Inside a cheapo NiMh charger with schematic.
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- Опубликовано: 25 авг 2024
- I bought this to see just how much of a charger you get for a mere £5. It turns out that it's actually quite nice inside and has good slow-charger (200mA) functionality.
It has a cut-off timer that may be as short as just 10 hours so it's probably best suited to cells under 2000mAh or for topping up larger cells. That timer section can be bypassed internally though.
If you enjoy my videos you can support the channel with a dollar for coffee, cookies and gadgets at / bigclive
I just realized I have been watching you way more than Dave on the EEV Blog. I shouldnt have to say anything about his voice,its the fact that you are more thorough with your teardowns ( and they work). Lately he has been stuck on the evaluation of electronic equipment and how many fluke meters with his name on them do we need to see. Keep up what you do. I have to say, I get more from your videos and it helps me understand how things operate,why they operate,and the diagrams really help,especially when you enlarge a board and show whats what.
+scott firman Dave likes to call everything garbage that's not using professionally class A designed surface mount multi layered PCBs.
Don't get me wrong, he has an awesome channel and I do enjoy his videos but sometimes he acts so full of himself when he "dumpster dives" in the secret tenants only garbage room..
+ElfNet Gaming He does have some interesting teardowns but he tends to work with things more on a industrial electronics scale as apposed to on a simple scale such as cheap or dangerous stuff available on the market that your everyday consumer buys. I watch an RC site where they review stuff all on an equal scale because of sponsorships,where I would rather hear the truth,not everything out there is great.It only flys till it hits the dirt.
@Phil Weatherley
It gets annoying very quickly. Good candidate for a voice changer circuit. "Bob's your Uncle" type things tend to cornfuse us Merkins. 🤔🤔
You are an encyclopedia of electronics, Clive.
I'm in awe of your knowledge. 👍
I love it when you talk electronics Clive
just wanted to say thank you Clive, I've learnt so much about circuitry thanks to your videos, the way you talk isn't flat n boring but rather interesting and easy to listen too
"Let's open it up and take a wee look inside"
yay
I'll just discharge this big capaci.......BOOM
17:15 The body diode of a MOSFET isn't designed for protection, it's a parasitic element that's there because the construction of a MOSFET just happens to have a P-N junction between drain and source.
Right. And if you're doing a circuit where the protection of that diode is needed, then an external diode is recommended. It will also tend to be faster than the internal one. I've seen this done with motor drive controls and similar stuff.
Thanks Clive! I am a big fan of your videos. I share your need to know whats going on in the things we use every day. You have literally saved me thousands of dollars! Watching you take "things to bits" lets me keep some of my things functional till they die, and possibly repair them when they take a dump.
You're channel is one of my top 5 favorites , keep up the great videos!
FLIR for charge state detection--> love it! Clever Clive.
Honestly, I prefer "slow" chargers for a few reasons:
1. Cells are cheap, chargers are expensive. Multi-channel chargers especially.
2. Slower chargers can be "dumb" without too much risk of things melting or burning. This makes them cheaper in money for being slightly more "expensive" in time spent charging.
3. Fast charging is hard on cells. A "20 minute" charger MUST be charging at slightly more than 3C, which is going to be hard on ANY chemistry of rechargeable cell. The result is that the cells won't take a charge (or won't hold a charge for as long as they used to) even when dead after 50-75 charges instead of the 100+ that they're capable of when properly cared for.
4. A fast charger isn't needed if you have enough cells, provided they can hold a charge for long enough ("pre-charged" or "Low Self-Discharge" NiMh cells can hold 80% of full charge for over 3 months after being charged). This means you can have a set in a device, a set on the charger, and a set ready to be swapped in when the ones in the device are discharged. With enough sets and always putting the dead cells on the charger, you'll never get stuck without any charged cells. This is cheaper in the long run because you don't need to buy new cells as often as if you had fewer sets of cells and used a fast charger.
+44R0Ndin wat? good cells are not cheap lol, and they have a limited lifespan, chargers are a one time deal.
+44R0Ndin My main niggle with "smart" chargers is that they can crash and jam the outputs on at full current. I had that happen with a Maplin charger and the only indication something had gone wrong was an odd smell. The heatshrink had split and shrivelled back on all the hot cells and they were stuck in the charger.
