### How to make a charger for a 4 volt 4.5 ah sla battery? Answered

I have a 4 volt 4.5 ah sealed lead acid battery out of a cordless phone battery backup thing and I have no way to charge it. Does anyone know how to make a charger for it or even at what voltage and amps to charge it at? Thanks.

Question by JasonYMN   |  last reply

### can you answer a few questions i have on SLA batteries? Answered

1.As you can see in the diagram i have eight 4.5 AH SLA batteries joined together to make four 12 volt 9 AH batteries. how would i incorporate my bigger 7 AH 6 volt SLA into this? 2.Is my math correct that i did up in the corner? 3.Does an amp an hour storage in a battery mean it will supply one amp for one hour? 4.If so and my math is correct i would have 516 watts of power for one hour stored in these batteries?

Question by harry88   |  last reply

### Need to make charge indicator for 4 V 1 Ah Lead Acid battery Answered

Hi,  I have made a solar study lamp. I am using 4 volts 1 Ah lead acid battery for the same and 3 Watt solar panel. It charges well with the current circuit. But it does not have a charge indicator. I am looking for a battery charging circuit with charge indicators as follows: 1. Low battery indicator  2. Battery full indicator 3. Charging indicator - to indicate battery is getting charged Trying to keep this simple and inexpensive as this lamp is a part of social initiative for rural areas. Thanks in advance!

Question by rahuldj   |  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

### How to hook up 2 batteries in parallel ?

I'm building a portable MP3 "boom box". I have two 12 V SLA batteries on hand, one is 12 V 4 AH and the other is 12 V 7 AH capacity. My question is: can these 2 batteries be connected, in parallel to power the amplifier I have ( 12 V) and 1) it would give me a ~ 11 AH battery? 2) could I charge them both, ( connected like that ) with a 12 V battery charger ( a automotive battery trickle charger) I have at hand?

Question by Phoghat   |  last reply

This one day, I was trying to open a page, and I noticed something funny. The thing at the bottom of the page that shows you how much of the page has loaded was going backwards! Seriously, it was on 99, and then it went to 97, 89, 78, 65, 55, 43, 20, 4... My Fasterfox timer (which counts how long it takes for your page to load) even started going backwards! Ah well. I guess that's just what I get for using an old version of Firefox. (2.00.01, I know it's old.)

Topic by YummyPancakes   |  last reply

### building a portable lead-acid charger?

I have two lead acid batteries rated 6v 4.5 AH (is AH ampere? or ampere/hour) boast/equalize 7.2-7.5v float 6.75-6.9v max charge current 1.35A both my batteries are identical the question now is.. i want to build a charger for it and something to lower is current so some feature i want is  1) rechargeable by a simple plug in adapter (i have a 12v 4A ac-dc adapter) 2) output of usb voltage and current (optional adjustable current and voltage) 3)led indicates 4)optional: a switch to power usb devices directly from the adapter/bypass battery to extend battery life 5)around 5 usb out puts? i want to build this project cos i have the won batteries which are in good conditions but not being used in anyway.. i hope someone can help me with the technical specs..especially on the circuit diagram   have access to an electrical components shop but it does not sell chips so i need to salvage them

Question by michaelgohjs   |  last reply

### Convert 48V battery bank to 12V for boat appliances - Is this inefficient?

I need a 48V bank for an electric motor on my boat. I also need 12V for my appliances. Obviously keeping both a 48V and 12V bank would be most efficient but the space required and cost of maintaining 2 banks is a bit much. So I was thinking of using a 48V DC to DC convertor to convert a 48V bank to 12V for my boat appliances(lights, pumps, etc.) http://pt.mouser.com/ProductDetail/Murata-Power-Solutions/HPQ-12-25-D48N-C/?qs=sGAEpiMZZMtwaiKVUtQsNaluUzA10QGezHFBNv8sYMI%3d But how much would I lose in terms of efficiency? Would the losses be too great? Would the bank of 4 x 12V 100AH batteries connected in series give me roughly 4800W ( 4 x 12 x 100 = 4800) or 16 hours of 300W use when drawing only 12V after the conversion?  Or would the available AH be much less due to the losses from the conversion?

