A123 Batteries (26650) with Mag hosts - now what?

[Flipside]

I'm not committed to Incan or LED, and thought this forum would be the best for posting this question. Mods, please feel free to move as needed.

I'm inspired by other posts where the suggestion is to determine what battery to use, then build on that as a foundation. I've decided to use the 26650 size battery from A123 (bought a new, opened package Dewalt host with 10 cells for $9.95 over the weekend), and I'd like to use the Mag product line for a host. I have older versions of the 2C, 5C and 6C available, so battery fit will be the least of my issues.

Because of the size of the batteries, I can easily fit 4 in a 6C host. With modification, I can maybe cram 2 in a 2C host. The 5C's are somewhere in between with a little machining. The batteries have no problem delivering lots of amps, so that's not an issue.

Various reflectors are available from a multitude of sources. Similarly, switches, soft starts, bulb holders, lenses and the like are available too.

My goal is lots of light... Throw would be great to have, too. Hotwires I've considered include using the 64458S (axial), 64625, 347118, and the 64623. P7 LED's are all the rage now, so those are an option as well. I'm leaning towards a hotwire just because of the sleeper value. The light may appear to be a 'regular' Maglite - until you turn it on.

I haven't found many lights or systems designed around the A123 cells. I'm puzzled by this, as they appear to be a very safe, high voltage cell with lots of amps available. Are they old technology, and there's something better, or ??? Or is it that these cells don't fit what is available for hosts / bulbs / leds?

 

[CM]

I gotta ask. Where did you get the 10 cells for $9.95. I want a few of those.

 

[HarryN]

The A123s are normally considerd very safe and very cutting edge technology, esp. compared to conventional LiPos that are so common in R/C use and the Li Ions that are seen more commonly in flashlights. Good voltage vs discharge current over a wide range and rapid re-charge capability.

Charging them takes a charger designed for them, but that is becoming increasingly common in the $ 100 / charger range. Probably some cheaper chargers as well.

According to the R/C type forum posters, the packs made from A123s tend to stay in balance much better than LiPo packs (but after a few cycles, so some balancing is still needed, unless you charge in parallel)

CM - There is an entire sub market of people buying dewalt battery packs and taking them apart for the A123 cells. There have been a few counterfeits packs show up as well, so it is useful to pay attention to details. The most common pack which is harvested is the 36 volt version, which I think has 10 cells and sells for around 100 - 140 depending on bidding, etc.

I suspect that a substantial percentage of replacement Dewalt packs are being used for the A123 batteries they contain, and not for the intended use.

IMHO, the biggest challenge will be getting used to the higher current capability vs the more common LiIons we are used to. Voltage sag will be a LOT less, esp. during the initial turn on, so filament thinking will need a few adjustments.

Resistance between cells will start pushing people toward soldered packs / sticks, and all of the related fun "experiences"

 

[Flipside]

I gotta ask. Where did you get the 10 cells for $9.95. I want a few of those.

Strolling through my local Sears store, I found the battery pack on their clearance rack. The charger was next to it. I took the pack to the checkout, and the kid running the register couldn't get it to ring up. So, he asked his manager what to do.

She told him to ring it up at $9.95, and told me that was the best that she could do. She added that it was a 'really good deal for this battery, 'cause they're like $80.' My thoughts were along the lines of 'Hell, $80 would be a good deal!'

 

[HarryN]

You got the whole pack for $ 10 ?

 

[Flipside]

You got the whole pack for $ 10 ?

Yes. I suppose that my Karma is going to be in the dumps for a decade or more after this deal... Oh well, at least I'll be able to see where I'm going when this light gets built.

Now, all I have to do is figure out what to do with everything... Any suggestions?

 

[CM]

Strolling through my local Sears store, I found the battery pack on their clearance rack. The charger was next to it. I took the pack to the checkout, and the kid running the register couldn't get it to ring up. So, he asked his manager what to do.

She told him to ring it up at $9.95, and told me that was the best that she could do. She added that it was a 'really good deal for this battery, 'cause they're like $80.' My thoughts were along the lines of 'Hell, $80 would be a good deal!'

You stole it fair and square You lucky dog :nana:

 

[gswitter]

Strolling through my local Sears store, I found the battery pack on their clearance rack. The charger was next to it. I took the pack to the checkout, and the kid running the register couldn't get it to ring up. So, he asked his manager what to do.

She told him to ring it up at $9.95, and told me that was the best that she could do. She added that it was a 'really good deal for this battery, 'cause they're like $80.' My thoughts were along the lines of 'Hell, $80 would be a good deal!'

Uh... yeah! :thumbsup:

I was trying to get the local Home Depot to discount the VPX packs a while back (all the tools were heavily discounted), but they wouldn't budge on the packs. Can't complain though, I got two great deals elsewhere this week.

 

[gswitter]

I haven't found many lights or systems designed around the A123 cells. I'm puzzled by this, as they appear to be a very safe, high voltage cell with lots of amps available. Are they old technology, and there's something better, or ??? Or is it that these cells don't fit what is available for hosts / bulbs / leds?

They're still cutting edge, but there's a couple years of hotwire developement based on Li-ions, and the voltage difference between A123's and Li-ion's is the primary stumbling block. Especially since the other LiPo cell (E-moli) matches Li-ion voltage.

 

[James35]

Yeah that was a steal! Current pricing is generally $14 per cell, and you got them for $1 per cell.

I can maybe cram 2 in a 2C host.

Nope, but you can fit 3 A123's into a 4C Mag with no modifications. You'll end up with 9.9V so you'll want to go with an incan setup or an LED with a driver than can handle that kind of voltage, like this one.

I've discovered the easiest way to use A123's is this:
Mag 2D
modified tailcap spring
Two A123 cells in some 1" tubing
Malkoff 4,5,6 cell drop-in module

This is a easy flashlight to make! Use a little Easy-Off to remove the anodizing inside the tailcap, cut a few rings off of the spring, curve it a little on the tip, and you are in business. Remember to put the A123 batteries in backwards since the battery casing is positive. You can use a rare earth magnet between the 2 cells to connect them.

 

[Flipside]

James35 - thanks for the thoughts! Really appreciate the input on the 2C being a no-go. That'll save me some frustration.

I really like the C size form factor in the Maglite. Right now, I'm thinking that I could get (4) A123's into the 6C Mag host using this bulb (from the Incan Forum), nice SMO reflector, a bulb holder and a lens. Then the monster is born.

Nominal 3000L at 12V would probably be close to 3000L out the business end at 13.2V :thinking:. The axial filament of the bulb will make a nice spot and could be focused. So, I think I'll start there, and see what goes ...