hybridfree/eevblog-posts huggingface dataset:
Characteristics of a soft-latch power switch - Page 1
Forum section: electronics / projects

author: asgard
author_rank: Regular Contributor
timestamp: September 20, 2012, 04:42:56 am
content: Enclosed here is a visual of an LTSpice simulation of a FET-based soft-latching power switch circuit. I also include the LTSpice .asc file:(I hope the graphic appears inline, but I digress).As I am still a relative noob I have some questions about the TP2 output waveform. The overshoot may be o.k. depending on the nature of the switching regulation intended to be downstream from this circuit. The strange undershoot during the odd-numbered events on the Vsw pulse train plus the stuff going on that makes the waveform look like the south end of New Mexico to me.Is this going to be acceptable to most of the buck converting devices around? The intent is for a 3.3V buck-regulated supply.The other question for me is speculative. I am aware that the potential exists for problems with slow-discharging capacitive loads when switch bounce is occuring. The inrush current is likely to be excessive for the main supply (a lithium cell with only 900 mAh storage capacity. I am aware of another design involving a diode, cap, and resistor added to a similarly simple circuit, which would seem to convert the pass FET into some kind of comparator so the slew rate is low for slow-charging of downstream capacitive loads. For various reasons I am leery of diving into that bowl of gumbo when this circuit seems to be working well enough for resistive loads. Ideas? Other concerns?J.R. Stoner from beautiful metropolitan Redding, CA (:-)

author: asgard
author_rank: Regular Contributor
timestamp: October 08, 2012, 10:10:37 pm
content: Probably a bad form to be replying to my own post, but it seemed the thing to do at the timeHere is another image of the project involved here. A soft-latching power switch-simulated with LTSpice.The output of the boost converter seems to have a really large amount of positive overshoot at the rising edge of the turn-on latch trigger. The output has a lesser overshoot of about 0.8V on the rising edge of the turn-off latch trigger. Okay, for a young-player such as myself, my question is how to get ride of the spikes on the rising edges? An R-C LP filter on the output? Didn't seem to work in the simulator.J.R.
Characterize DC motor - Page 1
Forum section: electronics / projects

author: aurmer
author_rank: Regular Contributor
timestamp: September 23, 2017, 12:08:51 am
content: I have experience with electronics, and I am just starting out with electromechanical.I bought this motor on the cheap (attached image), and I would like to characterize it to know what NOT to do with it. All it says is 24VDC. I tried looking up the part number, but perhaps I don't know what site to find the spec sheet on?If the spec sheet is obviously available, then I missed it. If not, what can I do to determine the motor's limits? Most importantly an amperage limit.Thanks for any guidance.

author: mjkuwp
author_rank: Unknown
timestamp: September 23, 2017, 12:39:14 am
content: Browse Pittman motors sitehttp://www.pittman-motors.comThey have excellent resourcesAlso, you may find good information in one of their videosand thishttp://www.pittman-motors.com/Portals/0/Resources/Understanding_DC_Motor_Curves_and_Temperature%20_pt1.pdfThe 24V is a nominal rating but the motor will operate over a wide range. The current limit is, of course primarily related to heat.Do you have a lab power supply? A photo tachometer or some other means to measure speed?

author: rstofer
author_rank: Super Contributor
timestamp: September 23, 2017, 01:48:13 am
content: Arrow is a huge distriibutor of electronic stuff. Have you searched their site?

author: aurmer
author_rank: Regular Contributor
timestamp: September 23, 2017, 02:38:27 am
content: My next question is, what is the least expensive way to measure the stalling torque of a small DC motor? After a youtube search, I see that this guy has the right idea.I suppose I can literally rig up an arm length, and a weight, but in terms of 'torque measuring equipment', what can I find on the low end? How well could I expect low end equipment to perform? +/-10%? 25%?Quote from: mjkuwp on September 23, 2017, 12:39:14 amI have a power supply, but I have no means to measure speed. The photo tachometer looks promising; I believe I am in for one tomorrow.Thank you for the video link. It was enlightening.Quote from: rstofer on September 23, 2017, 01:48:13 amI wasn't able to find my exact model, but I did find some 403a series motors from Globe Motors. The 24V models I saw in a spec sheet had a max current just over 1A. I think I have an idea now. I can test this through my benchtop power supply and monitor the current as I play with it.
Characterize Spread of IR LED for Remote Control System - Page 1
Forum section: electronics / projects

author: Phoxtane
author_rank: Regular Contributor
timestamp: October 12, 2016, 02:18:44 am
content: If I've got an infrared LED that I want to use in a remote-control application, how can I measure the spread of the output? I imagine with a visible-light LED you'd just put it up against a sheet of paper and rotate it while keeping an eye on the light cone formed on the paper, but that's a bit difficult to do with something you can't actually see...My first instinct is to use a digital camera, though from the previous thread regarding IR LEDs I made, the ones typically used in remote controls (~940nm wavelength) don't show up nearly as well on cameras. Would taking the IR filter out of such a camera solve my issue?In addition to this, I assume the best way to get the longest range out of my control system is to be running the LEDs at full power, or close to it - maybe even overdriving them since the control protocol only pulses the LED for a brief period of time.