Question by mchin2   |  last reply

### Is this lion battery bank expensive? 150AH @12-14v

I was thinking about how much would cost making a lion battery bank with enough amps/hours to feed a car audio system (stereo + sub amp). Since this setup would drain around 25-30AH I definitely want a battery bank with around 150 AH capacity to get at least around 4 hours of music at max potency. Woulds this be so expensive? I know that lion batteries are getting cheaper and cheaper, but any idea about how much would this cost? I have made a research on ebay and amazon, I could not get an average idea, and considering many brands lie about the specs, I better first ask here to hopefully get some references. Thanks.

Topic by johanx4   |  last reply

### Questions on building a lithium battery pack with pcb?

I have to build a pack to run my portable N64.  I have some experience building with NiMh and NiCad, but I havent built a li-ion yet. Ive done my research but would like some feedback before I start building. Parts 18650's - 3.7V  3600mAh ea 7.4V PCM for 18650 Li-Ion/ LiPo 7.4V Li-ion/LiPo charger at 1.2 Ah Plan Either to build a 2S2P pack or a 2S4P pack.  Currently the N64, 7" TFT LCD, Controller, and Audio amp w/ 2x 8Ohm speakers is consuming just over 1A from what i can tell.  its running off of a perfboard w/ regulator and rail, thats hooked up to a universal transformer that is set to 7.5V  1A.  Everything works but when I turn the volume up it cuts off and then powers back on.  I dont know any other way to find out the over all power consumption.  I cant just look up all the specs because the LCD is from china and i dont have any specs. Anyway, back to my plan.  obviousely I want as much run time as i can get out of it with out compromising weight and space.  all componants of the portable can run off of 7.4V or lower, to include the lcd even though its rated at 12V. it can run as loas 6.5V. I have been debating between the 2S2P which should yeild 7.4V 7.2 Ah, and give me a runtime, some where in the ball park of 4 hours. or a 2S4P which should yield 7.4V 14.4 Ah. It would only be slightly more space and provide approximately 8 Hours+ Thats if I am even calculating everything right Ok, Regardless of whether i run a 2S2P or 2S4P the connections to the Protection Circuit will be the same, Right? Pos --> B+ Neg --> B- + to - ( Between Series connection) --> B1 or BM I understand that Li-Ion are safer when it comes to balancing then LiPo, but is this right?  having 2 parallel cells or 4 parallel cells connected with the only balance connection between the series.  I just want it to be safe. Next  is the charging.  I bought a cheap smart charger for 7.4V 1.2A output.  Will it matter whether i build the 2S2P or 2S4P, or will it work for both.  I know it will obviousely take twice as much time to charge with the bigger pack, but is their a max number of individual cells that a PCB can handle, or does it only matter the overall voltage? I also Included in my diagrahm a setup for a DPDT switch to change between pack powered, wall powered and battery charging.  I want it to have an "ON" and "OFF" setting. while off, pack is disconnected and if wall charger is plugged in, it will charge the pack.  while in the "ON" position, pack will power the device, but if wall charger is plugged in, then it will run off that. Can I even use a wall charger for the Li-Ion pack to power the device, or will it not work.??