+bigclivedotcom You would have thought they'd have implemented a watchdog timer on something like that. I've have bought several expensive intelligent chargers and all but the last one have overcharged or undercharged the batteries I nearly threw out 8AA's and AAA that one charger indicated had low capacity and would only partially charge.
bigclivedotcom
This is exactly why I think it's a good idea to look for a charger that can do at most C/10 per cell, and switches to a C/100 "trickle" charge when the cells are finished.
Cells might or might not be expensive, but even cheap cells will last longer when charged slower.
+Blacktronics Good AA and AAAs are cheap, chargers have a limited lifespan ;-)
"So let's H O I N K this out"
-Big Clive, 2019
Funny way to spell 2016
A lot better than one I bought which looked almost the same. All it had was an LED and two resistors for each battery, a rectifier and capacitor, and a socket to plug into a separate PSU!
Opus BT-C3100 (BT-C3400) is the Cadillac of chargers. LOVE mine...n it's even smart enough that it "allowed" me to put some juice back into harbor freight freebie alkaline batteries..to get a few more days use out of them instead of driving a half hour to the store to get two AAAs...go figure. ...LOVE the built in fan and independent bay detection/control and settings ability too
As a fellow technician I love your vids, also, love your accent, you have a calm method and great presentation; it's fantastic how you present your videos in a way that makes it easy to understand, you should be a lecturer!
Good stuff there, Clive!
Agreed: Slow and low is the tempo...for charging batteries that is.
It's tough sometimes when you want to use a battery and you're tempted to fast charge it, but I don't.
I have the theory that many chinese manufacturers and vendors seem to interpret "mAh" as "micro-ampere hours", thus achieving ludicrous numbers to print on their products...
that would be sneaky because they should use mu!
Delta-V is tested without charge. It charges for a period then disconnects the charge current and tests the cell voltage with a very light load. With bubbles, which increase the cell resistance, the voltage will drop slightly. It is less noticeable with Ni-MH compared to the old Ni-Cd.
I got an older HAPE NV90 fast charger which I really love but it has had its best days so a couple of years ago I thought I get a new HAPE NV90 (newer model with LCD) and it refuses alot of still good but older AA/AAA-cells and you have answered the reason in this video. Always learning from your videos Clive :)
I just love your vids simple to the point if its crap you say so if its good you say so if your impressed you also say so. I went on Ebay and bought this charger for a fiver it will do the job. Thank you for making the vid and sharing. Steve Bristol :)
Clive I'd love too see you do more longer complicated circuitry similar to this. Stuff that involves a little more than simple lighting controllers or battery packs.
+Bob Nips Yea like the entire workings of the space shuttle
I was thinking something like an old vcr... or maybe a digital thermostat. something a little more complicated, without being ridiculous...
the videos on moving stage lighting he did a while ago were pretty cool
I love your videos, I love engineering and I'm 14 but mainly want to do civil engineering that electrical but I still find your electrical videos extremely interesting :)
more interested in the single cell one you started with - also great battery tech info, perhaps I I should look up a video on battery chemistry differences....
Audio on this is great! Sounds like you did a low pass filter so there is significantly less bass from your voice (lovely voice, it just activates my sub on occasion) Amazing video as always!
Years and years back I remember seeing an advert in one of those through the post book of bountiful things an advert for a battery charger that proclaimed it could charge non rechargeable batteries. Would be interesting if these things are still about, how they work and the risks involved in using one and how cells behave. Great vid as always.
+ThePlethora1980 I've seen the same thing, and yes they do exist:
www.amazon.co.uk/Good-Ideas-Battery-Wizard-598/dp/B000W9RHVY/ref=sr_1_3?ie=UTF8&qid=1458348344&sr=8-3&keywords=alkaline+battery+recharger
If you don't mind, I'm going to take "Chemical Noise" as my band name.
+Cherry Pepper I'd go to that show.
+Cherry Pepper My band is called Big C Live, Do Tcom is the first album ;-)
Slow chargers like this are great - stick the batteries in and leave them until they are needed! Also they don't stress the cells so they last longer!
