EMoli vs. A123 Fepo4

[Kraeuterbutter]

i have read here somewhere, that somebody was saying, that it will be interesting to see, which of this will be better in longterm use..

and i have found now this test:

http://www.mannertz.de/eflug/bechervg.htm

its german, but i think even when you can not read German you will understand the grafix...

the last grafix shows the cycles..

you can see: the A123-Fepo4 is much better on cycle-life than the emoli, which sees already after only 50cycles a 5% capacity loose..

don´t be shocked by the rest of the graphix...
he unfortunatly killed the emoli-cell after ~50cycles because he discharged it once to 0.4volt accidentily

(a thing, which is not a problem for the A123 Fepo4, tests at rc-groups with over 200cycles discharged to nearly 0Volt without heavy problem have been shown there)

 

[Lowell]

The Emoli cells definitely can't supply high currents like the A123 cells. What I'm most interested in is the cycle life at typical ebike discharge rates of 1-3c.

 

[Kraeuterbutter]

look at the link i posted posting above..

the cycle-tests were done with 2C (2c charging, 2c discharging)

and after 50cycles its already clear, that the cell can not keep up with Fepo4 (or Sony 26650, the other cell in the test) when it goes to cycle-life..
5% capacity-loose after 50cycles..

for Fepo4:
at rc-groups on a - i think it was a 10C test (charging with 3C, discharging with 10c) the cell lost 6% capacity after 400cycles..

and went under 75% of left capacity after ~1050cycles with providing nearly the same voltage (so no internal restistance-increase) during the first 1000cycles..

for cycle-life the a123 seems to be superior by far over the emoli

 

[Lowell]

I'd like to see the same test, but with a more relaxed charging rate. I don't think many EV'ers charge their batteries up at 2c.

 

[xyster]

The Emoli cells definitely can't supply high currents like the A123 cells. What I'm most interested in is the cycle life at typical ebike discharge rates of 1-3c.

15C versus 30C -- 45 amps from a 3ah emoli or 60+ amps from a 2.2ah a123. Not sure there'd be much of a difference in practice for EVs. 15C is still plenty because we'll use 'em in parallel.
Wondering about the longevity too. Milwaukee warrantees their V28 emoli powertool packs for 5 years or 2000 charges. Presumably this is based on rigorous tests.

 

[Instant Karma]

Our Milwaukee V28 battery is design to be used with a power tool. It contains many features appropriate for power tool applications and fulfills the needs of our customer base of power tool users. We cannot endorse the use of our batteries for any application other than for our own power tools. Milwaukee Tool may entertain certain OEM type of applications and those requests should be directed through our Marketing dept.
Thank You,
Sincerely,
Milwaukee Electric Tool Corporation
John M. Resch
After-Sales Service - Technical Support
-------------------------------------------------------------------
This is a reply i received after trying to probe some tech aspects of the V28 battery and ability to use them for -other uses- without mentioning exactly what, hehe. There were a couple people here who used these batteries for e bike use and I was contemplating using a couple in series with 3 parallel. 56V 9AH. Anybody else tried this using the original cases hooked together, not tearing them apart? The Fets in each BMS of the battery are rated at 40V each, and 3 V28s in series will definitely fry the BMS so the question is if two in series will hold up in varying scenarios of low voltage cutoff, max amp draw , etc.
Interestingly the guy mentioned they would 'entertain' certain other types of applications for the battery. Maybe Crystalyte motor sellers or e bike dealers could get something going with them. THey warrant these batteries (under normal use) for 5 years or 2000 cycles.

 

[jondoh]

I'm using milwaukee batteries 56v @ 9 ah. I'm using connector blocks and the stock charger. No problems so far.

I'll have to admit that the A123 are a better technology when it comes to durability and discharge rates but the milwaukee has significantly higher capacity. 3.75 v and 2.9 ah vs 3.3v and 2.3 ah for A123. While this doesn't seem too significant per cell, when you multiply this number over 20 cells, it adds up quickly.

I have a 20Amp controller. It would take about an hour to fully discharge all 6 of the packs i'm using. I believe this is similar to what they would experience in a powertool. We'll see how long these batteries last. If it becomes a problem, I'll have to upgrade to something else I guess. Still the performance is much much much better than SLA and the weight savings alone is reason enough to switch to Lithium batteries.

