LiFePO4 battery technolocy

My RC friends who use LiFePO4 swear by them. They handle high amperage drain and can be charged at higher amperage than other battery technology. They are not as popular in RC as they are heavier and larger than equal LiPo amperage. These differences are not a concern for sailplane use.

And of most importance, LiFePO4 cells do not have the explosion/fire risk of LiPo cells if charged incorrectly. FWIW,all LiPo cells I've seen are flat and thin and rectangular. All the LiFePO4 I've seen are cylindrical.

Absolutely, Lipo cells require balance maintenance. I cannot confirm but have read LiFePO4 cells are self balancing when connected in series and do not require an on board balance circuit or an external balancing plug.Please do your own due diligence.

Other than K2, all the LiFePO4 packs I've seen were home made packs using cylindrical cells taken from DeWalt tool power packs. It is my understanding the DeWalt cells are actually A123 brand LiFePO4 cells.

This is an outstanding battery and charger forum. http://www.rcgroups.com/batteries-and-chargers-129/

Safe flights.

On Monday, October 15, 2012 9:49:11 AM UTC-5, (unknown) wrote:
My RC friends who use LiFePO4 swear by them. They handle high amperage drain and can be charged at higher amperage than other battery technology. They are not as popular in RC as they are heavier and larger than equal LiPo amperage. These differences are not a concern for sailplane use.



And of most importance, LiFePO4 cells do not have the explosion/fire risk of LiPo cells if charged incorrectly. FWIW,all LiPo cells I've seen are flat and thin and rectangular. All the LiFePO4 I've seen are cylindrical.



Absolutely, Lipo cells require balance maintenance. I cannot confirm but have read LiFePO4 cells are self balancing when connected in series and do not require an on board balance circuit or an external balancing plug.Please do your own due diligence.



Other than K2, all the LiFePO4 packs I've seen were home made packs using cylindrical cells taken from DeWalt tool power packs. It is my understanding the DeWalt cells are actually A123 brand LiFePO4 cells.



This is an outstanding battery and charger forum. http://www.rcgroups..com/batteries-and-chargers-129/



Safe flights.

There are tons of non-cylindrical LiFePo4 batteries here
http://www.hobbyking.com/hobbyking/store/index.rc

They make cells of all types of cell numbers and capacities. I tried them in the past for RC use and they were not very reliable then(2-3 years ago).
The prices are modest since they sell the naked cells with balance charge plug and power leads. You need your own charger but they can also be had at Hobbyking. Note that they have a warehouse in the USA.

Yes J7, you are correct. However the flat rectangular cells offered by HobbyKing and are lower amperage cells and not suitable to soaring amperage requirements unless you combined multiple packs in parallel. This is too complicated for my likes.

My interest is having only four cells wired in series providing 10, 12, or better yet 15 amps such as these examples.

RAS moderators and et al please note. In no way am I endorsing the following products or trying to sell them. Information is for reference only.

http://www.ebay.com/itm/4PCS-12V-LiF...e m33752e1ec6

http://www.ebay.com/itm/4PCS-12V-LiF...e m33753e0bb2

http://www.ebay.com/itm/4PCS-12V-LiF...e m337698b7ad

The 10 amp and 12 amp cells should fit in existing battery wells. The 15 amps cells will probably require battery well modification.

LiFePO4 cells certainly are the "now" technology and in my opinion offer the best performance and longevity for the buck today.

Got juice?


On Monday, October 15, 2012 1:25:53 PM UTC-4, wrote:
On Monday, October 15, 2012 9:49:11 AM UTC-5, (unknown) wrote:

My RC friends who use LiFePO4 swear by them. They handle high amperage drain and can be charged at higher amperage than other battery technology. They are not as popular in RC as they are heavier and larger than equal LiPo amperage. These differences are not a concern for sailplane use.







And of most importance, LiFePO4 cells do not have the explosion/fire risk of LiPo cells if charged incorrectly. FWIW,all LiPo cells I've seen are flat and thin and rectangular. All the LiFePO4 I've seen are cylindrical.







