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Lithium polymer protector (LVCO)?

Has anyone used a very small low voltage cut off (LVCO) circuit on a lithium polymer battery? I found a nice collection of lithium polymer cells in a 'dead' laptop battery. Thing is, I don't want to be careful about over draining them and they don't seem to have a low voltage cut off circuit in the individual cells. Sparkfun sells batteries with a teeny LVCO system built into the cell package like this: What would be a reliable source of similar reliable boards that protect from over discharge?

Question by snotty    |  last reply

Piggy Backing a lithium battery (cell)

I have several questions.  But the basic idea is that I want to extend the runtime of a device (such as a cell phone, tablet, camcorder, whatever) by increasing the mah.  So here are the things I am wondering: 1)Many lipo batteries have 3 or 4 contacts, one is -, one is +, and the others are typically data or something.  can I simply connect additional lipo's (just the + and the -) in parallel with the corresponding contacts in the device? 2) Are there any ill effects of charging (presumably from the built in charger of the device, like a cell phone) and discharging (using the device) parallel lipo's? 3)  They will all have the same voltage rating, but do they all have to have the same mah rating? thankyou

Topic by guyfrom7up    |  last reply

Fixing a Dead Li-Polymer Tablet Battery by Over Voltage

Hello all,I find this Instructable need to use this method for a Pegatron battery G6BTA019H P/N:0B23-00E00RV I can't find a diagram of the pinouts for it, would it just be a case of connecting the very end wires, labelled + and -?How risky is that if it's wrong?Is there a way to test them with a multimeter?Thanks

Topic by PlexusIndustrious    |  last reply

How do I reduce a Lithium Polymer battery voltage?

I have a 7.4V lithium polymer battery ( and an 8.4V smart charger ( The issue is that I need to power a device that needs 6V. If I put a voltage regulator in line with the battery leads I'm sure it'll work, but then how do I charge the battery with that charger, as the regulator will also reduce the 8.4V the battery needs for charging? Maybe by introducing some kind of "bare metal tap" upstream of the regulator, so when I plug in the charger it bypasses the regulator and wires straight to the battery? (see the attached illustration) Would this work? Or should I do something else?

Question by Dgcaste    |  last reply

How long will a lithium battery store? Answered

If I bought 2 rechargeable lithium polymer batteries for a cell phone, but only needed one for now, could I store the unused battery until the first battery quit charging (and was garbage)? If the above question makes ZERO SENSE, let me try explaining it another way: Ok, you have this fancy gadget that you want to keep functioning for many years. Eventually, the battery inside won't be able to take a charge, and the battery will be obsolete and no longer sold. Would it make sense to buy extra batteries ('stock up') and store them for a time when the original battery went bunk; would the stored batteries be like brand new after many years (these batteries would have never been charged before.. they would be still originally packaged)? Hope that actually makes sense :D -Neph

Question by nepheron    |  last reply

Does a lithium polymer battery have too much amperage for a 555 timer? Answered

I'm using a 555 timer for a robot, and i was wondering, is a lithium polymer battery too much amperage for the 555 timer? because when i use it, the 555 timer warms up, to a point where i cannot touch it without getting burned instantly. If so, how can i reduce the amperage, so that it can be used with the 555 timer? I'm using a 7.4 volt, 1000mAh battery, it was originally used for a helicopter, but i re purposed it for my robot...

Question by Chowmix12    |  last reply

Lithium Ion Battery Shut Off

Hi, my name is Jackson Pugliese, and I am currently building a battery pack that will be consisting of multiple lithium ion batteries. Getting the pack itself together, is not an issue at all, however, what is an issue is battery shut off when charging.  I would like to be able to charge my battery pack with some form of laptop charger, that outputs 12v, for a 14.8 volt lithium battery pack. The main issue is overcharging. Lithium ions explode, or catch fire if they are over charged, and thus is not an option for me, so to find a solution, I searched the internet, and two things came up.  Option one, use some form of battery charger, that automatically shuts off when It is fully charged (which i do not want to do because I want to do it differently hence the instructable) And Option two, which came up alot, but i do not fully understand is I use something such as this;=1456701414&sr;=8-2&keywords;=protection+circuit+module+14.8+volt I do not understand what it truly is, nor how to use it, and would like someone to explain to me both of those things. Everything I am doing is safe, because I am using a en closer for lithium ions, in case if they explode or catch fire, so know one has to worry about anything not working. Thank you very much everyone for your time, and have a wonderful day!

