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

[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:

Zippy LiPo 15C flighmax 5Ah, 5 cell 18.5V nominal.jpg (73.55 KiB) Viewed 2042 times

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

[ZapPat]

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.

That's a pheonix, though, TD, so it'll just fly right back out of those nice blue flames to live again and again...

I actually ran three series packs to the ground the other day (until the power level dropped almost all of a sudden to almost nothing), without a BMS or any cell-level LVC. I then thought about all the over-discharged Lipo stories, where they catch fire while charging afterwards. So I charged them up anyways of course, and low and behold they sucked in all their Amp-hours without a problem, and still work great. Here's a site with very good battery info; read the end of the linked page, under "Lithium Charged but Not Guilty?". It's good to be vigilant and fully aware of possible dangers as with anything, but remember that fear is a mind-killer.

Anyways, anyone wanting to read/post about modern LiPos can check this thread here, and keep Doc's batt test thread here relatively clean (hit me Doc): LiPoly evolves while LiFePO4 is stagnant?

[Doctorbass]

like i said to Phil, this morning it was 4:20am when i was still playing with some A123 for preparing for test compare

I took some of those...(please note they come from "deffective pack" that had few cell low)

and i did a discharge to test the RI with 10 in parallel... and:

I measured....

1 miliohm.. lol .. exactly the corresponding 10 miliohm per cell but with 10 in parallel..

I'll measure every single cell of these 10 cells (picked from 2 or 3 dewalt pack) and will choose the 5 bests.

then i'll parallel them and measure them.

The pack with 5 parallel cells i showed was made owth the deffective low cells took appart from the deffective pack.

I always keep these cells eventhou they have 1700 or 1900mAh.. The last time i measured it it had 8750mAh out of 5parallel low cells.

I plan to test it too and will compare low cells with good cells.. that will give us a real comparaison with bad and good cells

In fact i would almost call them bad cause they had less than 1V each when i took them appart.

I plan that i'll need 4 days to measure them.

results soon!

Thanks for yuor encouragement guys!.. (is that the good word?..) I often use Babelfish translatoe..

Doc

[Doctorbass]

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.

Yeah.. that might be an idea since on google there is only 5 or 6 entry on that name...

But i dont know... it's been for long time i was called Doctorbass and that i adopted that name..

When i was almost playing with subwoofer and car audio amplifier few years ago, some friends called me that name and that continued for me.. that began on Dbdragracing website.. years 2000 or 1999 if i remember correctly..

I agree that ending doc with "bass" does less sens than batt..

but you guys what do you think..? does it really matter rebaptizing me?

... replacing 2 S with 2 T





Doc

[dnmun]

stick with drbass, can you measure the internal resistance on the individual bad a123 cells with your mega charger thingy, before charging them up? and then later of course.

[Doctorbass]

stick with drbass, can you measure the internal resistance on the individual bad a123 cells with your mega charger thingy, before charging them up? and then later of course.

i'll put that on the Biiiiiiig to do list

Doc

[oatnet]

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

That has been my experience, but I thought a read somewhere that LifeBatt was peak-charged 3.35v, must have been wrong. Since it is 3.65v, I am really suprised that the Lifebatt in Bob's graph discharged 20a at @ .1v lower than the Headway. Granted this is an original green cell, but still... Of course, the current PSI=LifeBatt that Doc tested discharges at higher voltage than the Headway, I guess that is the relevant comparison.

-JD