Hobbyking LiFeP04 ?

neptronix

neptronix

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First off, i noticed HK was havving a lipo sale.. looks like mostly odds and ends, but there are some good deals for the DE/AUS warehouses..
http://www.hobbyking.com/hobbyking/store/lipo_sale.asp

It looks like they are phasing out some old products!

Also check out what's in the 'new' section on the front page!!
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14074

8400mAh 4s!! :shock:

I wonder.. will we get 5s/6s 8400mAh batteries? in 20c for cheaper? could be so! Looks like these SKUs haven't even filtered into the main product database, so more could be coming.

RC guys must be psyched. That means they can run for 2 minutes longer... lol
 
Even weirder!
I just noticed those were lifepo4.

hmmm... 30c lifepo4? very weird!
 
For those of us in Europe, the 5000mAh packs from the German warehouse look reasonable. Better value in terms of Wh per $ than the 5800mAH packs. I'm tempted to get some 5S, 5000mAh packs, but as I don't need them until the Spring it seems a bit of a waste to buy them now and have them hanging around, unused, for months.

Jeremy
 
Jeremy Harris said:
For those of us in Europe, the 5000mAh packs from the German warehouse look reasonable. Better value in terms of Wh per $ than the 5800mAH packs. I'm tempted to get some 5S, 5000mAh packs, but as I don't need them until the Spring it seems a bit of a waste to buy them now and have them hanging around, unused, for months.

Jeremy
Click to expand...

I guess that's exactly why they are so cheap ATM. The whole rc world is waiting for spring to come. And HK probably overestimated the european market. I bought my batteries from hongkong for a lower price instead of using the german warehouse. Now the prices are almost the same, without taxes a.s.o.
-Olaf
 
I wonder how much life/capacity would be lost by just storing the cells in a cool place for a few months, after making sure they were all properly charged and balanced first?

I'm wondering whether or not to just go ahead and get some cells from HK now, rather than risk either a price increase or more severe shipping costs come the spring.

Jeremy
 
I could do, the problem is that I know that I need a fairly large pack for the revived Yamaha project, around 30Ah at 15S. It's quite a lot of money to risk on cells that might lose capacity or performance after a few months of storage. If I could be reasonably certain that the cells would be happy to be stored for a few months then I think I'd buy now, as I have a horrible feeling that shipping LiPo in quantity is going to get harder/more expensive before too long.

Jeremy
 
LiFePo4 Flat Packs!!!!!!!!! :)))



ZIPPY Flightmax 8400mAh 4S2P 30C LiFePo4 Pack
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=14074
Z84004S-30.jpg


Zippy Flightmax LiFePo4 flat Pack batteries deliver full capacity & discharge as well as being the best value batteries in the hobby market today!

Spec.
Capacity: 8400mAh
Voltage: 4S2P / 13.2V
Discharge: 30C Constant / 40C Burst
Weight: 1026g (including wire, plug & case)
Dimensions: 150mm x 52mm x 70mm
Balance Plug: JST-XH
Discharge Plug: 5.5mm Bullet-Connector




ZIPPY Flightmax 8400mAh 3S2P 30C LiFePo4 Pack
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=14073
Z84003S-30.jpg


Zippy Flightmax LiFePo4 flat Pack batteries deliver full capacity & discharge as well as being the best value batteries in the hobby market today!

Spec.
Capacity: 8400mAh
Voltage: 3S2P / 9.9v
Discharge: 30C Constant / 40C Burst
Weight: 772g (including wire, plug & case)
Dimensions: 147mm x 52mm x 53mm
Balance Plug: JST-XH
Discharge Plug: 5.5mm Bullet-Connector
 
need 8 packs for 40v 17Ahr ?

8 x $90 ... $720

which charger ?
 
I got all excited because i thought these were lipo & a lower price would appear for 15c/20c eventually. My bad :p

Anyways, i'm thinking this would be the most expensive pack of lifepo4 per cell ever, but those discharge rates are um... phenomenal if they are true.

These don't seem to be of any use to us. Ahh.. the hunt for the elusive > 5000mAh LiPo packs/cells continues.. :)
 
Minus a little loss of energy density, it's got all the things we love about hobbyking lipo:

High C discharge
High C charge
Modularity
A trusted vendor


And the best part about it is: I can order a lifepo4 BMS and charger from ping, bmsbattery.com, evassemble, or any of the other chinese websites for CHEAP! Plug and play baby!