Question by supramp

### HELP IDEAS for Mini A/C Unit for Truck

This is an idea that has been tried before with other type equipment & applications. However I think that I have found a way to limit the cost & over size of the application for the use intended. The rubb is that I need help with the fabrication. So I am hoping that the brain power will rally to help in a proto-type or test model of this idea.THE IDEA: A mini A/C unit to keep a vehicle cool for short periods of time 1-2 hours.Why needed?? I own a Private Investigation Agency and have very expensive electronic equipment inside sensitive to the high heat in south Texas during the summer.Equipment on hand for the idea:A. Small Cooler & HEater unit that can be found @ most Walmart, Walgreens, ect... Size 12"x 10" x 6"Input: 100-240VAC 1.2 A 40 watt Output 12 volt 4.0 A (looks like a tall showbox with a single hinge that opens like a center console-armrest-glovebox in a truck or van. Picture below...B. A DC/AC convertor also sold at same stores. The unit is very small but will power the unit very easy. 12 volt 5 A 100 watt, 4" x 3" x 3/4"C. a zeus sealed 12 volt battery 4-5 AH with the PWR use of cooler.D. VArious size small electric fans to be used a blower fans.E. PVC or duct work for the application.F. Optional Solar Cell for battery recharge to be mounted on roof of vehicle.I am sorry if my post is inapropiate for this forum or if I have used this post wrong for my purpose. This is my first time to post anything...If there is anything I can do to help with the concept please let me know.I will try and add Pic's of the parts later.THANKS!!!PS: total cost of everything brand new was less than \$50.00

Topic by leebarret   |  last reply

### Circuit for power bank? Answered

Hello, Need a circuit design for the following requirement. Checked online available circuit designs but not sure if they meet all needs.  Looking for circuit design as per following details. 1. It will have one or two, 3.7 volts 2600 mah 18650 lithium batteries 2. Batteries will be charged using smart phone mobile charger or solar panel 10 to 20 volts and around 500 mah to 1 ah input 3. Will have mini usb connection for the same on pcb 4. Circuit should have battery level indication. While being charged, when they are fully charged LED should turn on indicating battery full. Also there should be one LED to show that the charging is in progress. When the battery charge drops below specific level another LED should turn on. 5. If we use 2 batteries then they will be connected parallel 6. Output voltage of the batteries should be 5 volts (so step up is required) and current should be appropriate for mobile charging 7. There should be provision for 2 USB connections. Load can be mobile charging / USB mini fan / USB mini keyboard LED (could be 2 at a time) 8. Circuit should be safe enough so no damage is caused to batteries / load etc.

Question by rahuldj   |  last reply

### I sense... a disturbance in the Force...

Oh yeah. Bill Gates didn't go to work today.He doesn't work for Microsoft anymore....Even if you're not a Microsoft fan, you have to admit, without Mr. Gates, where would the computer industry be? Where would we be?Flash back time:Ah, yes, I remember my very first personal computer... It was a Hewlett-Packard (not an "hp" ;-) with a MONSTER-sized monitor that took up a good 3/4 of my desk, a clunky keyboard and a "ball" mouse. It was running the latest OS: Windows 95. And get this: we were the first people on our street to get this new thing called the "World Wide Web" - whatever that meant. Our Service Provider? MSN, of course! Man, with my new computer (okay, in truth, it was a hand-me-down from Dad), I was the coolest 6-year-old in kindergarten. I had it made.Yeah, MS has made a a few mistakes...*cough*Vista*cough* (doesn't that go without being said?), but Gates and his company really did shift the industry into gear, and they aren't stopping any time soon.So, gentlemen, I ask you to join me as I tip my hat to Mr. Gates. Without him, I don't know who I would be.