author: Augustus
author_rank: Regular Contributor
timestamp: October 12, 2016, 09:28:03 am
content: Just out of curiosity, why do you want to measure this? The usual way is to just look it up in the datasheet of your particular led, it's listed under "viewing angle" or "half angle" (theta) or something similar. There is usually also a nice graph picturing the permissible pulse current, depending on duty cycle. For a typical 5mm ir led in a remote control application this is usually somewhere in the range of max. ~1A or thereabouts. If you want something fancy a Osram "Oslon Black" SFH 4725S is able to handle up to 5A pulses. These are really nice, coupled with some narrow beam optics they would make a hell of a long range TV-B-Gone
Characterizing magnetic cores - Page 1
Forum section: electronics / projects

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 16, 2011, 03:49:46 am
content: I have a few ferrite cores from old monitor deflection coils and I'm looking to reuse them as inductor cores for power supply circuits.How would I go about characterizing them? One thing I did was to wind 7 or so turns on one of the cores, connect it in parallel with a capacitor, and use a pulse to excite it, at which point the resonant frequency (and thus the inductance) can be measured. It measured about 29uH. But that only tells a part of the story. Is there an easy way to figure out how many A*N (amp*turns) the core can withstand without saturating?

author: Psi
author_rank: Super Contributor
timestamp: March 16, 2011, 03:58:28 am
content: I have the exact same problem, lots of cores and no idea what frequency they are good for.At one point i planned to build a testing rig to scan frequency for a few different turn numbers and attempt to work out the core parameters.So far i've not had time to build one though, i figured it was probably more cost effetive to just buy the core type i needed than try to build something to reuse old cores.

author: jahonen
author_rank: Super Contributor
timestamp: March 16, 2011, 06:37:29 am
content: You could build a suitable setup for driving a pulse into an inductor and simultaneously measuring the current, that gives you saturation characteristic. I builtsomething like thata while ago. Losses are more difficult, though.Regards,Janne

author: tecman
author_rank: Frequent Contributor
timestamp: March 16, 2011, 05:00:39 pm
content: Simple tests can be made by winding some turns, and using a signal generator and a scope or AC voltmeter that will measure the frequency, and a couple of resistors, you can approximate the inductance by measuring Xl of the coil. You can also predict the saturation by increasing the drive level until you see saturation. A larger number of turns would be better to see saturation. Some calculation is required to determine the saturation level.paul

author: scrat
author_rank: Frequent Contributor
timestamp: March 16, 2011, 05:27:07 pm
content: I agree with Janne.If you're building a switching converter, you can just use one of its switches and an MCU to generate the pulse and change its duration live (if you have a debugger). Starting from a low duration makes the test safe.

author: AdShea
author_rank: Contributor
timestamp: March 18, 2011, 05:28:18 pm
content: If you have a scope, and a function generator (only needs to make sine waves (square waves can work too if you are doing SMPS)) you can get nice curve traces for B-H curves using a bifilar winding and a circuit as described athttp://www.cliftonlaboratories.com/type_43_ferrite_b-h_curve.htm. You run it at your target frequency. You can get the saturation just by reading off where the B-H curve closes over. Losses per cycle are just the area inside the B-H curve.
Charactoristics of an LED flash circuit - Page 1
Forum section: electronics / projects

author: raptor1956
author_rank: Frequent Contributor
timestamp: November 23, 2017, 06:21:55 am
content: I'm curious about the kind of circuits used to power the LED's as flash units in smartphones etc. These are obviously a lot different than Zenon flash units and I understand that among the differences is that the peak voltage is MUCH less. I would surmise a capacitor is used to store a charge and that a similar control circuit is used to fire and cutoff the current but, again, I'm not real clear on this. The LED's used would likely be an optimized type but I'd guess many other LED's could be used though at lower power and with lower output. So, looking at a typical smartphone that has an LED for autofocus, general illumination for video, as well as flash for stills what would be the typical values for charge, max/average current and voltage? Assuming a 5600K LED that would operate continuously at about 3.2V or there abouts I'd have to guess that the voltage would need to be somewhat higher but within the breakdown voltage.I'd like to test this out with some 4000K LED's I have but knowing a bit more before hand would be desirable.Brian

author: StillTrying
author_rank: Super Contributor
timestamp: November 24, 2017, 03:03:34 am
content: There quite a few phone LED driver ICs and circuits out there, I don't think they're all that special, mostly what they're doing is creating enough voltage.http://www.electroschematics.com/12394/camera-white-led-flash-illumination

author: raptor1956
author_rank: Frequent Contributor
timestamp: November 24, 2017, 05:39:18 am
content: Quote from: StillTrying on November 24, 2017, 03:03:34 amThanks, that's what I was looking for. The article is mostly related to the LED flash systems in smartphones with three or fewer LED's, but my application will have many more LED's so I should not have to drive them as hard.Brian
Charge a battery with a buck-boost converter from a solar panel - Page 1
Forum section: electronics / projects

author: Siddhat
author_rank: Regular Contributor
timestamp: April 01, 2020, 07:51:11 am
content: Hey Guys,Working on a project that will be able charge a battery from a buck-boost converter by tracking the Maximum Power Point(MPP) of a solar panel.I've already made a buck-boost converter and tracked the MPP from the solar panel using the Perturb and Observe Algorithm. The snapshot of the simulation in MATLAB is attached.But what I'm confused in is, the MPP is being achieved when there is a resistive load at the output of the buck-boost converter. I need to charge two 12V, 7Ah lead-acid batteries in parallel from the buck-boost converter(the resistive load now replaced by the batteries). Can I directly connect the output of the buck-boost converter to the batteries? If not, what should be the in-between electronics be to charge the batteries. Will the MPPT still be achieved when I connect the batteries. And how will the features of a battery charger like overcharge protection, over discharge protection, reverse polarity protection,etc be implemented and designed. I know that I need to have a current control feature. But I do not know how do I do that. And also,in the first place, can two batteries be connected in parallel directly?Need someone familiar with the topic! Got a lot of confusions!Thanks.
charge amplifier - Page 1
Forum section: electronics / projects

