This circuit with constant current is sometimes called a "current mirror". With the left side maintaining a constant base voltage with constant base current and the collector has almost the same current with emitter, collector 'mirrors' the current on the diode. A nice article explaining this in detail can be reached by searching "Bipolar Junction Transistor or BJT Current Mirror". In this circuit the LED is used as a diode and at the same time as an indicator. In addition to this, it is very common to use another one of same transistor and connect base and collector together to convert it to a diode with identical junction characteristics since each pair of Base-Collector and Base-Emitter is a diode by itself.
Wow - thats the exact same circuit I came up with as a unregulated input constant current NiCad charger back in the 1970s. It was a challenge with my boss to come up with a circuit with the least components. The transistor part is pretty standard - it was the use of the LED as the voltage reference and also charge indicator that was the clincher.
Transistors are attached to large copper areas, so they will handle 0.4W for a while, but they are normally limited to 0.2W in the standard thin trace condition. In a larger TO92 package you will only handle 300mW in any case, so they are being used (barely) within thermal limits in normal use. Nice design, and a pretty good regulation figure for such a cheap unit.
You are extremely intelligent and I love the analysis you do on all your videos. It's keeping my schooling fresh. A couple of notes: They could have put the diode in their circuit too to prevent backfeeding. Also, they are going to have on the order of beta times better current regulation than your design against supply voltage, temperature, cell type fluctuations, etc. But it's probably for the turn-off effect when the cell is charged that other commenters mentioned.
+tiger12506 It can't backfeed due to the PNP transistor in the actual circuit. Remember Clive's doodle is just an abstraction to make it slightly easier to understand. The current he's measuring by shorting +5V to ground flows through the base of the transistor and the 680 ohms, it wouldn't leak that much into the computer. His criticism of the circuit in case of a battery short still stands, though, as, typically, those little SOT-223 transistors are only rated for 250mW (as I found out to my chagrin after miniaturising one of my own circuits). Whereas the through-hole equivalent TO-92 package typically handles 400mW.
Clive, the reason they used switching and regulation is so that you don't over charge a cell and cause it to fail. Those little transistors will probably take half a watt without issue because of the size of the tracks they are on acting as passive heat-sinks. Also, you didn't calculate your circuit under dead short conditions... Your 30 ohm resistor will be carrying 146mA and dissipating 0.645W of heat. The LED would be forced to take 12mA
Clive i would like to thank you so much for making all your videos you have taught me so much about electronics and made me supposedly the smartest person in my science class thank you
Hi Big Clive, I came across this constant current circuit back in the early 1970s. It used a PNP TO3 transistor and a zener diode and resistors of suitable power rating supplied from a Tektronics 150 valve power supply to provide a constant current to a thermionic tension transducer. I can’t remember the actual details from then but I have used both PNP and NPN versions and used an LED instead of a zener diode more recently. Best wishes from Oxfordshire.
When you said it would possibly feed back voltage into the USB port I figured put a diode in line to prevent it, then I saw your circuit and said yes, that is it. I am not sure that feeding the batteries .300 milliamps would be all that bad, unless it just keeps going which it would until one took out the cells. I like the circuit, but like you said a bit more complicated than necessary.
My favourite explanation of the constant current circuit is: "If the transistor gain (beta) is high enough, the collector current will be virtually the same as the emitter current. I.e. The emitter current will be reflected in the collector as long as the supply voltage is sufficient to maintain the current in the load. The circuit is in common base configuration with the input (current) into the emitter and the output (current) out of the collector."
I have actually used a similar PNP configuration to create a constant current source for biasing audio circuits, effectively using the LED's constant forward voltage as a reference voltage much like a reverse-biased Zener diode. In an audio circuit, using a stabilized current for biasing makes the circuit very resistant to noise from the power supply, but that really doesn't do much good here. The only issue I see with your circuit is that shorting the battery would result in a roughly 0.64W dissipation through the 30-Ohm resistor, so your resistor would need to be rated at least 1W or so.
I have the very same Fluke model 23 meter. I bought it maybe 30 years ago for USD $169. Still works fine but doesn't do RMS so I recently bought a Klein CL2000 which also has the AC/DC clamp amp meter function.
