Search for mah in Topics

Would setting batteries in series combine their mAh? Answered

So say I have four 2,000 mAh batteries, and I set them in series. Would that give me 8,000 mAh?

Question by Sargebubbles26    |  last reply

How to increase life of a device using 3.7v li rechargeable? Wire second in parallel? Use battery with higher mAh?

Hi All Looking for some advice for a project I am working on. I am using mini-GPS trackers with a SIM card to track movements of small objects, so size is an issue. I have a GPS tracker I like that comes 3.7 v rechargeable lithium ion battery, I think it's something like 700 mAh (I will have to double check when I get home). Once removed from the case, the battery and card fit into the space of the objects I am tracking (spheres of about 45 mm diameter, so a little bigger than ping pong balls). Anyway, using the settings necessary for tracking these objects, the tracker only lasts 3-4 days before it's out of battery, and I would like it to last 10-14 days, ideally. How might I go about extending battery life once the trackers are deployed? Should I add a second identical battery in parallel? Try to find a rechargeable battery with same voltage and higher mAh? (And does increasing mAh increase battery size?) Cost and size are issues, and I also wonder if I could replace the batteries with, say, a disposable battery type in order to get more time -- I don't expect to recover the units after they are deployed. Normally replacing a rechargeable lithium ion battery with disposables would be dumb, I don't know enough about batteries in general to know if disposables of the same size/voltage might have more "oomph". Thanks for any thoughts or advice you can offer!

Question by kimwilliamsg    |  last reply

Question regarding LEDs and Amperes? Answered

Hi guys,             I want to build a project which has 3 blue leds which will take in almost 9 v. I could just use a 9 volt battery as it would be cheaper and easy but I want more mAh. So I have a few questions regarding if I use 6 AA batteries instead. 1. All of them connected (+ to -) will give me approx. 2500 mah and 9v right? And as 3 LED's would take about 3v 20 mah each, how much run time would 6 AA batteries give me? 2. How much run time would I get with the 9v battery? As it is only 400mah I think Thanks in advance -A Prickly Potato

Question by The Prickly Potato    |  last reply

Best rechargeable AA? Answered

I am looking for some really high capacity aa batterys. I found 4600mah batts on I thought that these looked a bit sketchy. Does anyone know some high capacity aa rechargeables??

Question by astroboy907    |  last reply

Mobile Phone battery? Answered

I have a cell phone who's original battery is 1800mah, 3.7 volts. I got a battery which is same size, 2700mah and 3.7 volts. Can I use it in my cell phone? Will it increase the battery timing of my phone? 

Question by Ahtasham Ahmad Mohtashim    |  last reply

can i add another battery? Answered

I am using a 3.7v 500mah battery that lasts 6 hours. if i add another one exactly the same in parallel, does that mean it will last 12 hours? and yes, the device can handle 1000mah

Question by fossilshark    |  last reply

Do Led Throwies really last up to 1-2 weeks?

I've been reading a post in Evil Mad Scientists about the scientifics and workings of Led Throwies and it got me thinking: If a CR2032 has a value of 250mAh (tops), and an LED consumes about 20mA, then doing the calculations (250/20) we have that the battery would run out of juice at about 12hours, then how are led throwies lasting weeks?!! Maybe I'm an idiot and this isn't the right calculation for this kind of thing. Can someone show me the light?

Question by Skyriam    |  last reply

What's up with Amps, voltage and current?

So I'm having trouble finding out where amps come in. Typical batteries (AAA,AA,9v,3v) don't say the output amps, just output voltage. But things like RC batteries, and wall transformers have a specific amperage output. So say my LED and 9v battery. I know I need to use a 150 ohm resistor. Since resistors limit current, then is there still 9v going to my LED its just the amps/current that being lowered before going into the LED? If resistors limit current, or in its unit of measure, amps, then my LED is still getting the supplied voltage just a lowered amperage?  How do I know how many amps my projects are drawing? How will I know if my DC wall transformer with 12vDC and 1 ma isn't going to fry my circuit? How would I know if 1 amp is too much or not enough for any my circuit? Please help, none of this makes sense, ~electricloser  

Topic by HavocRC    |  last reply

how meany mah is in 1 uf?

I need to know how meany mah is in 1050 uf and i need to know

Question by ALEXANDERS_CH97    |  last reply

How many mAh = 1 farad?

Question by 7654321    |  last reply

is there an advantage to having a battery with a higher mAh?

