B&D VPX batteries

I am surprised there hasn't been much mention of these new batteries. I found this interesting thread from a R/C site:

http://www.rcgroups.com/forums/showthread.php?t=768729

They have all sorts of info, plus a link for the specs:

http://www.elektromodely.sk/A123/APR18650M1_2007-05.pdf

It is especially nice that they are widely available (lower price) and presumably have a proper charge and any protections necessary for safe use. I have been staying away from Li based batteries due to safety issues and sticking to NiMH.

They discovered that they are made by A123, the same company making car batteries for GM Volt (gm-volt.com) and other power tool brands. Therefore, they are very tough!!!! No NiCd or NiMH can come close to it. RC people seem to be pushing them to 10C and beyond, yet they survive.

Standard charge is over 1C, so very quick to recharge. From that PDF:

"Maximum continuous discharge 30A" which is about 27C!!!!!

Operating temp range is also great. The last chart, lifespan @100% DOD is simply astonishing (however no mention of rate of discharge, so assume benign 0.1C) - about 2K cycles using 80% of original capacity rule!!!!

Am I not interpreting these numbers correctly? Is A123 is know to exaggerate like others? How much would you believe these specs?

I did know that Li chemistry can live a long life. Still I never heard of a Li chemistry cell handling many-C discharge rates AND living for well over 1000 cycles. Then again I don't know much about them.

So open question. What do you think/know of these new VPX power packs? What do you think/know of A123's cells for consumer market (power tools and such)?

Personally if this info is correct I would be very happy to switch to them for all higher current applications provided safe charger and operation (no explosions and such).

My latest power tools packs are 19.2V NiCd and cannot complain too much but: 1) heavy, 2) performance quickly tanks at higher rates (tougher jobs)
Even handheld vac drains its NiCds very quickly (not to mention slow charge rate kills cells over time).

I just noticed those at WalMart the other day, just before taking a dead 5-sub-C pack from my Ryobi drill in to Batteries Plus for rebuilding ($20, BTW).

Their pricetags were such that I couldn't tell what things cost what. I did see they have a 1-pack or 2-pack drill driver (the 2 would be comparable to my Ryobi), and an air pump was pictured but didn't seem to be actually there. The 3-tool kit had an icky (3 x T1 3/4 LED) flashlight and something else I didn't need.

Anyway, tempting to look into later. Even with the new pack, this Ryobi will likely be like any other NiCd/NiMH tool. It'll be stone dead every time I want to use it, and i'll cross my fingers it'll take a charge and work the next day.

There is a starter kit with a screwdriver/drilver and a cutting saw and led flashlight for $89. It being only a 7v battery though, what kind of amperage do they put out? Will it outpower an 18v battery pack on a Mikita or Ryobi?

bob_ninja said:

I am surprised there hasn't been much mention of these new batteries.

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It has been mentioned here already. I use the 18650s out of these in one of my lights.

I saw VPX batteries in Target today at $19.99. They are very small so I guess they contain two 18650s. There was also a battery/charger combo along with various tools. The tools seem designed for light applications; I don't think they will compete on power with big 18V or 14.4V tools.

saabluster said:

It has been mentioned here already. I use the 18650s out of these in one of my lights.

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And ....? What do you think? Comments?

radella,

Certainly they should hold their charge much better, especially after a 100-200 cycles when NiCd tend to develop a high SD. A single battery is about $20, or battery and charger combo about $40.

Phaetos,

Let's do the math. I have a 19.2V NiCd toolset. I don't know exactly what is their capacity or what discharge it can tolerate so I'll have to make some guesses. If you have more accurate numbers, feel free do redo my calcs:

NiCd
-----

C size cell, capacity 2Ah, 19.2V = 38.4Wh
Max output 4C = 8A x 19.2V = 153.6W

VPX
----

(note for serious tools like drills/drivers they use 2 VPX batteries, at least)
18650 cell, capacity 1.1Ah, 7V, 2VPX = 16.4Wh
Max output 15C (spec is 27C, but I am being conservative)
2VPX x 16.5A x 7V = 231W

So VPX based tool using 2 batteries has less than half the capacity of my NiCd pack, but can output about 50% more power on demand. What is more important is that at 15C I used it is still well below the spec (so not a huge strain on cells), while 4C is pretty hard on NiCds. Thus NiCds are likely to last shorter time and develop high SD sooner, thus diminishing their higher energy capacity advantage.

In fact, IF (this is a big IF) VPX can live over 1,000 cycles while outputing 15C or more than it would seem to me to be no contest. VPX would be a clean winner. Especially when it can be easily recharged in less than an hour, again without doing any damage to cells.

Mr Happy, according to this calculation seems a pair of VPX batteries actually supply more power than the biggest NiCd pack.

BTW, another advantage is that each VPX has only 2 cells, so likely to be more balanced for a longer time. Compare that to my 19.2V NiCd = 16 cells!!!!!! Packs are still new and work well. But there is no way pack cells will remain balanced for long.

bob_ninja said:

And ....? What do you think? Comments?

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Well I'm not crazy about the low capacity but that is not why I got them. I will be using them in a flashlight with 3 LEDs running at 2A each. I just didn't want to subject normal L-ions to that. Other than their high discharge ability they are just batteries.

bob_ninja said:

2VPX x 16.5A x 7V = 231W
...
Mr Happy, according to this calculation seems a pair of VPX batteries actually supply more power than the biggest NiCd pack.