Absolutely, Lipo cells require balance maintenance. I cannot confirm but have read LiFePO4 cells are self balancing when connected in series and do not require an on board balance circuit or an external balancing plug.Please do your own due diligence.







Other than K2, all the LiFePO4 packs I've seen were home made packs using cylindrical cells taken from DeWalt tool power packs. It is my understanding the DeWalt cells are actually A123 brand LiFePO4 cells.







This is an outstanding battery and charger forum. http://www.rcgroups.com/batteries-and-chargers-129/







Safe flights.



There are tons of non-cylindrical LiFePo4 batteries here

http://www.hobbyking.com/hobbyking/store/index.rc



They make cells of all types of cell numbers and capacities. I tried them in the past for RC use and they were not very reliable then(2-3 years ago).

The prices are modest since they sell the naked cells with balance charge plug and power leads. You need your own charger but they can also be had at Hobbyking. Note that they have a warehouse in the USA.

On Monday, October 15, 2012 7:13:11 PM UTC-5, (unknown) wrote:
Yes J7, you are correct. However the flat rectangular cells offered by HobbyKing and are lower amperage cells and not suitable to soaring amperage requirements unless you combined multiple packs in parallel. This is too complicated for my likes.



My interest is having only four cells wired in series providing 10, 12, or better yet 15 amps such as these examples.



RAS moderators and et al please note. In no way am I endorsing the following products or trying to sell them. Information is for reference only.



http://www.ebay.com/itm/4PCS-12V-LiF...e m33752e1ec6



http://www.ebay.com/itm/4PCS-12V-LiF...e m33753e0bb2



http://www.ebay.com/itm/4PCS-12V-LiF...e m337698b7ad



The 10 amp and 12 amp cells should fit in existing battery wells. The 15 amps cells will probably require battery well modification.



LiFePO4 cells certainly are the "now" technology and in my opinion offer the best performance and longevity for the buck today.



Got juice?





On Monday, October 15, 2012 1:25:53 PM UTC-4, wrote:

On Monday, October 15, 2012 9:49:11 AM UTC-5, (unknown) wrote:



My RC friends who use LiFePO4 swear by them. They handle high amperage drain and can be charged at higher amperage than other battery technology.. They are not as popular in RC as they are heavier and larger than equal LiPo amperage. These differences are not a concern for sailplane use.















And of most importance, LiFePO4 cells do not have the explosion/fire risk of LiPo cells if charged incorrectly. FWIW,all LiPo cells I've seen are flat and thin and rectangular. All the LiFePO4 I've seen are cylindrical.















Absolutely, Lipo cells require balance maintenance. I cannot confirm but have read LiFePO4 cells are self balancing when connected in series and do not require an on board balance circuit or an external balancing plug.Please do your own due diligence.















Other than K2, all the LiFePO4 packs I've seen were home made packs using cylindrical cells taken from DeWalt tool power packs. It is my understanding the DeWalt cells are actually A123 brand LiFePO4 cells.















This is an outstanding battery and charger forum. http://www.rcgroups.com/batteries-and-chargers-129/















Safe flights.







There are tons of non-cylindrical LiFePo4 batteries here



http://www.hobbyking.com/hobbyking/store/index.rc







They make cells of all types of cell numbers and capacities. I tried them in the past for RC use and they were not very reliable then(2-3 years ago).



The prices are modest since they sell the naked cells with balance charge plug and power leads. You need your own charger but they can also be had at Hobbyking. Note that they have a warehouse in the USA.

Dear Unknown,
Here is the battery I just ordered with the intent to replace my 10Ah NiMH battery dedicated to the transponder. It is ready for usage, no soldering except for the fuse and the plug.
http://www.hobbyking.com/hobbyking/s...dproduct=20645
This is a 8400mAh 4S cell with a 30C discharge rate, you can fry your eggs on the discharge of that thing (over 200A).

