"C" cells: A123 vs. Emoli?

[Germ]

I've done some research, but still haven't found a clear winner. For building an ROP, 5761, or Mag85 which would you choose, the A123 26650 or Emoli 26700 cell and why?

This is what I've read so far:

A123 - Available in single cells (Hyperion) or can be scavenged, lower 3.3 voltage requires special chargers, 2300mAh capacity, 5mm (.197 inch) shorter than the Emoli. I'm not sure how this effects usage, but the button end of the cell is negative.

Emoli - Must be scavenged from battery packs, 3.7 voltage uses common chargers, 2670mAh capacity.

What I don't know is if there is a difference in charging times, voltage drop, effective runtime, how many times the cells can be charged, or discharge rate when being stored.

I'd love to have a safe, simple solution that I could recommend to anyone for building a Mag Mod that didn't require battery adapters.

So which would you choose and why? If are using the cells please tell your experiences. If you are using the A123's what charger are you using?

If there is a shorter option I'm missing please let me know. What I'd really like is something that would let me build an ROP using a stock 2C Mag. I'm avoiding the AW protected C cells for now because they are currently unavailable and because I'm leary to recommend them to friends for safety reasons.

 

[SilverFox]

Hello Germ,

Since the lights you are indicating are direct drive, the Emoli cells will perform better. They offer higher voltage and higher capacity.

I am using some A123 cells and am charging them in a normal Li-Ion charger. No prolems so far, but I only have around 80 charge/discharge cycles on them.

Tom

 

[TKO]

Hello Germ,

Since the lights you are indicating are direct drive, the Emoli cells will perform better. They offer higher voltage and higher capacity.

I am using some A123 cells and am charging them in a normal Li-Ion charger. No prolems so far, but I only have around 80 charge/discharge cycles on them.

Tom

SF,

Are your A123 cells coming off the charger at 4.2 volts then like Li-Ion? Do they drop to their normal nominal voltage on load or do the only drop to 3.7 like Li-Ion due to the higher off charger voltage?

Are Emoli recommended for direct drive due to a better (flat) discharge curve? Would A123 be better for regulated?

Thanks!

 

[SilverFox]

Hello TKO,

The A123 cells charge to 4.2 volts, then immediately drop down to around 3.7 volts. Let them sit for a few hours and they are down to around 3.6 volts. Under load they drop to around 3.3 volts, depending on the load.

Please understand that this is not a recommended charging voltage. I am just trying to get a handle on what these cells can stand and am torturing them...

My comment about the Emoli comes from the fact that under load they are at 3.7 volts versus the 3.3 volts for the A123 cells. Higher voltage in a direct drive light means a brighter beam.

The Emoli cells also have higher capacity, so their runtime will be longer. In a regulated light, your goal would be to have the highest capacity cell that could maintain the voltage needed to hold regulation.

The A123 cells are best for high current applications. You can run them at 20 amps and charge them back up in around 8 minutes.

Tom

 

[jimjones3630]

Hi Mike,

Great topic, recently another cpf member told me about a side by side runtime comparison between 2xA123 2300mahand 2xEmoli 26700mah with NTC and 5761. NTC needed to bring vbulb down to 6.9vbulb or so. Initially, both as bright but A123 flater discharge keep the output consistant and ran longer due to NTC power comsumption.

A123's are shorter so 2 fit in a 3C, 2 in a 2D, 3 fit in a 4C, 3 in 3D, 4 in 5C and 2 will fit in a 2C using AW's driver since it's shorter than stock switch. And use Aw's c cell extender which most people will say won't fit. But they will if streached. See pic below that is an emoli and A123 with fitted cell extender

How that works is first to know all metal will streach given the proper conditions. For aluminum thankfully doesn't take much. I posted on this thread if interested

http://www.candlepowerforums.com/vb/showthread.php?t=155998

A123 cells charge way faster than emoli cells due to less internal resistance I suppose. A123 cells recharge cycles 1500 or so. So many that people who have been using these cells, RCs, debate what is an acceptable loss of recharging cycles so can recharge even faster.

These are indeed safe cells, had my first rupture on me and did so with an anti-climactic "pop"

http://www.candlepowerforums.com/vb/showthread.php?t=187586

I charge them on a bench power supply or an older li Io program. They are fully charged at 3.6v. There maybe other types of A123 cells but the ones I have had and do have come from Dewalt 36v paks, there is 10 to a pak and manufacture recommends terminal charge 3.6v. What happens if charge above 3.6v you shorten the cycle life of the cells.