9 лет назад+2
And thinking that there are dedicated ICs (to23-like 5 pin) that, with only one sense resistor and, perhaps one decoupling capacitor can safely PWM charge a MiMh cell in constant current and disconnect de cell on delta-peak or voltage cut-out or timer-cut-out... These are designed to damage cells, damage equipment and sell more stuff. :)
That was fun. But, with a PNP, shouldn't the LED and the CE (or EC, I'm not sure which way it is) of the PNP stop feedback current from the battery? I might just play with that circuit a bit, because you DID get leakage at the USB plug. It would be interesting to know if a USB port will suck power from the charged battery if the supply power to the port is turned off. Also, if the un-plugged charger actually puts a drain on a battery if one is left in. It also seems that without a battery in the charger, (again with the PNP) there would be 4.4v (5 - 0.6) across 691.5 ohms (11.5 + 680). I think that works out to 0.075v across the 11.5 ohms. With 0.6v across the PNP, that's only 0.675v across the LED. If I'm right, that's why the LED doesn't light without a battery.
Very nice analysis of this circuit! At my former workplace I had a similar Fluke multimeter and it was nearly as old as yours and it had to stand many falls from the table there. Very durable and valuable. I got myself a new Fluke 117 last year. PS: I am from Germany but I like your way of speaking/accent.
Neat little circuit. The LED is acting as a pseudo Zener voltage reference as well as acting as an indicator when the battery is charging. The LED will maintain about a 2.2 voltage drop while in operation, and also serves as the charge indicator since its being driven by the base current. With no battery or a fully charged one, base current stops flowing and the LED goes out. The open circuit output voltage is the voltage of the LED minus a diode drop, or about 1.5V. The current through the resistors when its shorted is also determined by the LED voltage reference, minus a diode drop, which gives around 100-160 mA, depending on what the actual voltage drop of the LED is, if Im reading it right. Edit: Another interesting point is that it requires a relatively shitty transistor to work. If the gain is too high, the LED wont light fully.
thanks Clive for forcing me to think too!! Its been a long time. . . but I think the pnp circuit might line regulate better with bias current + led current through 680R. . .or I could be completely wrong!
Interesting but same constant current circuit is/was popular for discrete cheap audio amplifiers as constant current source for long-tailed pair (or any place that need constant current).
At that current, it seems like an impractical charger for all but the very low capacity AA or AAA cells found in some solar lights. For example, nearly all my Ni-MH AAs are rated between 2000mAh and 2400mAh. So a 2200mAh typical cell charged at 110mAh would take at least 20 hours to fully charge. With efficiency losses, it's more likely to take 24 hours. Even those just doing an overnight charge such as using this as a travel charger will only be giving the batteries a 50% or less charge. As for overcharging, the charging current does have an interesting side effect in that most Ni-MH batteries can endlessly handle a trickle charge of 5% the rated capacity, which this 110mA current happens to work out at for 2200mAh and higher capacity cells.
The USB current limit of 500mA is probably a large factor in their design. That and the simplicity precluding the use of any end of charge sensing. So it's probably safer to treat it as a trickle charger.
Seán Byrne These days, many people don't have battery munchers running off NiMH any longer. Everything that takes a lot of energy has a Li-Ion cell. An xbox360 wireless controller will run for about a week to a month fully charged depending on use, a wireless mouse around half a year, with lower capacity Eneloop or similar low self discharge.
Interesting explanation Clive. On a side note, I accidentally clicked the subtitles button when I went to full screen it. They are hilarious in places. :-)
Try that wth the built in translation. The results are hilarious, and often have absolutely no relation to the video, even if it is english to english.
Hi Clive. I suspect the charging circuit here has been copied from earlier designs of charger. In Ni-Cad battery chargers that date from the 1980's and 1990's, I have seen both circuits (your resistor & LED network and the PNP transistor version) in these older chargers. Although back then the transistors were TO92 cased types. And often the DC supply was not smoothed.
Also, for some reason I tend to use more NPN than PNP as well, but they are both needed in a push pull amplifier circuit, but that is where I would use them.
looking through old stuff.. the mcp1700 ldo voltage regulator which could be "set" for 1.5 Volt out, could dissipate 1.6watt at 40°C ambient (i max ca 200mA) in a SOT-89 smd package.(datasheet, woaah!!) with diode + resistor in front of it (to get charging led function) it could be used as "smart" transistor... Would need to test if cap, then diode, then ldo@1.5V would allow the regulator to survive getting voltage fed in the output if unplugged with batteries still in.
