[NSRCA-dist8] Battery checkers

[Patrick Harris]

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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