Topic by merlinj    |  last reply

can i connect 4 11.1v lipo batteries in series AND parallel?

I have 4 11.1 v 2200mAh  lithium polymer batteries, and i want to connect 2 in series to give me 22.2 v with same aH and connect the remaining 2 in parallel to  give me 11.1v but 4400mAh.  is the a configuration of the two pairs i can do to archive max voltage and mAh. thanks in advance.

Question by icey.hood    |  last reply

Modify this circuit to make it lower voltage? Answered

What resistors do I change in this circuit to make it go red at <3.2V and green at >3.2V ? It is a battery monitor that uses op-amp, 2.5v voltage reference diode, and a 2-pin bi-color LED. The trimpot adjusts the voltage at which the colour changes.

Question by jdorne    |  last reply

How to 'load' a CIS solar panel to maximize power output and efficiency? Answered

I have 4 decent CIS solar panels that, in series and in bright sun, will give ~16V, and can offer ~ 200mA shorted. However, if shorted, the voltage obviously sags to almost 0V, so basicly no power is delivered based on the fact that V*I=P at the other extreme, there is almost 4V open circuit, but essentially no current flow. Again, 0W of power delivery. The voltage and current figures above are just memory and I did log the data at various resistances awhile ago. My intention is to charge 3 lithium batteries in series to 12.6V, that will then feed power to a modified car charger (basic buck circuit for downconverting 9V-18V to 5V) Since the current is so low, can I maximize efficiency by connecting the cells directly to the battery pack without any additional circuitry other than a blocking diode? Or in order to speed up the charging do I need to add some complex control circuit that will intelligently match the impedance? If the battery charging speed is based on current, does that mean a direct connection is best?

Question by -max-    |  last reply

iPod Touch Battery Thickness (need thin battery)

Does anyone know the thickness of the 4th gen ipod touch battery?  I'm looking for a thin lithium battery (less than 2mm thick) that has decent capacity (more than 300mAH).  If anyone knows the thickness of the ipod battery (or any other suitable battery) it would be greatly appreciated.

Topic by guyfrom7up  

brushed to brushless!

If you have been flying your RC planes a lot and have found them getting a bit boring, go brushless and get lithium polymer cells. brushless motors are lighter and twice as powerful as brushed. lithium polymer batteries hold the most electricity to weight ratio compared to standard Nicd and Nmh. Dont believe me look at your cell phone open the battery hatch and take out battery its probably a Lithium polymer or lithium ion notice how light it is and small it is now look at the volts/ mAH pretty amazing hu? Got a laptop it probably got a lipo to. you want to make the switch but dont know what motor, battery, ESC (ESC-electronic speed control) to get, just ask and ill give you a hand! i will need to know the motor and battery that came with the plane/ or that u are using. Are you flying glow (gas powered) and wana go electric? i can help u out their too! Their are 2 kinds of brushless motors outrunner and inrunner whats the difference? well outrunners spin slower with more power so it acts like it has a gear box (this eliminates the need for a gear box reducing weight and noise) it also has a different design (look at pics). inrunners have a brushed appearance but their much lighter and more powerful u might need a gear box through. update 2/20/08 new image added (not all comment boxes are working)