I'm using my bike to commute to work now. I'm pretty dependent on it so these batteries will see some good useage over time.

follow this link to see how I made my battery pack.
http://endless-sphere.com/forums/viewtopic.php?t=233&highlight=milwaukee

I've since added another parallel string to make it 9 ah total.

 

[Lowell]

Some Li battery discharge graphs, including the Emoli cell. The LG18650 vs. Tenergy 18650 is interesting as well.

http://www.candlepowerforums.com/vb/showthread.php?t=117117

Talking about the Emoli cells. Solid performance at 5c would be plenty for an EV, as I suspect most people would like their vehicles to go for more than 10-12 minutes.

15 amps is no problem for these cells, and you can push them harder. At 20 amps they started to heat up, so I stopped there.

 

[Instant Karma]

I'm using milwaukee batteries 56v @ 9 ah. I'm using connector blocks and the stock charger. No problems so far.

I'll have to admit that the A123 are a better technology when it comes to durability and discharge rates but the milwaukee has significantly higher capacity. 3.75 v and 2.9 ah vs 3.3v and 2.3 ah for A123. While this doesn't seem too significant per cell, when you multiply this number over 20 cells, it adds up quickly.

I have a 20Amp controller. It would take about an hour to fully discharge all 6 of the packs i'm using. I believe this is similar to what they would experience in a powertool. We'll see how long these batteries last. If it becomes a problem, I'll have to upgrade to something else I guess. Still the performance is much much much better than SLA and the weight savings alone is reason enough to switch to Lithium batteries.

I'm using my bike to commute to work now. I'm pretty dependent on it so these batteries will see some good useage over time.

follow this link to see how I made my battery pack.
http://endless-sphere.com/forums/viewtopic.php?t=233&highlight=milwaukee


I've since added another parallel string to make it 9 ah total.

Thanks jondoh for the reply, I messaged you a couple days ago but this answers some of my questions. About the connector blocks where did you get them, and do you solder 14 guage wire to them? And how much is the total weight of your batteries? and where do you put them on your bike. thx Karma

 

[Kraeuterbutter]

@jondoh

jondoh wrote:
I'm using milwaukee batteries 56v @ 9 ah. I'm using connector blocks and the stock charger. No problems so far.

I'll have to admit that the A123 are a better technology when it comes to durability and discharge rates but the milwaukee has significantly higher capacity. 3.75 v and 2.9 ah vs 3.3v and 2.3 ah for A123. While this doesn't seem too significant per cell, when you multiply this number over 20 cells, it adds up quickly.

don´t be trickt by the volt and mAh-rating alone..
you have also to considere the weight:

A123: 71g a single cell
emoli: 99g a single cell

that follows to:
106,9Wh/kg Fepo4
108,4Wh/kg for the EMoli
(with the nominal values)

measured under 2C continouse load:
102,8Wh/kg for the Fepo4
108,5Wh/kg for the EMoli
that are 4 percent-points less for the Fepo4

at 20A discharge:
93Wh/kg for Fepo4
95Wh/kg for Emoli
that are 2 percent-points less for the Fepo4

at 30A discharge:
90Wh/kg for Fepo4
89Wh/kg for emoli

here the emoli already gives you less energy than the fepo4

when you conider the cycle-test you see, that after 50 cycles the emoli can not keep up with Fepo4 anyway
the more cycles you have, the better the A123 will be compared to the Emoli

maybe you have 2% more drive-distance witht he emoli when you buy the packs..
but 2 years later things will look different !

data (cycletest and capacity versus weight test) from here, the link i posted already somewhere:
http://www.mannertz.de/eflug/bechervg.htm

 

[xyster]

don´t be trickt by the volt and mAh-rating alone..
you have also to considere the weight:

True, but their physical size is the same, and the emoli cells can be had a little cheaper.

I'm interested in later replacing my 300 laptop cells with emoli's or a123's. My minimum requirement is 20ah and 92 peak volts. Let's compare:

I'd need 154 emoli's in a 22s7p configuration, at current best price I could find costing $2,200.
http://tinyurl.com/3d9854

I'd need 234 a123's in a 26s9p configuration, at current best price I could find (ebay) costing $2,760.

The real deal-sealer for me is that I can easily fit 154 26650-sized cells on my bike in the boxes I've already got for my 300 18650s, I can't fit 234 26650's.