author: Skyland
author_rank: Contributor
timestamp: April 07, 2015, 03:20:49 pm
content: I have designed a charge amplifier to convert the charge from the force sensor into voltage. The force of the sensor is dynamic from 0 to 100N which is modelled as a voltage source V3 with a sine wave oscillating from 0 to 1KHz. C2 is the sensor static capacitance. The current source B1 is differentiating the voltage from V3. The system need to be able to respond between 0.1 to 1KHz. The problem is as shown in the AC simulation result the circuit on the right hand side does not give a low pass filtered response with a cut off frequency of 1KHz. I have made the circuit on the left hand side with a current source just to confirm that the charge amplifier is designed properly and the response is is as expected so the problem seem to be coming from the charge source. What could be the problem?

author: Marco
author_rank: Super Contributor
timestamp: April 07, 2015, 05:31:56 pm
content: Are you sure using DDT in AC simulations is kosher? (Also, Spice will almost certainly ignore this in AC ... but your opamp can't really put out 1000V.)

author: mikerj
author_rank: Super Contributor
timestamp: April 07, 2015, 06:52:33 pm
content: That's exactly what I would expect. Your current source has an output proportional to the differential of the voltage source, so the current output increases at 20dB/decade. Your simple integrator rolls off at 20db/decade above the pole formed by 1k/100n 1/(2*pi*1k*100n) = 1.5kHz. When combined this gives a flat response up to a few hundred kHz.Above this the op-amp is running out of gain/bandwidth, the output impedance increases and so the voltage at the inverting pin passes through the 100n cap to the output, and the output voltage starts increasing.
Charge battery when USB powered. Power circuit using latching switch otherwise. - Page 1
Forum section: electronics / projects

author: joseph.anand
author_rank: Regular Contributor
timestamp: September 03, 2015, 05:58:08 am
content: I'm working on modifying the power supply portion of a project of mine. This is a strictly battery powered circuit. I was earlier using a 3S lipo battery (11.1v) for powering my circuit and using a 3way switch to switch between charging, power off and power on modes. I now plan to operate from a single lipo cell and step up the the power using a DC-DC boost converter (which I have tested). I however would like to use a soft-latching switch to power the circuit and switch to charging mode when USB power is present. I will be using a microcontroller to take care of sensing the voltages on the USB and battery and automatically decide which mode to enable. I also will be using a dedicated lipo battery charger ic. I just want to ask here is using schottky diodes an elegant enough way to handle this dual supply. I did look at a power mux ic's blockg diagram from TI and they seem to be doing the same. The battery will be connected to the supply a soft latching circuit and then a schottky to the microcontroller's power supply while the VUSB power will be connected to the uC's power supply via the schottky only. The microcontroller handle's voltages from 2.4-5.5 (a pic16f1xxx series) so I do not think there is a need for a voltage regulator. Any ideas/suggestions for this.Basically the modes will be as followsVUSB LATCHSW MODE-------------------------------OFF OFF OFFON X CHARGEOFF LATCHED ON
Charge control IC LED control circuit (off-flash-on) - Page 1
Forum section: electronics / projects

author: awmt102
author_rank: Newbie
timestamp: June 26, 2018, 07:26:02 pm
content: Hi,I am using an MCP73831 LIon charge controller IC. It has a status pin with the following output:Shutdown/No battery: HiZCharging: 0Charged: 1This is obviously designed to be used with a bicolour LED like this:http://www.neufeld.newton.ks.us/electronics/?p=151. But I would like to drive a single LED with the following functionality:Shutdown/No battery: HiZ - LED offCharging: 0 - LED flashingCharged: 1 - LED onI have considered using a Schmitt oscillator to do the flashing (http://electronics-course.com/schmitt-trigger-oscillator). But I cannot quite figure out how to get it to work with the above functionality.I would like to keep the component count as low as possible. Any help would be appreciated.Thanks
Charge cycle terminates on connecting load - Page 1
Forum section: electronics / projects

author: Sai teja
author_rank: Regular Contributor
timestamp: October 23, 2017, 01:08:50 pm
content: HelloI am using MCP73213 IC for charigng Li Ion battery. On connecting load to charging adapter (9V/2A) during charge cycle , charge cycle terminates if voltage of battery is greater than 93 % of battery's maximum voltage.I don't know why is this happening. Please help me out.Datasheet mentions that threshold voltage for IC to start charge cycle is 93 % of VREG(8.4 volts)Link of the datasheethttp://ww1.microchip.com/downloads/en/DeviceDoc/20002190C.pdf
Charge Injection Cancellation on JFETs - Page 1
Forum section: electronics / projects

author: Echo88
author_rank: Frequent Contributor
timestamp: July 30, 2017, 08:15:51 pm
content: Hi,i want to add a auto-zero-feature to my selfbuilt DC-nanovolt-amplifier to cancel-out non-temperature-related-drift. Therefore i studied the 34420A-manual and the analog-front-end-schematics and concluded it would be best to use JFETs (since its the best solid-state-switch concerning offset voltage, see also Keithley 155 and Keithley 7168) as a half-bridge, which switches regularly between ground and measurement signal. This way offset drift can be compensated.Anyway: JFETs produce charge injection spikes, which id like to reduce. In the 34420A-schematic capacitors C201/202 are used, which cancel out the Cgs and Cgd-caused voltage spikes: Page 165 Q201/202/203 are the half-bridge, a 8-Bit DAC U204 produces an adjustable voltage. After a lot of fiddling with the values i seem to got good results for the cancellation.http://literature.cdn.keysight.com/litweb/pdf/34420-90010.pdfMaybe someone has advice or documents which allow me to get even better charge injection cancellation results?Greetings,Echo
Charge pump circuit question - Page 1
Forum section: electronics / projects