A very interesting video - many thanks. I bought an absolutely identical charger from Ebay (different brand name, but I guess a generic Chinese unit under the badge) a) because for the price I didn't have much to lose, and b) my more expensive intelligent chargers didn't like some cheap cells I'd also bought through the same channel.
My problem was, I needed rather a lot of AAA cells (30 or so) and I didn't need top-end jobs like Eneloop so I went for a bulk buy of 40 Chinese AAA cells for a stupidly cheap price. They were supposed to be 1200mAh and certainly weighed more than some 600mAh Duracell rechargeables I own, but nothing I had would charge them.
Until I tried this unit.
I agree that it's nothing really 'special', but for a basic 'not so intelligent' charger it certainly works as it should. It's not radically different on the output side to an old Uniross 4 cell charger I picked up in the mid-80's. Standard current limiting resistors in series with a stabilsed voltage to give you a (reasonably) constant current charging source.
As the cell voltage increases, the voltage across the LED and 470R resistor decreases to the point that the LED no longer illuminates, and this is why the brightness of the LED's varies during charging and then dims right out on a per pair basis as the cells approach full charge. However, the microcontroller as a timer is a bit of an odd concept...if different capacity cells are charged in different bays, then the timer may be plenty long enough for low capacity cells, and too short for high capacity cells. I guess they programmed it for some number picked off the top of their heads! To reset the timer, the charger has to be physically unplugged, left for about 20 seconds, then plugged in again.
For a fiver, don't expect miracles, but you couldn't build a simple charger that good yourself for £5, with etching a board and making a robust case. I know you open up some really scary Chinese rubbish, but hats off to a reasonably well thought out basic design with reasonable quality components mass produced in enough quantity to bring it down to the price point they have....and they must be making some profit, as are the ebay sellers.
The best Chinese fake NIMHs I ever bought were rated 2600mAh, and were actually a much lower spec'd AAA cell encased inside an outer shell to fill the space up to AA size. I discovered this when I accidentally dropped one, and noticed something shaking back and forth inside ... it's amazing what they can do with cardboard padding and metal end tabs.
+mharris1270 Ever see the Energizer NiMH line? AAs and Ds are both rated at 2500 mAh capacity. AA cells, same weight as alkalines and other NiMHs of that size. D cells, suspiciously light like dry cells or even lighter than that. Yup, pretty clear what's going on.
This is why I ditched all the D cell items I owned years ago and standardized with AAAs, AAs, and 18650s.
Just realised I just, today, bought the same screwdriver as you.
Clive. Have you ever thought of looking at the various NiMh cells that are now available very cheaply on eBay etc? I happened to purchase some AAA cells a few months ago. They were supposedly something like 1800mAh. So, one would expect them to last in a similar device somewhat longer than an old 900mAh AAA cell. Not so. They are quite rubbish (as used in a DAB radio which I do accept is a high current draw device). The old 900mAh cells (the radio takes 4 at a time) last for about 4 or 5 hours depending on volume. The 1800mAh (supposedly) last for around 3 hours maximum. I shall not buy those again. I would be interested to hear your thoughts on this matter.
I clicked on this video and got an ad from Boris Johnson...
I think that's a sign that I've gone too far down the rabbit hole of the Internet.
i like my chargers the way i like my girlfriends: not too smart and not pretending to be smarter than they are
I heard the Delta voltage drop is due to the sudden temperature rise when the battery is charged. You can't use negative Delta voltage charge termination with trickle chargers, as you need to high current to cause the temperature rise
No eighth vent to protect the power input section from spills etc.
i have that amecal meter too. its really good for the money. the only thing its missing is frequency/duty cycle
Maha makes some of the best NiMH chargers around, Negative Delta Voltage and heat termination of charge. Some have programable charge and discharge rates, forming, and cycling with analysis. That said, expect to pay a pretty penny for them. Mine (I cannot remember the name, it's like Charger Wizard something rather) was about $45 USD, but has the advantage of running directly off 12 volts for in the car and off a 12 volt solar charged battery. While it only charges four cells, it can charge individual ones.