Topic by i make shooting things    |  last reply

Charge batteries with a bike dynamo? Answered

I am experimenting with ways to charge batteries while cycling. Standard bike dynamos produce 3 watt 6 volts.  That's not a lot of power but 12 hours of cycling should charge a 36 watt hour battery.  I am thinking about about making my own battery pack.  It needs to be 4s1p 14.4 volts.   What I need help on is what sort of battery chemistry to get: lithium ion, LiMiNi, lithium poly, etc.  The batteries I need should charge efficiently at low current (about .25 amps).   The other thing I need help with is how to turn the dynamo power into charging power.  I know I need to rectify it and smooth it.  I have heard about Zener diodes.  They are used in solar applications because they are more energy efficient.  Should I use those? Lastly, dynamo power varies depending on the speed of the bike (Between 0 volts and 12 volts.)  Lithium ion cells need a 4.35 volt charge.  Would it be better to use a regular voltage regulator you get a radio shack or a switching voltage regulator.  I have an anyvolt 3.  Maybe there are PCBs you know of which automatically regulate a vacillating input voltage. 

Question by Noblenutria    |  last reply

Any way to test if my device will handle over voltage or will I just need to wire it and hope for the best? Answered

I want to use a lithium polymer battery in a controller I have, but I do not know if it can handle the voltage difference. It uses two AA batteries (3V) and I want to put a 3.7V lipo battery. Is there any way to test if my device will be ok with it or will I just need to wire it and hope for the best? Thanks. Davetech was successful in replacing the 2 AA's with a li ion battery here: I want to be able to test, before I fry my device.  Any help will be appreciated.  Thanks

Question by Nilson13    |  last reply

i need a very powerful battery (4000mah 10V or higher) and don't want to spend more then $30 please help! [answered]

I need a  VERY powerful battery (4000mah 12V or higher) and don't want to spend more then $30 please help! and i don't want i Puerkerts number lower than 1.2. can anyone help? oh, and the size of it has to fit in a 6V lantern. thats why lead acids bit the dust and (so far what i know) lithium polymer batteries bit the dust because they are way to expensive. with a 35W power consumption, its hard to find a power source that will fit in a 6V lantern, a affordable price (under $30) and powerful enough to power the load for more than an hour. (some calculations i did show i need at least 3500mah for 1 hour of usage ) but i think i might have a solution a 2 laptop batteries from amazon wired in parallel after they have been took apart. a drill battery doesn't even come close to the amount of i need and they suffer from memory effect and just plain out isn't near powerful enough (1.5 AH per cell) OR my second choice is to get many rechargeable AAA batteries and wire them to give 14.4V (BUT HOW DO I SOLDER THEM WITHOUT THE TABS? and what kind of array should i use? [68 AAA])

Question by -max-    |  last reply

How to make a USB charger from a tablet battery? Answered

I have a tablet battery, L10C1P22 and it's in good condition. I was scouting through Instructables to see if anyone has made a USB charger based on a tablet battery. And I couldn't find one. So may be I haven't found it despite it being there. Can anyone direct me to a source that instructs or at least provides a brief idea of how I can make this happen. Or if someone knows how to, please please share it with me. I'd be very grateful. Thanks Amol

Question by amoljoshi_bangalore    |  last reply

Help wiring a toggle switch??

Hi there, i need some advice on how to wire a toggle switch between a battery voltage monitor and a battery so that I can switch the monitor on and off as required. My problem is that i need to pass 4 seperate wires through the toggle switch however I do not know enough about how a toggle switch works to achieve this. Here is a video that shows what I am trying to achieve;;=feedlik This is a voltage monitor for a lithium polymer battery for use on an Airsoft Electric Gun (AEG) the battery is stored inside a plastic box ,which is shown below, and i would like to insert the voltage monitor inside the plastic box with a toggle switch for turining it on and off I have some pictures attached to show what exactly it is I am using and to hopefully explain more clearly. Any advice at all would be greatly appreciated as I am at a loss about how to approach this.

Topic by dwelby101    |  last reply

Electronic Circuit Design Help Needed?