On Oct 16, 9:44*am, wrote:
On Monday, October 15, 2012 7:13:11 PM UTC-5, (unknown) wrote:
Yes J7, you are correct. However the flat rectangular cells offered by HobbyKing and are lower amperage cells and not suitable to soaring amperage requirements unless you combined multiple packs in parallel. This is too complicated for my likes.

My interest is having only four cells wired in series providing 10, 12, or better yet 15 amps such as these examples.

RAS moderators and et al please note. In no way am I endorsing the following products or trying to sell them. Information is for reference only.

http://www.ebay.com/itm/4PCS-12V-LiF...Cells-38120S-1...

http://www.ebay.com/itm/4PCS-12V-LiF...Cells-38140S-1...

http://www.ebay.com/itm/4PCS-12V-LiF...Cells-40152S-1...

The 10 amp and 12 amp cells should fit in existing battery wells. The 15 amps cells will probably require battery well modification.

LiFePO4 cells certainly are the "now" technology and in my opinion offer the best performance and longevity for the buck today.

Got juice?

On Monday, October 15, 2012 1:25:53 PM UTC-4, wrote:

On Monday, October 15, 2012 9:49:11 AM UTC-5, (unknown) wrote:

My RC friends who use LiFePO4 swear by them. They handle high amperage drain and can be charged at higher amperage than other battery technology. They are not as popular in RC as they are heavier and larger than equal LiPo amperage. These differences are not a concern for sailplane use.

And of most importance, LiFePO4 cells do not have the explosion/fire risk of LiPo cells if charged incorrectly. FWIW,all LiPo cells I've seen are flat and thin and rectangular. All the LiFePO4 I've seen are cylindrical.

Absolutely, Lipo cells require balance maintenance. I cannot confirm but have read LiFePO4 cells are self balancing when connected in series and do not require an on board balance circuit or an external balancing plug..Please do your own due diligence.

Other than K2, all the LiFePO4 packs I've seen were home made packs using cylindrical cells taken from DeWalt tool power packs. It is my understanding the DeWalt cells are actually A123 brand LiFePO4 cells.

This is an outstanding battery and charger forum. * *http://www..rcgroups.com/batteries-and-chargers-129/

Safe flights.

There are tons of non-cylindrical LiFePo4 batteries here

http://www.hobbyking.com/hobbyking/store/index.rc

They make cells of all types of cell numbers and capacities. *I tried them in the past for RC use and they were not very reliable then(2-3 years ago).

The prices are modest since they sell the naked cells with balance charge plug and power leads. *You need your own charger but they can also be had at Hobbyking. *Note that they have a warehouse in the USA.

Dear Unknown,
Here is the battery I just ordered with the intent to replace my 10Ah NiMH battery dedicated to the transponder. *It is ready for usage, no soldering except for the fuse and the plug.http://www.hobbyking.com/hobbyking/s...dproduct=20645
This is a 8400mAh 4S cell with a 30C discharge rate, you can fry your eggs on the discharge of that thing (over 200A).

I've fooled around with RC model batteries enough to know that I will
never put one of these in my full scale glider. In addition to
chemistry -- we'll presume for the moment that the HK LiFePO4
batteries are discharge & overcharge safe -- there's the issue of
short circuit protection *in* the battery pack. K2 puts all the
balance circuitry and such inside a sealed box where the connections
can be strain relieved, solidly anchored and protected in a way that
simply cannot be done in a hobby pack like this.

Electrically, I like your idea. But mechanically I think it needs to
be more robust.

Evan Ludeman / T8

Dear Herbert:

Referenced pack looks good.

A K2 12 V x 10 amp LiFePO4 battery is +/- 151mm long, 65mm wide, and 98mm high.

Depending on how you stacked them, 2 of the referenced HobbyKing packs wired in parallel could be +/- 150mm long x 52mm wide x 140mm high with a good 1/2" of room on the side to "store" the extra wiring. If you can manage the additional 1-5/8" height, you are now sporting almost 17 amps per battery well.