I assume that if the transistor shorts out (including the base), it would blow the LED, since there is nothing limiting the current for it, and maybe stop the USB port from working (blown fuse or protection circuit). Am I right?
this would be great for some mobile application, where you need the device to be charged and be on at the same time while also could be battery operated when not charging
i wonder if it is designed so when it reaches 1.5v from a 100ma charge, it will turn off charging the cell? as at that charge rate it will have a full charge, with your plain resistor, it will never stop charging, and probably relying on the case to have a recessed positive connection to prevent reverse connection
bigclivedotcom but im still of the opinion that once the positive end reaches 1.5v it will turn off the transistor, which it will reach on eventual charging, plus these are more to match the lower capacity poundland cells, which are i think 800mah for aa and 350 for aaa, thus an 3-8 hours charging which isnt so bad. :}
ah long time reply! i have since bought one of these and yes you are correct, it actually has a use too, if you over discharge a nimh , my regular charger will reject the cell, i use this to give an hour or so of pre charge then put it back and it charges fine
Hi Clive, interesting charger. Have you ever actually tried making the NPN circuit that you drew? I used 3904 in a TO95, with a 2v green led. No illumination on the led and almost all the voltage (4.9v) is going the battery. Ya, I'm a rookie.
would I be right in thinking the led operation could be changed if the led and the 680 ohm resister was swapped ? I.e. led would turn on when the battery is fully charged ?
BillyNoMates1974 No, the circuit requires the LED to be exactly as wired. If you change the position of the LED and the 680 ohm resistor, it will no longer work correctly.
Hi.Just made one from your excellent reversed engineered schmatic (npn) Leds never go out after 8 hours with a new 700ma 1.2v rechargeable batt.Apreciate this is a trickle charge but how long??? MERRY CHRISTMAS TO YOU
The LED won't go out. Unlike lithium cells it's safe and normal to trickle charge NiMh cells continuously. Once they are at full charge they dissipate any excess current as a slight warmth.
@@bigclivedotcom ok I see. Leds indicate charging and can be left connected.If it limited say...100ma charge current for example then a 700ma AA would be in priciple 7 hr charge or is that completely wrong. So So impressed you replied. Thank You.
I had one of those chargers a while back, but I lost it. I will make one of these circuits my solution to devices that only take a single cell, as my super-expensive and complicated full-of-electronics charger cannot do a single cell.
In the early days of NiMh cells there was a lot of talk about how delicate they were and how you needed special chargers for them. I don't think that's really the case now. The cells should tolerate constant trickle charging of 100mA without any damage.
bigclivedotcom In the early days of NiMh when they didn't have that overcharge catalyst they started to produce a gas(oxygen?) and then exploded. Nowadays pretty much all NiMh cell have a catalyst capable protecting up to something like C/10. (Like ~220mA for an 2200mAh cell.)
m8e I didn't realise that in the early days they didn't have the facility to recombine the gasses to electrolyte like NiCd. I do know that the negative delta V charge end detection is more subtle in NiMh cells. That's probably why so many "smart" chargers end the charge cycle very prematurely on some cells. That and their inability to deal with older cells with a higher internal resistance.
This circuit with constant current is sometimes called a "current mirror". With the left side maintaining a constant base voltage with constant base current and the collector has almost the same current with emitter, collector 'mirrors' the current on the diode. A nice article explaining this in detail can be reached by searching "Bipolar Junction Transistor or BJT Current Mirror".
In this circuit the LED is used as a diode and at the same time as an indicator. In addition to this, it is very common to use another one of same transistor and connect base and collector together to convert it to a diode with identical junction characteristics since each pair of Base-Collector and Base-Emitter is a diode by itself.
Wow - thats the exact same circuit I came up with as a unregulated input constant current NiCad charger back in the 1970s. It was a challenge with my boss to come up with a circuit with the least components. The transistor part is pretty standard - it was the use of the LED as the voltage reference and also charge indicator that was the clincher.
Transistors are attached to large copper areas, so they will handle 0.4W for a while, but they are normally limited to 0.2W in the standard thin trace condition. In a larger TO92 package you will only handle 300mW in any case, so they are being used (barely) within thermal limits in normal use. Nice design, and a pretty good regulation figure for such a cheap unit.
Yep! I rarely use PNP transistors too. Only when I need a extremely symmetric circuit (like a power amplifier, for example) or slightly high gain.
You are extremely intelligent and I love the analysis you do on all your videos. It's keeping my schooling fresh.
