[NSRCA-discussion] FW: 10s LiPo Charger Recommendation

Thu Oct 8 17:10:57 AKDT 2015

Thanks for the response Robert.  I can definitely see doing this at low to moderate C rates as with your example.  I might run a test to see what the voltage difference is between parallel battery sets at higher C rates, maybe around 4 to 5C.  The thing that I have in mind is,  that depending on how things are connected, what the resulting resistance is in the path to the 2nd, 3rd, 4th parallel pack and so forth, and what the charging current is, then you might see a problem with some packs charging more than others.  If you keep the the wiring lengths the same from the charger to each pack, then there should not be an issue.  An example might be something resembling a bicycle wheel, with the charger at the hub of the wheel, and battery packs distributed around the hub with one pack per "spoke".
However, if you instead choose to wire it to resemble a train track, with a relatively simple charger at one end of the track and battery packs strung out like railroad ties along the rails, then a issue may exist at some point.  The reason is that the higher the charging current value is, the more voltage drop there will be along the wiring from one pack to the next, skewing the results from one pack to the next.  Now depending on how the charger algorithm is designed, that may not matter.  For example, an improved charger design could pulse the charging current on and off, and during each brief "off" time, take no load voltage readings that would be virtually unaffected by the extra resistance in the wiring to the 2nd pack.  More sophisticated methods could be applied that you might expect could vary from one brand or model charger to the next, but this should illustrate the point that results may vary depending on a number of factors.  
Careful monitoring and not pushing C rates really high as you have done will certainly tell you enough.  If someone wants to really push the limits without incurring too much risk, my suggestion is that they determine the wiring method based on an understanding of how the charging system will be able to measure what is happening.  If your charging system can monitor individual parallel pack voltages and suss out how those separate readings relate to the state of the group of batteries, you get easily push C rates higher without much regard to the wiring scheme (hub and spoke vs RR track, if you will).  If your charging system lacks independent battery voltage sensors, but is known to have an algorithm that can work around that, also good.  Personally, I wouldn't go against any manufacturer's specific recommendation to avoid parallel charging with their product.  
Ed
To: nsrca-discussion at lists.nsrca.org
Date: Thu, 8 Oct 2015 20:39:19 +0000
Subject: Re: [NSRCA-discussion] FW:  10s LiPo Charger Recommendation
From: nsrca-discussion at lists.nsrca.org.

I have done a lot of parallel charging this year. I was originally worried about cell balance charging this way when I started so I closely monitored the cell
 voltages before and after charging.  I’m typically charging 1800 75c 4s packs, 4 at a time at 14amps (2c per pack).  Every check of the cells after charging shows they balance very well and are within .02 volts each and I have about 100 cycles on each pack
 this way.  I use the RMRC ParaBoard ( 
http://www.readymaderc.com/store/index.php?main_page=product_info&cPath=84_387&products_id=2984 ).  Certainly not the 10s packs used in pattern, but charging them as 5s packs would work nicely using this system.

-         
 Robert Beaubien

-         
 Sr. Software Architect

-         
 Kool Software LLC

“Dear Algebra, Please stop asking us to find your X.  She's never coming back and don't ask Y.”

From: NSRCA-discussion [mailto:nsrca-discussion-bounces at lists.nsrca.org]
On Behalf Of Ed Alt via NSRCA-discussion

Sent: Thursday, October 8, 2015 12:54 PM

To: Keith Hoard <klhoard at outlook.com>; General pattern discussion <nsrca-discussion at lists.nsrca.org>

Subject: Re: [NSRCA-discussion] FW: 10s LiPo Charger Recommendation

Although I haven't done parallel charging, it seems like it would be ok within certain limits.  The main limiting factor might be the path resistance between parallel cells, but really only in the case of high C rate charging.  That's a
 theory anyway.  What has your experience been at high C rates? Does it seem to make much difference?

Ed

On Oct 8, 2015, at 3:09 PM, Keith Hoard via NSRCA-discussion <nsrca-discussion at lists.nsrca.org> wrote:

I have found that the loudest detractors of parallel charging have no experience parallel charging.  When I ask them to point to an  incident where parallel charging
 caused a problem, the answer is always “Well, I read on the internet . . . “
.
I do a lot of parallel charging, and have no problem “putting the spurs” to my packs during charge if I’m ready to get in the air.  To dispel one myth right now,
 a good quality charger **WILL** detect a bad cell during parallel charging.  

(steps up on soapbox) . . .

**I HAVE ACTUALLY SEEN IT WITH MY OWN EYES AND CONFIRMED IT WITH FURTHER TESTS**
**PLEASE DON’T KEEP REFERRING ME BACK TO “THE INTERNET”**
**IF YOU GIVE ME ONE OF YOUR CRAPPY PUFFED UP PACKS, I’LL PUT IT ON WITH ONE OF MY GOOD PACKS AND SHOW YOU**

OK, with that statement out of the way . . . . (steps down off soapbox) . . . .