author: Etesla
author_rank: Regular Contributor
timestamp: April 27, 2020, 09:54:01 pm
content: I am looking for a 4X voltage multiplier topology that limits the voltage across ALL the involved capacitors to the input voltage of the system.For example, if Vin = a 4V peak to peak sin wave, I want Vout to be 8V, and the maximum voltage across any one of the capacitors to be 2V. The classic voltage multiplier circuits all seem to charge capacitors further along the chain to a higher voltage, which is not what I want. Any ideas?

author: jbb
author_rank: Super Contributor
timestamp: April 27, 2020, 10:02:18 pm
content: How about a Cocroft-Walton multiplier?

author: Etesla
author_rank: Regular Contributor
timestamp: April 27, 2020, 10:25:43 pm
content: Cockcroft–Walton multipliers are close to what I want, but most of the caps have approximately 2*Vin_Peak across them. I want the caps to have at most Vin_Peak across them.

author: langwadt
author_rank: Super Contributor
timestamp: April 27, 2020, 10:32:06 pm
content: but why?
Charge pump for high side N-MOS switch, will it work? - Page 1
Forum section: electronics / projects

author: hbozyq
author_rank: Contributor
timestamp: June 11, 2023, 11:55:21 am
content: Hi all. I'm working on a anti-spark switch to replace my loop-key on the ESCs.Loop-key is a mechanical switch, just like this:https://electric-skateboard.builders/t/how-to-anti-spark-xt-90s-loop-key/204I got no those anti-spark connectors so I decide to use N-MOS to build my own version. For some reasons I'm not gonna use low side switch and P-MOS is not an option, for its high Rds(on). Over 10 amps may needed and I want everything stay cool.From a applicationote (https://www.infineon.com/dgdl/Infineon-HV_Floating_MOS_Gate_Drivers-ApplicationNotes-v01_00-EN.pdf?fileId=5546d4626c1f3dc3016c47de609d140a) I found this:But I need 100% duty cycle and no fast switching so I simplified it in LTspice:And it seems working in simulation. BTW V2 is 50%, 100k PWM generated by MCU and a 12v push-pull output stage. V1 is the input power, could be around 24-50V.When PWM is enable, D1 D2 C1 C2 working as a charge pump to generate a voltage a bit above the power supply voltage. If the PWM disabled, a pulldown resistor R5 discharges the gate.Now I wonder will it work in real world? I guess the problem could be bootstrapping may fail when the output is 0V.Any help would be much appreciated. Thanks in advance.

author: DavidAlfa
author_rank: Super Contributor
timestamp: June 11, 2023, 12:42:58 pm
content: RES pin will take the HV voltage and blow up?

author: wasedadoc
author_rank: Super Contributor
timestamp: June 11, 2023, 12:43:22 pm
content: It looks to me that you have 100k between the "ground" of the charge pump and the ground of the supply into the IR2125. Can that supply sufficient power to the IR2125?How can it start? With the MOSFET off there is no power to the 755.

author: hbozyq
author_rank: Contributor
timestamp: June 13, 2023, 02:12:39 pm
content: Any suggestion guys?

author: DavidAlfa
author_rank: Super Contributor
timestamp: June 13, 2023, 04:49:57 pm
content: Search for MOSFET driver with charge pump, like the mic5021.
Charge pump tripler ,will it work ? - Page 1
Forum section: electronics / projects

author: Kevin.D
author_rank: Frequent Contributor
timestamp: January 31, 2013, 09:20:02 pm
content: Please help guys.While searching for information about using the icl7660 voltage converter touse as a positive voltage multiplier (using cascaded devices to triple + input voltage).I found this interesting little snippet .http://www.maximintegrated.com/app-notes/index.mvp/id/297It shows a way to use a single max1683 voltage doubler as a tripler .I am not surehow this works ,my head is fried .Anyway do you think this could be done with a icl7660 using a single device to triple input voltage. .The icl7660 is slightly different in the way it works to the max IC by the look of it .here's data sheet to icl7660http://www.intersil.com/content/dam/Intersil/documents/fn30/fn3072.pdfhere the max1683http://datasheets.maximintegrated.com/en/ds/MAX1682-MAX1683.pdf

author: Bored@Work
author_rank: Super Contributor
timestamp: January 31, 2013, 10:02:26 pm
content: It is an old trick. A cascade driven by a charge pump or smps.

author: Marco
author_rank: Super Contributor
timestamp: January 31, 2013, 10:22:47 pm
content: You could, but essentially you're just using the ICL7660 as an oscillator (even with the doubler in the datasheet that's already the case). With the Maxim you're saving one diode drop compared to a full tripler.I'm surprised there are no general charge pump triplers available ... what you can do though is have two voltage doublers and simply use the doubled voltage as the supply voltage for the second and the original voltage for it's "ground". That way you have a fully synchronous voltage tripler (ie. no diode drops). I wish I could claim I immediately realised that myself ... unfortunately I ain't that smartRead it here :http://ww1.microchip.com/downloads/en/devicedoc/21516c.pdf

author: Kevin.D
author_rank: Frequent Contributor
timestamp: February 01, 2013, 12:39:15 am
content: Thank you marco for that reply .If you look at the icl7660 data sheet you will see in the example ofthe positive voltage doubling example requires two diodes in the output so you get 2 Vf diode drops , and then you'd get another two Vf drops if your cascading them again I think .The maxim chip and the one you linked to don't seem to need diodes on their output in order to double voltage . That's why I asked ,because of this difference in the way the caps and diodes are connected on the icl76660 chip , I don't thinkthat the trick of using one device to triple voltage will work . ?