As I'd not be charging or discharging at high-rates compared to spec, I'd expect the cells would last a good five years without too much capacity lost. Something much better will be commercialized by that time anyway.

 

[Kraeuterbutter]

of course some good arguments too...

was just, that i have read some posts in the rc-heli-forum that many switch to A123 because they are not pleased by the EMoli (loosing power after 50 cycles, or even dead) anymore (since there are the a123 available)

but when you do not need much power like ebike they are for sure a way to go

 

[maytag]

I'd like to point out that the RC guys were pulling 15-25A continuous and deeply discharging their 1p Emoli packs. For ebiking purposes running a few in parallel will usually be the case, I run a 3p Emoli pack and so does Jondoh which adds up to 9Ah's. For everyday riding my DrainBrain registers an avg of 16-24A discharge rate, that's less than 3c so it might be ok for us to expect at least half the cycles Milwaukee is claiming. :lol:

Of course only time will tell. Hey Jondoh, if youre really using yours 5days a week as a daily commuter you should be hitting that 1000th cycle in about 4yrs. My rig is just for recreational use so I'll be chiming in to report my 1000th cycle around 2015-2017 but by then I'm sure we've had all moved on to dylithium crystals or flux capacitors -hahaha

 

[Ypedal]

Hey maytag or John..

On a full charge.. how much V sag do you get at 20 amps ? ( i may have asked this before.. i surely thought about it.. but can't remember for the life of me.. so here it goes again ! lol )

 

[Lowell]

I'm going to guess 50-52v at 20A on a 14s3p pack.

 

[maytag]

Hey maytag or John..

On a full charge.. how much V sag do you get at 20 amps ? ( i may have asked this before.. i surely thought about it.. but can't remember for the life of me.. so here it goes again ! lol )

Havent really paid attention to the Vsag, let me take my rig down from its hangers :lol: and go on a quick spin. I know the pack is about 2/3 full, I'll be back in a few minutes.

UPDATE:

54.1v resting (about 2/3 charged)
51.7v @ ~20A

 

[pwbset]

The Fets in each BMS of the battery are rated at 40V each, and 3 V28s in series will definitely fry the BMS

Instant Karma above is stating that the fets in Milwaukee BMS are rated to 40V and that 3s2p will blow. I'm running 3s2p of unmodified Milwaukee packs. I have fechter's reverse diode "gate" system in place to protect the packs if one trips. It's working flawlessly so far at full power, which for me is 87.1v "hot off the chargers" and 20A Clyte controller.

So... why aren't my BMS "opening" because of over voltage... or if they are is the open/close/reset cycle so fast (on the order of milliseconds?) that I'm just not noticing? Thanks for any help.. just trying to understand why I seem to be running a configuration that's caused other's so much trouble and how I can assist others interested in running this powerful setup. Maybe I'm just running on borrowed time.

 

[TylerDurden]

So... why aren't my BMS "opening" because of over voltage... or if they are is the open/close/reset cycle so fast (on the order of milliseconds?) that I'm just not noticing? Thanks for any help.. just trying to understand why I seem to be running a configuration that's caused other's so much trouble and how I can assist others interested in running this powerful setup. Maybe I'm just running on borrowed time.

IIRC, the FETs are rated @55V...

Also IIRC, the packs only "see" their own voltage unless the BMS switches due to overcurrent or LVC or other. The FETs should be protected from "seeing" full pack voltage by your diodes.

Somebody correct me, if I have mis-stated this scenario.

 

[pwbset]

IIRC, the FETs are rated @55V

Which would make total sense if 2s is fine without any sort of protection. 55v with a little buffer I would say as "hot of the charger" 2s is around 59v for new packs, but, needless to say, that drops fast. Thanks for the info TD. You're a good egg despite that some few others may have a different opinion. :wink:

Edit: It may also be worth noting that I rode until exactly 5.2ah today @ 3s2p and just as I was pulling into my driveway the Cycle Analyst abruptly started reading mid-50s for volts so clearly the on board battery pack BMS are working as they are supposed to for LVC and shutting off packs. My packs were tired after today's ride, but this definitely, without a doubt, confirms 2.6ah useable per pack for Milwaukee packs... unaltered packs anyway. You could punish them a lot more bypassing the BMS I have no doubt.

 

[TylerDurden]

I don't drink, so Canadian beer is off my list... but Canadian batteries are fine like wine.