Yesa vs Headway vs PSI vs Ebike.ca 12Ah LFP test graph

[olaf-lampe]

Hi Doc,
why don't you give peakbattery.com a chance? They have very nice 26650 cells and a quite competitive 90AH cell as well. (300/700A)

I'm not related to them, just a satisfied customer
Olaf

 

[TylerDurden]

JD,

Thanx for posting your cell comparison and pricing info... it looks like more large EVs can get lithium this year (without paying through the nose).

 

[Doctorbass]

Hi Doc,
why don't you give peakbattery.com a chance? They have very nice 26650 cells and a quite competitive 90AH cell as well. (300/700A)

I'm not related to them, just a satisfied customer
Olaf

I should receive 5x K2 cells to test next week that's for an electric 911 porsche battery pack... 2500 of these cells! I have the job to make the battery pack ... using brand spot welder!

150kW Motor ordered!

http://porschestrom.blogspot.com/2008/11/project-start.html

i'll post graph.. dont worry!

Doc

 

[dnmun]

you ordered a motor from unique mobility? that is really a nice car. why couldn't they scrap a honda CRX. the ones from 84-87 would weigh under 1400lbs without the motor, there is space up front for some batteries along with the motor, and in the rear too. plus they are easy to find with the head gasket blown because the head gasket seems to blow after 15-20 years, so you can get them cheap for $200-300. then you could use 70kW motor and still get to 55-60mph easily. i doubt if the porsche 911 is gonna have space for the batteries since it is already so compactly designed. i have seen several CRX conversions, and i have 3 or 4 of them myself, just don't have the heart to convert one since they are already so efficient.

 

[Doctorbass]

you ordered a motor from unique mobility? that is really a nice car. why couldn't they scrap a honda CRX. the ones from 84-87 would weigh under 1400lbs without the motor, there is space up front for some batteries along with the motor, and in the rear too. plus they are easy to find with the head gasket blown because the head gasket seems to blow after 15-20 years, so you can get them cheap for $200-300. then you could use 70kW motor and still get to 55-60mph easily. i doubt if the porsche 911 is gonna have space for the batteries since it is already so compactly designed. i have seen several CRX conversions, and i have 3 or 4 of them myself, just don't have the heart to convert one since they are already so efficient.

The porshe project is not MY project.. I am associated with the guys that work on it and my job is the battery and all surrounding stuff.

They did not choose a CRX like Metric mind did or any others.. simply because the car that have acces is a porshe.
The battery pack will be spit into 5 modules to get the same handling vs weight placement than a normal porshe.
Now let's return to the original thread :wink:

Doc

 

[Doctorbass]

UPDATE.. 6feb 2009.. Ypedal green 12Ah LFP from ebikes.ca tested!

Please note that thisone is a 12Ah and not 10Ah like the rest of the tests.

Compared to the other cells the curve look more regular from one discharge to another..

But it did not the 12Ah rated... eventhou at 1A

I tested it at 1, 5, 10, 20, 30 and 35A.. just like the other cells.. not in C rate.. like 1C 2C..etc otherwise i would need to discharge 1C at 12A and that just can not be conpared to the rest of cells...

Please note that the last 35A curve stopped before reaching the 2.0V limit.. that is due to the temp limit of the CBA so i tried to extrapolate and continu the curve by drawing the rest of it.. you can see if you zoom on it..

The voltage measured directly on the cell screw correspond in the +/-1mV percision compared to the graph wich is still good and confirm that every connections between the cell and the CBA are still ok.. (cheched the calibration it few days ago and it was also still perfect)

Now here is the graph for you Ypedal.. and others :wink:

Doc

 

[Ypedal]

Sweeeet !!

I need to whip out my ruler and calculate the volume of the 12ah cell vs PSI vs duct tape cell .. what an exciting friday night !!

Damit.. i totally forgot to include a foil 12ah LFP cell from the early Cheer Ocean days.. prior to Ping ! ( only other person who i know that has used these cells is Oatnet. )

 

[oatnet]

UPDATE.. 6feb 2009.. Ypedal green 12Ah LFP from ebikes.ca tested!

Thanks again for taking the time to do this testing Doc - I know these cells really well, they powered a whole series of prototypes for me, so your tests give me an excellent baseline to compare other cells to. Sometime I would love to see the 35ah curves for your recent tests (yesa, headway, PSI, and ebikes.ca) overlaid, ah and wh - but is Friday night, you have worked hard, I hope you are out having fun. 8)

Damit.. i totally forgot to include a foil 12ah LFP cell from the early Cheer Ocean days.. prior to Ping ! ( only other person who i know that has used these cells is Oatnet. )

<grin> Oy, Cheer Ocean and the Flintstone Chargers (sounds like a cheap cover band) from the fleet of first generation of LiFePO4 packs I tested in summer of '07. This is the only one of those cheap packs I kept - I had overdischarged cell#11 on both 36v packs when bank#11 on a flintstone charger died , didn't seem right to pass them on like that. I later replaced the dead cells with two spare falconEV cells (like the ones doc just tested), and right now they are on the Prototype I am using to mess around with gear motors. That generation was the first and worst, but it definitely has lasted long beyond the three months an early naysayer was touting :lol:

I have a Cheer Ocean full-pack discharge curve from the dark ages, at a piddly 2.37amps:
viewtopic.php?f=14&t=2089&p=27604

BTW Gaston, thank you too, for sending the cell to Doc for testing!
-JD

 

[Doctorbass]

A little sumarry of all these 4 measureds cells.

(Important NOTE: all EXCEL data and CBA II files are still availlable to people that ask me for them :wink: )

 

[Doctorbass]

UPDATE.. 6feb 2009.. Ypedal green 12Ah LFP from ebikes.ca tested!

