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LiFePO4 chargers



 
 
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  #21  
Old November 14th 18, 09:09 PM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 230
Default LiFePO4 chargers

On Wednesday, November 14, 2018 at 2:56:35 PM UTC-5, kinsell wrote:
On 11/14/18 9:03 AM, moshe... wrote:
On Tuesday, November 13, 2018 at 11:11:52 PM UTC-5, kinsell wrote:
On 11/13/18 6:08 PM, bruce... wrote:
Mark, When K2 was fairly new on the market I contacted them asking if Battery Tender Jr. is okay and safe, they replied that it is perfectly okay and nearly the same as their charger. I also contacted Battery Tender Jr. with the reverse question and they said the BTJr is fine for LiFePO4. I used the BTJr for years on my K2 with no issues. They're about $25 on internet sites.


Have you measured the amount of charge you're getting into the K2's? It
will be considerably less than the rated amount due to using a lead-acid
charger.

Also, if K2 has cell balancing capability, it won't be used because your
Battery Tender doesn't put out enough voltage to make it work.


Many simple lead-acid chargers reach up to around 14.2-14.8 volts. That voltage would suffice to charge an LFP battery to well above 90% capacity if it stays there for a while. If it quickly shifts to "float" at 13.5V or so then it won't do well in charging LFP. So simpler is better in this case. Measure what your charger does. And disconnect it after several hours, don't leave it on "float".


Hate to break this to you, but at $24, the Battery Tender Junior is one
of the cheapest chargers on the market, and is fully featured with a
float mode.

14.2 volts wouldn't begin to charge an LFP to "well over 90%" as you
claim. If you found a charger that delivers 14.8 volts under load, then
it would overcharge an SLA and would be considered defective.

If you're going to spend big bucks for an LFP, you ought to get a proper
charger for it. Still waiting to hear just how much charge the K2's got
in them from a BTJ.

-Dave


That's the conventional wisdom, but see experimental results he
https://www.powerstream.com/lithium-...ge-voltage.htm
- well above 90% capacity even at a bit lower than 14V!

A cheap dumb 14.x volt fixed-voltage source with limited current output (and perhaps aided by the battery's BMS) would charge an LFP just fine. I'm not saying that's the ideal charger, but in a pinch it would work well enough. I am not happy with the several chargers I have that push SLAs well above 14V (even above 15V), but they may be handy for LFPs.
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  #22  
Old November 15th 18, 01:42 AM posted to rec.aviation.soaring
Graham Drinkell[_2_]
external usenet poster
 
Posts: 10
Default LiFePO4 chargers

At 20:09 14 November 2018, wrote:
On Wednesday, November 14, 2018 at 2:56:35 PM UTC-5, kinsell

wrote:
On 11/14/18 9:03 AM, moshe... wrote:
On Tuesday, November 13, 2018 at 11:11:52 PM UTC-5,

kinsell wrote:
On 11/13/18 6:08 PM, bruce... wrote:
Mark, When K2 was fairly new on the market I contacted

them asking
if=
Battery Tender Jr. is okay and safe, they replied that it is perfectly
oka=
y and nearly the same as their charger. I also contacted Battery

Tender
Jr.=
with the reverse question and they said the BTJr is fine for

LiFePO4. I
us=
ed the BTJr for years on my K2 with no issues. They're about $25

on
intern=
et sites.


Have you measured the amount of charge you're getting into

the K2's?
=
It
will be considerably less than the rated amount due to using

lead-ac=
id
charger.

