At work we use a lot of AA NiMh batteries for our microphones. Our GP chargers are a bit stupid and is quite fond of rejecting batteries, even though I know some of them to work in other chargers. I was looking through the forum but mainly found older threads with dead links.
So I’m looking for two new intelligent AA chargers. Features requested are as follows.
Individual charging of the cells.
Charger takes four AAs.
Intelligent charging.
Rejection of broken batteries.
Preferrably something that I can get on eBay, Dealextreme, Goodluckbuy and similar sites are also ok.
Budget is about $15 per charger, but not set in stone. We only charge NiMh AAs, so no need to spend money on chargers that takes more types of batteries.
The chargers are mostly charging over night, so fast charging isn’t really needed. But they have to be quite realiable. No one is on the boat (yes I work on a boat) during nights, and we don’t want a cheap charger to burn our job down.
What price are the Ikea Ladda chargers there? They would seem to be pretty much what you are looking for but I'm not sure about the rejection of bad batteries question.
Thanks for your reply!
The IKEA Ladda is on my list. It’s about $12, but as yyou are saying, it does’nt reject broken batteries. Perhaps I could get a couple of Ladda and a separate unit to check health on cells. What would that be?
“Dumb” (slow) chargers don’t care much what you put in there. They simply crank out a small current until you stop them or a built in timer does. You WANT one of these for over discharged cells (dead) to kick them back to life. A “smart” charger will reject a dead cell. Is this what you are calling broken? Put a dead cell in a dumb charger for a few minutes > and the voltage pops up enough for the smart charger to accept it. I do this all the time. A supposedly dead cell can be perfectly fine. (Single cells are a different subject than NiMh PACKS). If a cell won’t take a charge from a dumb charger it is indeed broken.
Fast chargers reject dead cells, which in fact may be OK. They will have trouble terminating properly with cells that have gotten old/abused/have a high internal resistance. If they fail to terminate they can overheat. This can possibly create a problem….not terribly likely, but possible.
These kind of cells will probably have reduced capacity, and certainly reduced flow/output. A cheapo charger of ANY sort won’t tell you anything of value about this kind of cell. It will not tell you it’s ‘broken’ reliably. You need more charger smarts for that.
Recommendation - get a (couple) small dumb/slow/overnight chargers. Put the batteries in at night and forget about them. At that level of input you can’t get much safer. Pull them out the next day. Throw them away when they stop doing their job. This kind of charger is simple and easy on cells.
If you+ really +want to know much more about the cells you have to jump up quite a bit in price and complexity. No charger in that price class will do something like you want.
Personal note - HJK gave his seal of approval to the Ikea. He know a hell of a lot more about this stuff than I do but, I personally wouldn’t charger my cells at 1A on a routine basis. As he said, it gets hot with 4-cells. If it did fail to terminate it could get very hot indeed. I have had cell that simply will not terminate even in a good charger. Now THAT’S a ‘broken’ cell.
Beyond that I have no personal experience so can’t comment, except to say I wouldn’t buy it. 8 bays for $10 (US)? Can’t be much of quality there. NOW, if it was a PURE dumb charger……that might be worth it. That charger is full of contradictions.
There are a few reviews in here for this Shan SH-168DLCD. It will give individual data for each cell which may be useful in detecting those which have reduced capacity but I don't know if it has any way of saying "bad" right at the outset.
Typically, what you are referring to as a "broken cell" probably means high Internal Resistance, faster self-discharge, reduced capacity or some combination of all of these.
HJK doesn't specifically mention what happens if you put a "bad" cell in there but I would think a discharge capacity test might give you a good idea. A missed termination should be pretty easy to spot just by reading how much charge has been put into the cell, and there are also temperature sensors for each bay in this charger.
If HJK still has the Shan charger maybe you could PM him to ask? BLF user Chloe did a review on it - perhaps she might have a bad cell to test? I bought one for my brother a while back but he is geographically a few hours away, otherwise I would offer to check for you myself.
You might try posting that question in the Fasttech discussion forum as well.
If you got the Shan charger (or another analyser) you could use it periodically to check the health of your cells and then mark them "OK" with a sharpie or some other means. Most of the time you or anyone else could just put them in the Ikea charger but perhaps once every few months run a cycle in the Shan to see if they are still holding up.
My MAHA C9000 will reject a cell with high IR, displaying the word HIGH on the screen. For really old or bad cells it just keeps resetting that bay. I would highly recommend one of these if you want to track/test a lot of NiMH but it is way above what you listed as your budget. Could you get work to pay for it? Or claim it on tax to ease the pain?
That’s probably about as cheap as you can go to get a serviceable analyzing charger. Bump it up a little more and you can get and Opus, but it doesn’t sound like you require lithium charging.
And it seems a dumb charger might suit the asked-for specs best here.
I’ve used these for years with no problem, even forgetting about having them plugged in for days on end (not recommended). I have another semi-smart charger (rejects bad cells, two LED status indication for bad, charging, and finished) that seems to do no better. My only problem with the ones I have is that cells can be charged only in pairs- a single cell will not activate the charger- so I pop in whatever second cell I have handy and let it go. Everything seems happy like that. Note that I use only generic cheap AA NiMh’s as I don’t need better.
If you have costly NiMh cells or want only the best for them, use a smart charger. But as the AA cells most folks (other than flashaholics here) use are rather cheap it will take years to justify the higher cost. Get a small dumb charger for this usage alone, and use the money saved for a better charger and cells for your other needs.
There is definately more to NiMh charging than I knew.
I spoke to my boss and we decided to go for “most bang for your buck” approach instead.