author: Marco
author_rank: Super Contributor
timestamp: February 01, 2013, 01:25:38 am
content: It can work, but you're looking at 4 diode drops with the ICL7660 ... hardly ideal.

author: codeboy2k
author_rank: Super Contributor
timestamp: February 01, 2013, 10:40:12 am
content: also as you start cascading icl7660's the final impedance goes up, so you need to be sure that you don't end up with such a high output impedance that you can't drive the load anymore.Just something to watch out for with charge-pumped voltage doublers and triplers, and cascades of these.
Charge scooter accu with RC charger ? - Page 1
Forum section: electronics / projects

author: JanJansen
author_rank: Frequent Contributor
timestamp: September 09, 2017, 02:27:59 pm
content: Hi, someone asked me to charge his scooter accu with my RC lipo charger ( Turnigy Accucell 6 )it can charge :PB BattNicadNimhLipoIs it possible to charge a 12 volt accu from a scooter ?, wich setting should i take ?thanks in advance

author: stmdude
author_rank: Frequent Contributor
timestamp: September 09, 2017, 02:52:43 pm
content: It's quite possible, but it depends on the battery in the scooter. Most of them use Pb batteries, but there's no guarantee, so you'll have to check.There might be several batteries in series, and the Accucell can "only" charge Pb up to 18-20 volts, so you might need to charge parts of the battery bank at a time.

author: JanJansen
author_rank: Frequent Contributor
timestamp: September 09, 2017, 03:07:07 pm
content: I dont know, i measured 7,7 volt before trying PB, then tryd PB it sayd full within 1 minute,then i measured again, it was under 5,8 volt.oops.

author: Benta
author_rank: Super Contributor
timestamp: September 09, 2017, 05:44:17 pm
content: Define "scooter". 2-stroke? Electric? Kickboard with e-motor? and and and...This kind of no-info question gets no-info answers.

author: JanJansen
author_rank: Frequent Contributor
timestamp: September 10, 2017, 01:51:00 pm
content: Oh sorry, its a thing with 2 wheels and they smell very bad.

author: cs.dk
author_rank: Unknown
timestamp: September 10, 2017, 02:01:00 pm
content: Probably a SLA/LA with a shorted cell or two..

author: kathy45
author_rank: Newbie
timestamp: December 28, 2017, 05:51:06 am
content: That automotive charger might be a little rough on those small batteries.It will probably work but reduce their lifespan.Here's a link to a fabulous charger for your purpose.I use several of them.They are on sale for around $6.

author: oldway
author_rank: Super Contributor
timestamp: December 28, 2017, 08:54:50 pm
content: Without having precise informations, it is difficult to answer a question correctly .....We must guess ...... let's guess then !The battery in question is probably a sealed lead battery type vrla 12v AGM, of unknown capacity.If you have measured voltages as low as 7.7V, it means that the battery is completely discharged and probably sulphated.In fact, your question is poorly asked .... You should ask: how to recharge a lead battery that is fully discharged and sulphated?Is that right ?
Charge voltage battery charger - Page 1
Forum section: electronics / projects

author: hismaimai8888
author_rank: Newbie
timestamp: November 13, 2018, 08:48:13 am
content: Hi all,I want to ask if there is differences between IC charger in charging voltage. I've a tried recently an IC LiIon charger with LiPo batteries (BQ2407x series from TI, seems an affidable brand) and found that battery is charged up to 4.11v/4.12v and never up to 4.2v. Also I've read that some battery chargers charge up to 4.27v.

author: Peabody
author_rank: Super Contributor
timestamp: November 13, 2018, 02:44:02 pm
content: According to the datasheet, the BQ24072 thru BQ24075 charge to a typical 4.2V, with a minimum of 4.16V, but the BQ24079 charges to a typical 4.1V. Do you perhaps have that one?

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 14, 2018, 08:06:31 pm
content: Quote from: hismaimai8888 on November 13, 2018, 08:48:13 amYes there is. Depends on the exact battery chemistry. There are typically two classes of Li-ion batteries, with max voltage of 4.1V and 4.2V respectively. Most LiPo batteries are 4.2V max, but you have to check. Some chargers made for specific batteries may get a bit higher than 4.2V, but they should usually not be used for just any random Li-ion battery.The charging circuit should be adapted to the battery - using a charger with 4.2V max voltage with a 4.1V battery may overcharge it. The well designed charger ICs will end up aborting the charge cycle while still in constant current mode as the battery's voltage will never reach 4.2V, but that may not be good for the battery either way.Some general stuff here (not too bad):https://www.digikey.com/en/articles/techzone/2016/sep/a-designer-guide-fast-lithium-ion-battery-charging
Charge voltage battery charger - Page 1
Forum section: electronics / projects

author: Yaro
author_rank: Contributor
timestamp: March 28, 2016, 10:56:10 am
content: Hi all,I want to ask if there is differences between IC charger in charging voltage. I've a tried recently an IC LiIon charger with LiPo batteries (BQ2407x series from TI, seems an affidable brand) and found that battery is charged up to 4.11v/4.12v and never up to 4.2v. Also I've read that some battery chargers charge up to 4.27v.If the last statement is true, maximum voltage reachable is related to charger or battery?Can you advice me a small footprint/small price IC battery charger(1 cell, 4.2v) that you've tried and charge batteries at full?Also, there is battery charges that allows to change maximum charging voltage?(this question is a plus, I'm not really interest to try this devices)Thank you!

