Accumulator / battery suggestion (LiFePO4)


glenn

Still Fresh
Joined
Jun 19, 2006
Messages
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Please consider using LiFePO4 accumulator in Pandora:

Information:

http://en.wikipedia.org/wiki/Lithium_ir ... te_battery

Example: Pdf-file: http://www.rc-netbutik.dk/getdoc.asp?id ... 101E37DAE1 Quote: "...Curent test projecting excellent calendar life: 17% impedance growth and 23% capacity loss in 15 [fifteen!] years at 100% SOC [state-of-charge], 60 deg. C..."

http://wiki.openmoko.org/wiki/Wishlist/LiFePO4_Battery
Quote: "...
Advantages:
*1000+ (dis)charge deep-cycles.
*Low self-discharge; 5% / month at 25 deg. celcius
*Very electrically robust
*Very mechanically robust - can literally be nailed without explosion danger.
*-30...60 deg. celcius operating
*a123systems ANR26650M1 3.3V 2.3Ah can be charged in 15 minutes.
*a123systems ANR26650M1 3.3V 2.3Ah cells are laserwelded instead of crimping, which lower water losses and therefore extends celllife.
..."

-

Traditional (Li-ion (polymer)) lithium-accumulator only handles 300-500 (dis)charge deep-cycles:

How to prolong lithium-based batteries:
http://www.batteryuniversity.com/parttwo-34.htm
Quote: "... A lithium-ion battery provides 300-500 discharge/charge cycles. The battery prefers a partial rather than a full discharge. Frequent full discharges should be avoided when possible...Increasing internal resistance with cycle life and age is typical for cobalt-based lithium-ion, a system that is used for cell phones, cameras and laptops because of high energy density. The lower energy dense manganese-based lithium-ion, also known as spinel, maintains the internal resistance through its life but loses capacity due to chemical decompositions..."
 
Did you read the entire article you linked? LFPs have significant drawbacks, the two that stand out most being their comparatively low energy density and the fact that they are not available in any legitimate quantities.

These batteries are more suitable for applications where cost is more of a concern than size. Even if they were available (and even if the battery wasn't already set in stone), they would not be suitable for the Pandora.
 
Chip said:
Did you read the entire article you linked?

Yes.

( This correct link - not my former:
http://en.wikipedia.org/wiki/Lithium_ir ... te_battery
)

LFPs have significant drawbacks, the two that stand out most being their comparatively low energy density and the fact that they are not available in any legitimate quantities.

A few months/years ago this was correct. But not today:

http://www.google.dk/search?hl=da&q=a12 ... OR+euro%29

http://www.first-products.de/APR18650M1Beschreibung.htm
Quote: "...Für alle Aufträge die bis zum 31. Juli 2008 bei uns eingehen, gilt der Einführungspreis von Euro 9,99 pro Zelle inkl. MWST zzgl. Versandkosten..."

They can even be bought in Denmark:

Hyperion A123:
http://www.rc-netbutik.dk/group.asp?group=135

LiFeP04 batterier akkupakker
SUNHIGH LiFe batterier:
http://iccom.dk/Hobby/Batterier/LiFe%20 ... terier.htm

This was in 2005: A123Systems Launches New Higher-Power, Faster Recharging Li-Ion Battery Systems:
http://www.greencarcongress.com/2005/11 ... s_lau.html
Quote: "...Twice the energy density of other Li-Ion HEV cells, with the highest power to weight ratio of any commercially available battery (2,700 W/kg at continuous discharge)...A123Systems’ first battery is now in production and being delivered to the Black & Decker Corporation for use in DEWALT power tools..."
 
Those round cell batteries are nearly as thick as the Pandora. They will not fit.

And again, the battery is already set in stone.
 
Chip said:
Those round cell batteries are nearly as thick as the Pandora. They will not fit.

And again, the battery is already set in stone.


are the batteries for the pandora customized? Or can I get a better one with more MaH juice?
 
Chip said:
And again, the battery is already set in stone.