A couple of notes:
They could have put the diode in their circuit too to prevent backfeeding.
Also, they are going to have on the order of beta times better current regulation than your design against supply voltage, temperature, cell type fluctuations, etc.
But it's probably for the turn-off effect when the cell is charged that other commenters mentioned.
+tiger12506 It can't backfeed due to the PNP transistor in the actual circuit. Remember Clive's doodle is just an abstraction to make it slightly easier to understand. The current he's measuring by shorting +5V to ground flows through the base of the transistor and the 680 ohms, it wouldn't leak that much into the computer.
His criticism of the circuit in case of a battery short still stands, though, as, typically, those little SOT-223 transistors are only rated for 250mW (as I found out to my chagrin after miniaturising one of my own circuits). Whereas the through-hole equivalent TO-92 package typically handles 400mW.
Poor you. If he was intelligent he wouldnt play with RUclips - he would own RUclips.
Clive, the reason they used switching and regulation is so that you don't over charge a cell and cause it to fail.
Those little transistors will probably take half a watt without issue because of the size of the tracks they are on acting as passive heat-sinks.
Also, you didn't calculate your circuit under dead short conditions...
Your 30 ohm resistor will be carrying 146mA and dissipating 0.645W of heat.
The LED would be forced to take 12mA
Clive i would like to thank you so much for making all your videos you have taught me so much about electronics and made me supposedly the smartest person in my science class thank you
Hi Big Clive, I came across this constant current circuit back in the early 1970s. It used a PNP TO3 transistor and a zener diode and resistors of suitable power rating supplied from a Tektronics 150 valve power supply to provide a constant current to a thermionic tension transducer. I can’t remember the actual details from then but I have used both PNP and NPN versions and used an LED instead of a zener diode more recently.
Best wishes from Oxfordshire.
When you said it would possibly feed back voltage into the USB port I figured put a diode in line to prevent it, then I saw your circuit and said yes, that is it. I am not sure that feeding the batteries .300 milliamps would be all that bad, unless it just keeps going which it would until one took out the cells. I like the circuit, but like you said a bit more complicated than necessary.
My favourite explanation of the constant current circuit is:
"If the transistor gain (beta) is high enough, the collector current will be virtually the same as the emitter current. I.e. The emitter current will be reflected in the collector as long as the supply voltage is sufficient to maintain the current in the load. The circuit is in common base configuration with the input (current) into the emitter and the output (current) out of the collector."
I have actually used a similar PNP configuration to create a constant current source for biasing audio circuits, effectively using the LED's constant forward voltage as a reference voltage much like a reverse-biased Zener diode. In an audio circuit, using a stabilized current for biasing makes the circuit very resistant to noise from the power supply, but that really doesn't do much good here. The only issue I see with your circuit is that shorting the battery would result in a roughly 0.64W dissipation through the 30-Ohm resistor, so your resistor would need to be rated at least 1W or so.
I have the very same Fluke model 23 meter. I bought it maybe 30 years ago for USD $169. Still works fine but doesn't do RMS so I recently bought a Klein CL2000 which also has the AC/DC clamp amp meter function.
And thinking that there are dedicated ICs (to23-like 5 pin) that, with only one sense resistor and, perhaps one decoupling capacitor can safely PWM charge a MiMh cell in constant current and disconnect de cell on delta-peak or voltage cut-out or timer-cut-out...
These are designed to damage cells, damage equipment and sell more stuff. :)
That was fun. But, with a PNP, shouldn't the LED and the CE (or EC, I'm not sure which way it is) of the PNP stop feedback current from the battery? I might just play with that circuit a bit, because you DID get leakage at the USB plug. It would be interesting to know if a USB port will suck power from the charged battery if the supply power to the port is turned off. Also, if the un-plugged charger actually puts a drain on a battery if one is left in.
It also seems that without a battery in the charger, (again with the PNP) there would be 4.4v (5 - 0.6) across 691.5 ohms (11.5 + 680). I think that works out to 0.075v across the 11.5 ohms. With 0.6v across the PNP, that's only 0.675v across the LED. If I'm right, that's why the LED doesn't light without a battery.
Very nice analysis of this circuit!
At my former workplace I had a similar Fluke multimeter and it was nearly as old as yours and it had to stand many falls from the table there. Very durable and valuable. I got myself a new Fluke 117 last year.
PS: I am from Germany but I like your way of speaking/accent.