The only time that bad cell **MAY** be masked is if you are parallel charging 4 or 6 packs.  In practical use, you would only be parallel charging that many batteries
 on very rare occasions, perhaps once per season.  Besides, most chargers out there don’t have enough ass to charge 6 pattern packs in parallel and be done before sundown anyway.  However, you should not be relying on your charger as the only point in your
 routine to detect bad cells.

In my experience,  folks with bad cells and puffy packs are doing a myriad of other no-no’s.  The worst is taking their batteries home on a full charge and letting
 them sit all week or all winter.  My soapbox finally broke down on that one and now I just smile and say “That’s too bad” and keep walking down the flight line. 

Ironically, the “straw that broke the camel’s back” for me was an H1B German Engineer who flies at our field asked me how I keep my packs from puffing up. Every
 time I said “storage charge at the end of the day”, he would reply “I don’t do that.” Then I said, “Yes, that’s why your batteries are all puffy and trashed.”  To which he replied “Yes, I charge my batteries to 100% before taking them home.”  . . . <Sigh>
 . . .

I now understand how VW got busted.

From: NSRCA-discussion [mailto:nsrca-discussion-bounces at lists.nsrca.org]
On Behalf Of Vicente Bortone via NSRCA-discussion

Sent: Thursday, October 8, 2015 13:16

To: James Hiller <jnhiller at earthlink.net>; General pattern discussion <nsrca-discussion at lists.nsrca.org>

Subject: Re: [NSRCA-discussion] 10s LiPo Charger Recommendation

For some reason TP does not recommend parallel charging.  Probably because it is difficult to keep track of each cell and values are averaged.   Is this really an important factor?  At this point I just following instructions.  This factor
 could be important to decide what charger to buy.

Vicente "Vince" Bortone

On Thursday, October 8, 2015, James Hiller via NSRCA-discussion <nsrca-discussion at lists.nsrca.org> wrote:

Plug & play charge box from Progressive RC (see photo).

Parallel charging 5 flight packs in one session while having a couple cold ones!

Jim

-----Original Message-----

From: NSRCA-discussion [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Dr. Michael Harrison, DDS via NSRCA-discussion

Sent: Thursday, October 08, 2015 9:46 AM

To: 'Earl Haury'; 'General pattern discussion'

Subject: Re: [NSRCA-discussion] 10s LiPo Charger Recommendation

lol

-----Original Message-----

From: NSRCA-discussion [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Earl Haury via NSRCA-discussion

Sent: Thursday, October 08, 2015 8:26 AM

To: Budd Engineering; General pattern discussion

Subject: Re: [NSRCA-discussion] 10s LiPo Charger Recommendation

Jerry

Hard to beat the iChargers. The CellPros taught me that a fuse between the pack & charger is a good investment! No issues with 3010b iChargers  (about

3000 charges over 5 years or so). They  will report cell IR / voltage and charge a 10S pack at 2C with a 24v supply without breaking a sweat. The newer 4010 can handle 2x10S and displays data from both packs simultaneously. They don't meet your criteria of
 charging through the balance leads, but haven't really found that to an issue as the balancing system works fine. Can't really comment on service, haven't needed any (that should jinx me).

Earl

-----Original Message-----

From: Budd Engineering via NSRCA-discussion

Sent: Thursday, October 08, 2015 4:59 AM

To: List NSRCA-list

Subject: [NSRCA-discussion] 10s LiPo Charger Recommendation

Hi all, I m in need of some advice/suggestions for a new LiPo charger for 10s packs.

For the past several years I ve used CellPro-10S chargers with good results.

However recently one of my CellPro-10s' emitted the dreaded  magic smoke  when I connected a 10s pack for charging.  This also happened at the Nats 3 years ago, fortunately Mike M. from F3AU was there with inventory and I was able to purchase a replacement
 charger and press on.  However, after having a second one give up the ghost a few weeks ago (and after not many charge cycles - I don t fly very much), I m interested in exploring other options.

To try to add some focus to this here s my search constraints:

1.  It must be able to charge each cell individually through the balance connector, and give me a relative readout of each cell s condition compared to the other 9 cells.

2.  I m not interested in chargers that have separate balancers from the charger (e.g. like the TP1010C).

3.  Reliability and value are important, as is ease of use.

4.  Cost no more than a replacement CellPro 10XP (<$180), unless a single charger can charge two 10s packs simultaneously, then I d consider spending a bit more.

5.  Customer service matters, if I can buy it through F3A Unlimited, that would be a PLUS.

With this in mind does anyone have a suggestion for what chargers I should

consider?

I don t get out much these days so it s difficult to see what everyone s

using that works well.  So I really do appreciate everyone s help with this.

Thx, Jerry

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-- 

Vicente "Vince" Bortone

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