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Raptor E325 › OK to use a 30C?
05-09-2011 09:39 PM  7 years agoPost 1
JRAY

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LaGrange, Georgia, USA

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So I just got a E325 last week and love the thing, but I need more batteries and can't seem to find any 25C's (3S 11.1V 2200mah 25C). I'm new to the whole electric thing. Would it be OK to use a 30C (3S 11.1V 2250mah 30C) instead? Thanks for the help.

I am serious.....and don't call me Shirley.

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05-09-2011 10:04 PM  7 years agoPost 2
Heli 770

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USA.

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I would use a 35C or better.

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05-09-2011 10:25 PM  7 years agoPost 3
JRAY

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LaGrange, Georgia, USA

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So I would have to worry about frying my ESC bumping up the discharge rate?

I am serious.....and don't call me Shirley.

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05-09-2011 10:32 PM  7 years agoPost 4
Heli 770

rrProfessor

USA.

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Your discharge rate is determined by what the motor needs. Hot motors and ESC are caused by not having enough discharge rate.

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05-09-2011 11:43 PM  7 years agoPost 5
BarracudaHockey

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Jacksonville FL

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The C rating is how much a battery CAN deliver.

Its really the internal resistance. A higher C battery will just run cooler. The drawbacks are it cost a little more and weighs a little more, but if you have old batteries the higher C will probably weigh less in any case.

Andy
AMA 77227
http://www.jaxrc.com

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05-10-2011 12:10 AM  7 years agoPost 6
Ben-T-Spindle

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Central Illinois

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I would use a 35C or better.
30C is 60/30 or 2 minute full discharge.
35C is 60/35 or 1.7 minute discharge.
I really don’t thing that the packs will discharge that fast.

What you really want to know is the packs internal resistance (IR). They should start publishing that information. Higher C packs tend to have lower IR but it varies between brands. Lower IR is what actually makes packs run cooler, have more punch, and less bog down.

... BTS

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05-10-2011 12:30 AM  7 years agoPost 7
JRAY

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LaGrange, Georgia, USA

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Cool. Thanks for the info guys.

I am serious.....and don't call me Shirley.

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05-10-2011 05:01 PM  7 years agoPost 8
BarracudaHockey

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Jacksonville FL

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Well in reality the C rating is the internal resistance.

Publishing hard numbers would force manufacturers to reign in the sometimes fanciful numbers they slap on batteries

Andy
AMA 77227
http://www.jaxrc.com

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05-10-2011 10:22 PM  7 years agoPost 9
JRAY

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LaGrange, Georgia, USA

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Well see, I've got a shop telling me that i need at least a 66 amp esc to run a 35C and the one on my Titan is a 40 amp which was my concern. Is that not accurate? I didn't want to drop to a 20C for spares but it doesn't appear there are many offerings in 25C for this thing.

I am serious.....and don't call me Shirley.

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05-10-2011 10:35 PM  7 years agoPost 10
BarracudaHockey

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Jacksonville FL

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They are doing the math backwards.

Again, the C rating is what your battery is capable of delivering if asked. Its not forcing more amps because its higher rated, it will just deliver those amps without overheating and puffing.

Lets look at some numbers.

You have a 40 amp ESC. Lets assume we're talking 3S 450 size batteries, 2200mah.

A 25C 2200 Mah battery can deliver 55amps safely
C*Mah /1000 (25*2200)=55000 /1000 to convert to amps.

As you can see you have a battery thats 15amps of capability over what your speed controller is going to ask so thats a good safety margin and will keep you from over stressing your batteries.

A 35C battery can deliver 77 so it can still safely cover 40 amps but will run cooler (and probably last more cycles) while doing so.

Now....if you were to change your motor/pinion combination and the system tried to draw more than 40 amps, then your ESC would burn up, but not because the battery was trying to push more than 40 amps, it would be because the load (motor) was trying to pull more.

EDIT: Assuming 2200 batteries, 20C is pushing your luck at 44amp current capability, but if you had say 2600mah batteries that becomes 52amps and you have almost the safety margin that you have with 25c 2200 batteries.

Andy
AMA 77227
http://www.jaxrc.com

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05-11-2011 02:14 AM  7 years agoPost 11
JRAY

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LaGrange, Georgia, USA

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Got ya. Thanks a bunch Barracuda.That makes perfect sense and helps tremendously. I greatly appreciate everybody's input. Thanks, I know what to order now.

I am serious.....and don't call me Shirley.

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