Topic by Labot2001   |  last reply

### LED Questions

Help, I'm afflicted with inspiration in quantities that exceed my skills!So I came up with an idea for a project that would probably require the use of LEDs, which I know next to nothing about. Ah, said I, the Internet can teach me much... so I turned here and found the (nearly) perfect Instructable, "LEDs for Beginners":https://www.instructables.com/id/LEDs-for-Beginners/Having read this most helpful I'ble, I certainly came away more knowledge than I'd previously had, but still not enough to properly plan my project.Basically, I'd like to create a 2D "array" of LEDs to use as a light source, in order to backlight a roughly 8.5" x 11" translucent panel.It seems like it would be straightforward to just wire up a bunch of white LEDs in series to a power source and a resistor, and be done. I'm not afraid of a little trial-and-error, but I prefer to know at least roughly what I'm doing going in, so I'm asking for your help. Here are my lingering questions:1. Should I wire my LEDs in series, or in parallel? (Or some combination thereof)? In series, I gather that one LED failing will break the whole circuit, which could be a pain. On the other hand, I've seen several projects and sites that cryptically recommend against wiring these in parallel.2. Are there pre-built strips of LEDs I could acquire that would make this project simpler?3. If I want to vary the brightness of my light source, can I use a variable resistor (potentiometer), or does the nature of the LEDs preclude the use of this type of dimmer switch? If so, could I vary the brightness with multiple switched circuits, turning off half the LEDs for half brightness, 3/4 off for quarter-brightness, etc?4. I've got a slew of transformers from old tape decks, telephones, cell phone chargers, etc. Can I appropriate one of these as my DC power supply?5. How do I gauge how many LEDs I'll need, and what density is best to lay them out? I'm looking to create even, diffuse light, with no noticible bright/dark spots.6. Do I need to worry about heat?7. Are LEDs even the correct way to go here? Should I consider fluorescent light instead?I realize these are a lot of questions, but if you're an expert on LED projects, you could save me a lot of research time. If (I build this gadget, it will definitely show up here as its own Instructable.)Thanks!-JD

Topic by jdtwelve12   |  last reply

### Ideal Energy/Battery Source for a Battery Powered Lamppost

Hello everyone,First time posting, so, thank you ahead of time for all your help!Project:I was tasked with creating an outdoor lamppost for an event at a campground (IE: no immediate electricity source). At first, it seemed quite simple, but, looking at the necessary requirements, it seems to be more complex than I thought. Requirements:I need to find a way to power a high-powered LED light bulb (ideally 12W equivalent) for 10 hours a day (for 3-4 nights - for a total of 30-40 hours) without immediate access to an electrical outlet. So, it would be around 20 watt hours a day. This battery source needs to be able to be outdoors, and face rain/weather. There may be a tarp, tent to cover it. I may have access to a generator to recharge my battery source at another location if need be.I currently have a bright DC 12V light bulb that would be ideal for this project, but, I could also use a AC light bulb if need be.Potential Solutions: Connected 6V Lantern Batteries: Connecting multiple lantern batteries together, and swapping them out on a daily basis. Walmart has a set of Rayovac Heavy-Duty Lantern Batteries for around \$2.50 each. Pro: Connecting these batteries in parallel and series would give me the 20 ah, and 12v specs needed. \ It would come out to around \$15 a day. Would be easy to put in a large water-proof container and connect to the lamppostCons: Bit wasteful - I'd burn through around 20 of these batteries, and would have to recycle/dispose of them Sealed? - Unsure if I could put them in a waterproof container. Do they need venting? Mid-range cost: Would come out to around \$50-60 due to the number of batteries needed12V Deep-Cycle 20Ah+ Battery: A simple 20ah+ deep-cycle battery would provide me the DC power needed on a daily basis. I would then detach it during the day, and bring it to the generator to charge. Pro: Cost - Relatively cheap, at around \$50, this battery option would be affordable Set it and Forget It - No need to connect multiple batteries together. This would just be an easy wiring job.Con: Venting - Unsure if I could place this in a simple waterproof container outside. Does it need to vent? Or, would a AGM deep-cycle battery be ok in a vent-free container? Recharging - Unlike the lantern batteries, I would need to bring this to a generator on a daily basis to recharge. Not the end of the world though.Ideas:I am vacillating between both options. Ideally I would like to go with the deep-cycle battery, but I am quite concerned with the venting problem. I don't believe the 6V batteries need to vent, so they could be placed in a simple container.Question(s): Does one of these solutions stand out more to you as the better fit? Are there other battery solutions that you think would work better? Do I need to use a deep-cycle battery, or would something like this battery work?Again, thank you ahead of time for any guidance you could provide!

Question by EddieGRA   |  last reply