Thanks again for taking the time to do this testing Doc - I know these cells really well, they powered a whole series of prototypes for me, so your tests give me an excellent baseline to compare other cells to. Sometime I would love to see the 35ah curves for your recent tests (yesa, headway, PSI, and ebikes.ca) overlaid, ah and wh - but is Friday night, you have worked hard, I hope you are out having fun. 8)

-JD[/quote]

:lol: Friday night.. lol.. I play with these cell measurement. this is not depleasant job for me!

here are your graph JD :wink:

 

[AndyH]

I have $10US that says the BMI cell won't perform significantly better than the PSI cell... 8)

 

[Doctorbass]

Have you ever saw a Cells meeting?

:lol:

 

[slayer]

hey doc how about a 5p a123 test.?
i would like to see that

 

[Doctorbass]

lol!!! Do you mean this A123 group?




you just read my mind man! :lol:

Comming soon!! watta nice idea !!!


Doc

 

[oatnet]

lol!!! Do you mean this A123 group? you just read my mind man! :lol: Comming soon!! watta nice idea !!!
Doc

Oh YEAH! Doc, this thread just keeps getting better and better.

Friday night.. lol.. I play with these cell measurement. this is not depleasant job for me!

Friday night... And we're sitting here reading it - not an unpleasant job for us either! Fascinating how the 10ah/5c Headway and 12ah/3c Green cells line up on much of both curves, similar powder? I wonder why the Headway's voltage drops off early and then aligns with the Green cell again.

I have $10US that says the BMI cell won't perform significantly better than the PSI cell...

Sucker Bet!

Ya know, I lost track of the fact that PSI=BMI, that discharge curve is higher than I would expect, having seen that early LifeBatt cell curve Bob published. I was thinking LifeBatt were 3.3v, am I confused, or are the later cells charged to 3.65v?

-JD

 

[GGoodrum]

Pretty much all LiFePO4 cells have a "nominal" voltage of around 3.3V, and all optimally get charged to 3.65V.

 

[liveforphysics]

I'm going to send you regular cheap zippy 5Ah LiPo cells soldered together to be a single 10Ah cell.

We can see if you can find any measureable voltage drop with just a 35amp load

Then you can calculate energy and energy density so people can see what the lure of the "darkside" battery chemistry is all about,

 

[olaf-lampe]

I'm going to send you regular cheap zippy 5Ah LiPo cells soldered together to be a single 10Ah cell.

We can see if you can find any measureable voltage drop with just a 35amp load

Then you can calculate energy and energy density so people can see what the lure of the "darkside" battery chemistry is all about,

yes, and after the discharge orgy, we overcharge all of them about 10% and then make a judgement

just kidding
Olaf

 

[liveforphysics]

Ok, but we do the overcharging at your house, not mine

 

[Deepkimchi]

I'm running the Lifebatt 10 ah pack & FalconEV Green 12 ah packs in series without an LVC. I'm glad in the past I picked 8ah as a "be home" point.

Namely if I went joy riding, wouldn't go past 4 ah use then I'd turn it back home.

The graphs seem to show my choice was a good idea. Not starting any long stories why I'm running w/o LVC.

DK

 

[Deepkimchi]

Since a 29V cutoff on a 36V pack gives 2.4V (when you have to start pedalling), I wonder which is better?

Seems like PSI and Yesa give more uumph V for a shorter time before pedalling.

Headway and the 12ah pack are lower immediately, but a longer time before the pedal point.

DK

 

[Toorbough ULL-Zeveigh]

man, that LFP discharge is billiard table flat
whats especially impressive that it holds steady even at the highest rates.
which means it can deliver even higher amps where the other would probably start to tank.

Doc, which characteristic do u place more importance on, higher voltage maintenance or flat discharge?
i'm thinking the latter is preferable since u can compensate for the voltage sag by adding only a few more cells.
this may be why Justin chose to sell these out of all the different ferro-phosphate flavours he tested.
a123 should be equally flat, but with 5 in parallel with little drop in V i expect, interested in seeing how much exactly.
great work as always.

 

[ZapPat]

I'm going to send you regular cheap zippy 5Ah LiPo cells soldered together to be a single 10Ah cell.

We can see if you can find any measureable voltage drop with just a 35amp load

Then you can calculate energy and energy density so people can see what the lure of the "darkside" battery chemistry is all about,

I picked up five zippy flightmax 15C packs when you pointed out the special a couple weeks ago, and I am very impressed by them so far.

Here's a picture of one pack (5 cells, 18.5V nominal, 5Ah), and it measures 145mm X 40mm X 50mm:
View attachment Zippy LiPo 15C flighmax 5Ah, 5 cell 18.5V nominal.jpg
Since a lifebatt/PSI/BMI is about 140mm long X 38mm dia, this would mean that a LiPo pack made with these would be almost 2.5X more energy dense than a same sized PSI/etc pack!

GO Doc, Go!!! You really should consider changing your name to DocBatt after this, since your excellent comparison charts are certainly going to be used by many internet surfers everywhere to make enlightened battery choices.

 

[TylerDurden]

I picked up five zippy flightmax 15C packs when you pointed out the special a couple weeks ago, and I am very impressed by them so far.

Blue flames... truth in packaging.

 

[liveforphysics]

I'm glad you are enjoying those batteries Once you go LiPo, it's very tough to want to lug around anything else, and put up with wimpy discharge rates, battery heating, saggy voltage etc. Of course if your application requires a saftey chemistry, then you gotta pick from the saftey chemistry batteries.

And Fantastic work Doc! You are a major asset to not only this forum, but to people all around the world who have an interest in making battery powered devices. PM me your address.

Best Wishes,
-Luke