I haven't had one set of batteries long enough to tell self discharge rate, reportedly it's very low. I using a built pak factory recommends parallel charging which you can adapt a harness to your older charger. I've only run these A123 cells consistently in 4S, 3s, 2s retaining the factory welded tabs. When recharge have charged in series and none of mine have gotten out of balance yet.

Emolis are steel cans, A123 aluminum. Carrying 4 A123 cells in a 5C light seems light as a feather compared to emoli cells. A123 case is positive ground is possible to create a short, see first link above, and melt your tailcap spring with instant 70A dump. I like to run my A123 lights with pos grounded light.

Power per ounce A123 cells are the most concentrated energy source we have at this time. 3xA123 cells will power up 1185 with very good steady output through entire run time. 2xA123 will power up a ROP. But why go with less lumen bulbs that cost more money? AW's Chinese mystery bulb has more lumen output than 1185 or ROP and is half the price. About the same price is Tungsram 56580 and with available data it and the "Top Chinese Bulb" 64430 output over 3,000 lumens.

jim

 

[Northern Lights]

Thanks, Jim.
My last comparison was a run between A123 and Emoli powered 5761. The emoli with the NTC of our discussions and the A123 both deliver 6.9 volts to the 5761 when the appropriate tail cap and switch fixes are done to compensate for resistance. 6.9 is a voltage for the 5761 that always works. If you get a particular batch or bulb with soft start you may find some that will run on 7.1 and if you do it is a screamer around 900 torch lumens. The emoli has a slightly higher capacity but the NTC cuts that a little bit so run time should be so close to equal as not to be an issue. These batteries both handle high loads because of that capacity they also deliver higher than expected Vbulb. In this case I ran both until they got warm to the touch then I cooled them and started again until one dimmed out.. The A123 out lasted the Emoli on this test but that is not definitive and should be tested under controlled parameter. The test demonstrated approximately a 25-minute run time.

After the second or third round when first started the emoli showed a slightly higher Vbulb by being a hair brighter on a close up white wall/yellow wall test. After about a minute the A123 would take the lead each time I ran a round.

I expect this because the A123 has the flattest discharge curve, the Emoli was dropping faster towards equilibrium than the A123 but not enough to say one is better than the other.

When all was done the only advantages lie in the case length or shortness and by using an NTC or any soft start you should lengthen the bulb life. So without a driver the Emoli mod would be expected to give slightly more bulb life. The NTC could be used in series with AW soft start Vin=Vout driver, the Delta V achieved by the @ 0.30 voltage drop of the NTC to the Emoli is necessary to maintain bulb life and avoid insta flash.

My personal favorite is A123 5761 because I prefer the KISS priciple and this is a Direct Drive solution.

JS- our new moderator, Congrats to him in that endeavor, originally informed me about the A123 cells and that is when I started planning to use them. Credit is due to JS!!!!!!!!!!

An acquaintance did this for me:

that is quite likely the best direct-drive solution of any flashlight
of ever...

this is the 64430 light comparing the hotdriver vs NTC direct-drive
solutions.. as always i used 30mohm ckt resistance and for the NTC i
used 45 mohm.. half way between 60mohm for 5A and 30mohm for 10A...

the solid lines are the hotdriver solution and the dotdash lines are
the NTC DD solution..

there is a bit of a spike in the beginning.. it should be not a
problem, the lamp re-rates to about 6 hrs even at the 'spike'
voltage.. and without the NTC i'd be concerned.. non-issue with the
NTC..

A123 test

Misc. test data

 

[LuxLuthor]

Nice chart.

 

[SnowplowTortoise]

Germ,
It doesn't appear that many people have found these tables very useful so far, but they were very helpful for me last week when I was trying to decide which C cells to use for my new lights. Hope they're not all wrong!

http://www.candlepowerforums.com/vb/showthread.php?t=188063

 

[Germ]

Thanks for the awesome answers Thanks for the pictures jimjones3630. I love pictures.

I asked jimjones3630 to give his thoughts on this subject after reading his thread on using the A123's with the 5761 lamp:

http://www.candlepowerforums.com/vb/showthread.php?t=172471&highlight=26650

I especially liked the youtube video he linked to showing A123 and Li-Ion cells being punctured :

http://www.youtube.com/watch?v=A9ayuFBDrSg

I like that the A123 has a flat discharge curve and doesn't require the NTC thermistor to be used with the 5761 bulb. I also like that it is 5mm (.197 inch) shorter than the Emoli which adds up when you start adding cells.

More questions:

jimjones3630, are you saying both the AW soft start switch and the extender are required to use two A123's with a 2C Mag? I'd love to be able to get two A123's or Emoli's in a Mag 2C without the adapter. I don't suppose three A123's can be used with a 3C Mag?

