Looking For a Decent Battery Charger For AA/AAA Ni-Cd & Ni-Mh Batteries

[Haenk]

Maybe SkyRC NC2500 Pro?
They make great chargers and this one has 6 slots.
There are chargers with more slots, however with less "intelligence" - maybe that's OK too. Like https://www.conrad.de/de/p/voltcraft-bc16-rundzellen-ladegeraet-nimh-liion-mignon-aa-micro-aaa-9-v-block-2127444.html - does not support NiCd it seems, if that is still necessary...

[GLouie]

I don't know that charger, but would personally like to know the charge current, full charge detection method, and trickle charge rate. My reasoning is that I like to charge Eneloops at less than 1C (helps keep heat down) and more than 1/2C (helps delta-v charge termination detection). AA and AAA cells can have quite different capacities (C), so I like selectable charge current.

My understanding is that most smart NiMH charge algorithms constantly check cell voltage and when it starts to level out near 1.4v, terminates the charge (delta-v). IIRC, NiMh don't like trickle charging, where this is standard with NiCd. I assume chargers claiming NiMH/NiCd charging use one algorithm. I have no idea if NiCd suffers with this NiMH charge method. I just pull NiMH out soon after the charger says DONE to avoid trickle.

I have a couple of 4 slot analyzing chargers, and seldom use the refresh or analyzing functions. Yes, it may be useful to verify a cell's capacity, but the test involves selecting a discharge current and going through a charge/discharge cycle or two, which can take most of a day. I don't seem to have a problem with Eneloops, so never feel a need to constantly check their capacity.

I can't see a charger automatically and immediately saying whether a cell is "good" other than a cursory check of voltage and internal resistance. Various chargers seem to handle such checks differently; I have an older Maha C9000 that gives an error with some older Eneloop AAA (I'm guessing internal resistance), but a different charger handles them fine.

Most people would prefer everything automatic and simple, but not everything can be so. I also recommend  https://lygte-info.dk/info/indexBatteriesAndChargers%20UK.html   even though too detailed for most people.

Thanks for all the replies. Seeing that I'm quite limited when it comes to chargers with more than 4 slots, I may settle on something with 4 slots.
My USB charger still works fine with the only issue being that only 3 of the 4 slots work. I'll still keep my other chargers but will still definitely consider buying a new charger that will give me a more accurate indication on what batteries are good and which ones are bad.
Do chargers with a "Refresh" function actually extend the life of batteries? I tried using the Refresh function on my Varta charger and it appeared to work but then the batteries I tried to refresh lost their ability to hold a charge and begun to leak shortly after.
https://outdoorcameras.com.au/shop/16-cell-battery-charger/?gclid=Cj0KCQjwguGYBhDRARIsAHgRm49GThiQbaLSKPnrgtsTM85tmpbUxA353ki6knkCs1-SAK5BrB1EwPQaAmTkEALw_wcB
This is what I was thinking of. Does anyone have experience with this charger? It will be perfect for all my Ni-Mh batteries and my USB charger can take the Ni-Cd's as it's very good at charging the good ones and rejecting the bad ones.

[108CAM]

Sorry for the lack of a response, I've been very busy but during the time away, I've learnt more about rechargeable batteries and how their chemistries degrade over time.

I've also found a way to spot bad cells based on their recharge behaviour in a specific charger. This was done by taking various batteries that needed a recharge and observing how long it took the charger to bring them up to full capacity.

Most of the good batteries took between 12-14 hours to reach full capacity however there were some exceptions such as cells with a lower capacity or batteries that were already near full capacity so therefore less time was required to reach full capacity.

The bad cells would often charge within minutes and then self-discharge really quickly which is a telltale sign of internal degradation that has not yet leaked to the outside.

Thanks for all the help.

[BILLPOD]

I don't know that charger, but would personally like to know the charge current, full charge detection method, and trickle charge rate. My reasoning is that I like to charge Eneloops at less than 1C (helps keep heat down) and more than 1/2C (helps delta-v charge termination detection). AA and AAA cells can have quite different capacities (C), so I like selectable charge current.
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As I mentioned in my response #15, the SKYRC MC3000 will do what you want to do.   It can connect to your computer, (USB), and using an easy app. configure your charging or discharging any way you want.   And it calculates the milliamphour capacities of your batteries.  But it can only do 4 batteries at a time

[Rick Law]

A few years ago I scored a used Opus BT-C700 on an auction site, very cheaply because it looks like everybody wants Li-Ion support nowadays. Nice little charger (and discharger), my only complaint is that there is no way to force it to start charging a cell depleted down to zero, it just thinks the slot is empty.

More than you ever wanted to know about battery chargers:
https://lygte-info.dk/info/indexBatteriesAndChargers%20UK.html

I use the LaCrosse branded BTC-700 which is the same as OPUS with a different branding.  There is a way to charge cells depleted down to zero.  You need a good cell (one that requires charging seem to work better), and a metal paper clip (or a breadboard jumper wire).

You insert your depleted cell in a slot, and the a non-depleted cell in the next slot.  The good cell will begin charging while the bad cell say NULL.  Now find a metal paper clip.  Bend the metal paper clip to create a contact between the depleted cell's + and the non-depleted cell's +.  When the contact is good, you should see that the depleted cell begin to charge.  You can remove the paper-clip and it should keep charging.  I keep a short breadboard wire by my charger specifically for this use.

If after you remove the metal paper clip and it turns NULL again, your cell was too depleted (to hold voltage long enough), you will need to maintain the contact a bit longer before removal.  A couple of seconds for the first retry.  If it still go back to NULL, try even longer.  5 seconds or so is the longest I've needed, but a cell is in very bad condition may well need more.