I have an HP WebOS TouchPad and the Power adapter has died. I do not want to buy the same changer since it's the 3rd one that has stopped working. Would anyone design the power adapter electronic circuit for me? Also note that if I try any other changer that might have a lower amperage it will not change. AKA I get a screen that says, "use the correct changer outside the OS" Any help would be greatly appreciated. Power Adapter Wall AC to USB power adapter, which has input specifications of 100–240 Volt 50–60 Hz 0.4 Amp AC, and output specifications of 5.3 Volt 2.0 Amp DC. It is cylindrical roughly the size of a "D" battery with a foldable 2-prong AC connector and a Standard-A USB socket. Battery The TouchPad uses a rechargeable 6000 or 6300 mAh Lithium-ion polymer battery rated at 3,7 V (total 22,2 Wh). More info at

Question by nfarrow    |  last reply

Portable hydropower

Hi! I am in a senior in high school and am required to do a project as a part of my stem class. I am planning to make a portable hydropower power bank that someone could use when they're camping to charge their mobile devices. The problem is I don't know how to go about actually doing this. I was planning on making a small stator and rotor for my generator but after further research I found out that I could use a motor and a diode instead. Any help on which would be better would be greatly appreciated. I also am confused on what type of battery to use(it will be inside my device and will be the power bank for charging devices). I was planning on using a 5000 mAh, 5V lithium polymer battery, but am not sure where to buy one(If u just search 5000mah 5v battery, the responses come up with 3.7V.  I will also need at least 2 usb charging circuits. Honesty any guidance in what I should would be helpful. Thanks! If your looking for examples of this I would look up the blue-freedom portable hydropower.

Topic by sonnyp99    |  last reply

Arduino resets periodically while being powered via an external power supply. Answered

I am using an 5V Arduino Mini ( While the Arduino is plugged into the 5v USB power coming from my computer it runs as expected (the lights flash in the right order and with the right timing, it accepts code etc.), but when it is powered through a regulated power supply it will turn on for a few seconds, then restart, run for a few more seconds, restart and repeat this indefinitely. I am programming it via an FTDI programmer (, and using two Polymer Lithium Ion Batteries ( wired in series to get it up to the necessary voltage. I have tried disabling auto reset via bridging 120 ohms equivalent resistance between RST and VCC and connecting a 10 micro-farad capacitor to RST and GND, but that did not solve the problem. I am fairly certain there are no problems with the code, because it runs perfectly when plugged into the computer, and I get the problem when running any code. If you need clarification or have any questions just ask. Thanks.

Question by GenAap    |  last reply

How can I make a DC to DC step down voltager regulator?

I want to make my own BEC (battery elimination circuit) for my RC helicopter, so that I don't have to spend $50 and buy one. I'm also very impatient when it coming to waiting for things to arrive in the mail. I have some basic electronic parts.  I have some N-channel MOSFETs, Diodes, Resistors, OP-amps, and comparators, A butt load of Capacitors, My helicopters ESC(electronic speed controller) uses a 11.1v Lithium Polymer(LiPo) battery, but my RC receiver can only handle 6volts Maximum, at about 2-3Amps. I don't have any wheels, so I can't exactly run out to my nearest RadioShack to buy an LM317 voltage regulator. so I'm here to ask if anyone knokw how to build a [step dowm voltage regulator] from basic components? Schematics ,and parts list would be appreciated. I have no idea how much current the LiPo battery is pushing, it exceeds the max range of my Multimeter which is 10Amps. fried couple of diodes, and blew the fuses it trying to measure the raw current. I need help please.