OK, I have searched a little for you - but I do not know the Pandora battery dimensions:

Polymer Li-Fe-PO4 Cell: 8790160L 3.2V 10 Ah, 2 C Drain Rate (LFP-8790160L):
http://www.batteryspace.com/index.asp?P ... rodID=4053
Quote: "...
$59.95
...
New Generation Polymer Li-Fe-PO4 Battery: High discharging rate, non explosive, lighter weight and much safe
...
* Energy density: 124 wh/kg
...
Dimensions (HxWxL) 8.9mmx92.5mmx163.0 mm
...
Weight 258 grams
..."

Detail Data Sheet:
http://www.batteryspace.com/prod-specs/ ... 4_poly.pdf

You could contact / ask them if a suitable flat-pack is available:
AA Portable Power Corp:
http://www.aaportablepower.com/

Li-ion (LiFePO4) Battery Packs:
http://www.batteryspace.com/index.asp?P ... egory=1171

-

For comparison:

http://en.wikipedia.org/wiki/Lithium-ion_battery
Quote: "...
Energy/weight 160 Wh/kg [which "quickly" drops! After 1 year @ 25C 0.8*160 =128 Wh/kg]
..."

How to prolong lithium-based batteries:
http://www.batteryuniversity.com/parttwo-34.htm
Quote: "...
The speed by which lithium-ion ages is governed by temperature and state-of-charge. Figure 1 illustrates the capacity loss as a function of these two parameters.
...
25 C...[100% charge level]...80% after 1 year
40 C...[100% charge level]...65% after 1 year
..."

Compare that to LFP's 124 wh/kg [drops slowly!]
 
Glenn said:
Dimensions (HxWxL) 8.9mmx92.5mmx163.0 mm
Thin enough, but too large in the other dimensions. Pandora's dimensions are 140x83x27mm (whole device, not just battery compartment).
 
Really if you're talking performance right now it's pretty tough to beat a lithium-polymer, although these can be quite volatile. A123 systems batteries are not simple LiFePO4. They have a very specific design, with specific applications, this is not one. I've been working with high performance batteries for the last 12 years, so believe me that I am keeping this very brief. The battery that they selected for the pandora is pretty much as ideal as it could be. The charactoristics of Li-ion batteries have been proven many time over. There is a reason why they are the current standard in electronics exactly like the pandora. If the performance and cost were are far reaching as you seem to be implying they would have already been adopted by many communities dealing with high performance batteries which they have not. Beleive it or not, the best bang for your buck in high drain electronics, which certainly does not include the pandora, are still NiMH, given that they are very cheap compared to their capacity and reliability. Even Lithium Manganese is more widely used than Litium-Iron-Phosphate last time I checked.
 
Loswave said:
...Even Lithium Manganese is more widely used than Litium-Iron-Phosphate last time I checked.

The reason could be that it is a very new battery type?:

http://en.wikipedia.org/wiki/Lithium_ir ... te_battery
Quote: "...
LiFePO4 was identified as a cathode material for rechargeable lithium batteries by John Goodenough's research group at the University of Texas in 1997.
...
Products using the carbonized and doped nanophosphate materials developed by Chiang are now in high volume mass production by A123Systems and various other companies and are in use in industrial volumes by major corporations including Black and Decker, DeWalt, General Motors, Daimler, Cessna and BAE Systems among others.
...
Being a lithium-ion-derived chemistry, the LiFePO4 chemistry shares many of the advantages and disadvantages of lithium ion chemistry. Key differences are safety and current rating. Cost is claimed to be a major difference, but that cannot be verified until the cells are more widely accepted.
...
Lithium Technology Corp. announced in May 2007 the immediate availability of cells large enough for use in hybrid cars, claiming they are "the largest cells of their kind in the world."[5].

This type of battery is used on the One Laptop per Child (OLPC) project [6].

Segway Personal Transporters advanced from a 10 mile range to a 24 mile range with Valence Lithium Phosphate technology.[citation needed]

OLPC batteries are manufactured by BYD Company of Shenzhen, China, the world's largest producer of Li-ion batteries. BYD, also a car manufacturer, plans to use Lithium Iron Phosphate batteries to power its own PHEV, the F3DM and F6DM (Dual Mode), which will be the first plug-in hybrid vehicles on sale in the world. It plans to mass produce the cars in 2009.
..."
 
