[NSRCA-discussion] Battery discharge/storage question

Wed May 8 15:01:28 AKDT 2013

I leave my packs on full charge all of the time except during the winter
when I store them at between 50 - 75% charge (storage charge).

I've only had one pack act up.

A few weeks before I re-charged my packs for the first time this spring
after being in a storage state all winter I noticed a strange chemical smell
in the ammo can I use to store them in.  I didn't think anything of it.
Well about 3 weeks later I decided to charge them up to go flying when I
notice one of the packs had started to leak.  I threw that one away (full
discharge then salt water bath).

Otherwise, all of my packs (2+ years old) seem to have the same amount of
power as some of the newer ones I've purchased recently.

Ron

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Scott Pavlock
Sent: Wednesday, May 08, 2013 2:51 PM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] Battery discharge/storage question

I have found that when I fly after work around 6, after charging the night
before, the pack will lose about 7%. This is enough for the auto lipo
setting on my HV85 to only detect 9 cells. I assume I could fix this by
going to a custom cutoff voltage, but with current settings it forces me to
top off my packs before I fly.

I wasn't aware that topping off was an issue; I'd like to see some
supporting data however.

Scott
On May 8, 2013 2:33 PM, "Scott McHarg" <scmcharg at gmail.com> wrote:

> For what it's worth,  I did just go online to see what others were saying.
>  I found forums that said it's no problem and others that said don't do
it.
>  Of course, a lot of them that were "for topping off" were talking
> about charging from storage and not truly topping off.  My comment was
> only for topping off say, above 90+%.  I'm sure chargers still detect
> it but I'll take my scolding and just do as he said.  Gaining <5%
> doesn't seem worth it to me.
>
>
> On Wed, May 8, 2013 at 1:29 PM, Jay Marshall <lightfoot at sc.rr.com> wrote:
>
>> This is an interesting issue. I'd like to hear more justification for
>> not doing it. Never heard it before or seen anything in the
>> literature.****
>>
>> ** **
>>
>> *Jay Marshall*
>>
>> ** **
>>
>> *From:* nsrca-discussion-bounces at lists.nsrca.org [mailto:
>> nsrca-discussion-bounces at lists.nsrca.org] *On Behalf Of *Scott McHarg
>> *Sent:* Wednesday, May 08, 2013 2:06 PM
>> *To:* General pattern discussion
>> *Subject:* Re: [NSRCA-discussion] Battery discharge/storage
>> question****
>>
>> ** **
>>
>> I got scolded not too long ago for even suggesting it by a
>> ThunderPower rep.  I wanted to top off because after a week, one of
>> my packs had dropped down to like 94% (yes it was an older pack and
>> had a little over 180 cycles on it).  I was told that topping off
>> "could" cause damage to the packs immediately regardless of age.  It
>> was a fairly stern warning.  Honestly, I didn't ask more because I
>> was already hanging my head from the scolding.  I just said "Yes sir,
>> sir".  :)****
>>
>> ** **
>>
>> On Wed, May 8, 2013 at 1:00 PM, Atwood, Mark
>> <atwoodm at paragon-inc.com>
>> wrote:****
>>
>> Okay, I'll bite. Why don't you want to top off the charge? I know a
>> lot of people who insist on doing this even if they just flew the day
before.
>>
>> Sent from my average intelligence  phone
>>
>>
>> On May 8, 2013, at 1:44 PM, "Scott McHarg" <scmcharg at gmail.com<mailto:
>> scmcharg at gmail.com>> wrote:
>>
>> I haven't seen any issues with a battery left a full charge for a
>> week but I wouldn't recommend longer at full charge.  Just make sure
>> that you DO NOT top off the charge prior to flying.  I have started
>> doing what Keith does as well which eliminates all concerns.  The
>> worst part is having to wait at the field while you bring that
>> battery back up to 50%.  Last one out has to lock the gates.
>>
>>
>> On Wed, May 8, 2013 at 11:23 AM, Keith Hoard <klhoard at hotmail.com<mailto:
>> klhoard at hotmail.com>> wrote:
>> I take my batts to the field at 50% and leave the field at 50%
>> charge. If I can't do that, then I discharge when I get home. My
>> batts seem to last a long time.
>>
>> The (dis)charger is supposed to get hot, that is where the energy
>> from the battery is going - into the heat sink. That's Ok, my PL 8 gets
hot too.
>>
>> The PL8 can only discharge 100 watts by itself, but can do much
>> higher if it is using "regenerative" discharge - dumping your LiPo's
>> charge back into a lead acid battery. I don't know if the 10X has that
capability or not.
>>  Otherwise I'd just keep using the low discharge rate, or plan your
>> flying day to end with a storage charge.
>>
>> Wow, that was a lot of typing to do on a phone!!
>>
>> Sent from my iPhone
>>
>> On May 8, 2013, at 11:15, "Bob Kane" <getterflash at yahoo.com<mailto:
>> getterflash at yahoo.com>> wrote:
>>
>> I have had to abort a couple of planned flying sessions so far this
>> spring due to weather.  I have read that lipos should not be left at
>> full charge for any significant length of time. So what is a
>> significant length of time?
>>
>> Hours?  Days? Weeks?
>>
>> My Turnigy 10XS charger has a discharge/storage mode, but the maximum
>> discharge current is 1 amp. It takes a couple of hours to bring a 10S
>> pack down to storage level, and the charger gets pretty warm(!)
>> during the discharge.  Up to now I have only worried about
>> discharging the pack for long term storage.
>>
>> If leaving the cells fully charged for more than a day or so is bad,
>> I am considering building a dedicated discharger, there are some
>> pretty simple yet effective designs on RCU.
>>
>> Bob Kane
>> getterflash at yahoo.com<mailto:getterflash at yahoo.com>
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>>
>>
>> --
>> Scott A. McHarg
>> Sr. Systems Engineer - Infrastructure
>> _______________________________________________
>> NSRCA-discussion mailing list
>> NSRCA-discussion at lists.nsrca.org<mailto:NSRCA-discussion at lists.nsrca.
>> org> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
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>> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion****
>>
>>
>>
>> ****
>>
>> ** **
>>
>> --
>> *Scott A. McHarg*
>> Sr. Systems Engineer - Infrastructure****
>>
>> _______________________________________________
>> NSRCA-discussion mailing list
>> NSRCA-discussion at lists.nsrca.org
>> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>
>
>
>
> --
> *Scott A. McHarg*
> Sr. Systems Engineer - Infrastructure
>
> _______________________________________________
> NSRCA-discussion mailing list
> NSRCA-discussion at lists.nsrca.org
> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>

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