(Note to self...reminded again engineers usually know what they are talking about.)

On Tuesday, October 16, 2012 9:44:32 AM UTC-4, wrote:
On Monday, October 15, 2012 7:13:11 PM UTC-5, (unknown) wrote:

Yes J7, you are correct. However the flat rectangular cells offered by HobbyKing and are lower amperage cells and not suitable to soaring amperage requirements unless you combined multiple packs in parallel. This is too complicated for my likes.







My interest is having only four cells wired in series providing 10, 12, or better yet 15 amps such as these examples.







RAS moderators and et al please note. In no way am I endorsing the following products or trying to sell them. Information is for reference only.







http://www.ebay.com/itm/4PCS-12V-LiF...e m33752e1ec6







http://www.ebay.com/itm/4PCS-12V-LiF...e m33753e0bb2







http://www.ebay.com/itm/4PCS-12V-LiF...e m337698b7ad







The 10 amp and 12 amp cells should fit in existing battery wells. The 15 amps cells will probably require battery well modification.







LiFePO4 cells certainly are the "now" technology and in my opinion offer the best performance and longevity for the buck today.







Got juice?











On Monday, October 15, 2012 1:25:53 PM UTC-4, wrote:



On Monday, October 15, 2012 9:49:11 AM UTC-5, (unknown) wrote:







My RC friends who use LiFePO4 swear by them. They handle high amperage drain and can be charged at higher amperage than other battery technology. They are not as popular in RC as they are heavier and larger than equal LiPo amperage. These differences are not a concern for sailplane use.































And of most importance, LiFePO4 cells do not have the explosion/fire risk of LiPo cells if charged incorrectly. FWIW,all LiPo cells I've seen are flat and thin and rectangular. All the LiFePO4 I've seen are cylindrical.































Absolutely, Lipo cells require balance maintenance. I cannot confirm but have read LiFePO4 cells are self balancing when connected in series and do not require an on board balance circuit or an external balancing plug..Please do your own due diligence.































Other than K2, all the LiFePO4 packs I've seen were home made packs using cylindrical cells taken from DeWalt tool power packs. It is my understanding the DeWalt cells are actually A123 brand LiFePO4 cells.































This is an outstanding battery and charger forum. http://www.rcgroups.com/batteries-and-chargers-129/































Safe flights.















There are tons of non-cylindrical LiFePo4 batteries here







http://www.hobbyking.com/hobbyking/store/index.rc















They make cells of all types of cell numbers and capacities. I tried them in the past for RC use and they were not very reliable then(2-3 years ago).







The prices are modest since they sell the naked cells with balance charge plug and power leads. You need your own charger but they can also be had at Hobbyking. Note that they have a warehouse in the USA.



Dear Unknown,

Here is the battery I just ordered with the intent to replace my 10Ah NiMH battery dedicated to the transponder. It is ready for usage, no soldering except for the fuse and the plug.

http://www.hobbyking.com/hobbyking/s...dproduct=20645

This is a 8400mAh 4S cell with a 30C discharge rate, you can fry your eggs on the discharge of that thing (over 200A).

On 10/16/2012 8:06 AM, Evan Ludeman wrote:

Dear Unknown, Here is the battery I just ordered with the intent to
replace my 10Ah NiMH battery dedicated to the transponder. It is
ready for usage, no soldering except for the fuse and the
plug.http://www.hobbyking.com/hobbyking/s...dproduct=20645


This is a 8400mAh 4S cell with a 30C discharge rate, you can fry your
eggs on the discharge of that thing (over 200A).

I've fooled around with RC model batteries enough to know that I
will never put one of these in my full scale glider. In addition to
chemistry -- we'll presume for the moment that the HK LiFePO4
batteries are discharge & overcharge safe -- there's the issue of
short circuit protection *in* the battery pack. K2 puts all the
balance circuitry and such inside a sealed box where the connections
can be strain relieved, solidly anchored and protected in a way that
simply cannot be done in a hobby pack like this.

