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Old 06-19-2018, 09:29 AM
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Thanks Ronaldopn you alerted me to something I had overlooked. The issue over the right charger. Mine only go up to 6S. My intention was to go for new 7S batteries from scratch so another charger will be required. I want to use two per flight on a 14S set up. My only concern was whether 2 x 10000s would give me 5-6 minutes of flight (that's all I do per flight) with a 100cc equivalent electric motor. I do just standard aeros as I am not a 3D exponent.
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Old 06-19-2018, 05:10 PM
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Put your plane + power system data as accurately as possible on PAR Calc and it will give you a very close flight time value.
Ronaldo
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Old 06-20-2018, 05:55 AM
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Quote:
Originally Posted by ronaldopn View Post
Exactly, the decision depends on OP's budget and convenience. Some pilots already have 6S 5000mAh packs from other planes or Helis and ordering only 4S packs will be much cheaper.
If you already have 6S packs, the even cheaper option is 6S+6S+2S.
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Old 06-20-2018, 09:54 AM
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Interesting smdub. I have some 6S lipos all the same make etc. I understand how to wire them for 12S, but how would I wire in a 2S to make up 14S? thanks.
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Old 06-20-2018, 04:53 PM
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You can string as many batteries together + to - as you want. You get the sum of all the voltage. All the batteries should be of the same capacity and C rating. Preferably the same brand, age and usage history.
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Old 06-21-2018, 08:04 AM
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I programmed the PAR Calc and also powered a few 100cc 35% airframes over the last four years. A picture is usually helpful with visual thinkers like me, so if you want a few images of the parallel and series configurations mentioned here, let me know. I probably have most of them posted on the power thread over at RCG.

I'm also using Castle 6.5mm bullets all the way around on batteries, chargers, and controllers, because they enable all kinds of battery cell and capacity configuration. With a few 6.5mm parallel Y-connectors, I can do anything I want, from a simple 2x 6S 3300mAh pack for my 74" plane, to a 1x 6S5300 plus 2x 4S5300 for a 14S 5300mAh config, to a 3x 4S4000 in series stacked with 3x 4S4000 in parallel for 12S 8000mAh main pack.

I'll also mention that I always try to keep my discharge C rating under 25C, so for my 74" 12S setup to 70A, I do 3300mAh for a 21.2C, and for my 102" setup to 156A, I do 7000mAh for 22.3C.

Since C is all about Amps per Amp Hour, the same discharge usually means a relative flight time as well. So of I get 5.5 minutes at 22C, regardless of the number of cells I'm using, the same discharge C will give me the same flight time. So if I was doing 6 minutes with my 74" setup to 3100W with 3300mAh, I'd need 7360mAh for the same 6 minutes on my 102" to 6930W.

I should also mention here that every 1S 1000mAh you add to a system, you add about an ounce of weight. so going from my 12S5300 to my 12S8000 packs, I'm adding about 1.7 pounds.

I was lucky to find a 12S7000 pack that weighs only 1745g so that helps a lot, and if you shop around, you'll find a wide range of cell weights out there.

To help accommodate my need for big electric planes, I also designed the 102" and brought it in at 25.34 pounds with a 1380g power system spinning a 26x12 electric beechwood.

I then went to a geared reduction unit, and at the same weight for the motor and drive unit, I'm spinning a 28x12 PJN now which pulls about 55 pounds on my Rapala. The gear reduction is also about 11% more efficient than my Hacker Q80-6L and about 14% more efficient than my SII-6540 155Kv, which I ran on 14S.
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Old 06-21-2018, 08:26 AM
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BTW - I'm also reprogramming the PAR Calc because I originally only programmed in for 12" to 25" props never expecting that a 8.5 HP power equivalent would be so easy to manage and that I'd ever have a 35% electric plane would come in under 26 pounds. I flew at an event with a friend who had a 3DHS 106" Edge 540 with the same power system weight as my 25.5 lb 102" -- 133.8 oz for the motor, ESC, and main pack -- but his plane was 31.5 lbs. Plus his setup was pulling about 48 lbs at 171A while mind was pulling 55 lbs at 156A. Big difference.
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Old 06-21-2018, 12:53 PM
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Thank you Aeroplayin for your in depth reply I much appreciate you explanation. I am a visual thinker too so if you can point me in the direction of some parallel and series configurations I would be much obliged, as I have not progressed knowledge-wise beyond a simple basic 12S two lipo battery configuration in series. Thanks again.
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Old 06-21-2018, 05:06 PM
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Quote:
Originally Posted by superleccy68 View Post
Thank you Aeroplayin for your in depth reply I much appreciate you explanation. I am a visual thinker too so if you can point me in the direction of some parallel and series configurations I would be much obliged, as I have not progressed knowledge-wise beyond a simple basic 12S two lipo battery configuration in series. Thanks again.
I believe Jim (Aeroplayin) takes advantage of the separated battery leads to wire them in series without the use of any series connector. To use his method you need to solder one male and one female connector on each lead (+ and -). This is a very efficient method as it reduces the amount of connectors (and resistance) in the system.
I prefer a different approach as I fear even the remote possibility of accidentally connecting a male/ female plug on the same battery thus causing a short and also because I want to be able to power the SBEC (and radio system) without arming the ESC.

