[NSRCA-dist8] Battery checkers

Fri Jul 31 19:56:30 AKDT 2015

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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>>>
>>>
>>>
>>
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