FesixGermany When I started work in the late 1980's, I was a trainee. The teams I worked with used Fluke 77 or Fluke 79 multimeters.
@@Mark1024MAK Mine is 179 from 2010 IIRC.
Neat little circuit. The LED is acting as a pseudo Zener voltage reference as well as acting as an indicator when the battery is charging. The LED will maintain about a 2.2 voltage drop while in operation, and also serves as the charge indicator since its being driven by the base current. With no battery or a fully charged one, base current stops flowing and the LED goes out. The open circuit output voltage is the voltage of the LED minus a diode drop, or about 1.5V. The current through the resistors when its shorted is also determined by the LED voltage reference, minus a diode drop, which gives around 100-160 mA, depending on what the actual voltage drop of the LED is, if Im reading it right. Edit: Another interesting point is that it requires a relatively shitty transistor to work. If the gain is too high, the LED wont light fully.
thanks Clive for forcing me to think too!!
Its been a long time. . . but I think the pnp circuit might line regulate better with bias current + led current through 680R. . .or I could be completely wrong!
Interesting but same constant current circuit is/was popular for discrete cheap audio amplifiers as constant current source for long-tailed pair (or any place that need constant current).
At that current, it seems like an impractical charger for all but the very low capacity AA or AAA cells found in some solar lights. For example, nearly all my Ni-MH AAs are rated between 2000mAh and 2400mAh. So a 2200mAh typical cell charged at 110mAh would take at least 20 hours to fully charge. With efficiency losses, it's more likely to take 24 hours.
Even those just doing an overnight charge such as using this as a travel charger will only be giving the batteries a 50% or less charge. As for overcharging, the charging current does have an interesting side effect in that most Ni-MH batteries can endlessly handle a trickle charge of 5% the rated capacity, which this 110mA current happens to work out at for 2200mAh and higher capacity cells.
The USB current limit of 500mA is probably a large factor in their design. That and the simplicity precluding the use of any end of charge sensing. So it's probably safer to treat it as a trickle charger.
Seán Byrne These days, many people don't have battery munchers running off NiMH any longer. Everything that takes a lot of energy has a Li-Ion cell. An xbox360 wireless controller will run for about a week to a month fully charged depending on use, a wireless mouse around half a year, with lower capacity Eneloop or similar low self discharge.
Perfect for cheap poundland cells :)
Interesting explanation Clive. On a side note, I accidentally clicked the subtitles button when I went to full screen it. They are hilarious in places. :-)
Try that wth the built in translation. The results are hilarious, and often have absolutely no relation to the video, even if it is english to english.
Hi Clive. I suspect the charging circuit here has been copied from earlier designs of charger. In Ni-Cad battery chargers that date from the 1980's and 1990's, I have seen both circuits (your resistor & LED network and the PNP transistor version) in these older chargers. Although back then the transistors were TO92 cased types. And often the DC supply was not smoothed.
He was charging a battery with another battery. GENIUS!!!
+Aperson A lot of people do that. Power banks are made for that ;)
Also, for some reason I tend to use more NPN than PNP as well, but they are both needed in a push pull amplifier circuit, but that is where I would use them.
i believe the circuit they built is not dependant on the supply voltage (or beta dependant either). it is very good used as LED driver, also
looking through old stuff..
the mcp1700 ldo voltage regulator which could be "set" for 1.5 Volt out,
could dissipate 1.6watt at 40°C ambient (i max ca 200mA) in a SOT-89 smd package.(datasheet, woaah!!)
with diode + resistor in front of it (to get charging led function) it could be used as "smart" transistor...
Would need to test if cap, then diode, then ldo@1.5V would allow the regulator to survive getting voltage fed in the output if unplugged with batteries still in.
I assume that if the transistor shorts out (including the base), it would blow the LED, since there is nothing limiting the current for it, and maybe stop the USB port from working (blown fuse or protection circuit). Am I right?
this would be great for some mobile application, where you need the device to be charged and be on at the same time while also could be battery operated when not charging
i wonder if it is designed so when it reaches 1.5v from a 100ma charge, it will turn off charging the cell? as at that charge rate it will have a full charge, with your plain resistor, it will never stop charging, and probably relying on the case to have a recessed positive connection to prevent reverse connection
The circuitry doesn't really monitor the cell voltage, so I think it would just keep on trickle charging it as long as there was something there.