I have a Pentax digital camera that came with a D-LI88 rechargeable Lithium-ion battery with a 3.7V, typ.740mAh (2.8Wh), and min.700mAh. I want to buy an extra battery for it. I can find batteries with the same 3.7V, but the mAh are different.

Question by joypain    |  last reply

Current switch? Answered

I have some solar panels that produce 3v at 175ma. I was wondering if i could somehow make a switch to have it turn on when the panels are producing at least 100ma. Maybe also a switch for 150ma too :) Any ideas?? If additional voltage is needed it shouldn't be a problem :) Thanks!

Question by astroboy907    |  last reply

What is the supply (MAh) of a 9 volt battery? The draw of an arduino in genral use? And a standerd led? Answered

I was building a fancy arduino supply and need to know the draw from these three things. Can anyone tell me. What a arduino duemilanove draws (in standerd use) (MAh)? What a 9 volt battery supplys (MAh)? What a adverage led uses (Mah)

Question by David97    |  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

Is 4 amps too high of a rate to charge a 3000 mah 7.2 volt nimh battery? Answered

Is a 4 amp charge rate to much for a nimh 6 cell battery with 3000 mah?

Question by Whitedude0728    |  last reply

Arduino battery 9.6V 650mAh. Help?

I have alot of rc plane Ni-MH recharagables that I dont have a use for since my reciver blew up. Can I run my arduino deumonlative on these batterys they are 9.6V and 650mAh. Also I wold like to know how many mA can I draw from the arduinos 5V supply. Thanks for any help, David.

Question by David97    |  last reply

Can I run different voltage LEDs off a 9V battery?

I have a small project that uses a 3 light LED list that runs off of 3 AAA (4.5V) batteries, but I also want to power a 12V LED string (for cars about 24" long) and I am uncertain the mA draw for either. This is for a follow-up to fine tune my son's 2014 Halloween costume. I run the 12V string off of 10 LR-44 batteries and get about 3 hours use out of these, so I know the mAh draw is relatively small. I'd like to extend the use of the 24" string. The 3 LED light goes for days on the AAA's.  Because both lights are used for the same application, I wanted to see if I could join them together in a single power source and power off of 1-9V or 2-9V (in serial for a total of 18V) batteries. I think my preference would be the 18V with an in-line resistor, but I do not know which resistor to use. Is this the correct approach? What are other alternatives?

Question by BillJ1    |  last reply


Lolcat picture I found while crusing teh intarwebs. If you havn't seen the movie "Office Space", you won't get the joke, mm'kay?

Topic by thefonz101    |  last reply

Connecting batteries in series without wasting the mAh? Answered

Okay, if you connect two 1.5v 1000mAh AA batteries in parallel, you'll get 1.5v 2000mAh, right? And if you connect two 1.5v 1000mAh AA batteries in parallel, you'll get 3v 1000mAh, still correct? What if you connect seven 1.5v 1000mAh AA batteries in parrallel and one 1.5v 1000mAh AA battery in series, you SHOULD get 3v 7000mAh, will that work?

Question by j0rd4nkzf    |  last reply

Will it be safe to charge a 3.7v 2000 mAh lithium battery with a 5v usb cord

I am making an Altoids USB charger with a 3.7v  2000 mAh battery. The project will have a 2.5 female connector. Would it be safe to charge it with a 5v usb to 2.5 cable?

Question by Sargebubbles26    |  last reply

Can a 7.2 volt battery with 3000 mah substitute for a 8.4 battery with 1100 mah ? Answered

Hi, I am Planning on going airsofting with my echo 1 m4 commando, but do not have enough batteries to make it. The batteries my gun came with were 8.4 1100 mah NIMH rechargable batteries but i have some 7.2 volt , 3000 mah NIMH batteries lying around that i use for my rc car. I would like to know whether using the 7.2 volt batteries will either harm the gun or the batteries.

Question by Whitedude0728    |  last reply

i have a battery just say 1 volt 1000 mAh and charge it with another battery 2 volt 1000 mAh how long will it take? Answered

How many mA go from the battery to the other? how do i calculate this??

Question by ismael01    |  last reply

BATTERY help? Answered

i have a rechargeable battery that is 7.2 volts and 3000 mAh Ni-Mh now is it safe to add a Voltage Regulator to run an led or if not how do i? what also is scaring me is the 3000 mAh if its good or bad

Question by MACKattacksnipe    |  last reply

Increase battery of a portable usb charger?