Electrically, I like your idea. But mechanically I think it needs
to be more robust.

THe HobbyKing pack is designed toys that don't have people in them. I'd
have more confidence in it if it had a battery management system built
into it and there was a datasheet listing the manufacturer, charging
requirements, cycle life, etc.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

On Tuesday, October 16, 2012 12:40:54 PM UTC-5, Eric Greenwell wrote:
On 10/16/2012 8:06 AM, Evan Ludeman wrote:



Dear Unknown, Here is the battery I just ordered with the intent to

replace my 10Ah NiMH battery dedicated to the transponder. It is

ready for usage, no soldering except for the fuse and the

plug.http://www.hobbyking.com/hobbyking/s...dproduct=20645





This is a 8400mAh 4S cell with a 30C discharge rate, you can fry your

eggs on the discharge of that thing (over 200A).



I've fooled around with RC model batteries enough to know that I

will never put one of these in my full scale glider. In addition to

chemistry -- we'll presume for the moment that the HK LiFePO4

batteries are discharge & overcharge safe -- there's the issue of

short circuit protection *in* the battery pack. K2 puts all the

balance circuitry and such inside a sealed box where the connections

can be strain relieved, solidly anchored and protected in a way that

simply cannot be done in a hobby pack like this.



Electrically, I like your idea. But mechanically I think it needs

to be more robust.



THe HobbyKing pack is designed toys that don't have people in them. I'd

have more confidence in it if it had a battery management system built

into it and there was a datasheet listing the manufacturer, charging

requirements, cycle life, etc.



--

Eric Greenwell - Washington State, USA (change ".netto" to ".us" to

email me)

Eric and Evan: you can't have it both ways, either the LiFePo chemistry is safe or it isn't. If you agree that there is no safety difference between the cheap HK cells and those you find in the referenced motorcycle batteries, the fact that HK is used in "toys" should not make a difference. Apropos toys, what do you think the average American Joe is calling our gliders? I will of course encase the HK battery and provide a 5A fuse inside that enclosure before trying it in my glider. I'll let you all know how it goes.

On Oct 17, 9:39*am, wrote:
On Tuesday, October 16, 2012 12:40:54 PM UTC-5, Eric Greenwell wrote:
On 10/16/2012 8:06 AM, Evan Ludeman wrote:

Dear Unknown, Here is the battery I just ordered with the intent to

replace my 10Ah NiMH battery dedicated to the transponder. *It is

ready for usage, no soldering except for the fuse and the

plug.http://www.hobbyking.com/hobbyking/s...dproduct=20645

* This is a 8400mAh 4S cell with a 30C discharge rate, you can fry your

* eggs on the discharge of that thing (over 200A).

I've fooled around with RC model batteries enough to know that I

will never put one of these in my full scale glider. *In addition to

chemistry -- we'll presume for the moment that the HK LiFePO4

batteries are discharge & overcharge safe -- there's the issue of

short circuit protection *in* the battery pack. *K2 puts all the

balance circuitry and such inside a sealed box where the connections

can be strain relieved, solidly anchored and protected in a way that

simply cannot be done in a hobby pack like this.

Electrically, I like your idea. *But mechanically I think it needs

to be more robust.

THe HobbyKing pack is designed toys that don't have people in them. I'd

have more confidence in it if it had a battery management system built

into it and there was a datasheet listing the manufacturer, charging

requirements, cycle life, etc.

--

Eric Greenwell - Washington State, USA (change ".netto" to ".us" to

email me)

Eric and Evan: *you *can't have it both ways, either the LiFePo chemistry is safe or it isn't. *If you agree that there is no safety difference between the cheap HK cells and those you find in the referenced motorcycle batteries, the fact that HK is used in "toys" should not make a difference. *Apropos toys, what do you think the average American Joe is calling our gliders? *I will of course encase the HK battery and provide a 5A fuse inside that enclosure before trying it in my glider. *I'll let you all know how it goes.