These cheaper ones are *okay* usually at best, but you're better off getting a higher end charger from the point of view of the life cycle of the cell. 0.5 C is a good happy rate for a NiMH cell, and they'll last you a good long time if you avoid much over about 1 C. Also you want a good quality cell. Maha's PowerEx and Envelop batteries are the current cream of the crop, with Energizer and Duracell's towards the bottom.
i like your vidoes very much. I have this charger and can recharge alkalines very well. it's plugged into a timer set to charge with 15 min on and off.
As I understand it, the -ΔV chargers periodically disconnect the charging current to sample the cell voltage (which is how they detect the battery voltage going down instead of the charging voltage going up). I have a fairly nice charger that does both voltage and temperature based charge termination, and you can faintly hear it switching the charging current every ~1.5s. (I don't remember it having a relay for the switching, so I'm not exactly sure what's making the noise.)
+MrRaineth I think it's the switching regulator cycling on and off. It's quite a loud click.
I've still got a Uniross battery charger I bought at Woolworths in about 2003, not long before they went breasts up, though I rarely use it as I never seem to use anything battery powered these days that doesn't use USB charging... :)
As a middle school student interested in electronics, I think you should do a video explaining the basic components of a circuit and what they do (capacitor, rectifier, etc) or something like that. I can understand what most things are from context, but a video on it would be cool. Love your content btw
Nate A. he already has ...use the search function lol
That reverse diode in the MOSFET is not "added for protection", it's actually a parasitic diode that exists because of the way MOSFETs are made in silicon. However, it can take a small amount of current and does add some small protection. They really cannot take large current spikes though, as they are parasitic and not designed to really act as good diodes.
I have an UltraFire 18650 with... wait for it..... 9800Mah! Tested at 72Mah.
Honestly whenever I find a shitty NiMh that I've had since I was about 7, of which there are quite a few, and it doesn't take a charge at all, I stick it on the bench power supply, and blast it with 5V and shove an amp through it for a couple seconds, and that seems to burn off whatever oxides are present causing high impedance. I'm sure it shortens cell capacity but honestly those old ones I usually only use in stuff like television remotes. Often I'll ask friends if they have any old rechargeables they were going to recycle and I'll take them, nuke them with the 5V, then get a few more years of basic operation out of them before finally putting them out to pasture.
I got myself a Nitecore Intellicharger a while back to charge my 18650's - I haven't used it much but appears to be a reasonable piece of kit - Supposedly charges a wide range of Lithium and Ni-Mh cells, has polarity detection and shut-off. Only about 15 quid, and has a lot of claims about how good it is on their website - I wouldn't mind seeing a teardown of one of those someday.
A lot better than one I had, it had single wave rectification and a linear transformer.
i have one like that 😉 mains transformer centre tapped to 'ground', with 2 diodes each end feeding opposite polarity cell pairs, , also has a higher voltage tap for 2 '9v ish' pp3 types, it does work but as the diodes conduct mostly on the tips of the sine wave, it has fairly high current pulses to get the 'average' 130ma charge level,,
The cooling slots on the 8th battery would have been re-filled in (on the mould), once they realised the AC rails would have been accessible via a paperclip or similar.
Ahh the good 'ol Si2302 ... I've used those in projects before :)
"Chemical Noise" is a good band name.
Very Nice
I got a branded one from 7dayshop for £6.99 (they call it the V8 - vrooom!), and wondered why the 2700+ mAh didn't fully charge, it'll be the 10hr cut off!
Also the label on the bottom of mine states it charges AA at 200mA and AAA at 100mA too.
Do a teardown on the Vapex charger, i've got one myself and it was getting so hot that I took it apart to retro fit a thermal switch, i'm certainly inclined to not believe all the sales hype on that one.
Ooow not a constant current charger then, ive allways given batterys a constant charge.
The old 7805 and resistor turns any old dc to instant charger lol, yep its simple like me :D
+zx8401ztv It is more or less constant.
+Binkey Bideos
O.o
+Benjamin “Ozias” Esposti shh im baiting for attention
+Binkey Bideos
i love these comments so much, so random, so rude and yet just a joke that harms nobody :D
ikr
Why no thermistors? I've torn a half dozen of these down that I got randomly from Goodwill. All had them. Curious. So cheap to do.