I have a  portable usb charger that has these specs: Li-ion 3.6V    1200 mAh Input: DC 5V    400 mAh Output: DC 5V    450 mAh Can i add an old battery that has 3.7V and 1150mAh to the charger and increase the battery life of it? Would it be safe to just hook up the the negs to negs and pos to pos? Also what would be a better way to increase battery of the charger without buying a new unit?

Question by yitmat    |  last reply


Here is a pic of me firin mah MP5K! LMFAO

Topic by DrWeird117    |  last reply

Help with recharagables

First off I'm pretty expierenced with electronics, but I've not been using rechargables that much. I'm not sure how to build a charger for nimh batteries. I want to charge a 3.6v battery, 70 mah (3x 1.2 volts, 70 mah each, I know, it's a small battery for a small device) as cheaply as possiable. I also want it so that it can still power the circuit (takes about 20 maH to run the circuit) when charging. If possiable, I want to charge like 5 or 6 of these at once. Help please!

Topic by guyfrom7up    |  last reply

Firefox add-on for Chinese?

Arrgh! I want to do mah extra-credit math project, but mah browser is making it hard to read any Chinese!!! (It all comes out as weird symbols- see the screenshot) Is there a FF3 add-on to fix my problem? Or is it something else I need to download?

Topic by watermelonhead    |  last reply

airsoft charger. answer!!!!!!!!!!!!!

I wanna buy a smg air-soft gun from a friend but he doesnt have the charger. the gun's specs are 4.8V and 400 MAH, A computer usb is 5V and 500 MAH so can i use a computer usb to a air soft battery effectively 

Question by pancho del rancho  

Battery Pack

I want to start a battery pack but I don't know how to connect series/parallel to get most mAh but also 5V-12V output I plan to buy 8 3.7V 2600mAh Lithium Ion Battery but I don't know how to connect those together to get the most mAh as possible but also between 5V to 12V output . It is possible to do that with 

Topic by Kyosoul    |  last reply

Boost Converter help

I need a dc-dc boost converter that will step 25.9 volts at 2600 mah up to around 388v at 360 ma will I need a battery back with a greater amp output I can get up to 12000 mah at the same voltage any suggestions I am trying to charge a .1 farad cap bank that consists of only 10 caps Any help is appreciated -TDC

Topic by ThinkDesignConstruct    |  last reply

can a double a battery pull out 1 amp? Answered

If its rated 2000 mah it should be able to right?>

Question by ismael01    |  last reply

It is possible to get 8 AA battery to series/parallel circuit? Answered

I want to build a battery pack for my project to have most mAh but able to charge an laptop I plan to buy 8 AA 3.7V battery with 2600 mAh I going to tries to have 4AA battery in series circuit and 4AA battery in parallel circuit and some how connect those 2 to get  a battery pack with 14.8V output and about 10000mAh  It is possible

Question by Kyosoul    |  last reply

What battery should i use?

So I started a little home project where I am using 28 LED lights and I need to know what kind of battery I should use. The lights I have are 5mm, 3-3.2 volts, 20mA-30mA. I want to wire the lights in a parallel circuit for each one. I want the LEDs to be bright! They are rated at 2,500 mcd @ 20mA. -I need a battery that is a very small battery less than 1"x1"x2" or very close to that. -Also is it possible to use a battery that is a 3.0 volt battery that is something like 2000 mAh - I did the math and it seems that my mAh is 560 because (20mA)x(28 LEDs)= 560 mAh. Is that right? if so could I use a battery that is 3 volts and 2000 mAh and have a battery life of 3.5 hours? because 2000/560. is that right? So in a summary, I need a small battery powerful battery that can EQUALLY light up 28 LEDs and if so what kind of resistors would i need if I use a battery that is 3/ 6/ 9/ 12 volts. Also do i need to have a resistor for each LED light or can i have one at the end of all the parallel circuit? Thanks!!!!

Topic by jnajmy    |  last reply

volts or amps wich is better to improve performance for my rc car?

Have a 7.4 volt 5400mah lipo batt whats 11.1 gonna do should i worry bout mah with the 11.1 volt bat

Question    |  last reply

Batteries and charger? Answered

So I got one of those one cell battery bank that come also with a little crank generator. So far I took both of these apart to make one into a 2cell. So now these batteries are a parallel, my ? is if the voltage stays the same with the charging board and the mah is double this should not effect the board correct? and or the batteries. So far its been working both batteries reads the same voltage so the charging board must work. Now hear is the thing that I am concerned with, if I was to add 6 more into a parallel then all batteries would be the same MAH right. This should not damaged the board?

