Spring Cleaning and Battery Testing

On 3/19/2011 5:40 PM, Paul Remde wrote:
Hi Eric,

Thanks. I'm a little surprised you use the 4A charger. The largest one I
sell so far is a 2 A charger. Are you charging multiple batteries with
the same charger at once? Or do you have a very large capacity battery?

The ASH 26 E can carry two 12 volt, 18 AH batteries, which I do. These
batteries can be charged at 4 amps; since I charge them in parallel, I
could actually use an 8 amp charger, and that's one reason I'm attracted
to the Batteryminder 12248.

--
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

On 3/19/2011 5:40 PM, Paul Remde wrote:
Hi Eric,

Thanks. I'm a little surprised you use the 4A charger. The largest one I
sell so far is a 2 A charger. Are you charging multiple batteries with
the same charger at once? Or do you have a very large capacity battery?

The ASH 26 E can carry two 12 volt, 18 AH batteries, which I do. These
batteries can be charged at 4 amps; since I charge them in parallel, I
could actually use an 8 amp charger, and that's one reason I'm attracted
to the Batteryminder 12248.

--
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

I should have posted this link before. Here's an excellent document
describing all aspects of SLA batteries from construction to use/ca

http://www.power-sonic.com/images/po...hManual-Lo.pdf

Hi,

Nice document. I'll add that to my Power-Sonic web page.

Good Soaring,

Paul Remde
Cumulus Soaring, Inc.

"Westbender" wrote in message
...
I should have posted this link before. Here's an excellent document
describing all aspects of SLA batteries from construction to use/ca

http://www.power-sonic.com/images/po...hManual-Lo.pdf

On Mar 16, 11:20*pm, SP wrote:
On Mar 16, 7:01*pm, Nyal Williams wrote:



I know nothing about battery technology. *I take my batteries to Battery
Plus, who claims that they can recondition batteries and bring them up to
their proper rating. *Sometimes I get a battery back with the indication
that it is at say 113%; if the work brings it back to less than 95% there
is no charge and I throw it away. *The cost last year was $5.00 per
battery that came out well.

Am I getting good value?

At 00:40 17 March 2011, brianDG303 wrote:

On Mar 16, 4:00=A0pm, ContestID67 *wrote:
Each year I like to test my batteries and replace those that do not
have enough capacity for a typical flight of 3-4-ish hours with all
the electronics running. I run two batteries so that removes a worry
about loosing power during a record flight. =A0But how do you perform
a
good real world test?

My test is basically connecting a resistive load to the battery,
measure the battery voltage every 10 minutes or so. =A0Then wait for
the
battery voltage to drop to 11.5Vdc (an arbitratry but safe value).
Simple.

I create an Excel spreadsheet that explains all this - the testing
that I perform, the test rig that I used and templates for gathering
the data and then graphing the results. =A0
Seehttp://aviation.derosaweb.=
net/#batterytest.

I=92d love to hear any comments that you might have. =A0Enjoy.

John DeRosa
Johnderosaweb.com

John,
I have used that method and it works well, but.............
First, as I am sure you know, you want a load that is similar to the
real-life load. *I use a 12 volt lamp (AKA light bulb) and because I
have a lot of stuff I use a 10 watt lamp to create a 830 mA load which
is about what I pull.

If you are testing every 10 minutes you are working kind of hard. *My
battery, a 12120, takes hours to run down.

11.5 volts cut off is way too conservative. *The published data curve
for the 12120 ................................wait, I am wrong. I
looked it up and I use 11.8 volts. but 11.5 is fine as well.

I use an Eagle Tree MicroPower V3 logger and get a computer generated
log of the discharge. *Then I fly with the logger and get an idea of
my real-world consumption and compare the two. *Works great. *Others
use a pretty common logger with a built-in load, I prefer the Eagle
Tree because it will log a flight one day and a battery the next.

Do you do your test in cold air to simulate high altitude, or just
room temp?

ps. If you are replacing the 12120 battery look at the 12140 or the
12150. *Same size, heavier, and more capacity.

Brian

Has anyone tried a LiFePO4 battery such as the Shorai brand that can
be seen at:http://www.batterystuff.com/batterie...L2-BS12.html*?

Weight of the 12v 14ah LiFePO4 battery is 1.6 lb vs 13 lb for a sealed
lead acid battery. And, it's smaller.

Steve

Steve,

I just bought a 4500 mAh 4-cell LiFe battery from Hobby King, the
Hongkong supplier of RC equipment that I have bought LiPo's from
before. Here is the link:
http://www.hobbyking.com/hobbyking/s...dProduct=16201
I got two of these and connected them is series. Discharge tests
using the Eagle voltage and amperage recorder mentioned in this thread
indicate they have the stated capacity. They discharge at a very flat
and constant voltage. Will use these as my primary battery for
instrumentation and radio. I have a 10AH NiMH battery dedicated to the
transponder.and a stand-by battery in the tail (also NiMH) in case the
LiFe goes dead.

Herb, J7