I am looking for some help to understand what kind of battery could power a Dometic cfx50w 12/24/120V compressor fridge, while on-the-go. Here are the electrical specifications:     Input voltage (AC) 120-240 V   Input voltage (DC) 12/24 V   Rated input current (AC) 0.79 A   Rated input current (DC) 7.8 A   Input frequency 50/60 Hz     ()  Most people choose a dual battery DC/DC setup for their car. I am looking for a more compact and portable solution, to get a few hours (minimum 4) running in normal conditions. I am thinking of a battery pack like those used in the RC hobby. Would this work?  I am looking for best battery chemistry and recommended ah rating considering the fridge would run for 10 minutes every hour and battery would have to provide 4 hours of power without getting damaged. Fridge has a cutoff voltage of 11.1v. I am wondering if lipo or lifepo4 batteries could replace a flooded lead acid and what would be the usable capacity. Battery would be charged at home by small rc charger.
121308
I have an interesting mathematical/electrical dilemma and I'm not sure where to start.  I am considering buying  (specs on page).  I will be hopefully buying a battery pack with it to support a long-road trip (a few months) wherein I'll keep medication in the fridge (powered by the battery pack when parked and by the car when driving). The medication needs to be keep between 2 and 8 degrees C at all times.  Here's the  I'm thinking of getting:  Can someone please help me understand what I need to do in order to calculate whether or not this fridge + battery combo will work, and if so, how much time will I be able to power the fridge for.  Ideally, I need a combination of fridge and battery which will allow me to have the fridge constantly powered, assuming I sleep in the car for approx. 8 hours a night and drive for the rest of the day (although, there will be times which I'm away from the car during the day for several hours + times where I hope to have access to a wall outlet).   Specs:   Fridge:   Input voltage (AC 220-240 V Input frequency 50/60 Hz Rated input power (AC) 64 W Rated input power (DC) 46W DC12V/50W DC24V W Input voltage (DC) 12/24 V   Battery:   Capacity: 453Wh Battery Type: Lithium-ion Input Voltage: AC 110-220 V, 50/60 Hz; Solar Power: 18 V; Car Input: 12 V Output Voltage: AC 110V 60 Hz; DC Output: 4 * 12V 4 A (Max.10 A); USB Output: 4 ports: 2* 5V 2.1 A and 2* 5V 1 A Power Output: Rate 500 W Peak/Surge 1000 W
45266
Below is a picture of a battery shell for a NiMH circuit for a power assist wheelchair battery.  I'm taking a guess that each of the 20 batteries is 1.2V because the entire circuit is 24V.  These are rechargeable.  I'd like to convert this circuit to the same voltage (24V) and same capacity (3Ah).    First, is this possible given the space you see in this wheelchair battery shell, and the circuit board in the pictures?  Second, what are the material requirements to be able to convert this circuit from NiMH to Li-Ion and the type of charger as well?  What materials will I need to solder/weld the materials together, etc.. for the actual labor?  I'm an electrical novice, so please ask me more questions (as comments) and I'll do my best to answer.  Note: right click image and open in a new window to make it larger!
78706
I'm new to electrical engineering, and probably asking the wrong question. Not sure how else to phrase it.  For the question, I'm going to use an example layout of simply a 9v battery attached to a toy DC motor.  From my understanding of my , the voltage coming from the battery through the motor will be around 9v. The current will be from 0amps to however much the battery can supply without frying. What decides how much current goes through the motor?
6269
I wanted some opinion on my set up here, just to make sure I got the basics right.  I have a Li-ion battery charging circuit based on the MCP73113. This is designed to be a single-cell battery charger.   The battery itself (3.7V, 650mAh) comes with its own PCB with Schottky diode and current regulators as protection. EDIT: Not a Schottky diode. Current limiter and a Protection IC.  By design, they work together just fine.  I have more batteries from the same manufacturer and wanted to make higher capacity packs by putting two cells in parallel. The two cells come with their own PCB, but I only kept one of them, as I soldered their leads together. It seems to work and they are charged and discharged just like regular batteries (3.7V, now 1300 mAh).  However, not all the packs I made work smoothly and I get a failure rate of 2 in every 10 packs. They all start out normally, but occasionally when the batteries are not charged for some time, or are used up, they tend to not work anymore. So far, in only 1 pack I found the voltage to be different (both now below 2V, aka dead).  I assume my method is not the right approach to ensure 100% success rate, so I was wondering how can this be solved. All the controllers I looked into was designed for multiple cells in series, not parallel. Am I fundamentally missing something here?