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OK, I agree with this nominal calculation, but where I have a slight doubt is in the current required. Power is more easily delivered at higher voltages and lower currents. When you reach currents of 16A the I-squared-R losses start to mount up. Every contact resistance becomes important, and every wire, every motor winding, has to be fatter. You can do it, but the engineering becomes more difficult and more expensive. I wonder about this aspect in low cost $20-$30 tools. The proof is in the actual hands-on testing of course...

Hmmm, good point. thanks

While it is true that these batteries can deliver power very quickly, it is unlikely that tools will be designed to draw 16A since this 15C rate would deplete the battery in less than 4 minutes. Not too many users will be satisfied with this short life. The tools that require more power use more than one battery, so they can keep the current lower. So the larger tools are 14V or possibly more.

-- Alan

So based on the constraints of afforable tools I will limit current to 5A.
I measured about 5A sustained on my older B&D dustbuster so assume that would be a common current for power tools and such.

NiCd
-----

C size cell, capacity 2Ah, 19.2V = 38.4Wh
5A output = 2.5C = 5A x 19.2V = 96W

VPX
----

(note for serious tools like drills/drivers they use 2 VPX batteries, at least)
18650 cell, capacity 1.1Ah, 7V, 2VPX = 16.4Wh, 3VPX = 23.1Wh
5A output = 4.5C
2VPX x 5A x 7V = 70W
3VPX x 5A x 7V = 105W

Also tried a 3VPX combo.

In this scenario we limit current to 5A to keep tool components simple/cheap (which seems to be the trend these days

In this case the 2VPX combo is weaker, while a 3VPX combo is bit stronger.

Also I thought more about other aspects. For instance, 5A is a 4.5C load for VPX cells which according to the specs is well below the limits. This should ensure a very long lifespan. For NiCds it is a 2.5C load which is significant, shorter lifespan.

More importantly, such large NiCd packs tend to suffer from cell imbalance causing premature death. Even a 3VPX combo consists of only 6 cells, compared to 16 NiCd cells. Moreover, VPX cells are charged in pairs thus making it easier to maintain the balance and repair (you only throw a pair of cells as opposed to entire pack of 16 NiCds).

In summary, 2VPX combo offers a lower peak power and shorter runtime, but can be charged quickly. 3VPX combo offers more power peak power, still shorter runtime. VPX batteries have a much longer lifespan and are cheaper to replace (fewer cells discarded/wasted).

For me VPX is still a clean winner.

I bought 2 of the VPX packs to scavange the 18650's out of them. Easy to get them out and they do say A123 on them. I'm going to use them in my 24 watt WE Boxer HID since it has a habit of killing regular Li-Ions. While the voltage is a tad less it seems to work fine so far and the A123's will definitely handle the current draw as opposed to the Wolf-Eyes supplied batteries that so many have had trouble with. AW's batteries seem to do okay with it but these A123's are likely to do even better I believe with standing the high current draw. Does anyone use a LiFePO4 charger like the Ultrafire 3.0 volt charger on the A123's? You need to make an adapter but since it limits charging to cutoff at 3.6 volts (for the 3.0 volt batteries) I think it should work for these.

If you are able to disassemble the VPX pack without destroying it, you could put it back together and use the official VPX charger, perhaps? I have not taken one apart, but maybe you had to break some welded tabs or something? That would make it harder to reassemble I imagine.

saabluster said:

It has been mentioned here already. I use the 18650s out of these in one of my lights.

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If you dont mind can you measure the mAh from the Walmart battery? I mean just the one 18650 not the whole pack? Thanks much

Chris

Since those are rated 1100 mah but they say they can handle 20C I'm guessing you might be able to pull a little over 20 amps from it! I can't find my Fluke meter at the minute or I'd check for you.

I bought a few of these, and indeed they are the 1100 A123 18650 cells as in my photo.




Now I ordered one of the Makita packs which should contain 10 Emoli 18650 (5s2p) cells, since their spec is 3.6V 1500mAh nominal values, and these are 18V 3000mAh. Gonna take this apart with photos in a couple days. :naughty: It would be nice to find some of these 2400mAh Emoli 18650 cells though.

Eventually gonna weld together packs with balance taps.

Lux - is that for sure those Makita's contain Emoli 18650's? That's a nice deal if they do.

Hello Chris,

At 1 amp they are coming in at around 1030 mAh. At 10 amps they drop down to about 1022 mAh.

Tom

Lux - I've been digging around all day on batteries like this. I'm getting the impression that you may not be getting actual Emoli cells in a Makita 28v pack as I came across this info: "Makita uses the Konion type cells in a 5S2P configuration supposedly only good for about 7C discharge" as opposed to the roughly 15C discharge you can supposedly get from Emoli's. I believe it is the Milwaukee packs that use real Emoli and I was seeing 3000mah rates being stated on them but less cells in a pack I think. I also saw these Li-Fe-PO4 Rechargeable: 18650 Cylindrical Cell 3.2V 1200 mAh, 15C (18A) Drain Rate at batteryspace.com for $6.95 ea. Seems these are close to the VPX A123's but not quite the same probably as I think the A123's can do up to 30C continuous and 52C burst