You have to remember: A Chinese mAh is very different from a Western mAh ;)
Especially because it's mAh, not MaH. ;)
Yeah. Chinglish. ☹️☹️
Well i never knew Delta V was a phrase used in electronics, im guessing the V is voltage? (Im used to hearing it in a physics context where V is Velocity) I know very little about electronics but still love watching :)
I've had enough cells killed by fast chargers, at least there's little chance of overcharge with one of these!
I love your catch-phrase "but that's OK". Is there any circumstance where you would not use it?"I've just cut my leg off - but that's OK"
As long as I survive that's OK.
13:50 A 300 mAh battery marketed as 3000 mAh? That's just cruel. That's like selling someone a model kit claiming it's the actual car. "Whoopsie, that extra zero was a typo!"
nice charger
I bought a car battery minder about 3 years ago and I think I like it but I'm not sure if it's a real deal. Does this device really work or is it a waste of money? It's made by CTEK. I live in San Antonio Texas where it gets very hot. Thanks.
I'm not sure how effective they are. The simplest just hook across a fully charged battery and shunt it with brief spikes of current.
Please... Share a link to your screwdriver! 👍
I got a 8 cell charger cos I prefer to do single cells for my solar lights. Its labeled Maha with a PowerEx logo on the side, m/n MH-C801D. Ithink something was wrong with it out the box as my first use involved charging several Energizer 1700maH batteries for testing its charge time. I checked back on it after 1 hour and some were showing fully charged except one at the far right, it was worryingly hot so I removed it and started again with some 1300maH cells. The same thing happened. The far right battery was very hot so now I dont use it as I think its probably going to kill any batteries charged in it. Il stick to my 4 cell (individual) Technoline BL700 smart charger. Im not sure how to begin finding out if there is a fault in the charger, with these things it could be anything from software to hardware :(
+JohnnyX50 If you put a fully charged cell into a charger it may struggle to detect that charging is complete. The cells often get hot at end of charge. Some good chargers detect that.
Wonder how well ebay liitokala engineer chargers are built, they are more capable smart chargers that can do lithium ion batteries, but the price on these things has gone through the floor, interesting if they are cutting corners.
The uC could pulse trickle charge, or output a train of pulses with a low to very low duty cycle. Also theoretically it could not turn the MOSFET on all the way, although that might be difficult. So...no thermal cuttoff, and apparently, no way to detect minus delta V?
+rchandraonline With NiMh cells it would be hard to detect negative delta V (negative change in voltage) at such a low charge current anyway. Turning the MOSFET partially on would require a feedback circuit and would result in a lot of heat dissipation in the MOSFET. PWM is much more efficient.
Not a deathtrap?! Doesn't by default put live mains to the battery terminals? Damnit china, I want my money back. For this kind of cheap I want dangerous entertainment!
direct mains to a battery, how Michael bay spent rainy days as a child
Dylan Collins *pop*
You got to get the pink ones for that...
if I send you my battery bar would be able to test it why it don't work SilverCrest solar panel battery bar it don't matter if if it gets damaged or broken
do the cheap 18650 chargers
Just a thought... could those "vents" actually be drainage for a leaking cell? If it leaks out and through the pcb it would stop the other batteries from shorting in a pool of battery acid, and the vent missing closest to the mains is intentionally like that to prevent mains shortage?
If you would, make a pic of the schematic, and give a link to download it, under your info above.
Recently I had a problem to get a simple charger, that is able to do slow charge. All chargers available in local stores were too quick.
When you take apart any of the electronics that you do, what do you do with the board and casing after? Do you keep all of the stuff in a large cabinet somewhere in your house or do you just toss most of it?
I usually put it back together.
bigclivedotcom Do you actually use most of these devices? Also, out of curiosity, does the UK have a decent way of recycling electronics and circuit boards?
As usual, lots of useful information. Now I know that NiMH cells can be trickle charged at low current without it actually damaging the cells. That means I could build NiMH cells into a project and just provide a port for low current charging. Very useful info, indeed.
How sensitive are NiMH cells to over discharge? What sort of protection do they need? Is it possible to rescue a virtually flat cell?