Also, if K2 has cell balancing capability, it won't be used

because
yo=
ur
Battery Tender doesn't put out enough voltage to make it

work.
=20
Many simple lead-acid chargers reach up to around 14.2-14.8

volts.
Tha=
t voltage would suffice to charge an LFP battery to well above 90%
capacity=
if it stays there for a while. If it quickly shifts to "float" at 13.5V
o=
r so then it won't do well in charging LFP. So simpler is better in

this
c=
ase. Measure what your charger does. And disconnect it after

several
hour=
s, don't leave it on "float".
=20

=20
Hate to break this to you, but at $24, the Battery Tender Junior

is one=
=20
of the cheapest chargers on the market, and is fully featured

with a=20
float mode.
=20
14.2 volts wouldn't begin to charge an LFP to "well over 90%" as

you=20
claim. If you found a charger that delivers 14.8 volts under

load, then=
=20
it would overcharge an SLA and would be considered defective.
=20
If you're going to spend big bucks for an LFP, you ought to get a

proper=
=20
charger for it. Still waiting to hear just how much charge the

K2's got=
=20
in them from a BTJ.
=20
-Dave


That's the conventional wisdom, but see experimental results he
https://www.powerstream.com/lithium-phosphate-charge-
voltage.htm
- well above 90% capacity even at a bit lower than 14V!

A cheap dumb 14.x volt fixed-voltage source with limited current

output
(an=
d perhaps aided by the battery's BMS) would charge an LFP just

fine. I'm
n=
ot saying that's the ideal charger, but in a pinch it would work well
enoug=
h. I am not happy with the several chargers I have that push SLAs

well
abo=
ve 14V (even above 15V), but they may be handy for LFPs.
Personally, I would fly a model aircraft with a lipo battery. Full

size, definitely not! They deform at high altitudes, with the
possibility of fracturing cells? The best bet is to use military spec
batteries that work in space?


  #23  
Old November 15th 18, 01:47 AM posted to rec.aviation.soaring
Graham Drinkell[_2_]
external usenet poster
 
Posts: 10
Default LiFePO4 chargers

At 00:42 15 November 2018, Graham Drinkell wrote:
At 20:09 14 November 2018, wrote:
On Wednesday, November 14, 2018 at 2:56:35 PM UTC-5, kinsell

wrote:
On 11/14/18 9:03 AM, moshe... wrote:
On Tuesday, November 13, 2018 at 11:11:52 PM UTC-5,

kinsell wrote:
On 11/13/18 6:08 PM, bruce... wrote:
Mark, When K2 was fairly new on the market I contacted

them asking
if=
Battery Tender Jr. is okay and safe, they replied that it is

perfectly
oka=
y and nearly the same as their charger. I also contacted Battery

Tender
Jr.=
with the reverse question and they said the BTJr is fine for

LiFePO4. I
us=
ed the BTJr for years on my K2 with no issues. They're about

$25
on
intern=
et sites.


Have you measured the amount of charge you're getting

into
the K2's?
=
It
will be considerably less than the rated amount due to

using
lead-ac=
id
charger.

Also, if K2 has cell balancing capability, it won't be used

because
yo=
ur
Battery Tender doesn't put out enough voltage to make it

work.
=20
Many simple lead-acid chargers reach up to around 14.2-

14.8
volts.
Tha=
t voltage would suffice to charge an LFP battery to well above

90%
capacity=
if it stays there for a while. If it quickly shifts to "float" at

13.5V
o=
r so then it won't do well in charging LFP. So simpler is better in

this
c=
ase. Measure what your charger does. And disconnect it after

several
hour=
s, don't leave it on "float".
=20
=20
Hate to break this to you, but at $24, the Battery Tender Junior

is one=
=20
of the cheapest chargers on the market, and is fully featured

with a=20
float mode.
=20
14.2 volts wouldn't begin to charge an LFP to "well over 90%"

as
you=20
claim. If you found a charger that delivers 14.8 volts under

load, then=
=20
it would overcharge an SLA and would be considered defective.
=20
If you're going to spend big bucks for an LFP, you ought to get

a
proper=
=20
charger for it. Still waiting to hear just how much charge the

K2's got=
=20
in them from a BTJ.
=20
-Dave


That's the conventional wisdom, but see experimental results

he
https://www.powerstream.com/lithium-phosphate-charge-
voltage.htm
- well above 90% capacity even at a bit lower than 14V!