bigclivedotcom
but im still of the opinion that once the positive end reaches 1.5v it will turn off the transistor, which it will reach on eventual charging, plus these are more to match the lower capacity poundland cells, which are i think 800mah for aa and 350 for aaa, thus an 3-8 hours charging which isnt so bad. :}
jusb1066 No, as long as the input is about 5V and the cell voltage stays below about 3V, the "charge" current will stay at about 110 to 115mA.
ah long time reply! i have since bought one of these and yes you are correct, it actually has a use too, if you over discharge a nimh , my regular charger will reject the cell, i use this to give an hour or so of pre charge then put it back and it charges fine
Hi Clive, interesting charger. Have you ever actually tried making the NPN circuit that you drew? I used 3904 in a TO95, with a 2v green led. No illumination on the led and almost all the voltage (4.9v) is going the battery. Ya, I'm a rookie.
Never mind. Bad battery connection. Circuit worked great and charged the 1.2v NiMh AA perfectly. Thanks from -across the pond-.....
would I be right in thinking the led operation could be changed if the led and the 680 ohm resister was swapped ? I.e. led would turn on when the battery is fully charged ?
BillyNoMates1974 No, the circuit requires the LED to be exactly as wired. If you change the position of the LED and the 680 ohm resistor, it will no longer work correctly.
Rite Big Dude, Old'n but Gold'n! TFS, GB :)
Rating on the transistor and diodes please?
In ur circuit, does the led turns off when the battery is fully charged?
The cct diag seems to show a NPN transistor...
keeboudi As he said in the video, the PNP version melted his brains... so he drew an equivalent circuit using a NPN transistor....
It was a very long time ago!
It was a tektronix 160 power supply 🙂
Hi.Just made one from your excellent reversed engineered schmatic (npn) Leds never go out after 8 hours with a new 700ma 1.2v rechargeable batt.Apreciate this is a trickle charge but how long??? MERRY CHRISTMAS TO YOU
The LED won't go out. Unlike lithium cells it's safe and normal to trickle charge NiMh cells continuously. Once they are at full charge they dissipate any excess current as a slight warmth.
@@bigclivedotcom ok I see. Leds indicate charging and can be left connected.If it limited say...100ma charge current for example then a 700ma AA would be in priciple 7 hr charge or is that completely wrong. So So impressed you replied. Thank You.
They have used the led as the constant current supply through the bass of the transistor that is it!!
I have one in grey from Maplin ~1991 still going strong :-)
So that's all you really need to build a battery charger? I'm probably not going to try it just yet but it'd be handy to know.
Great explanation! But what’s a doo da?
I had one of those chargers a while back, but I lost it. I will make one of these circuits my solution to devices that only take a single cell, as my super-expensive and complicated full-of-electronics charger cannot do a single cell.
BigClive, your 2nd W calculation doesn't include the junction fail temp of the Qs. People forget that & reach alarming & wrong conclusions.
Very interesting, what I could understand :)
Used that sort of circuit before!!
You lost me, you're just too fast for me. Keep up the great videos
Sorry, sometimes I do go into turbo mode.
bigclivedotcom no problems Clive, you do a great job, I've learned a lot from your videos.
Motors act as generator, so if you spin the motor the LED will light.
Genius!
So weird that battery want to escape 3:10 he he he.
I sell Fluke meters and they are expensive as balls!!
even more so when you buy from RS !!!
Wouldn't use that to charge NiMh, but woudn't hurt NiCd cells.
In the early days of NiMh cells there was a lot of talk about how delicate they were and how you needed special chargers for them. I don't think that's really the case now. The cells should tolerate constant trickle charging of 100mA without any damage.
bigclivedotcom In the early days of NiMh when they didn't have that overcharge catalyst they started to produce a gas(oxygen?) and then exploded.
Nowadays pretty much all NiMh cell have a catalyst capable protecting up to something like C/10. (Like ~220mA for an 2200mAh cell.)
m8e I didn't realise that in the early days they didn't have the facility to recombine the gasses to electrolyte like NiCd. I do know that the negative delta V charge end detection is more subtle in NiMh cells. That's probably why so many "smart" chargers end the charge cycle very prematurely on some cells. That and their inability to deal with older cells with a higher internal resistance.
Thanks,
that's very good to know.
Does it just keep overcharging and never indicate when the batteries are full once the batteries are full?
if so then it's a terrible design!
700th like lol
I am not suprised it melted your mind.I do not believe any word you say, here.