+Jocke “Hattmannen” Nilsson To rescue a NiMh cell that has been discharged to zero... Just stick it in the charger and charge it up again. The simplest charger is a diode and a resistor. That's all you need. It's a very robust technology.
Thank you! That's very helpful, and indeed very practical. That means that I don't have to worry about over-discharging and can run them down until whatever they're powering stops running doe to low charge.
Perfect! Cheers!
+Jocke “Hattmannen” Nilsson It's not recommended to run them completely flat if you have several in series, as the first ones to go flat will then be reverse charged by the current from the remaining cells, and it may reduce their future capacity. But they certainly won't blow up or die completely like the more delicate lithium technologies. It's generally best to recharge NiMh cells when the intensity or performance suddenly dips, indicating that one cell has been depleted.
That was more or less the idea I had - when circuit X stops working or when things suddenly become very dim or quiet or whatever the case may be, turn it off and charge the batteries. None the less, I appreciate the advice. I shall keep it in mind.
Thanks again! I've learned lots of useful things from watching your videos. Your at the very top of my list of people to patreonise, as soon as possible, which is hopefully in a couple of months.
Incidentally, where did you get that nifty little screwdriver? I kind of like it.
Roflcopter4b I think he mentioned he got it from poundland in another video. You can get screwdrivers of that style from some hardware stores too.
Would you recommend the vapex charger? And would I be able to charge small capacity battery's like 500mah without damaging the battery's?
+X-FLIGHT101 It's a fast charger so I wouldn't recommend it for anything below about 1500mAh or 900mAh for AAA's.
+bigclivedotcom thanks for the help :)
What happens if you put a dummy battery next to a single battery to get it to charge?
Not recommended with this simple circuitry.
do these accept lithium cells as well?
No. Just NiCd and NiMh.
Watched the vid through and I'm not clear about the timer. does it start from power on to the unit?
Just wondering how I could make it work with people coming along and adding pairs of cells to it throughout the day, wouldn't want to entirely disable the timer, but it's be a pain if someone put a pair of cells in - saw the charge light start but then that pair was still flat next day, otoh wouldn't really feel good about cooking batteries for 2 weeks over holidays etc.
It runs from power on for a fixed time. To restart the timer you have to unplug the unit and plug it in again.
Thanks, you're very good at answering questions on old threads bigclive.
I think I'll probably still get one and either hack in a reset button (which I'll label start) in or put it on a plug-in timer so that if I'm not there the batteries can only cook for 10 or 12ish hours out of 24.
Or maybe just write 'power off and on again at plug after inserting batteries' on the top with a sharpie.
The unit charges at a low enough current not to damage cells if they were put in in a nearly fully charged state. The LED indicators are useful as a reminder that the unit has turned the charging current off.
can you make a video on how you test the capacity? thx
What screwdrivers do you use? plz link on ebay if it is
Hey Clive, I had a question; would it be possible for me to build my own 240Vin variable switch mode power supply? How difficult would that be?
+offbeatwitch Cheaper and easier buying it as a series of modules online or better still, if it's for test use then get a proper bench power supply.
+bigclivedotcom Have had a look, even on eBay the proper bench supplies seem kinda expensive - but I agree totally after looking that a series of modules would be better than building from scratch.
+bigclivedotcom Am I just looking in the wrong place for proper bench supplies?
@@offbeatwitch
On eBay you can buy a China made 0 to 30VDC, 0 to 10 amp switching supply here in the US for $53.00. That's a tenth of the price of name brand power supplies.
would it be possible to modify this and add a usb connection for the 5v?? because I have a 8 Watt 5v usb solar panel and would like to have a NiMh battery charger to go with it. but I'd probably keep the psu so I could still plug it in if I wanted.