Right now we are using these chargers http://www.bike24.com/p260885.html They seem pretty good on the paper but the big con is that they charge cells in pairs. They are also quite keen on rejecting batteries.
Keeping track of which batteries are bought and used together is not an option. Single cell chargers seems to be the proper approach for us.
So how do I make this good and easy for not so very technical people. Should I get a dumb slow charger to resurrect the dead cells? And then also get something more advanced for standard charging. Something that also will tell me if the cells have lost a lot of capacity or have something else wrong with them?
I would not be bothered trying to "resurrect" dead cells. It isn't worth the time and effort. If a "forming cycle" or two - 16hrs at 0.1C gives no improvement then no amount of charging with a "dumb charger" is going to somehow magically repair them.(Even if it does allow you to "cheat" the smart charger with a kind of kick-start process.)
You say you are using them in microphones at work. I'm going to assume that whatever you are using mics for in a professional setting does not need to be cocked up by a perceived need to save a few bucks trying to reclaim dodgy batteries. Not at a couple of dollars each - or less.
A number of users here and at CPF will tell you they retire the cells or move them into non-critical roles (TV remotes, toys, etc) when they drop to 80% of their original capacity. A smart charger - even a cheap one such as the Shan can tell you that.
You don't want to be charging cells in pairs unless you know for sure they have been kept in and used as matched pairs. Different states of charge or capacity will ensure that neither cell is charged accurately. I wonder if this might also be affecting the number of cells you currently say are being rejected? Or perhaps this is contributing to making them go bad in the first place.
The Ikea charger is about as cheap and simple as you can get whilst still giving you proper charge termination and overheat protection. Surely even your most non-technical people can put cells into it and plug it in?
If you find a microphone is failing, even with supposedly freshly charged cells, take those cells out of regular rotation until your more technical person can run them through your one analysing charger to see what's going on.
And if money is really a problem, even the Ikea Ladda cells are deemed to be OK; just not as good as the Japanese Eneloops.
IMO not a very good charger. First the claim: [Fast charging (2-4 hours)]. Charge rates on AA cells much above an amp aren’t very good for them. Since it also does it in pairs any discrepancy between cells is going to be exaggerated by the fast charge rate. (Those old 15 minute fast chargers were hell on AA).
[charge rate 1400/700 mA for AA batteries] - 700 is OK, 1400 is simply too high unless you are in a particular hurry. Not good for the long haul.
Note - with a s…l…o…w dumb charger it doesn’t much matter if the cells are out of balance. Conventional wisdom is ‘charge them in matched pairs’, but the rate is so slow that the cell topped off first simply sheds the excess while the other catches up.
If you’re relying on these cells for professional use I retract my previous post. You will find it wisest and cheapest in the long run (say within a year) to use only the best cells with an appropriate charger. Thereafter you will be saving a bunch of money and any low-cell problems will cease to exist. Your ’Pro’ knowledge and image will then rise with your customers hopefully brightening your business prospects and profits!
With my cells, the purchase date (M/Y) goes on with a Sharpie marker. Identical cells bought in a batch are numbered after that (eg 8-15-3=Aug 2015 3rd in that batch) Matched pairs or sets can be lettered similarly. At a glance you will instantly know what’s in your hand, how old it is (so you can gauge it’s potential for problems) and whether there are more like it which need to be checked if a problem is found.
I’m not the most orderly person around but if something needs to be monitored I’ll find a simple way to do it.
Monitoring the batteries and keeping them in pairs would be a good idea. But it’s not something I thing would work at my job. It needs to be very quick and simple.
Yes, we are relying on the microphones for professional use. We do have enough batteries right now for running on full power. Right now we don’t have a problem with that.
The problem for me is this:
This is about a third of the batteries that the Varta charger are rejecting. Some of them are less than a year old. I don’t think all of them has lost a lot of capacity or has other problems.
Buying better batteries is something for the future. Right now we got a heap of batteries that need some type of analyzing or just slow charging. I don’t like throwing away stuff that works.
The Shan charger looks good to me. I think I might get one or two of those and then we’ll see if there is a need for a slow charger or anything more.
GuruX, how many cells does each microphone take in series? If they run on 6V (4 cells) for instance and you run them so low that one or more cells is subjected to "reverse current" this could kill them quickly. It is also technically possible with only 2 cells but less likely I would think.
The weaker cells become even weaker with each use. Unless they were really crap to begin with, it's hard to understand what else might kill them so fast.
In a flashlight you can sometimes detect when the cells are spent because the light output drops - at least on the higher modes anyway. Is there any low-voltage warning with the mics? If so, then it is best to swap them out as soon as you get the warning rather than waiting until the mic (or flashlight) stops working.
If the charger is rejecting the cells my guess would be that it's because of high IR. Have you tried making sure both the poles on the batteries are clean and free from corrosion and ditto for the contact points on the charger?
A forming charge of 16hrs at 0.1C (190-200mA for an Eneloop) should be done periodically according to some sources. The C9000 manual recommends this once every 3 months for batteries that have been in storage or once every 30 cycles otherwise. "Break in mode" as they call it is a forming charge, followed by a discharge at 0.2C, followed by another forming charge, with an hour between each part. The entire process can take around 40 hours.
They advise to repeat this several times if the cells show improvement of 10% or more but otherwise, dispose of them.
I took all the batteries and had them run a program that first discharge them and then charge. After that I ran all the batteries on the discharge program. There were typically two categories of our batteries now. Some of them kept around 2000 mAh of charge and the other ones 1000 mAh or less. All of them are rated from 1800 mAh to 2300 mAh. So the decision was easy, keep the 2000 mAh batteries for the microphones and use the 1000 mAh batteries in less power hungry devices.