I'm thinking 6 of these http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10311 @ 3s2p 58v9ah for $420 and as I get more money I can just add more batteries.

Sure the 9ah isn't much of a battery, but it's 5c charging. I could charge in less than 15 minutes! Of course that'd be a hard on a pack, so It'd be easier to go 1c.

I wonder though; If I get a 24s BMS can I only use 18s in it? This way I don't have to upgrade the BMS each time I upgrade my pack?
 
These work out to 79.7 cents a watt-hour; whereas the 20c zippy 6s lipoly packs go for 44.6 cents per watt-hr, the 30C Zippys go for 68.1 cents per watt-hr, and the 40c go for 68.5 cents per watt hr. The lifepo4 you mentioned carries energy density of 99.1 wh/kg, while that of the others is 132.8 wh/kg.

Lipo has higher energy density, the 40c packs are cheaper and lighter, and each pack carries more total energy (89.1 W-hr for Lifepo4 vs 111.0 for Lipo).

Hope that answers your question; I don't mean to shoot your idea down or anything because there's a major upside to lifepo4 and that is the safety factor. I wonder if these packs are really capable of 30-40c though...that seems very out there for the lifepo4 chemistry. The most powerful cells I've heard of are the A123 cells and I don't think those went much over 20c but don't quote me on that... could easily be more because they are known to be robust.
 
holy shit guys:

8400mAh 4S2P
http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14074

The swarm price is $75

$450 gets you 72v8.5ah a123 lifepo4

there's a major upside to lifepo4 and that is the safety factor.
Click to expand...

Not to mention not having to fool with chargers, balancers, and other R/C tomfoolery. Also a 1000 cycle lifespan.
 
From my understanding they are grossly overrated in the discharge. If they were remotely close to the Lipo in either power or capacity value you can bet more people would be using them.
 
Would love to see some discharge graphs, but it is still going to cost you $1000 to get a 16Ah 20cell pack made up and that is without the BMS...probably not needing of a BMS when using RC Chargers.

Is the 20 to 30 C real? Or is it uber saggy like most Lifepo4?
 
auraslip said:
a3162346-70-Normalized_30A.jpg

http://www.rcgroups.com/forums/showthread.php?t=1206770&page=4
:(
Click to expand...

Yeah, that's not terrible..... but it doesn't look like 30c.
The highest C rating i have ever seen for a lifepo4 cell is 10c thus far, and i think that is even an exaggeration or probably a burst discharge number. That is on ultra pricey lifepo4.

This stuff also consists of paralleled small cells.. and we know how variable the cell mAh can be on turnigy/zippy batteries.. yikes.

Also, these cells run at a lower voltage, so you will need more of them. 6s = roughly 5s

Yeah i thought these were cool too, for a few minutes :p
 
Super saggy, perhaps. But if put on a bike that only draws 2-3c, they should work ok. For the amp freaks, lipo baby.
 
72v of 10ah headways = 18lbs

72v of 8.5 ah hobbyking lifepo4 = 14lbs

Also building it up a pack out of these would be less stressful then with cylindrical cells. I wouldn't have to worry about my cat bbqing herself on accident. JK, but really I would probably mess something up. With these, all I have to solder is some bullet connects and the bms connections.

Brand new LiFePO4 batteries have been found to fail prematurely if they are deep discharged below 33% capacity too early. A break-in period of 20 cycles is currently recommended. While testing has shown that this battery can be charged at up to 5C rates, it recommended that this battery not be charged at rates higher than 2C to maximize the lifespan of the battery. Additionally, LiFe batteries should not be discharged below 2.5V per cell to avoid pre-mature failure and maximize battery life span.
Click to expand...

I wonder if the people testing these break their cells in. It would certainly explain all the complaints of cell swelling.

I also kinda wonder about the c rating. 1c? 3c? swbluto said 15c. ---- such variation....

In any case it might make a practical low power 36v battery - $300 for a 8.5ah battery that should last a few years.
 
Also, the advantages to Lifepo are more charge cycles.
They are probably cheaper in the long run.
And the headway/PSI cells are easier to change out a bad cell from a pack.
 
^--- what he said.

And with a lot of negative reports on these cells, i would stay away.
Our application is not a hell of a lot different than a lot of the RC stuff. We draw quite a bit of amps for sustained periods of time. If the RC guys are having problems, i'd steer clear.

It also seems like headways would be on par for the price.. then you'd have no worries about the pack itself ever. 1 cell in parallel vs 4 in parallel
 
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