[NSRCA-dist8] Battery checkers

Sat Aug 1 08:07:59 AKDT 2015

Lyle, during my evolution to E-power I've used several plugs most of which were on components.
When I went to E-pattern I considered several things. The batteries were to be used in series in the airplane - charged in parallel - when retired from pattern I'll use them individually in smaller airplanes - standardization of plugs - and most of all I wanted a polarized connector to counter brain fade.
I settled on the Deans plug and install a wire harness in the airplane with one ESC lead to the arming plug and the other to a multiple plug battery connector that puts them in series. Pretty much a fool proof system; requiring minimum concentration both in the airplane and when charging. I wanted a real no brainer.
I also use only LIPO batteries for the same reason - no need to change the charger.
The bottom line is how attentive do you want to be. Fueling through a vent line oils your pants but plugging a battery in wrong can give you a heart attack.
Jim

From: NSRCA-dist8 [mailto:nsrca-dist8-bounces at lists.nsrca.org] On Behalf Of Lyle Laughery via NSRCA-dist8
Sent: Saturday, August 01, 2015 6:39 AM
To: Patrick Harris; ID MT, OR, WA, WY AK
Subject: Re: [NSRCA-dist8] Battery checkers

Now that all of you have beat the wadding out of battery checking can you help this soon to be electric flier,choose the best battery connectors between the speed controller and battery .Castle 80 and 5000 battery?
On Jul 31, 2015 8:55 PM, "Patrick Harris via NSRCA-dist8" <nsrca-dist8 at lists.nsrca.org> wrote:
Real men fly eight times....102....wuss! 

On Fri, Jul 31, 2015 at 8:43 PM, Karl Watts <karlwatt at sarmc.org> wrote:
Eight times!  You need counseling.  I flew 3 times, 102 degrees and became more gusty.  Went home for a beer and we were out.

Sent from my iPad

On Jul 31, 2015, at 8:50 PM, Patrick Harris via NSRCA-dist8 <nsrca-dist8 at lists.nsrca.org> wrote:
I flew eight times today and my twisty thing in the front went round and round and yes boys and girls, I am proud to say "I am an admitted Parallel Charger." Can I get an AMEN!  

On Fri, Jul 31, 2015 at 5:58 PM, Gordon Anderson <gaa at owt.com> wrote:
Don't get me started on parallel charging!

G

Sent from my iPhone

On Jul 31, 2015, at 5:15 PM, Patrick Harris via NSRCA-dist8 <nsrca-dist8 at lists.nsrca.org> wrote:
OMG...Jim...don't say "parallel charging' around Gordon....he'll have a fit! 😀 

On Fri, Jul 31, 2015 at 3:59 PM, James Hiller <jnhiller at earthlink.net> wrote:
Tried to fly today 17 MPH 101 degrees, this is getting old.
I use a free volt meter from HARBOR freight to check before flying to insure I'm not installing a used pack.
Before charging I check the voltage of each twin 5S pack to select packs with nearly the same voltage - usually within 2/10 V before parallel charging. I always charge at 1C. Takes about two beers to recharge a day's usage.
I monitor charge Mah, which is a total when parallel charging, that I average to a single battery to get a feel for per flight consumption.
Occasionally I'll charge individual batteries to try to negate the affects of parallel charging.
I've also noticed it takes longer to balance when the batteries are getting tired and I'll check the IR for weak cells ( IR Spread ). 
I'm also not working the batteries very hard only gaining maybe 20 degrees over ambient. 
Jim

From: NSRCA-dist8 [mailto:nsrca-dist8-bounces at lists.nsrca.org] On Behalf Of Patrick Harris via NSRCA-dist8
Sent: Friday, July 31, 2015 3:32 PM
To: Gordon Anderson
Cc: AK, ID, MT, OR, WA, WY
Subject: Re: [NSRCA-dist8] Battery checkers

All very true. I pick up on average about 5 percent after my packs set awhile. I find the checker I use to be pretty close, but always about 5 to 10 percent off what the true level based on what I actually put back into them. 

On Fri, Jul 31, 2015 at 3:25 PM, Gordon Anderson <gaa at owt.com> wrote:
Karl,

Here is my 2 cents worth....
Predicting battery capacity from the open terminal voltage is not very accurate, I believe that is where this capacity prediction is coming from. I will bet if you let the batteries "rest" a few minutes after your flight and then check them again the capacity values will change. Battery chemistry is very non linear. I think the best predictor of battery health is the internal resistance, a lot of chargers will calculate and display this value. Keep an eye on trends, as the batteries age the internal resistance will increase and they will also get hotter during the flight and eventually start to puff up. The nice thing about monitoring IR is you can see if a cell is getting significantly different than the rest of the cells in the pack.
The best way to know the capacity you have taken from the pack is to use a data logger that is measuring voltage and current and then calculating the maHr usage. Even in this case you will have to put more back in than you took out, this is because of the IR that burns some up in heat and the fact that the process is not linear.

--Gordon

On Jul 31, 2015, at 12:11 PM, Karl Watts <karlwatt at sarmc.org> wrote:

Do any of you guys or gals use battery checkers?  Are they reliable?  I have one that I use to check my batteries before and after I fly.  For my flight packs – 2 5000 mAh packs it consistently reads 97-99% and after flying 14-33%.  My confusion is when I take a pack that say reads 14% after flying and charge it I am only putting in about 3000 mAh.  Seems to me the battery checker should show 40% not 14%, I used 3000 mAh which is 60% of the pack.  Should I discard the battery checker?

Karl

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