors change as the voltage goes up. It’s a rough estimate when the charge is done which helps. Of course you can invest in a more advanced charger that has an actual display etc.
Many thanks for a detailed review 🙂
Nice review. I wonder if you’ve tried the Energizer Pro? It’s quite nice and charges at 500ma for AA and 280ma for AAA. Has an audio beep when finished as well as lights to show charging/charges/etc. The only thing I find fault with it is you must charge either 2 or 4 batteries at a time. There’s a user manual link toward the bottom that shows the specs:
https://www.energizer.com/battery-chargers/nimh-pro-charger
Johnny – neither Jim nor I have ever tried the Energizer Pro, so we can’t give an informed opinion. In general, though, I only recommend chargers that have independent charging bays, because paired charging means that one of the two batteries in each pair will either by under or over charged when the charging stops.
Thanks alot! I hadn’t considered that and it makes very good sense. I just purchased a used CC-17 on ebay. I hope you try out the new recycled Energizer batteries however, they seem really great even with the charger not being overly kind to them. I really appreciate the help.
Hi Joe,
I really appreciate you taking your time to publish this data. It’s rare to come across something like this for an electronic product these days. What are your comments on the following (it’s about the BQ CC55 charger that I own):
1. About the charging current: I’ve read elsewhere about an upper limit of the charging current where the battery chemistry can’t absorb the energy fast enough. Every document that I read indicated I < 1C to be safe provided there are control mechanisms in place. The other effect of higher current is the heat output. So, is the higher charge current of the BQ-CC55 really that much of an issue?
2. Impact of the battery life: This is my primary concern about this charger. Your data suggests that it runs a few degrees hotter than the CC17 and heat is bad for battery life. On the other hand the CC55 would finish charging much quicker than the CC17, so the amount of time the battery stays at an elevated temperature is less. So, given this, is it possible that CC55 probably gives a better battery life?
Hi Amith – Good questions on the BQ-CC55 and heat in general.
1) I am not really sure if the high charge current in and of itself is an issue. I don’t have the technical capability to test that, and I’ve never heard anyone claim that it’s the current in and of itself that hurts the battery. It’s internally generated heat that is the issue – heat is bad for batteries. The hotter the worse. And if it gets hot enough, the battery can melt or in some instances cause a fire (I’ve read many reports of both).
2) The impact on battery life is why I don’t recommend using the CC55. As we say in the article, the heat isn’t too bad for CC55 with 3-4 batteries (though still higher than I prefer). And if the batteries are half full, then as you say, it won’t be charging long enough to get really hot. But the CC17 is not just a little cooler, it is a LOT cooler. In my experience, the temperatures are more toward the low end then the average with the BQ-C17. Try touching the batteries after you’ve been charging for over an hour and it is a dramatic difference between the two. Even after 2 hours of charging, I can very comfortably touch batteries in the CC17 with my fingers, and I never have to worry about it.
If you want a battery charger to charge at a relatively high rate, as happens with the CC55 with only 1 or 2 batteries inserted, you want some thermal management features in place, which are generally two things:
a) lots of space between each charging bay
b) a fan
If you don’t have at least one of these on your charger, then charging at 1400 mA is simply not a good idea, and even 750 mA is higher than I prefer.
I am currently testing an 8-bay Maha charger that charges at 1000 mA by default. But it has very widely spaced bays and a fan. So the batteries don’t heat up much beyond room temperature and I have no worries about battery life in a product which such ample spacing and a (noisy) fan.
I am pretty disappointed by the CC55’s high temperatures. I find 4 AA hit 50C or above despite the lower current. I found the older 550mA (MDR02) rate to be perfect, wish they had a 4ch current model with that. 330mA is slower than it needs to be to stay cool.
As far as a fan, I agree. If I ever want to use the CC55 for a full charge I’ll point a fan at it. Probably I’ll just use it if I’m in a hurry, especially if so much of a hurry that I’ll pull the cell before it hits green.
I’d like to ask in the event of a prolonged power outage, most usb battery chargers charge batteries in pairs. If that’s all you have, what is the best way to use them to keep your batteries charged? It’s hurricane season, and I’d like to be prepared. I have a foldable solar phone charger that’s capable of powering a usb battery charger. If I could use it to keep some batteries charged it would be a real help. I use an Opus charger or a BQ-CC17 when A.C. is on. What do you suggest?
Doug – With a paired charger – if you simply charge a battery one battery at a time until fully charged – you should be good as it cuts off when fully charged – there’s no problem with a 2nd battery being over or under charged. Also – there is a decent USB smart charge I’ve recently become aware of – the Nitecore UMS4 USB. I haven’t personally tested it but it seems like it should be good in theory.
Thank you for the article, it was well written and detailed. It kept me from buying the BQ-CC55 and I got the BQ-CC17 instead.
Great article. Shall now be sending off for the BQ-CC17.
Can the BQ-CC17 charger charge any battery of other brands without risk?
Juan – The short answer is yes. Any NiMH battery will do fine in the BQ-CC17. It works better than many fancier chargers on lower quality batteries (high self-discharge or older NiMH batteries) thanks to it’s low charge rate.
