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])

Comments

[Jack A Lopez]

You know, there are a number of decaffeinated brands on the market that are just as tasty as the real thing.

[yoyology]

Do you still run?

[Jack A Lopez]

Only when chased.
;-)

[Neotechnical]

You can have your cake and eat it too. Lipo batteries are very expensive IF they are made in the US, but you can order them from china for a fraction of the cost. The catch? You will have to wait for up to 4 weeks for delivery. Try hobbyking.com

[The MadScientist]

Two lantern batteries will work if put in series.

[-max-]

It needs to fit in one 6V lanternbut if I were to wire in a voltage dobler I think that will last an long time

[The MadScientist]

Two 9v batteries in series paralleled four times to get 4 Amps 18v.

[-max-]

I'm afraid that will burn up the ballast (9-16 volts rating)

[The MadScientist]

Why not just for 9volts in paralleled then?

[-max-]

too minimal volts, after the battery's are used a little, the voltage will drop too low

[-max-]

never mind. i (if my parents ever give me a chance) instead of using a lantern, i will make a torch (like a mag-light) out of PVC tubing, the batteries will be 4 18650 3600mah lithium batteries wired in series. the ballast will be one of those "super slim" models. the reflector will be scrap from another torch i find around the house. it shoud work now all i need are more exact specs for it.

[Jack A Lopez]

If you want some insight into how custom battery packs and portable power supplies are built, I think it would be worthwhile to browse some of this site:
http://www.powerstream.com/home.html

Regarding the question of how to wire individual cells together, as you say,  WITHOUT THE TABS, the way the pros do it is by spot-welding their own tabs onto the cells, as shown in some very sexy videos here:
http://www.powerstream.com/spot-welder.htm

I attempted to built my own capacitive-discharge spot welder one time, but the results were kinda meh.  I have not got around to building a version I can be proud of, but I posted some pictures of  the old one here:
http://www.instructables.com/answers/HOW-CAN-WE-MAKE-BATTERY-TAB-WELDER/#CYHKICHGJ285N7B

BTW, would it be cheating to put your cells in battery holders, or to build a DIY battery holder for to hold them?

[-max-]

i think a accidentally built one of these when i was working in the "how to fix ni-cad batteries" instructables

[Jack A Lopez]

This might mean that I can use my broken spot welder as a zapper to revive unchargeable batteries. Thanks for the idea!

[-max-]

http://www.instructables.com/id/How-to-fix-old-Ni-Cad-cells-disclamer/

[-max-]

hers the link on how to build it if you haven't seen it yet http://www.instructables.com/id/How-to-fix-old-Ni-Cad-cells-disclamer/

[-max-]

i did find nimh AA or AAA will work but i need to figure out how to solder them without tabs. and then how to wire them to give 10-16V at close to 9000 mah. but how???

[orksecurity]

1) Don't solder; use spring contacts. You REALLY DO NOT WANT TO HEAT advanced batteries unless you know EXACTLY what you are doing.

2) If you don't know how to arrange them, how do you know they "will work"?

3) Typical AA NiMH cell puts out somewhere around 1.2 to 1.5V. That means you need about ten in series to get 12V. Their maximum safe current output is around 3A, I believe (depends on the exact make and model), but I Seriously Doubt that they can supply that for an hour so you're going to need a whole bunch of those series connections, in parallel with each other, to get the current you need. AAA puts out less current for a shorter time, so you'd need even more of those.

You can websearch for detailed specs as well as I can, so I'll leave it at that.

Note too that drawing power too rapidly from a NiMH cell can be Actively Dangerous. There are some scary videos illustrating progressive meltdown and explosions of a laptop battery pack. Anything with that much energy in that small a space will not be kind to you if you abuse it.

That brings me back to myt first answer: You can get the power, you can get it cheaply, you can get it compactly... but probably not all at once.

[-max-]

nimh putout 1.2V max. alkalines putout 1.5 and lithium 3.7V. but how do i connect the batteries without soldering? i don't have a spot welder.

[orksecurity]

I say again: Spring contacts.

[-max-]

I don't have room for a bulky battery case

[orksecurity]

Done properly, spring contacts shouldn't take much more room than the batteries themselves. Look at the solutions used in consumer gear.

It might help if you told us what you're actually trying to do. We might be able to suggest an alternative solution which was cheaper or more compact or both.

Or we might not. This may be something that really can't be homebrewed unless you pay more than you want to. Reality is like that, sometimes.

[-max-]

http://www.instructables.com/answers/how-can-i-make-a-super-bright-HID-flashlight/ is where I ask about how to make a 35W hid spotlight. I got all exept the battery figured out.

[steveastrouk]

In fact, NO-ONE making cells would EVER solder their terminals directly. Weld yes, but only with very special machines, solder, no

[ARJOON]

then you should sacrifice space

[-max-]

i cant

[steveastrouk]

Sometimes your requirements are incompatible, here's a good case. you aren't going to get a reliable 8Ah 12V battery for less than 30 bucks - only LiPo will fit in the space available.

[-max-]

or lithium ion or some high tech nimh

[-max-]

actwaly i discovered to last close to a hour, it only needs to be 3000 mah (3 AH) but i still prefer it to last almost three hours. (8 AH)

[orksecurity]

Let's see. You want powerful, compact, and cheap. You may not be able to get all three.