A cheap dumb 14.x volt fixed-voltage source with limited current

output
(an=
d perhaps aided by the battery's BMS) would charge an LFP just

fine. I'm
n=
ot saying that's the ideal charger, but in a pinch it would work

well
enoug=
h. I am not happy with the several chargers I have that push

SLAs
well
abo=
ve 14V (even above 15V), but they may be handy for LFPs.
Personally, I would fly a model aircraft with a lipo battery. Full

size, definitely not! They deform at high altitudes, with the
possibility of fracturing cells? The best bet is to use military spec
batteries that work in space?





  #24  
Old November 17th 18, 04:04 AM posted to rec.aviation.soaring
Eric Greenwell[_4_]
external usenet poster
 
Posts: 1,088
Default LiFePO4 chargers

kinsell wrote on 11/14/2018 12:55 PM:
On 11/14/18 9:03 AM, wrote:
On Tuesday, November 13, 2018 at 11:11:52 PM UTC-5, kinsell wrote:
On 11/13/18 6:08 PM, bruce... wrote:
Mark, When K2 was fairly new on the market I contacted them asking if Battery
Tender Jr. is okay and safe, they replied that it is perfectly okay and nearly
the same as their charger. I also contacted Battery Tender Jr. with the
reverse question and they said the BTJr is fine for LiFePO4. I used the BTJr
for years on my K2* with no issues. They're about $25 on internet sites.


Have you measured the amount of charge you're getting into the K2's?* It
will be considerably less than the rated amount due to using a lead-acid
charger.

Also, if K2 has cell balancing capability, it won't be used because your
Battery Tender doesn't put out enough voltage to make it work.


Many simple lead-acid chargers reach up to around 14.2-14.8 volts.* That voltage
would suffice to charge an LFP battery to well above 90% capacity if it stays
there for a while.* If it quickly shifts to "float" at 13.5V or so then it won't
do well in charging LFP.* So simpler is better in this case.* Measure what your
charger does.* And disconnect it after several hours, don't leave it on "float".


Hate to break this to you, but at $24, the Battery Tender Junior is one of the
cheapest chargers on the market, and is fully featured with a float mode.

14.2 volts wouldn't begin to charge an LFP to "well over 90%" as you claim.* If
you found a charger that delivers 14.8 volts under load, then it would overcharge
an SLA and would be considered defective.

If you're going to spend big bucks for an LFP, you ought to get a proper charger
for it.* Still waiting to hear just how much charge the K2's got in them from a BTJ.


Bienno Power has a $25, 12V/4A LiFePO4 charger. I'd trust that over a BT Jr, and
it's the same price.


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf

  #25  
Old November 17th 18, 04:18 AM posted to rec.aviation.soaring
Richard Pfiffner[_2_]
external usenet poster
 
Posts: 123
Default LiFePO4 chargers



Craggy Aero has a 5A LiFePO4 Smart Charger

http://www.craggyaero.com/lifepo4_battery.htm

Richard

  #26  
Old November 17th 18, 04:20 AM posted to rec.aviation.soaring
Eric Greenwell[_4_]
external usenet poster
 
Posts: 1,088
Default LiFePO4 chargers

kinsell wrote on 11/13/2018 9:18 PM:
scinating videos on YouTube.

However, "safer" isn't actually the same as "safe", LFP's are quite
capable of burning, despite what the scholarly articles say.* There have
been a number of fires, particularly when they're used as starter
batteries.* High charge rates and very high discharge rates seem to
cause problems, as homebuilders of small power planes have discovered.
There was also that LFP battery fire in an EB-28 in Finland this summer.

-Dave


Dave, if you look around youtube long enough, you will find that a AAA battery
can make a fire. Certainly a 12V lead-acid has enough juice to do that if
circumstances are right. The overwhelming evidence of many years of usage of
LiFePo4 chemistry in glider batteries suggests that they are as safe as the old
gel-cells. Give progress a chance, I'm not saying be a Progressive.
Herb

If you come across a YouTube video of an AAA battery filling a cockpit with toxic
smoke, you be sure to post the link, OK?