I have 2700 batteries, I think it will not be charged since in theory it needs 14 hours to charge and I think this charger automatically shuts down for security at 10 hours. Somewhere I read that after the lights go out if the battery goes down, the battery is reconnected to refill (I don’t know if it’s true)
Juan – Are you talking about Lithium Ion Batteries or NiMh batteries? The BQ-CC17 cannot handle Lithium Ion Chemistries. If it’s a NiMH battery, you won’t damage the battery if it shuts down on you. Simply take them out and put them back in again.
sorry I forgot the detail, they are from NiMh .. thanks for the replies 😉
Have you ever used the Panasonic BQCC 87? Mine came with 4 AA Eneloops. You can use the batteries as a battery bank, to charge USB devices. It charges AA batteries at 500 ma. and AAA at 250 ma. It’s a USB charger, the first I’ve seen from Panasonic.
The BQCC-87 is not a charger I’ve ever tested. It’s been available in the U.S. for less than a year. But it seems quite interesting – one device you can carry around that is small and can charge a phone or AA/AAA batteries on an emergency basis. It doesn’t carry much capacity according to some reviews – I couldn’t find the exact capacity even when visiting Panasonic’s site. But it’s still a cool gadget!
How’s the IKEA Kvarts charger compared to the BQ-CC17?
Regev – I’ve never tested the IKEA Kvarts charger so I don’t have an opinion. IKEA claims individual (not paired) charging. Assuming this is true, then that is a big step in the right direction of being a decent charger.
I am at this point, a good rechargeable battery and a good charger. I have checked out the EBL 609 and thought it’s a good charger.
This article is a gem for giving clarity on the type of charger to look for.
I found tha on paper, the EBL 609 charges @ 1000 mah for AA & AAA so I am sticking to the CC17 unless you have insights on the EBL 609?
Airam – You really can’t go wrong with the CC17.
I have not personally tested any EBL chargers. Part of what causes me to steer away from them is that one of the best reviewers on Amazon, NLee the Engineer, has given a few of the EBL chargers mediocre reviews after extensively testing them. I did not look to see if he tested the EBL 609 specifically.
I don’t get it…
Why would the 1+4 positions be any different on the BQ-CC55 compared to other positions?
Especially compared to the 2+3 positions, if you are thinking that there is some separate power distribution for two battery pairs…
How can someone explain this?
Could the proximity between batteries have SUCH a strong effect?!?!?
This is not 1 or 2 degrees of difference.
Have you tested multiple times and using only eneloop batteries?
Jim Hyman performed these tests 5 years ago. He did not take the unit apart and try to understand what was going on electrically to explain his findings. However, it’s common with chargers that don’t have fans to run hotter if batteries are adjacent and it is running at the fastest charging mode. Some more expensive chargers have either wider spacing or a fan (or sometimes both) to keep the batteries cool.
It was tested multiple times, using Eneloop and Fujitsu batteries (which are nearly identical as they come from the same factory in Japan).
I had a BQ-CC55 as well. I did not do the testing Jim did, but . . . in daily use, if I charged just two batteries, the BQ-CC55 ran much hotter than any other charger I’ve ever used. Alarmingly so.
I like budget chargers and personally use some. But I do NOT like budget chargers that attempt to charge batteries quickly. If I want to charge quickly, I use one of my high end models that has either wider spacing between batteries, a fan, or both. The 8-bay Maha Powerex charger I’ve tested is the unit I own that is most capable of charging at high rates without overheating as it has a strong fan (but it’s quite a bit more expensive):
https://www.filterjoe.com/2019/05/13/powerex-mh-c980-turbo-charger-analyzer-review/
Is BQ-CC17 still a good choice for a battery charger in 2022?
Yes – BQ-CC17 has withstood the test of time. Technology of AA battery charges changes very slowly so if you have a good one, you can keep using it for a very long time. I have several quality chargers over a decade old that work fine, though this model in particular hasn’t been around that long.
Thanks for the article. And thank you, Joe and Jim, for keeping up with the comments for the past five years!
My cc17 is in shipping, but was tempted by the cc55. Overheating is a risk I don’t want to take.
Just a quick question. Could damage be done to any sort of rechargeable battery if I top it off every 2-3 months and stop charging when it gets to 100%? I have a jump starter with lithium battery with instructions that state to charge every 2-3 months and to charge after each use to maintain efficiency and prolong battery life. Then there are some lithium batteries that says to keep charge at around 50% for storage to prolong battery life. Which is correct? Is there any fault by recharging battery from 90% to 100% and stopping right after, over and over? Especially with eneloop and cc17 which doesn’t tell the charge percentage. Thanks.
AV – So far as I know, small consumer lithium ion batteries are best stored at a capacity of around 50%-60% in long-term storage. So, for example, if you have a smart phone that you’re not using for a while, get it to around 50%-60% then totally shut it down. You can check it once every few months thereafter to see if it needs a small amount of charge.
I just looked up for Electric Vehicles and the general recommendation is similar: Even in every day use, if you want to prolong the life of your battery, try to not go beyond 80% charged. It won’t harm the battery to charge it to 100% and you should certainly do so when you intend to travel long distances right away. But leaving it topped off at 100% then sitting for days is likely to shorten the life span of the battery.
Note also that storage temperature matters. Best to keep at or below room temperature.