Because the case is positive on the A123's do you put them in backwards? Is there anything you need to be careful of because of the positive case?

How long does it take to charge the respective batteries? A quick charge time would be great.

What charger would be recommended for the A123? I'm guessing one can't be had for $12 like the DSD charger. I'd hope for something $50 or less.

Is the A123 smaller in diameter than the Emoli? Will honing a C Mag be required for either batteries?

Has anyone tried the Hyperion A123's? Where do you get the scavenged batteries? I don't think I want to buy a whole pack and scavenge them myself.

Do these batteries turn off all at once like a protected Li-Ion or can you continue to use your light until the cells are fully drained? I probably wouldn't completely drain the batteries, but having the light dim to give you some warning and have enough light left to find your spares would be nice.

 

[Northern Lights]

Germ,
It doesn't appear that many people have found these tables very useful so far, but they were very helpful for me last week when I was trying to decide which C cells to use for my new lights. Hope they're not all wrong!

http://www.candlepowerforums.com/vb/showthread.php?t=188063

That is a good starting point, I missed the original post. One aspect of batteries you do not know without trying them is how accurate the makers specifications are. Most over rate their cells but occaissionally like the GP2000 and the Powerex you find under rated cells. That is to mean the genearal average voltage and capacities are higher than the advertised nominal. Another parameter I found that can beat you up when modding is just how well a battery can handle a load.
Keeping within the scope of this threads topic we have found that although the emoli and a123 have a nominal voltage our 1185 and 5761 bulb do not drop the battery into the nominal as soon as the load is applied, e.g. A123 Vbulb 5761 should be 6.9V but nominal is 6.6V that is what you expect. For comparison you can see how these cells drop very quickly on a 5761 although their nominal is 3.6 and charge to 4.2 the 5761 is the limit. They drop fast, start out a little hotter than the A123 but quickly dim away... Look at the flat line in the above graph of A123.
Discharge data for Phillips 5761 on AW's new C Li-ion cells

The chart is a good starting point. We have been invited to add to it, we can add our experience of actual performance. Like I just pointed out. I loved my 2C cell 5761 with an AW driver, but because of the experience and my love of lumens I gave it up for The 3C, A123 which because I used a spacer on the 2C to make a jack the 3C was only 40mm longer.

 

[Germ]

SnowplowTortoise, I saw your chart and saved it immediately. I found it very useful. I think the batteries are just too new for most people to comment on.

The more I think about these batteries the more I like them. First I thought, why would you want a C diameter battery that barely had more capacity than an 18650 at 2200mAh? I'm liking them for their safety and ability to power the bigger hotwire bulbs.

I wonder, while the AW protected C Li-Ion is rated at a whopping 3300mAh how much of that do you get to use before the protection circuit kicks in?

 

[BentHeadTX]

I have not used the individual cells but have used the Milwaukee V28 (emoli) and DeWalt 36V (A123) packs in drills. The emoli packs got a big thumbs down due to massive self discharge, in a month they went from fully charged to dead.

The A123 cells in the DeWalt packs last months of no use without going dead. I am not sure if it is the emoli cells that self-discharge so quickly or it is the battery management board draining them. All I know is the DeWalt packs give much better life when not it use. YMMV

 

[jimjones3630]

Thanks for the awesome answers Thanks for the pictures jimjones3630. I love pictures.

I asked jimjones3630 to give his thoughts on this subject after reading his thread on using the A123's with the 5761 lamp:

http://www.candlepowerforums.com/vb/showthread.php?t=172471&highlight=26650

Hey Mike,

Glad you like the clip on youtube. Safety is a huge issue and some people don't know "the facts", have many misconceived ideas. For our actions to be sensable and safe we need to base out actions on facts not scary half truths no matter how well intented.

To promote our "hobby" when one knows the limits can be pushed without drastic consequences then can have fun experimenting. Every once in awhile someone will tell me something close to the truth like "soldering batteries is dangerous." Getting batteries too hot is dangerous. With proper technique one can solder batteries without problems.

I especially liked the youtube video he linked to showing A123 and Li-Ion cells being punctured :

http://www.youtube.com/watch?v=A9ayuFBDrSg

More questions:

jimjones3630, are you saying both the AW soft start switch and the extender are required to use two A123's with a 2C Mag? I'd love to be able to get two A123's or Emoli's in a Mag 2C without the adapter. I don't suppose three A123's can be used with a 3C Mag?

Mike, both AW driver(either ver 1 or 2) or any switch of that size and his c cell extender are needed to fit 2xA123 cells in a 2C mag. The "way" to do so I outlinned in the link with previous post.