author: mikerj
author_rank: Super Contributor
timestamp: March 29, 2016, 01:28:28 pm
content: Quote from: Yaro on March 28, 2016, 10:56:10 am
Charger for cordless drill (Tinkering with) - Page 1
Forum section: electronics / projects

author: soldar
author_rank: Super Contributor
timestamp: May 20, 2024, 06:56:49 pm
content: I have a cordless drill that came with NiCd battery which died and I had it unused. I have rebuilt the battery pack with NiMH cells. The cheaply made charger is just a transformer followed by a full diode bridge and capacitor. The resistance of the transformer itself is what limits the output current.When charging the transformer gets HOT. Like really hot. I did some measurements.The primary, 230 V, 475 ohm.The secondary, 25V, 6 ohm.After rectified, no load, 32V dcWhen connected to the battery the voltage falls to about 22 V and the current is about 500 mA. The transformer gets very hot. Maybe it is designed for that but I would rather charge a bit slower and not have it get so hot.The first thing I thought was to insert a resistor in series with the output but then I thought it is more effective to put a resistor in series with the input. I tried several values and I made a chart with the resistor value in ohms versus the charging current in mA.Even a small decrease in current makes a very noticeable difference in temperature. Decreasing the charging current to 300mA and the transformer barely gets warm.So I am thinking of having three settings:- High (say 400 mA)- Low (say 200 mA)- Trickle (say 50 mA)Or maybe I could have four instead of three. Maybe even add a timer or voltage sensor to switch from high to low and from low to trickle.Maybe someone can find something useful in this.Maybe someone has ideas I could use.
Charger IC  charging Mode  - Page 1
Forum section: electronics / projects

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: December 19, 2017, 01:58:51 am
content: Hello sir,I am little bit confused what my co worker wanted to do.Take a look on the schematic design, this contains a power management IChttp://www.ti.com/lit/ds/symlink/bq24074.pdf.They wanted to charge a host mode smartphone using this technique.While the main MCU is off, by the USB connector they think to charge that phone.If you look this application,1. When main MCU is off, V_USB_MGCN, V_BAT_OUT( an external battery output 4.2v) is also off.2. As MCU is OFF so the NTC and CHG_ING_1 is also inactive.3. How they are considering charging current mode (see the attachment) while EN1 and EN2 is set as 0 or 1?4. Do you think in this IC setting after STOP the main MCU the charging function will work?Kindly help me.
Charger IC recommendation for four 4 Li cells - Page 1
Forum section: electronics / projects

author: BreakingOhmsLaw
author_rank: Frequent Contributor
timestamp: June 06, 2022, 11:53:56 am
content: I have a battery powered design that calls for extremely low noise positive and negative power rails. Thus, rail splitting with charge pumps and buck converters is out of the question, which is why the design uses two lithium 18350 cells in series for each rail to provide positive and negative rails. These then go into low-drop linear regulators.+718350 cell18350 cellGND18350 cell18350 cell-7VThe positive rail has much more load as it powers the logic. Thus the positive rail cells deplete much faster.Ideally, I want to charge the cells from a single +5V supply (USB). I would expect that charger ICs exist that will pulse charge the cells by multiplexing them.Note: The device will be powered off while charging, operation during charging is not desired.I have little experience with charging cells, so if anyone can point me to a go-to part for this type of application and tell me which the common pitfalls are it would be much appreciated.

author: voltsandjolts
author_rank: Unknown
timestamp: June 06, 2022, 12:52:19 pm
content: Technically, the easiest solution is to make the batteries removable and get the user to put them in a seperate dedicated Li charger.Also, being removable means you can ship your product 'batteries not included' to avoid shipping regulations hassle.But, yeh, it's a bit clumsy solution.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: June 06, 2022, 04:39:34 pm
content: If the charging circuit can be made separate, say with a wall wart, just charge from the minus rail to the positive rail. Look at the TI buck-boost chargers.

author: tooki
author_rank: Super Contributor
timestamp: June 06, 2022, 05:44:27 pm
content: Quote from: BreakingOhmsLaw on June 06, 2022, 11:53:56 amDoes your design even require regulators at all? A battery is a cleaner voltage source than any regulator, so if your reason for needing dual rails is running op-amps, just run them directly.

author: BreakingOhmsLaw
author_rank: Frequent Contributor
timestamp: June 06, 2022, 08:05:23 pm
content: Quote from: voltsandjolts on June 06, 2022, 12:52:19 pmNever underestimate the stupidity of your customers. They can and will reverse the batteries :-D
Charger upgrade with LM317 - Page 1
Forum section: electronics / projects

author: ieskela
author_rank: Newbie
timestamp: May 07, 2016, 08:20:00 pm
content: Hi everyone, I’m trying to upgrade a battery charger for NiMh batteries. One thing that I want to change is a value of charging current. For battery 7.2 V and capacity of 1400 A*h the value of charging current is 500 mA, and it’s looks a little bit bigger. According to a common formula, charging current I = 0.2*Capacity = 280 mA. I chose LM317 for this application, and to provide charging current stable during all time of charging I want to use it in current regulator mode. So is it possible to do it this way?Thanks!