Again, all the listed applications for these batteries in the last quote you gave are high drain, the pandora does not fit in this category. Besides which, if you feel that strongly, there will be nothing keeping you from finding a LFP battery to put in your pandora when you get it. Another thing I will however point out, and warn you of is the fact that every battery chemistry has it's own unique charging characteristics, as well as their own unique discharging characteristics. Such as:
NiCd - Negative deltaV - meaning to get a full charge, you charge until the battery voltage starts to drop
NIMH - 0 deltaV - when the battery voltage stops rising, it's full
lithium ion - CC/CV - First charging phase is at a constant current, second is constant voltage
lithium polymer - also CC/CV- however there are important differences between the two, mostly having to do with the discharge cycle.

My point being that these have to be planned for in hardware, because the charger for the battery will actually be onboard, as well as the battery management circuitry, and the design is already done. So you'll need a go between board to manage your new battery, or to completely change hardware.

I'm not saying it's a bad chemistry, I'm just saying it's not totally ideal for this situation. Availability is also and important factor, I mean, it's incredibly easy to get your hands on a Lithium Ion battery.

If you want to talk pure performance wise LiFePO4 is still not even close to the best. I'd happily take one of the newer, and safe variants of a lithium polymer which supports high discharge rates, and trumps LFPs with an average of ~170 Wh/kg. Then there is always zinc air at 370 Wh/kg and aluminum air at 1300 Wh/kg, although neither of these two are rechargeable.

Finally, you talk about how fast the capacity drops on lithium-ion batteries...the problem there being that the article you reference is talking about batteries that drain at rates between 20 and 40C. If your not familiar with C in the litium battery world, allow me to clarify. C is the standard charge rate. With batteries the size we are talking, it is usually between 1 and 1/2 the current of it's capacity. ie, a 4000 mah high-drain li-ion battery would typically have a C of between 2 and 4 amps. Meaning it will charge in an hour or two. So, we're talking about discharging at up to 40 times that! These high performance batteries will tend to wear themselves out. At no time do I expect that the pandora will draw anything over an amp, in fact, the only reason I can even fathom it drawing an amp is because the USB Host port is said to be able to sink the full and proper 500 mA. In a non-high drain situation, as can be extrapolated from your data, the capacity on pandora's battery should in fact decrease very slowly.

To be honest though I'm half suprised no one has come on with the idea that we should scrap batteries entirely and power it with Supercapacitors...
 
Loswave said:
Finally, you talk about how fast the capacity drops on lithium-ion batteries...the problem there being that the article you reference is talking about batteries that drain at rates between 20 and 40C. If your not familiar with C in the litium battery world, allow me to clarify. C is the standard charge rate.

How to prolong lithium-based batteries:
http://www.batteryuniversity.com/parttwo-34.htm
Quote: "...
The speed by which lithium-ion ages is governed by temperature and state-of-charge. Figure 1 illustrates the capacity loss as a function of these two parameters.
...
25 C...[100% charge level]...80% after 1 year
40 C...[100% charge level]...65% after 1 year
..."

I could not find the degree sign - 25 C is just 25 degrees celcius (temperature). Please look in the articles table.
 
Very well, but that does not address any of my other arguments, besides which, quotes from another article can not be a de facto retort in and of themselves. Besides which I have several lithium ion batteries which I have had for over 2 years and haven't exhibited more than a 5% capacity loss, and yes, I really do keep track of my batteries. I've been into hobbies where this is necessary for far to long not to.

In any case, if you can provide the charging characteristics as well as the pertinent discharging characteristics, that would be handy as I have been unable to procure them for comparative purposes.

P.S. The ° sign is mapped on a U.S. English keyboard in windows to holding alt while entering 0176 on the numpad. You can find it in the charmap, accessible under accessories>system tools.
 