3 A123 cells can fit in a 3 C if you have enough, IIRC it's 3 or 4, extenders. Only one extender needs streatching.

Because the case is positive on the A123's do you put them in backwards? Is there anything you need to be careful of because of the positive case?

Mike,
Yes I put them in backwards which effectively makes the light positive grounded. The circuit on mags doesn't matter if pos or neg ground. AW's driver does require neg ground to work, unless of course you mod his driver.

How long does it take to charge the respective batteries? A quick charge time would be great.

What charger would be recommended for the A123? I'm guessing one can't be had for $12 like the DSD charger. I'd hope for something $50 or less.

Mike,
I recharge 3 A123 in Series in about 10-12 min. at 6A to 10A. Haven't really timed it but is quick. I bought my 2nd bench power supply a Motorola 0-40A, 0-40v, ac and cc capible for $50 used on ebay, my first an EMI 0-72v, 13A paid $35. But I was comitted to learning how to use a bench supply. There is a learning curve and don't have the convience of a BC 6 or any battery charger. If price is a consideration you can spend time in learning instead.

Is the A123 smaller in diameter than the Emoli? Will honing a C Mag be required for either batteries?

Has anyone tried the Hyperion A123's? Where do you get the scavenged batteries? I don't think I want to buy a whole pack and scavenge them myself.

Mike,
A123 2300mah and Emoli 2670mah cells have a spec sheet from the factory stating they are same diameter. My experience is A123 are oh so slightly smaller and some older and even some new C mags I've found need no honing. I look watch ebay, and some rc groups for bargins. 10 A123 2300mah cells are in Dewalt 36v paks, 7 emoli 2670mah cells are from Milluakee paks.

Do these batteries turn off all at once like a protected Li-Ion or can you continue to use your light until the cells are fully drained? I probably wouldn't completely drain the batteries, but having the light dim to give you some warning and have enough light left to find your spares would be nice.

Mike,
These cells can be killed by overdischarge. They are harder to kill, in fact I've heard A123 charging programs now include one for discharged cells below 2.0v. Both A123 and emoli are flat discharge cells, A123 flater and when either start to decrease light output it's time to recharge. I run a 62138 with 3 emoli and when it dims cells measure around 3.0v and at times 2.8v.

jim

 

[Germ]

Thanks for answering all the questions Jim.

Safety is definately a concern. I could be better with the Li-Ions that I currently have. I charge in a safe area and try to be around when cells are charging. I say "try" because I have forgotten and gone to sleep with the batteries still on the charger. I've taken my cheapo multitester and checked the voltages, but I probably am not diligant enough in doing that. Not having to worry about all of that would be great. I sure wouldn't want to be around when a pair of C size Li-Ion's vent with flame :duck:. I can't know what anyone else might do so I don't feel comfortable setting up others with Li-Ion lights.

In the video the A123 is venting a little gas. Is this gas as harmful as that given off by a Li-Ion? If I recall correctly the gas vented by a Li-Ion is really nasty, not something you want to breathe at all.

 

[jimjones3630]

Mike, I don't know if A123 gas from venting cells is less more or not as bad as other Li chemisty.

Talking about safety, I am trying out Northern Light's frosting technique and the bulb will burn off excess material from the process. Recommended to leave the window off til gone. I found out how hot 3xA123 with Tungsram 56580 can get tonight. The dripping blue stuff is the window gasket on a old kel lite I modded with kiu socket, heat sink.

Thanks for answering all the questions Jim.

Safety is definately a concern. I could be better with the Li-Ions that I currently have. I charge in a safe area and try to be around when cells are charging. I say "try" because I have forgotten and gone to sleep with the batteries still on the charger. I've taken my cheapo multitester and checked the voltages, but I probably am not diligant enough in doing that. Not having to worry about all of that would be great. I sure wouldn't want to be around when a pair of C size Li-Ion's vent with flame . I can't know what anyone else might do so I don't feel comfortable setting up others with Li-Ion lights.

In the video the A123 is venting a little gas. Is this gas as harmful as that given off by a Li-Ion? If I recall correctly the gas vented by a Li-Ion is really nasty, not something you want to breathe at all.

 

[Northern Lights]

I have not used the individual cells but have used the Milwaukee V28 (emoli) and DeWalt 36V (A123) packs in drills. The emoli packs got a big thumbs down due to massive self discharge, in a month they went from fully charged to dead.

The A123 cells in the DeWalt packs last months of no use without going dead. I am not sure if it is the emoli cells that self-discharge so quickly or it is the battery management board draining them. All I know is the DeWalt packs give much better life when not it use. YMMV

The pack has a pcb that regulates charging I bet it is draining the pack and is always on as all lithium is low self discharge and I have not seen that with emoli.