Question by alien200049655    |  last reply

Record Solar Powered Flight

UK-built solar-powered plane has set an unofficial world endurance record for a flight by an unmanned aircraft.The Zephyr-6, as it is known, stayed aloft for more than three days, running through the night on batteries it had recharged in sunlight.The flight was a demonstration for the US military, which is looking for new types of technology to support its troops on the ground.Craft like Zephyr might make ideal platforms for reconnaissance.They could also be used to relay battlefield communications.Chris Kelleher, from UK defence and research firm QinetiQ, said Unmanned Aerial Vehicles (UAVs) offer advantages over traditional aircraft and even satellites."The principal advantage is persistence - that you would be there all the time," he told BBC News. "A satellite goes over the same part of the Earth twice a day - and one of those is at night - so it's only really getting a snapshot of activity. Zephyr would be watching all day." The latest flight was conducted at the US Army's Yuma Proving Ground in Arizona.The Zephyr flew non-stop for 82 hours, 37 minutes.That time beats the current official world record for unmanned flight set by the US robot plane Global Hawk - of 30 hours, 24 minutes - and even Zephyr's own previous best of 54 hours achieved last year.However, the Yuma mark remains "unofficial" because QinetiQ did not involve the FAI (Federation Aeronautique Internationale), the world air sports federation, which sanctions all record attempts.The US Department of Defense funded the demonstration flight under its Joint Capability Technology Demonstration (JCTD) programme. The 30kg Zephyr was guided by remote control to an operating altitude in excess of 18km (60,000ft), and then flown on autopilot and via satellite communication.It tested a communications payload weighing approximately 2kg.At first sight, the propeller-driven Zephyr looks to be just another model aircraft, and it is even launched by hand. But this "pilotless" vehicle with its 18-metre wingspan incorporates world-leading technologies.Its structure uses ultra-lightweight carbon-fibre material; and the plane flies on solar power generated by amorphous silicon solar arrays no thicker than sheets of paper. These are glued over the aircraft's wings.To get through the night, the propellers are powered from lithium-sulphur batteries which are topped up during the day."A lot of effort has gone into power storage and light-weighting the systems," explained Mr Kelleher. "Lithium sulphur is more than double the energy density of the best alternative technology which is lithium polymer batteries. The engineers from the Farnborough-based company are now collaborating with the American aerospace giant Boeing on a defence project codenamed Vulture.This would see the biggest plane in history take to the sky, powered by the sun and capable of carrying a 450-kilo (1,000lb) payload.US commanders say the design must be able to maintain its position over a particular spot on the Earth's surface uninterrupted for five years. QinetiQ is the public company that used to be the British Government's military research department, before they privatised it.BBC articleQinetiQ's page on Zephyr

Topic by Kiteman    |  last reply

Using LiPo batteries in coil guns

Hello all, this is my first post! I have been theorizing for a while about coilguns, and have been doing calculations. here is how it goes: A single Lithium polymer battery can hold up to 3.3 Ah and discharge at about 30c (safely). We multiply 3.3Ah by 30c and get 99 A of continuous discharge. That’s a LOT of current, but, it is still not enough to fire a good projectile. So, I’m planning on having four of these hooked up in parallel to give out 396A. This is quite a bit of dangerous current, so my wiring will have to be gauge-perfect. The magnetic field that this produces is about 9.9 teslas, as  twice much as your average MRI machine. Yes, I’m utilizing a miniature MRI to shoot stuff. If you want to know how much force an MRI puts out, here is a great video to show you I am planning on having a 2,000 turn coil, with the average distance from the projectile being 1cm. The ammunition is going to be BB bullets, which means our cross-sectional area is at least 7.65*10-4m2. Using those numbers, the initial force on the BB is 3,015,030N. This is enough to lift up 25 semi-trucks. On paper, this seems magnificent. However, I’m accounting for about 2% efficiency, taken into account at this step, giving us 60,300N. This is still an enormous force to take to a .5g BB I’m implementing the Impulse to be .05s using standardized E = F * t,  this gives us 3,015 joules of energy. Huh. that’s way more than we should expect. Let’s take into account the 2% efficiency rating again, and we get a more realistic number: 60 joules. 60 joules is ridiculous for a BB pellet. We’ll use Ek = 1/2*m*V2 to solve for V. I got about 1,553 m/s. This is faster than most guns shoot regular bullets. I will be using a 2-stage setup, and will make sure to  use proper electrical equipment. My question to you is; How accurate are these calculations? if I build this thing, what can I excpect?

Topic by bjohnson45    |  last reply