13659
I want to estimate the current maximum capacity (in kWh) having the current power consumption (in kWh) and the state of charge of the battery (in %) available in a time series.   I do not have a full battery charge circle recorded but only a snippet with the state of charge going from ~95% to ~35% in a 1 second data recording interval.  At first, i cumulated the current power consumption and noticed that the progression between cumulated power consumption and state of charge was almost the same (see figure 1 and 2).   progression of state of charge vs. cumulated power consumption   So i tried to use a linear regression model to predict two values of cumulated power consumption at 0% and 100% state of charge. In my assumption the delta of these two leaves me with the current maximum capacity of the battery.  Ideally i want to monitor the capacity during the data recording. Which means i only have data of a few percent of state of charge. In figure 3 and 4 you can see my attempt of trying to create a linear regression model for every 2% state of charge. As you can see in the right plot, the estimated capacity has a very high variance.  LEFT: regression lines (green) of every 2% state of charge; RIGHT: estimated capacity of every 2% state of charge   Since i am not an expert in neither the matter of regression nor batteries/physics, my questions are:   Is there a much simple or more exact way (or both) to estimate the current maximum capacity of the battery? If yes, is there a good way to estimate an sufficiently exact capacity with an even smaller snippet in an ongoing process, lets say every 2% state of charge? (maybe using a characteristic curve of the discharge process)
15015
I have two pieces of single-phase fans and they are literally the same, it is ac motor and whenever I rotate it manually it produce voltage about 160-190vac. I just get the idea that it can be an ac generator, but the problem is when I connect it to 110v-220v cellphone charger, the charger is not working, the voltage drops and the generator seems to run from the voltage itself, I search it and the answer is the backfeeding. I also connect the generator to christmas lights and there is no problem maybe because it has resistors, I also conect Led bulb using an adaptor 110v-220v and the led is blinking(it should not be) and everytime it blinks the generator get a shock, it seems to get backfeed. The other problem is I connect these 2 ac fans and I rotate it to be a generator(160v-190v each) but they seem to be run from the voltage themselves. I had this idea to use a full rectifier, inverter or somewhat to make them a working generator with a stable of 220vac even if using. My ideas/plans (in order):  To stop the backfeed of the generator when using. If there is no possible way to do that then using an inverter is the last option. If ac-dc is the best way then i'll connect dc's from positive to negative, making dc volts step up then convert it to 220v ac. AC-DC-AC in short If no. 2 didn't work, then i'll suppose to make an inverter for each generator making them ac-dc-ac and avr for each to stabilize their voltage.  Please help me guys, I need to make it possible. Another thing I recently know, is it possible to put a ground wire to a single-phase generator to stop getting backfeed instead of transfer switch ? The picture is the single phase motor.
90807
I am currently working on a project that uses a 9.8V 1000mAh battery to power a solenoid, and as I understand it (please correct me if I got this wrong.) a battery capable of delivering 1000mAh is also capable of delivering 1Ah, or 2A for 1/2 hour, 4A for 1/4 hour, etc.  So, assuming I got the above correct, I need to know how to limit the battery output current to 1.0A (My circuit would get really hot otherwise.)
45677
This is a followup to my previous question:   This is a real world circuit with losses. The losses are in the resistance of the battery, the switch, the capacitor, and the inductor.  The inductance value of the L1 inductor has been left out because it was not known or measured. It's not a value of 0 however as it has some inductance.  The capacitor starts out with an initial energy of 0 Joules as well as an initial voltage of 0 Volts.  The switch is closed only one time and left closed. The capacitor charges to the same voltage level as the battery of 12.33 V therefore it now has 76.014uJ of energy in it.   The question is:   Does the 50% loss of energy that normally occurs when charging a capacitor from a battery (without the inductor) still apply to this circuit, even with the L1 inductor in place?  In other words, the capacitor will charge up to the same voltage level as the battery of 12.33 V as confirmed with an actual physical circuit. Has only 50% of the energy been transferred into the capacitor than what came from the battery?  The actual physical circuit has actual inductance in the inductor, but it is unknown, but it's not 0.   Summarized and to the point:  In this circuit, how much energy is transferred from the battery and into the capacitor when everything comes to rest and all processes are completely done? 50%?, 99.8%?, how much energy was transferred from the battery to the capacitor?           &ndash; Schematic created using
121650
let me say if I have a pack of lithium batteries connected in series and parallels, and i want to connect it to an Inverter, BUT...BEFORE I connect it to inverter, lets say it gives out 12 volts "hypothetically" some informations like 3.7 volt batteries, and 2500 mAh,  lets say then the pack gives 12 volts in DC and hypothetically again I calculate it ((still in DC)) is .....  W = V* Amp ... then it means wattage = 11.1 V * 5 Ah which is 55.5 W. then we got 55.5 watts, THEN....after we want to change the dc into ac it gives you 120 volts "please hypothetically" just answer me this, ARE the Wattage And Ampere are remains the same as DC? what would it be the result after AC?