I'm looking for some batteries for my camera and I have seen that NIMH batteries are the best. does anyone know what brands are good and what charger is good for them?? thank you
My fancy charger that detects delta voltage drop varies the charge current on and off, I think it checks the v drop in-between these on/off cycles. It even detects the drop at low charge currents.
erm, how about charging-load voltage?
silly question. Lithium battery's are fussy about changing and discharging needing protection circuitry.
just how fussy are- ni cad and ni hm. I'm looking at building a solar / wind up torch. With a low power boost converter in but can't diside on the batterys. Thanks in advance
:-)
+Simon Hopkins The NiMh cells are simple (NiCd is now mostly outlawed due to the RoHS ban on cadmium except in specialist applications). They have a lower energy density than lithium, but are more rugged and less prone to explosive failure. The one thing that does cause issues though is when you have several in series and run the pack down so low that the first ones to go completely flat get current pushed through in reverse by the other cells. That can shorten their life a bit.
+bigclivedotcom thanks for the quick reply. oh well back to the drawing board :-)
تحياتي لك من سوريا
I hope you have a good mains isolating transformer in front of the lead that you plug stuff for videos in. I'm not questioning your skills but just in case something goes wrong...
+nrdesign1991 You must be new here
I did not understand where the 6.7 volts came from, sine the supply only was 5V.
+Robin Jønsson That was a bit weird. I think it was a capacitive effect showing switching transients.
I work with a variable voltage & currant supply and I charge the battery's accordantly.
Vapex? Is it for a Vaporizer?
Sorry for being too nit-pickish, but at 17:20 you called the built-in diode a protection diode. Actually, it is intrinsic to the construction (doping profile if you prefer).
what is the difference between rectified loop and a normal loop?
+GlazedLukem121 When a diode is used it only allows the current to flow in one direction. In this charger it is used to prevent the cells from discharging through the circuitry when the unit is turned off.
+bigclivedotcom Is the vapex charger any good?
I already own one but batteries charged in it don't seem to last as long as the same batteries charged in my "plug type" Uniross 4 x AA/AAA charger.
The wall plug charger will show red for about 4 hours when batteries are inserted and the charge time seems to be the same whether i put in full or dead batteries.
The Vapex does seem to read the voltage and only charge full cells for 15 minutes or so but I am thinking there's something wrong as the batteries do not last as long....
the batteries may be degrading/going high resistance , the vapex may then shut off too early.. try slow discharging them somehow, maybe use a small torch bulb as load,then slow charge with a cheapo low current charger, this 'might' improve matters...
1:06 - "...as in the god Zeus..." Whenever I hear the name Zeus I can't help but think of the line in the movie _Die Hard With A Vengeance_ that Samuel Jackson said to Bruce Willis. Rather than repeat it here and be flagged for vulgarity, watch this RUclips clip: ruclips.net/video/BquyQj8TX_w/видео.html Sorry for the quality...it was the only one I could find with the scene I'm referring to.
I have a AA battery charger called Mighty charger. Supposedly it can charge alkaline batteries but I had one made by Rayovac it was branded "Rayovac Renewal" and it had special rechargeable alkaline batteries. The batteries started to leak after awhile so I don't believe you can charge Alkaline batteries.
+coondogtheman1234 In my experience any attempt at charging alkaline cells results in leaking. Even super-low trickle charging.
bigclivedotcom
I just tried a 9V battery in my mighty charger and I unplugged it and left it for maybe a half hour and when I came back it was dead. I had to "jump start" it in order to get the charger to see it. I can buy 9V rechargeables and they work well.
+bigclivedotcom Just out of interest, how do you work out the "true" mAh of a battery? I begin to question the validity of a AA that goes above 2500mAh if that is even possible. There are AAA now apparently doing 1500mAh and 9v PP3's supposedly doing 450mAh. Would that be accurate or is it just a pile o mince?
+Lee Sanderson The boring way is to connect it to a suitable test load (power resistor) and a voltmeter, then time how long it powers the test load, until the cell voltage drops to the end point voltage. For NiCad and NiMh, this is normally 0.9V per cell. Then calculate the current used by the test load and multiply by the time taken. This gives you the capacity in Amp-hours (Ah) for that discharge current. Note the capacity will vary depending on how fast the discharge is. A high current, fast discharge will result in a low capacity result, as will very low current, really long and slow discharge.
1024 MAK bigclivedotcom Surely there must be a more practical not so long winded and time consuming way than that?
What's the difference between this and a charger that charges ICR or IMR batteries?