After full charge, you should do a Charge-Test to see what the capacity is.  If appropriate (you got time), you should do a Discharge-Refresh.  Discharge-Refresh mode will charge full then discharge and show mAH capacity.  If this cycle has better capacity than the last time, it will do the charge then discharge cycle again until it doesn't improve.  The user manual describes improvement as the only measure it use to terminate cycling and it doesn't have a cycle limit.  It typically works very well, but this approach has a short coming -- it could be running for weeks, and use up the remaining charge-discharge cycles the cell can do before it totally dies.  Even the Eneloop has a charge-discharge cycle limit of 2000 (first gen) to 2500 (later gen).  So infinite cycling will degrade your cell.  May be after a few days, terminate it manually when you feel further improvement is no longer worth the cost of lost cycles.

Look for a charger on a site like Amazon.  They have a lot of different ones at different prices.

Look for one that also TESTs cells not just charge them.  That way you can test a cell after it has been charged to get an idea how well it works as it gets older.  These are typically 4 bay chargers that have an LCD display.
They also have different current settings for NiMH cells such as 500ma, 1000ma, 1500ma, 2000ma, etc.
They also sense the condition of the cell and if the resistance is too high they automatically cut back on the current so the cell does not get too hot.
They also show the terminal voltage while charging, the ampere hours, the time, and of course the actual charge current which may vary for each cell.
The discharge test tells you if the cell is getting too old.  For example if the cell can hold 2000mAh when new and it is tests as low as 1000mAh then it must be getting old and so wont run a device as long as when new.

A typical charger that does all that is the OPUS BT-C3400 but i am sure there are others in that price category which is probably around $40 USD.

I also use the OPUS BTC-3400.  The BTC3400 firmware/hardware look and work exactly like the BTC700 except it also do LiIon batteries.  I like the BTC3400 a lot.

Two other differences:
1. The Discharge-Refresh has cycle limit of 3 for the BTC3400, so it wont cycle your cell to the point of degrading it.  I actually would like it to be a selectable limit but it cant do that.  It is fixed at 3.
2. The BTC3400 has back-lighting for the LCD screen.  Press DISPLAY and it will light up for a few seconds, great help when the room is dim.   The back-light has a hidden feature.  If you hold down the DISPLAY button for 5 seconds, it stays ON.

I purchased the BTC3400 after having the BTC700 for a bit over a year.  Both are in use -- The BTC700 is for family use and BTC3400 is for me only -- I am the only one dealing with LiIon.

EDIT:
re: "...The BTC3400 firmware/hardware look and work exactly like the BTC700 except..."
I worded the sentence wrong which will likely lead to confusion.  The "hardware" there I mean only the user interface hardware.  Same words on the LCD display, same buttons, so on.  The guts are not "exactly" the same since the BTC700 does NiMH only whereas the BTC3400 does NiMH and LiIon accepting cell size up to 18650 (with a few mm extra for protected cells).  The BTC3400 also has higher current capability.

[108CAM]

As I mentioned in my response #15, the SKYRC MC3000 will do what you want to do.   It can connect to your computer, (USB), and using an easy app. configure your charging or discharging any way you want.   And it calculates the milliamphour capacities of your batteries.  But it can only do 4 batteries at a time

Just had a look at the Skyrc website and found out that it can charge lithium batteries such as LiFePO4's which is something I've been needing for ages as I have a few in need of a charge but have no method to charge them.
The charger is a bit pricey but I'll see if my parents are happy with buying it as a Christmas present even though it will arrive late.
Thanks for the recommendation!

[BILLPOD]

     I've had my MC3000 for a couple years and I use it to charge ALL kinds of cylindrical cells, especially 18650 Li-ions.   What I found handy is that I can fully charge a cell and then discharge it to determine it mAH capacity, and it's internal resistance.  It has 8 buttons for programming, but I prefer the computer program, which lets you chose every possible parameter.  I'm sure you will find it as useful as I have.  Enjoy

[108CAM]

Update:
After reviewing this thread and researching different chargers, I've decided to get a Skyrc MC3000 and my parents were happy to pay for it as my main Christmas present for this year.
The USB charger I have been using will now be used as a backup and for when I go camping. I don't want to risk damage to a $230 charger so I will continue to use the USB charger on camping trips.
The reasons for my decision on the MC3000 are:
- A true Smart Charger
- Can charge lithium batteries such as LiFeP04's & 18650's. Been needing a charger with that ability for quite a while.
- Has a computer program so I can get all the information I need about a particular battery and it's condition.
- Tells you the actual capacity of your batteries, useful for older cells that may have lost some capacity due to age.
- Can (Hopefully) breathe new life into old cells

[108CAM]

My Skyrc MC3000 arrived today and I've fallen in love with it instantly!




I originally started this thread because I was only looking for a Ni-MH/Ni-CD charger but when I begun salvaging 18650's from battery packs, I realised that I needed a way to charge the 18650's as well. When I discovered that the MC3000 could charge Ni-MH, Ni-Cd, 18650's and 14500's, I knew it would be the perfect fit.

I've charged a few batteries already and although the AAA cells sometimes slip, it works great. I've even downloaded the app and connected my iPad without any issues!

I'd like to give a big thanks to everyone who has participated in this thread. My battery charging experience wouldn't be where it is without you!

[108CAM]

Update #1
After my first few days of using the MC3000, I'm very happy with it and have already revived a few batteries which showed as "Bad" or . I've also set up all 30 programs and have already used many of them.
Without a doubt, my favourite feature is how the charger tells you the actual capacity of your batteries, very useful for batteries that are old or don't have their capacity printed on the case.