author: stmdude
author_rank: Frequent Contributor
timestamp: May 07, 2016, 08:40:58 pm
content: Well, add in some decoupling-caps, and it would charge your battery at a constant current.There's no cut-off though? Even 280mA will slowly cook your battery once its full.7.2V @ 1400mAh sounds like the battery for an RC-car or boat. You can charge those at C2 (2.8A in your case) if you want to, with no damage to the cells. But, again, you'll need some kind of end-of-charge detect to not cook the battery once full.

author: ieskela
author_rank: Newbie
timestamp: May 07, 2016, 09:01:30 pm
content: For decoupling I will use two optocoples PVG612 for charging and discharging the second one is need for “training” new batteries. And for end–charge detector I will use some kind of comparator or adc from atmega, I know exact value of voltage of full charged battery, it’s about 8.1 V.
Charger with booster not working  - Page 1
Forum section: electronics / projects

author: maxpayne
author_rank: Regular Contributor
timestamp: December 11, 2016, 05:07:18 pm
content: When I power this circuit via CN1 and no battery present at J3, I am getting only 1.10V at VBAT. When a discharged battery is present, the scenario still remains same. Is there anything I am missing in the design ?

author: bktemp
author_rank: Super Contributor
timestamp: December 11, 2016, 05:52:17 pm
content: Most lithium chargers start charging when they detect a battery. If there is no voltage at the output, they shut down.What happens if you connect a battery supplying at least 3V to J3?

author: maxpayne
author_rank: Regular Contributor
timestamp: December 11, 2016, 06:25:22 pm
content: Its running ok then.I have put this one powered via microusb ans battery plugged in and will run for 5/6 hours and see if the bat terminal voltage decrease.
Charging 2S li-ion batteries using TP5100 to lower voltage - Page 1
Forum section: electronics / projects

author: Sulfate9859
author_rank: Newbie
timestamp: March 18, 2024, 02:46:19 pm
content: Hello, I have a TP5100 charger and want to charge a 2S battery pack to lower voltage to extend the lifespan of the batteries.I've seen some people on this forum suggest adding a schottky diode in series with the charger to introduce a voltage drop in the charging voltage thus lowering the voltage among the batteries. I'm wondering if that would work since I don't understand how would the charger be able to sense the battery voltage if there is a diode in the path? Thanks for the help.Here is the schematic of how I would wire it all up (there's also under-voltage protection before the load):EDIT: I just noticed I drew some wires wrong, fixed now

author: tunk
author_rank: Super Contributor
timestamp: March 18, 2024, 05:29:09 pm
content: I guess it doesn't sense the battery voltage, only the outputvoltage from the TP5100. Also, the balancer may not workwith this setup.

author: Siwastaja
author_rank: Super Contributor
timestamp: March 18, 2024, 07:35:48 pm
content: Diode is indeed not a good idea. Instead, use another charger IC, one with lower charge voltage option available; or one without internal feedback resistor network (so that it requires two external resistors to configure the output voltage); or one with digital control interface.

author: Sulfate9859
author_rank: Newbie
timestamp: March 19, 2024, 08:14:09 am
content: Quote from: Siwastaja on March 18, 2024, 07:35:48 pmThanks, I just ended up charging it to the full voltage to avoid problems... But If I wanted to redo it in the future, which charging chip/board would you suggest me to use?
Charging 3x 3.3V LiFe (Lithium) Cells? - Page 1
Forum section: electronics / projects

author: FenderBender
author_rank: Super Contributor
timestamp: February 22, 2012, 01:43:15 am
content: Hey guys,I'm going to try to implement Lithium into my next project. Fingers crossed it works...I am going to try to use 3x A123http://www.a123systems.com/products-cells-prismatic-pouch-cell.htmLiFe cells...to make a grand total of 9.9V. I'm pretty confident that each cell has to be balanced individually?I know they make pretty simple ICs that can charge a set voltage battery. However, 3.3V cells are not too common so I would probably have to use a different IC.Does anyone have any ideas? Hopefully in the QSOP, SSOP, or SOIC packages so I can prototype with them. BGA won't work. I doubt there are any in DIP.

author: Wartex
author_rank: Frequent Contributor
timestamp: February 22, 2012, 03:29:05 am
content: I highly recommend you get a prebuilt BMS and then study it. There are tons of iron phosphate BMS for real cheap from RC websites. Also, where are you getting the prismatic cells, ebay?

author: amyk
author_rank: Super Contributor
timestamp: February 22, 2012, 12:30:32 pm
content: LiFePO4? TI makes a few chargers for those like the bq24620 and bq24630. They're QFN though.

author: FenderBender
author_rank: Super Contributor
timestamp: February 22, 2012, 08:53:16 pm
content: I would get the A123 cells off a hobby site who guarentees they are genuine...Hate to not follow through but NiMh is sooo much easier...

