OK, from a complete neophyte...

Building a Primary Force with an E-Flite 15, Hubin 2a timer, ICE 50 ESC. Expect to be using 2200 mAh, 4S batteries.


OK, I went to hobby-King to look at batteries. They have four major brand/varieties, Zippy, Zippy Compact and
Turnigy and Turnigy Nano-Tech. A couple of buddies mentioned Zippy (I presume as the more economical). I’m not upset by the comparable price differences if you think The Turnigy’s are a better battery!

My major question though is what is the difference (in english, not, Numeric formula) between a 20C and a 45C, and the in-betweens. Is the higher number going to give me a longer run time? (or leave more juice in the battery after shut down). Will they provide more power in the violent maneuvers? My motor spec sheet says my E-flite 15 draws 34A continous, and Max Burst of 42A. I’ll be using a 2200mAh 4S battery. My current (bad) Gadex batteries are rated 25C but I think that was the only choice when I ordered them a year or more ago. Are there better choices now? The lower rated batteries are of course lighter in weight, and dollars, but I want to get the right ones first time!


Ward-O
 

Hi Ward,
    I speak English,I'll try.20c is plenty for your motor current draw.The c rating will not increase flight times.A 2200 mah battery with a 20c rating will discharge at 44 amps continous.A 45c will discharge at 99 amps.As far as the batteries I like the Zippy Compact.I just got 4 25c 2700mah 4s Zippy Compacts for my Barf Nobler.For less than $100.00 I might add from the US warehouse.I was able to get 38 flights this weekend at the team trials in between my pit boss/pull test duties and these batteries perform better than expected.I was a bit concerned about the "Compact" in the name but not any more.Zippy Compact has a 2450mah 35c for less than 25 bucks as well.I do like a higher c rating with this being said just for the extra "headroom" and higher c's will run a bit cooler.At the trials Orestes had 25c batteries in his ship and kept them in a cooler but his friend Josias had 70c batteries in his Shark and they barely felt warm.Hope this helps.Trax

Hey Ward-O:

The "C" rating is part of a mathematical formula, so it's kind of hard to avoid.

But: if you're flying control line stunt, and if your flight time is between 5 and 6 minutes, and if you're not sucking the batteries completely dry each flight, then 10C is barely enough, 20C is better, and the only thing that a 45C discharge battery gets you is slightly less temperature rise and (possibly) quicker charging.

If your case doesn't match all the "ifs", then you need to play with math a bit to get the right number.

The last time I checked there was no industry standard way to establish the "C" rating on a battery.  Some manufacturers may rate the pack for what will give a life that's only a teeny bit shorter than if you used the battery "perfectly", others may rate it for what won't burst into flame the first time you try it out.  Most will be someplace in between.  Each manufacturer is going to find their own balance between impressive marketing numbers and honesty.  What this all boils down to is that a cheap Chinese pack's "C" rating may be much higher than a "name brand" pack's "C" rating even if the packs are identical in every way.

May be it is easier to understand it from opposite side. 1C means that you can discharge battery minimally 1 hour of constant current (for example 2Ah battery at 2 Amperes or less). 2C means you can drain it 2x harder and discharge it in 1/2 hour  (means 4A). 10C means you can do it in 1/10 hour means 6 minutes. 20C means you can dischrage it in 3 minutes. So if we fly 5 minutes, we do not discharge by constant current and we need some reserve, the minimal discharge rate is 20C.

Higher C rate will give you also better discharge efficiency (because of lower internal resistance) but it also means heavier battery.

How come the 2200s are dead?

Steve,

Batteries 'dead' due to ignorance. Bought them more than a year ago (mebbey two) and were never charged. One had two very nearly dead cells and wouldn't charge. The other had one very low cell. I'm going to try and bring that one back by running it in balance mode, perhaps with a higher charge rate. Error msg says to charge it at .5 amp while balancing. Of course it's possible they were bad to start with!

Ennyway we're going to try the Zippy 2450's.

Thanx all

W.

Steve,

Batteries 'dead' due to ignorance. Bought them more than a year ago (mebbey two) and were never charged. One had two very nearly dead cells and wouldn't charge. The other had one very low cell. I'm going to try and bring that one back by running it in balance mode, perhaps with a higher charge rate. Error msg says to charge it at .5 amp while balancing. Of course it's possible they were bad to start with!

Ennyway we're going to try the Zippy 2450's.

Thanx all

W.

If you have a batt with one cell way below the others then you should discard that battery and not use it anymore.  If your charger would let you put a higher rate into it you would probably get a very bad result...

When I start a charge I usually take a quick peek at the starting voltage for the cells that way I know they have all discharged evenly across the pack.

If you should run a battery evenly across all cells below the 20% line and the charger wont start up and says voltage too low you can try this trick.  Flip the charger to NiMh and charge it at .5 for just a few minutes at a time.  Then flip it back to LiPo and see if the voltage is there.  If not go a few more minutes etc etc until you get minimum voltage in your battery. Then charge at a 1c Rate balance for the next charge.  Keep it in an open area and stick around while charging.  Once you get a full charge in it monitor it closely when in use or relegate it as a test battery only using it for short trimming flights.  I have done this very thing on a car battery and it worked.

If you get MA look on page 109 in the Sept 2013 issue.  There is a pretty easy to follow break down on LiPos. Its not the same discipline but batteries are batteries and what they are attached too makes no difference when learning the dos and donts.

Hope this helps.