And if we're going to use archaic electronic terms, let's have a one-farad condenser powering the Pandora during battery swaps so it doesn't turn off. :p
 
Loswave arguments were pretty much correct up to the point where he messed up real bad about the 20C and 40C.
no one is looking to painfully almost short our batteries, right? (making it empty in ~1,5min is not a good idea) :p
( and yes, it should've been °C )
 
All of my arguments were correct, just that one of them was addressing an issue derived from me having a brain fart and forgetting completely that it was a reference to temperature... :wacko: It's been a long couple of days...
 
hehehe :p
anywayz, for the original purpose of having better battery life:
follow the recommended instructions on usual liion battery usage
have an extra battery, just in case i dont think its gonna be practical to keep switching batteries, i think its more suitable for replacing old ones that have lost their original life
maybe have a portable charger
and be happy that your pandora is very well designed when it comes to battery saving
the battery chosen for the pandora should have plenty of juice for you to play. you won´t be 2 or 3 days away from a chance of recharging it anyway ^_^
 
Loswave said:
In any case, if you can provide the charging characteristics as well as the pertinent discharging characteristics, that would be handy as I have been unable to procure them for comparative purposes.

Here you have it (again). Please ask the manufacturer about the exact charging and discharging characteristics:

http://wiki.openmoko.org/wiki/Wishlist/LiFePO4_Battery

A part of the page the link points to:


Info-links a123systems:
http://www.a123systems.com/
http://en.wikipedia.org/wiki/A123Systems
http://a123systems.textdriven.com/produ ... T_2008.pdf
http://media.hyperion.hk/dn/a123/123-brief.pdf
http://media.hyperion.hk/dn/a123/packas ... ckassy.pdf
Pdf-file: http://www.rc-netbutik.dk/getdoc.asp?id ... 101E37DAE1 Quote: "...Curent test projecting excellent calendar life: 17% impedance growth and 23% capacity loss in 15 [fifteen!] years at 100% SOC, 60 deg. C..."
* http://www.rcuniverse.com/forum/m_5921365/tm.htm
* Quote: "...according to our tesing, for 2.3AH high rate LiFe cell, the self-discharge rate is 4% of rated capacity per 28days...Jason's information is pretty close. We rate the cells at 5% cpacity loss per month...."
*DeWalt 36V Technology (A123 Systems):
** http://www.slkelectronics.com/DeWalt/index.htm
**Quote: "...The M1 cells behave differently from other Lithium technologies. The specified end of charge voltage is 3.6 volts rather than 4.2 volts....The M1 cell, on the other hand, accepts very little additional energy above 3.6V....So how do the M1 cells compare? Tests so far show that over the course of a couple of weeks, the loss of capacity is close to zero. That's a good thing!..."

Info-links sunhigh-battery:
* http://www.sunhigh-battery.com/sdp/4264 ... 38920.html Quote: "...The chemical structure of LiFePO4 used in SUNHIGH battery is very stable. The cycle life is extraordinary. The performance of the SUNHIGH's Fe- Battery is excellent for cycling at high temperature as well as for overcharge and over discharge..."


*Info AA Portable Power Corp:
**Polymer Li-Fe-PO4 Cell: 8790160L 3.2V 10 Ah, 2 C Drain Rate (LFP-8790160L):
** http://www.batteryspace.com/index.asp?P ... rodID=4053
**Quote: "...
**$59.95
**...
**New Generation Polymer Li-Fe-PO4 Battery: High discharging rate, non explosive, lighter weight and much safe
**...
** Energy density: 124 wh/kg
**...
**Dimensions (HxWxL) 8.9mmx92.5mmx163.0 mm
**...
**Weight 258 grams
**..."

**Detail Data Sheet: http://www.batteryspace.com/prod-specs/ ... 4_poly.pdf

**Ask for a suitable flat-pack:
**AA Portable Power Corp: http://www.aaportablepower.com/
 
No I don't think it is, for one it is not in the LiFePO4 section of that website and it has the cautions associated with regular Li-ion batteries. Either way 10ah will be quite a step up from four so I may do just as I said earlier and attach them to the bottom of the pandora since they fit the dimensions.
 
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