[NSRCA-discussion] Battery discharge/storage question

Wed May 8 10:50:50 AKDT 2013

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>
>> _______________________________________________
>> 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
>>
>> _______________________________________________
>> 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
>>
>>
>>
>> --
>> 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
>> _______________________________________________
>> 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
>>
>
>
>
> --
> *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
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.nsrca.org/pipermail/nsrca-discussion/attachments/20130508/786b3f82/attachment.html>