Question by dominick.j.pezza    |  last reply

Can a 5v 500mah charger charge a 6v lead acid battery? Answered

I bought a solar lighting kit from a local electronic store that has a fold-able 3.4w 9v solar panel and a 6v 4500 mah lead acid battery built-in. Then I recently bought another solar light kit that has a 1.7w solar panel, a 3.7v 2200 mah Li-ion battery and came with a 5v 500mah wall charger. So my question is would it be possible if the wall charger that came with the solar kit that had it charge the other solar kit that has a lead acid battery?

Question by zeuszaku    |  last reply

What is this called? Answered

Does anyone know what this thingy is called? I plan on making an instructable on how to make it as soon I find out its name. Thanks

Question by fearme36    |  last reply

a few battery questions

I got 2 questions1st. i was shopping at target today and noticed that the big energizer rechargeable "D" size batteries has the same mAh rating as the smaller "AA" rechargeable energizers i have at home (2500 mAh) can any one explain this?2nd. i've seen some pics around the site of custom "D" sized "AA" battery holders that hold 4 "AA's" in a "D" sized space ( ), but i haven't seen any instructions on how to make them. can some one make an instructable about this? (preferably one that can be made to hook up the" AA's" in parallel)

Topic by clasic_traveller_diehard    |  last reply

3.6v 250mAh Ni-MH battery to run 10 5mm LEDs?

I would like to use a rechargeable 3.6v 250mAh Ni-MH battery to directly power 10 5mm LEDs, is that too much mAh?

Question by lifeofB    |  last reply

Super usb Charger?

Im planning on building myself a portable rechargeable large capacity (Ah not mAh) usb charger. Im a bit of a electrical newb but I am a mechanical engineer in training, If someone could point me in the right direction or at a good instructable that would be awesome

Question by Douglerful    |  last reply

6v solar panel for charging

Is a 6v solar panel (260 mah) enough to charge 4 AA NIHM battery? The four batteries in serie amount to 4,8 volts, and  fully charged they can amount to 5,5v. I'm planning to add a diode, that can drop the voltage by 0,2v.

Topic by jemor143    |  last reply

[~7.4V 800mAh] alkaline battery pack Answered

I need to create a battery pack with 7.4 to 7.5 volts and 800 mAh (or greater) in the lightest package possable with alkaline batteries. If circuitry is needed that would be fine. Its for a mid-small sized RC Helecopter

Question by physics_dude    |  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

How to charge a salvaged Li-ion battery pack?

I've recently salvaged a 11.1 V Li-ion battery pack from an old laptop battery.  Details : Voltage           :  11.1 V  (  ~ 4400 mAh ) Cell                 :  6 x Samsung 18650 22f  cells  (  3.7 V  and 2200 mAh ) Arrangement  :  3 packs in series , each pack having two cells in parallel  The charging circuit is intact.  How should I safely charge them? I'm well aware of the hazards related with improper charging of Li-ion batteries.  Can anybody please suggest some ways to charge it ? any tips ?   I need to know the proper procedure to safely charge (and discharge ) a Li-ion battery and what does a "protection circuit" do ? Thanks !

Question by electro18    |  last reply

can't charge battery with home made hydro power

i built a hydro powered generator and although it will run a string of  LEDs but will not charge a batery .i read 6 volts on my multimeter and am using a 6 volt 3400 mah batery

Question by feedbuck    |  last reply

Charge level indicator for small 4x AA Solar Battery Setup? Answered

Is there a simple way to build a charge indicator for 4 AA NIMH 1.2V 2000 mAh batteries? I thought a small 1-10 volt indicator would do it, but was told it would depend on battery type, etc...

Question by rocktot    |  last reply

can some one cut some thing open for me?

Energizer seems to have a history of hiding stuff in their batteries (coin cells AAAA's stuff like that) so I'm wandering if some one can cut open an energizer rechargeable D cell (one thats rated for 2500 mAh) and see whats inside

Topic by clasic_traveller_diehard    |  last reply

How to resize Halo armor?

OK, I need to resize my Halo Armor (Link- to my size. I would have asked the 405th but the parental controls won't let me, and my mom wont either. Any suggestions?Note- got mah templates here-

Question by GearsOfAwesome    |  last reply