author: sonicj
author_rank: Frequent Contributor
timestamp: February 22, 2012, 10:48:24 pm
content: Quote from: FenderBender on February 22, 2012, 08:53:16 pmi didn't think the prismatic cells were distributed through the hobby channels...LSD NiMh is a nice contender if you don't need the extra current or weight savings.-sj

author: RCMR
author_rank: Frequent Contributor
timestamp: February 23, 2012, 03:20:15 am
content: I use 2S LiFePO4 packs in my RC model aircraft (for the RC gear) and 3S packs in my RC transmitters.It's been my experience that the packs don't need to be balance-charged -- the genuine A123 cells seem pretty well matched capacity-wise so if you ensure that each cell is fully charged at the start, they'll take many charge/discharge cycles without getting too much out of whack.For instance, I have a pack I built 3 years ago and has been charged/recharged about 15 times. I did a balance check the other day and found that one cell was 50mAH out compared to the other after all that time and 15 cycles.If you're concerned, you can buyvery cheap balancersin the hobby marketplace that also double as DVMs, current and watt meters.The only thing to watch with the A123 cells (especially the 1100mAH ones) is that if you try to overcharge them they will simply go open-circuit and be ruined. No fire, no smoke, no flames -- just a dead cell/battery.

author: FenderBender
author_rank: Super Contributor
timestamp: February 23, 2012, 03:20:40 am
content: Quote from: sonicj on February 22, 2012, 10:48:24 pmOh they're not prismatic. Theyre cylindrical type. I thought my link was for the cylindrical types. I guess not.
charging 4 NiMH AAA from USB - Page 1
Forum section: electronics / projects

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 18, 2010, 01:41:13 am
content: Is there a chip or circuit that can charge 4 NiMH AAAs from USB? It would obviously have to be based on a boost converter. The application is recharging calculator batteries from its USB data port. Charge speed is not critical (less than 8 hours), but it must automatically stop charging or switch to a trickle charge.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: July 18, 2010, 02:44:13 am
content: Well with the current NiMH mA , any USB charger are useless .But if you insist , with less than 10$ there is lots "ready ones" .There is no need to start from scratch , just for that.

author: kmossman
author_rank: Contributor
timestamp: July 18, 2010, 03:26:23 am
content: What is the mAH rating of your batteries? The usual guideline is to charge at not more than 1/10 of the mAH rating. USB ports, supposedly, can handle up to 500mA, but most limit the current to 100mA.your 5V (USB voltage) can be used to charge 2 batteries in series (at least 2.4V are needed to charge), or all four (at least 4.8V). Personally I would charge 2 sets in parallel (a set being 2 batteries in series) - does that make sense?You can use a simple constant current circuit to limit the charge current, and just turn it off after 10 hours.

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 18, 2010, 05:16:06 am
content: It will be permanently installed in the calculator itself, so the batteries must remain connected in series. They're 750mAh.

author: Unknown
author_rank: Unknown
timestamp: July 18, 2010, 05:42:48 am
content: Charging in series doesn't work very well, and slow charging at 0.1C for 14-16 hours is recommended for NiCd,but not for NiMH. If you have to boost the voltage, the ~2W that USB supplies will not be enough for proper fast charging at 0.5C+ or so. Any chance you can charge them one or two at a time at high speed with some switching, you should have enough current if you step down the voltage? I would get a dedicated charge controller (eg. from Maxim) with proper -dV/dt termination for that.
Charging a 3.7V  18650 LIPO cell - Page 1
Forum section: electronics / projects

author: makebit
author_rank: Unknown
timestamp: October 01, 2025, 11:35:31 am
content: Hi,We need to charge a 18650 LIPO battery at 1.25A from a 5V rail. We prefer a switch mode charger, eg, synchronous Buck.We would like the charger to do the "current taper" final charge, and not just charge up to 4.2V and stop.At the moment, am flexible about the type of internal monitoring and protection functions available.Please recomend part numbers? The BQ range looks very good. We are looking through, but if you know a "master" part, then please tell of it?Also, we would like to do coulomb counting into/out of the battery, so should this be a separate IC to the charger IC?, or do you know of a charger IC that does both charging and coulomb counting?

author: HumbleDeer
author_rank: Contributor
timestamp: October 01, 2025, 09:50:35 pm
content: If 1 A instead of 1.25 A is acceptable, there's nothing better than a TP4056 if you need or like it simple.If you have a supply current limit on a CV supply of 4.2V then it'll stay under your limit until the current drops low enough to be at a constant voltage; it'll keep charging until it reaches a defined cutoff point.But once it's at 4.2V you're very nearly fully charged, so you *will* need to set a cutoff current at which you consider it fully charged. That is, once current drops so low as to be as low as your threshold, you do cut off.So that's correct: this means not using a charging IC/solution will never cause charging to stop once a CV of 4.2 V is reached. I don't know what "undesired" charging solution you're thinking of when you mention> We would like the charger to do the "current taper" final charge, and not just charge up to 4.2V and stop.As for coulomb counting? Yes, that'd be a separate IC. They're battery fuel gauge IC's.
charging a lithium ion 16s battery pack - Page 1
Forum section: electronics / projects

author: m3vuv
author_rank: Super Contributor
timestamp: September 27, 2020, 01:46:31 am
content: Hi all,i am building a 16s battery pack for an ebike,im using 18650 cells,these are standard cells not the phosphate ones,ie 3.7volt per cell,i have a charger that outputs 67.2 volts,will this work for these type of batterys ?,i just wondered if i need to buy a new charger,i already have the bms.,cheers m3vuv.

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 27, 2020, 02:22:00 am
content: 67.2V/16S gives 4.2V/cell, the standard charging voltage. You might want to charge to a lower voltage to prolong lifetime and leave room for regen braking, in which case use an external circuit to stop the charge early, say 4.1V/cell or even lower.

author: m3vuv
author_rank: Super Contributor
timestamp: September 27, 2020, 09:08:26 am
content: so it should be ok then?,ive got lithium colbalt cells.