A123 and li-ion when discharge too far for the program in the BC-6 the charger will say low voltage and not charge. A trick I learned from battery space is to charge it on Auto in NiMh mode for a minute or two, I watch the voltage so when it hits the voltage the charger will recognize tahe battery has taken on a surface charge, I switch to the appropriate progarm and it kicks in. Save a lot of 17mm 123A rechargeables that way. That is a problem with unprotected cells but emoli and A123 recover from that. I learned to do that by adapting the NiMh technique outlined in the link; Here is a good battery reference page:
http://www.batteryspace.com/index.asp?PageAction=Custom&ID=3

 

[Northern Lights]

...Talking about safety, I am trying out Northern Light's frosting technique and the bulb will burn off excess material from the process...

What!! HOly!! :mecry::shakehead :huh: :whoopin:

When you use Armour Etch to frost a bulb you put it on the glass you want to chemically etch, it leaves a frosted look. I frost the lower 2/3 or from just above the filament down leaving a clear top, it is filament wires that leave the artifacts.

I put it on and leave it 35 minutes a coat. 5761 work good at that, the 64430 need two coats. It dries leaving a crust.

GUESS WHAT THE INSTRUCTION ON THE BOTTLE OF A.E. SAYS?

Wash off all traces...
you do not leave it on! It is a chemical etch not paint.

Yep, if you wash off the excess like you are supposed to and return a clean bulb you will have no excess material to ruin your reflector and you will have more lumens out the front and I am very surprised that the salts left over did not fracture the bulb when you turned it on. I use a tooth bruch, dish soap and finish with alcohol and tissue. We need to back to basics on Halogen bulb envelope integrity and safety.

You gave me a good chuckle and shock! Change your ways! 'love ya anyway. Your were kidding, weren't you?

It should look like this, immediately after final wash:

 

[Northern Lights]

Talking about safety, I am trying out Northern Light's frosting technique and the bulb will burn off excess material from the process. Recommended to leave the window off til gone.

But lets talk about burning things off anyway. There is a post about fogging up using ROP, Pelican 3845 bulbs. I had the same problem with pr to bipin sockets too.

Turns out the potting material retains water for water based ceramics, believe this is the Pelican problem and some hardener with epoxie base like what is used in Norhern Light Pr to bipin sockets. The solution is to burn off the lamp first use with an open head.

The fumes will crack lens when it condenses and boils on the glass and it will tarnish vacume aluminized reflectors. You will see a condensate on the window.

I cured the problem with the sockets I build. I bake them to set the ceramic and clean any residue before any off you get them.

 

[jimjones3630]

From the amount of smoke coming out the front and for so long I began to wonder. But yes I did remove the crust and still all the etched bulbs have so far smoked a bit but not like melting the gasket.

Also, the ceramic insulation smokes some, may have some moisture content.

But lets talk about burning things off anyway. There is a post about fogging up using ROP, Pelican 3845 bulbs. I had the same problem with pr to bipin sockets too.

Turns out the potting material retains water for water based ceramics, believe this is the Pelican problem and some hardener with epoxie base like what is used in Norhern Light Pr to bipin sockets. The solution is to burn off the lamp first use with an open head.

The fumes will crack lens when it condenses and boils on the glass and it will tarnish vacume aluminized reflectors. You will see a condensate on the window.

I cured the problem with the sockets I build. I bake them to set the ceramic and clean any residue before any off you get them.

 

[Germ]

Jim, darn it I was still hoping to go with a 2C without an extender with two of the A123's. It looks like fivemega has run out of his wide tailcaps too. I was hoping maybe to do a tailcap mod, but to get an A123 into the stock tailcap it looks like you'd have to just about machine to the outer threads. Now I know why fivemega used stainless steel for his caps as the walls must be very thin at the threaded area.

My interest in all of this is because one of the guys at work saw my Mag 2D ROP and now wants to make one for his Dad. I used a modamag 6AA adapter. Those aren't available and I'd like to avoid an adapter anyway. I have a cousin that I think would love to have an ROP too.

I'd like to keep things simple and as inexpensive as possible for others so it looks like a 3C or a 2D with a tailcap mod will be needed with two A123's. I wouldn't mind doing one for myself. I could go for the fivemega wide C tailcap for myself if he offers it again.

My biggest stumbling block now is finding the right A123 charger. I don't want to make others spend a lot on a charger. The batteryspace charger is pretty inexpensive at $19.99, but I want to do some more research.