117931
I have a battery pack of NiMH batteries. It is ten cells with 1.2V, 4000mAh each, put together in series. So rated voltage is 12V. After charging, i.e. when the charging device says that it is finished, I measure 14.3V.   When I now discharge, at what voltage should I consider my battery as "empty"? Is this the lowest voltage that I can discharge it to without damaging it? Which voltage is that?
75843
I have a 30A 5-30V Single Brushed DC motor driver that will be used with a 12V 30A gear motor.  I have a MegaWatt 36 Amp 12 Volt 13.8V DC Regulated Power Supply that I wanted to use for the driver pwr source. But, I just realized the driver docs say to ALWAYS use a battery as a power source if an inductive load is used.  The docs say that a battery must be used in parallel with the power supply to protect the driver against possible flowback when the motor is stopped.   My question is: can I use a 12V car battery, and simply wire the power supply and motor driver to it, then set pwr supply output to 13.5V? The pwr supply would always remain ON.
108048
I have a project that runs off a 4S LIPO battery and I want to switch to 24V wall power when I plug in an DC wall adapter. I have two designs, an inexpensive one with discretes and one with an expensive LTC4412HV IC.   I simulated both and they seem to work fine. In terms of safety since the battery is a LIPO, is the discrete design okay? Is there anything I should add other than a fuse which I already have?  Edit: The reason I use a PFET instead of a schottky diode is because the diode consumes too much power and I want to maximize battery life.
65384
I want to make a power DC supply with voltage rating 0-200V. I want it to be a variable power supply with voltage from 1V to 200v. What should be my approach?
22692
I'm trying to determine which battery to use for my application. I'll be using a class 1 or class 2 Bluetooth (not low energy) module, which requires about ~50/60mA of RX/TX current. In addition, there is a microcontroller and some low power analog IC's. I require a continuous stream of data from the device for 1-10 minutes.  Are coin cells completely out of the question? I'm talking about CR2450 Lithium-ions. I don't really mind if they don't last long, but will they work? Because in my application, size is key, and battery life is a trade off that I'm willing to make.
105450
I want to have a stable voltage of 2.47V using TLV431AC which is a precision voltage-adjustable shunt regulator.   I am able to get it by putting a 5k potentiometer and a 500 ohm resistor in series connected to the REF pin of the regulator. Since the cathode current limit is 15mA, I have used a 500 ohm resistor between the source and the CATHODE pin to limit the current to about 10mA.    On choosing the right load capacitor for stability, I have referred to the table to the datasheet and it looks like 10uF is outside the unstable range of values so I chose that one as my load capacitor.  My problem is while the time goes by, my output is slightly increasing by a few millivolts and would not stop which I think is bad because I am planning to use the output of this circuit as a voltage reference. What could be the problem? Is there anything wrong with my circuit?
27137
Currently I run all my gadgets from batteries and don't use decoupling capacitors.  Are they generally needed/useful when drawing energy from a battery?
78235
I just bought a  for my car. It's input is 5V/0.3A and is powered via a 5V/1A USB power adaptor that is plugged into the 12V/10A/120W max. socket in the center console of my 2004 Honda Accord.   It turns on automatically when I turn my key halfway, but when I start my engine it shuts off, and I have to unplug it and plug it back in to get it to power back on.   I emailed the company, and this is what they said:     "We are sorry for all the inconvenience it caused to you. As you know, there is no internal battery for the SoundSync. The power is from the car or car charger. For some cars, when we turn the car ON, the SoundSync will power on at the same time. However, when we start the engine, the power shut off for a very short time. It shuts the SoundSync off and the SoundSync will not auto power on again. Therefore, we will change it to button control version in the short future."   I'm trying to figure out a way that I can fix this. Unfortunately, my knowledge of electronics is limited.  If I had a capacitor between the device and my car, would it solve the problem? I.e. the capacitor takes 1-2 seconds to charge, which interrupts the on-off-on of the car starting, and provides continuous power to the bluetooth module?   I have a soldering iron and am pretty tech-savvy, I just don't know where to begin troubleshooting the issue. Any input would be greatly appreciated.   Thanks!  Edit: How would I go about adding a capacitor? Solder together a circuit board, capacitor, and male/female USB pieces? Cut an existing USB cable and use it instead of the USB components?