Herb: there's a lot to go wrong here that has nothing whatsoever to do
with chemistry, and this was my point. A fuse external to the pack
will do nothing to protect you from an internal short or a short
across one of the cells. Be especially critical of those balance
leads, I've had issues with those on LiPo packs.

We're talking about low probability events here... but event with
potentially high impact. If you install this battery and use it in
your glider, chances are 99%+ that it will work out fine for the next
year.

Here's my second point: this will not prove that this is safe. Humans
are extraordinarily bad at assessing risks in the 0.01 - 1% range. We
do something a little edgy and get away with it 20 times (thermalling
off a ridge with 150' of clearance, let's say) and think "we've got
this figured out"... when statistically we'll almost certainly see it
go wrong if we do that same thing 1000 more times. If ten thousand of
us install those HK batteries, I am confident that we *will* have
problems. Those batteries are designed for high discharge rate
performance and the compromise is safety. This is acceptable for
toys. Much less so for human carrying vehicles.

LiFePO4 cells designed for safety will be far more robust
structurally, and the necessary compromises will be lower performance
and higher cost (more material for the same capacity, better QC,
circuitry for internal charge/discharge regulation and cell balancing,
etc.). It looks like this is what the K2 guys are pursuing.

My $0.02. I'm not a battery engineer, just a skeptical self educated
end user. Sorry if this came off as rock throwing.

Evan Ludeman / T8

On 10/17/2012 7:35 AM, Evan Ludeman wrote:
On Oct 17, 9:39 am, wrote:

Eric and Evan: you can't have it both ways, either the LiFePo
chemistry is safe or it isn't. If you agree that there is no
safety difference between the cheap HK cells and those you find in
the referenced motorcycle batteries, the fact that HK is used in
"toys" should not make a difference. Apropos toys, what do you
think the average American Joe is calling our gliders? I will of
course encase the HK battery and provide a 5A fuse inside that
enclosure before trying it in my glider. I'll let you all know how
it goes.

Herb: there's a lot to go wrong here that has nothing whatsoever to
do with chemistry, and this was my point. A fuse external to the
pack will do nothing to protect you from an internal short or a
short across one of the cells. Be especially critical of those
balance leads, I've had issues with those on LiPo packs.

We're talking about low probability events here... but event with
potentially high impact. If you install this battery and use it in
your glider, chances are 99%+ that it will work out fine for the
next year.

Here's my second point: this will not prove that this is safe.
Humans are extraordinarily bad at assessing risks in the 0.01 - 1%
range. We do something a little edgy and get away with it 20 times
(thermalling off a ridge with 150' of clearance, let's say) and think
"we've got this figured out"... when statistically we'll almost
certainly see it go wrong if we do that same thing 1000 more times.
If ten thousand of us install those HK batteries, I am confident that
we *will* have problems. Those batteries are designed for high
discharge rate performance and the compromise is safety. This is
acceptable for toys. Much less so for human carrying vehicles.

LiFePO4 cells designed for safety will be far more robust
structurally, and the necessary compromises will be lower
performance and higher cost (more material for the same capacity,
better QC, circuitry for internal charge/discharge regulation and
cell balancing, etc.). It looks like this is what the K2 guys are
pursuing.

My $0.02. I'm not a battery engineer, just a skeptical self
educated end user. Sorry if this came off as rock throwing.

Evan Ludeman / T8

Herb, I completely agree with Evan. The HK batteries were not designed
for our use, there is no evidence they've been tested for our particular
pattern of usage, nor is there a history of successful use for our
purposes.

Given the safety and low cost of SLA batteries, I don't see a compelling
reason to use HK batteries. If a pilot needs more capacity, I suggest
finding a way to add another SLA, or reducing the battery drain so the
present SLA is adequate. At the very least, wait another six months
until the soaring season is near, and see what is on the market then. I
bet there will be better, maybe much better, choices than we have now,
as battery situation is changing quickly.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl
- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what
you need to know tinyurl.com/yfs7tnz