+MalleusSemperVictor The chargers for lithium cells have tio stop as soon as they reach 4.2V toi avoid damaging the cell. With these ones they can just keep trickling current if required. These ones are a LOT simpler.
which screwdriver is that?
what happens if you put an AA in the first slot and an AAA in the second slot of a pair? or the other way around? will it either charge the AA at lower current or the AAA at higher current? will that make a bang? shouldn't you try? :)
+na rc The type in the current regulated slot will determine the current ghat goes through both cells. But it's not actually high enough to be an issue whether it's 100 or 200mA.
Makes sense, thanks! I'd bet somewhere in the "user manual" they have something like "don't mix and match batteries"... or they just didn't think someone would have both AA and AAA around the house.
Have you seen the battery genies? They claim to charge alkaline batteries too, is this safe?
+BigAlFiGala I've never seen a charger that can put any decent charge back into a normal alkaline cell. They also tend to make the cells leak.
If it is charging two batteries in series how does it not over voltage one of the cells? Add a charged and uncharged battery an the charged one will be over voltage?
+BillyBag2 It doesn't matter. The current will be the same through a flat and full cell and unlike lithium cells you can keep charging a full cell at modest current without harm. It will just get warm.
+bigclivedotcom They won't catch fire or anything, but it seriously reduces their life to do that.
I much prefer smart chargers; but not fast chargers; that way you can top them up whenever, and they last longer, both more cycles and longer in operation because they're properly charged up.
OK, I do have my lipo head on. I thought Nimh was C/10 for slow charge. 1C for fast charge and 10mA for trickle charge. If they can trickle charge at 100mA+, but get warm, but there is a timer, then I guess the 10-50mA figure is more a "storage' charge. I think you can charge at 10mA "indefinitely". So this raise the question how do the smart chargers accurately measure the capacity? Is the transition from charging to charged that hard and detectable? I suppose the real smart one measure the capacity over the discharge phase of a two charge cycle.
+BillyBag2 when charged at constant current there's a small voltage drop when they become fully charged
So, any opinions on "best NiMH cells"? Personally, I've stopped trying to max out the mA rating and instead favour batteries that are "precharged". I found the non-"prerecharge"able high rated cells discharge so quickly you might as well not bother for anything you're not using today or tomorrow. I'll take a 2000 mA rating if I can put it in a device and have something like 2/3 of the charge left after a week or a month.
try camillion always ready
+TheJohn8765 eneloops! hold much longer than a few months, and over 2000mah, well worth buying some, they are the best of the bunch
+TheJohn8765 the higher profile brands with low self discharge are actually worth every penny. So I'll also suggest Eneloop cells. Real ones, because I bet they sell fakes.
bigclivedotcom + to the Eneloop ones.. most of my Duracell cells (the "white tops") are re-marked Eneloop (and I carefully sequester those guys and charge them slowly to extend their lives.. lol)... still, I don't buy much battery-wise from the Net since it seems 99.4% of it is bullshit. What are everyone's guides to avoid the BS?
jusb1066 I agree and I have many pairs of them, but there are fewer and fewer choices, especially if you buy online. Panasonic cells are fine for 18650 cells, but quality AA NiMH can be hard to come by.
How to charge batteries? like, I would love to charge an Li-ion battery with overcharge protection but is it really as simple as connecting + to +, - to - and putting more current and voltage than the battery can output? what if I put too much of it, for ex. if I wanted to charge 3,7V 800mAh, would 12V kill it fast? is it the current that charges? and what about NiMh ones? would it be safe to charge them in series without protection if I make sure they never charge to full capacity? what about overdischarge, is a single zener diode a good option? I only want to make solar powered lighting and some other stuff using an 12V panel, I don't know the current yet. so dumb. lol.
With lithium batteries you have to limit the current and voltage accurately. Fast charging them excessively will make them fail in flames.
Lithium batteries charge similarly to Pb batteries; their charge has two phases- constant current and constant voltage. You start in CC mode, which is the max charging current the battery is rated to handle (typically 1C). When the voltage reaches 4.2V per cell (for a 3.7V nominal cell), the charger starts lowering the current to maintain 4.2V. When the current goes to zero, the battery is full. You could in theory build your own lithium charger with a voltage regulator and a current limiting resistor.