In the 50cc setup below (my first) I'm using AS150 connectors (with anti-spark). In this configuration I can't connect 2 batteries in series without an additional series cable (which is already soldered to the ESC). Note the SBEC leads soldered to the first series connector.
Ronaldo
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Old 06-21-2018, 05:19 PM
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Originally Posted by superleccy68 View Post
Interesting smdub. I have some 6S lipos all the same make etc. I understand how to wire them for 12S, but how would I wire in a 2S to make up 14S? thanks.
As already mentioned you can wire as many batteries you want in series and the resultant voltage will be the sum of all (see drawing below just for illustration).
i.e:
6S+6S+2S=14S
6S+4S+4S=14S
2S+2S+2S+2S+2S+2S+2S=14S
etc

Just keep in mind all batteries must have the same capacity and discharge rate (and also similar condition/ quality).
Ronaldo
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Old 06-22-2018, 02:41 AM
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Thanks Ronaldopn for your patience to do this. The info gives me food for thought and explains clearly, thereby reducing my level of ignorance enormously! Thanks again to you and Aeroplayin. Adrian
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Old 06-22-2018, 07:18 AM
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No problem...

And yes, I keep the individual bullets on the individual wires loose so I can configure every conceivable combination of cells and capacity. For example, on my 35% SU-26, I can use a 26x12 or 27x10 on 14S, and a 27x12 on 13S, and a 28x12 on 12S. I can use the same 6S 3300mAh batteries I use in my 60" with 6S3300, in my 74" to 12S3300, and parallel the 12S config to get 12S6600 in my 102".

Here's a diagram of a 4-pack with two in series and two in parallel.

The connectors and spark arrestors drawn in the image are also represented in the two pics. The spark arrestor is something I don't use much anymore since my Hobbywing Platinum Pro V4 200A and my SPIN Pro 200A both have internal suppressors.

The last image is a 3-pack for 14S and you can see how I have that wired with my individual bullets.

A lot of guys will not consider loose bullets because they may have connected a battery to itself at one point. This is a real potential, but I work around that by wiring the pack before placing it in the airplane, then connecting the low end (black) connection once it's in the plane, then connect the high end (red) when I'm ready to fly.

In the 4-pack image, I numbered the connectors showing the connection sequence when arming, and I reverse the process when disarming.
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Old 06-22-2018, 10:22 AM
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I keep coming back to your diagram, thanks for posting.
It is lightweight, bare minimum weight without having to use a big harness.

In the end, I think I am still going to use 2 parallel harnesses and 1 series harness. I just do not trust myself enough to never mess up that plug sequence.
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Old 06-22-2018, 10:38 AM
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I just do not trust myself enough to never mess up that plug sequence.
Same for me, I prefer foolproof methods, specially when dealing with me
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Old 06-22-2018, 10:50 AM
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Thanks Ronaldopn for your patience to do this. The info gives me food for thought and explains clearly, thereby reducing my level of ignorance enormously! Thanks again to you and Aeroplayin. Adrian
My pleasure Adrian.
The thread Jim (Aeroplayin) mentioned is this one, I post my power system questions there and always learn a lot from all the highly experienced fliers who participate.
Jim is the developer of the PAR calc and one of the most knowledgeable guys when it comes to power systems and very active on the same thread.
Ronaldo
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