Meanwhile, this is the sort of progress I can live without:

https://www.pilotsofamerica.com/comm...-fires.102016/


I did not see any indication the burning battery had a BMS. Some builders put in
the "starter" LiFe batteries that do not have a BMS, so perhaps that is the reason
the battery burned. I think LiFe batteries from the usual suppliers (Bienno, K2,
Stark - for example) with a BMS, used for instrument batteries, and charged with
the recommended charger are as safe as a comparable capacity SLA.


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf

  #27  
Old November 17th 18, 06:22 PM posted to rec.aviation.soaring
Richard Pfiffner[_2_]
external usenet poster
 
Posts: 123
Default LiFePO4 chargers

On Friday, November 16, 2018 at 7:20:53 PM UTC-8, Eric Greenwell wrote:
kinsell wrote on 11/13/2018 9:18 PM:
scinating videos on YouTube.

However, "safer" isn't actually the same as "safe", LFP's are quite
capable of burning, despite what the scholarly articles say.* There have
been a number of fires, particularly when they're used as starter
batteries.* High charge rates and very high discharge rates seem to
cause problems, as homebuilders of small power planes have discovered..
There was also that LFP battery fire in an EB-28 in Finland this summer.

-Dave

Dave, if you look around youtube long enough, you will find that a AAA battery
can make a fire. Certainly a 12V lead-acid has enough juice to do that if
circumstances are right. The overwhelming evidence of many years of usage of
LiFePo4 chemistry in glider batteries suggests that they are as safe as the old
gel-cells. Give progress a chance, I'm not saying be a Progressive.
Herb

If you come across a YouTube video of an AAA battery filling a cockpit with toxic
smoke, you be sure to post the link, OK?

Meanwhile, this is the sort of progress I can live without:

https://www.pilotsofamerica.com/comm...-fires.102016/


I did not see any indication the burning battery had a BMS. Some builders put in
the "starter" LiFe batteries that do not have a BMS, so perhaps that is the reason
the battery burned. I think LiFe batteries from the usual suppliers (Bienno, K2,
Stark - for example) with a BMS, used for instrument batteries, and charged with
the recommended charger are as safe as a comparable capacity SLA.


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf


Several years ago I had a bad batch of batteries from one of the suppliers you mentioned in your post. 4 to 5 aH capacity in a 10 Ah battery. I quit selling them. I now sell LiFePO4 batteries that I personally test before shipping with a West Mountain Radio computer tester. Document is supplied with the battery.

http://www.craggyaero.com/lifepo4_battery.htm

Richard
www.craggyaero.com
  #28  
Old November 18th 18, 03:51 AM posted to rec.aviation.soaring
Eric Greenwell[_4_]
external usenet poster
 
Posts: 1,088
Default LiFePO4 chargers

Richard Pfiffner wrote on 11/17/2018 10:22 AM:
On Friday, November 16, 2018 at 7:20:53 PM UTC-8, Eric Greenwell wrote:


https://www.pilotsofamerica.com/comm...-fires.102016/




I did not see any indication the burning battery had a BMS. Some builders put in
the "starter" LiFe batteries that do not have a BMS, so perhaps that is the
reason the battery burned. I think LiFe batteries from the usual suppliers
(Bienno, K2, Stark - for example) with a BMS, used for instrument batteries,
and charged with the recommended charger are as safe as a comparable capacity
SLA.



Several years ago I had a bad batch of batteries from one of the suppliers you
mentioned in your post. 4 to 5 aH capacity in a 10 Ah battery. I quit
selling them. I now sell LiFePO4 batteries that I personally test before
shipping with a West Mountain Radio computer tester. Document is supplied with
the battery.

http://www.craggyaero.com/lifepo4_battery.htm


I test every battery before installing it, also using a West Mountain tester. Over
the years, I've had three SLA batteries that had half their rated capacity, and
returned them. I've only used one LiFe battery, and it had exactly the rated
capacity. Couldn't believe it - tested it again, and got the same answer.
 




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