[NSRCA-discussion] LiPo Fun Fact 'O The Day

Sun Oct 11 19:34:02 AKDT 2015

For discharging I use a 17~ 100 watt resistor with noodle wire and a
matching connector to connect directly to the 10S discharge wires.

To monitor the battery I use a EOS battery tester on the balance connectors
for the voltage and the % of capacity remaining.

Simple and it works great to discharge down to storage voltage and you can
observe each cell as you discharge.

Usually I discharge lower than storage then charge back to storage and
balance the cells at the same time.

This setup discharges at 2.5A initially and slowly drops as the voltage goes
down.

David Harmon

NSRCA 586

Sperry, OK

From: NSRCA-discussion [mailto:nsrca-discussion-bounces at lists.nsrca.org] On
Behalf Of Robert L. Beaubien via NSRCA-discussion
Sent: Sunday, October 11, 2015 9:39 PM
To: General pattern discussion <nsrca-discussion at lists.nsrca.org>
Subject: Re: [NSRCA-discussion] LiPo Fun Fact 'O The Day

As far as discharging, the Turnigy Reaktor I have (
http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=70272 ) has a
regenerative discharge feature.  It can discharge at the full rate it can
charge at as long as you use a battery to charge with. It will return the
current back to your charging battery.  Really kewl and nice feature to be
able to discharge your packs in 15-20 minutes.

-           Robert Beaubien

-           Sr. Software Architect

-           Kool Software LLC

“Dear Algebra, Please stop asking us to find your X.  She's never coming
back and don't ask Y.”

From: NSRCA-discussion [mailto:nsrca-discussion-bounces at lists.nsrca.org] On
Behalf Of Karl Watts via NSRCA-discussion
Sent: Sunday, October 11, 2015 1:37 PM
To: General pattern discussion <nsrca-discussion at lists.nsrca.org
<mailto:nsrca-discussion at lists.nsrca.org> >
Subject: Re: [NSRCA-discussion] LiPo Fun Fact 'O The Day

Ok, so hearing all the discussion here I am trying to capture some take home
points to use in the care of my batteries.

1.  Do not keep them at full charge for extended periods of time.  Charge
prior to flying and the ones I do not use discharge after getting home.  My
problem is it takes sooooo much longer for my charger (iCharger 208B) to
discharge a battery to storage than to full charge a battery from storage.
Question - My charger will discharge a battery to 50% capacity for storage,
is it OK to store them at lower capacity?  What is the low limit?

2.  Discharge for storage over the winter or in between flight sessions.
Question - Is it better to store them in the refrigerator for longer life?

3.  Warm up cold batteries before charging.  Warm up cold batteries before
using.

4.  Do not discharge batteries below 25% capacity.

5.  Charge batteries at 1-2 C, no higher, to be on the safe side.  Note
there is controversy with this point.

Is that all?

Karl - an enthusiastic intermediate pattern pilot

Sent from my iPad

On Oct 10, 2015, at 8:08 PM, Jeff and Claire via NSRCA-discussion
<nsrca-discussion at lists.nsrca.org <mailto:nsrca-discussion at lists.nsrca.org>
> wrote:

Yes, warm to at least 50deg F before charging.  Was charging at the field
last winter and the Powerlab6 was stopping charge at  90% of capacity.
Thought the charger was broken.  Turns out they use the internal temp sensor
to check ambient as well and if below 50F, it will stop at 90% to keep from
damaging the battery (with the assumption that battery is also <50F).  The
Powerlabs allow lowering that threshold to 41F, once I did that started
getting full charges (but made sure the batteries stayed warm before charge
via thermo-nuclear fusion (truck dashboard).       

>From FMA Revolectrix engineering group: Lithium is a poor performing battery
in cold weather. If the pack is cold, the cell damage voltage reduces from
4.35V down to 4.20V. That means charging a lithium pack to 100% when it is
below 50 deg F will reduce cycle life. Automatic temperature monitoring
prevents pack over-charging at low ambient temperatures

They also say:   LiPo packs charged to 100% should not be cooled below room
temperature. Cells at 90% or less capacity can be cooled below 32ºF (0ºC). 

From: NSRCA-discussion [mailto:nsrca-discussion-bounces at lists.nsrca.org] On
Behalf Of Stuart Chale via NSRCA-discussion
Sent: Saturday, October 10, 2015 9:01 AM
To: chuenkan at comcast.net <mailto:chuenkan at comcast.net> ; General pattern
discussion
Subject: Re: [NSRCA-discussion] LiPo Fun Fact 'O The Day

What about if you store them in the fridge  during the week.  Should they
warm to room temp before charging or is charging them cold OK?

On 10/10/2015 10:08 AM, Phil Spelt via NSRCA-discussion wrote:

Correct!!!  I don't do that...

  _____  

Apparently you guys never put them on charge when they're hot!!  Then they
definitely cool down while charging.  :)

Sent from my average intelligence  phone 

On Oct 9, 2015, at 8:44 PM, Robert L. Beaubien via NSRCA-discussion
<nsrca-discussion at lists.nsrca.org <mailto:nsrca-discussion at lists.nsrca.org>
> wrote:

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