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Old Apr 04, 2015, 04:01 PM
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10v lipo

Hi guys my motor is an A2208 Kv800. Specs 10v:0.8amp.
I could not find 10v/0.8amp lipo batteries.
Where shall I find this battery?
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Old Apr 04, 2015, 04:40 PM
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Please provide a link to the motor so we know exactly what you're talking about.

But that's not a battery specification. There are no 10V lipos. It might be something like the no-load current for that motor.

Steve
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Old Apr 04, 2015, 05:20 PM
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http://www.ebay.com/itm/A2208-KV800-...-/301252250635
Perhaps?

What is being used for? What plane are you looking to build?
Specs say a 2-3 cell lipo - (7.4 or 11.1V)

Since it has a 9A (60sec) rating, I'd guess a 3 cell lipo with a 1000mah capacity swinging an 8x4.5" prop might work.

Previous post for background: http://www.rcgroups.com/forums/showt...0#post30853137

This is a must read for newcomers on lipo batteries. - https://sites.google.com/site/tjingu...arging-how-tos
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Last edited by hoppy; Apr 04, 2015 at 05:39 PM.
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Old Apr 05, 2015, 03:32 AM
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Quote:
Originally Posted by hoppy View Post
http://www.ebay.com/itm/A2208-KV800-...-/301252250635
Perhaps?

What is being used for? What plane are you looking to build?
Specs say a 2-3 cell lipo - (7.4 or 11.1V)

Since it has a 9A (60sec) rating, I'd guess a 3 cell lipo with a 1000mah capacity swinging an 8x4.5" prop might work.

Previous post for background: http://www.rcgroups.com/forums/showt...0#post30853137



This is a must read for newcomers on lipo batteries. - https://sites.google.com/site/tjingu...arging-how-tos
Hi Slip and Hoppy thanks for response.
Yes that's the same motor I have. So even if this motor specs are 10v one can put from 7.4v to 11.1v at 1amp?
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Old Apr 05, 2015, 04:12 AM
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From web site :

Specification Motor:
Name : A2208-KV800 Brushless Outrunner Motor .
Motor for small fixed-wing , helicopter , Multi-axis aircraft .
Motor for ESC 18A - 30A .
Motor for 7045 , 8045 , 9045 propeller .
RC Pull weight : 250g - 600g .
Note : RC Pull weight Different , Optional ESC and propeller Different .
Internal Resistance : 65m .
No load current / 10V : 0.8A .
Number of battery(Ni-MH) : 6-10 Ni-MH/ 2-3 Li-Po .
Current capacity : 9A / 60s .
Max efficiency : 80% .
Size : 27.8 x 36 mm .
weight : 39g .


The No-load figures are 10v / 0.8A ....

The real figures to be interested in are the "Number of battery(Ni-MH) : 6-10 Ni-MH/ 2-3 Li-Po . Current capacity : 9A / 60s .

Which seems a bit low in Amps ! for such a combo with a 30A ESC.
If its spec'd for "7045 , 8045 , 9045 propeller " - then I think the amps quoted at 9A may be quoted low.. I would expect the motor to pull more amps than that particularly if a 9 x 4.5 prop fitted.

The motor looks like an RC Timer motor, but its specs are nothing like.

For that money - $17.99 + shipping - I'd look elsewhere to be honest.

My honest opinion.

Nigel
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Old Apr 05, 2015, 07:06 AM
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The closest battery I know of would be a 3 cell life pack which is 9.9 volts. But as stated in the previous post this doe not sound right to me. Every power system I've seen has its battery limits listed like this. 7.4v 2 cell Lipo or 7.2 volt NIMH. Or 3s Lipo and so on. I've never seen a system show a 10 volt limit. But if 10 volts is the limit and you want as close as possible to that limit the LiFe chemestry is closest.
Guess I should have read the previous post before making my statement.
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Old Apr 05, 2015, 07:12 AM
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Quote:
Originally Posted by guruji View Post
Hi Slip and Hoppy thanks for response.
Yes that's the same motor I have. So even if this motor specs are 10v one can put from 7.4v to 11.1v at 1amp?
You're confusing the current it uses, which is given as maximum 9A (amps), with the size of battery that Hoppy recommended which was 1000mAh (the "h" is important, that makes it battery capacity NOT current).

The motor recommends a battery which is either 2S or 3S. The capacity is never specified because it depends mainly on how much weight you can carry in whatever you're using it in and on how long you need it to fly.

Steve
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Old Apr 05, 2015, 10:19 AM
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Quote:
Originally Posted by solentlife

The real figures to be interested in are the "Number of battery(Ni-MH) : 6-10 Ni-MH/ 2-3 Li-Po . Current capacity : 9A / 60s .

Which seems a bit low in Amps ! for such a combo with a 30A ESC.

Nigel
9A at 11.1V would be 100W
Motor weight - 39g
Assuming W/g motor weight = 3, max output would be 117W

9A is probably correct.
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Old Apr 05, 2015, 12:06 PM
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Quote:
Originally Posted by hoppy View Post
9A at 11.1V would be 100W
Motor weight - 39g
Assuming W/g motor weight = 3, max output would be 117W

9A is probably correct.
Fair enough, but given its supplied with a 30A ESC .....

I realize a 2208 motor is not large .... but would expect given the props quoted to pull more than 9A.

Nigel
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Old Apr 05, 2015, 02:46 PM
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They probably had a whole bunch of 30A ESCs they needed to get rid of.
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Old Apr 06, 2015, 06:54 AM
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Quote:
Originally Posted by hoppy View Post
They probably had a whole bunch of 30A ESCs they needed to get rid of.
Does this mean that the ESC have to be 30A only to this motor?
What happens if it's less?
Thanks
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Old Apr 06, 2015, 08:17 AM
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Quote:
Originally Posted by guruji View Post
Does this mean that the ESC have to be 30A only to this motor?
What happens if it's less?
Thanks
Slow down ... think a little about it.

When you read the specs on motor's - you look for a few items :

Max watts power output.

Maximum Volts (in LiPo terms that's 2S .. 3S ... 4S etc).

Maximum Amps

Prop range designed for.

Weight of motor.

You match with your model and you get a flyable machine.

Now as to ESC .... it is my usual way to see what max Amps are in spec and add 50% to that figure. That's my ESC size to aim for initially. So lets take this motor in this thread : 9A ... add 50% = 13.5A So IF the 9A is true, then a 15A ESC should be good enough in normal use.

What you need to do once you have the motor and it's gear is run it up with required prop on a Wattmeter. Read the REAL Amp / voltage results. Once you have the Amps figure at FULL throttle - then you add 50% to that Wattmeter reading to arrive at real ESC Amp size needed.

Reason you have 50% greater capacity in ESC than actual amps - is to avoid overstressing ESC by pushing it to limits all the time. You can go as high a rating as you like - but do not go down to minimum or less - ESC will not appreciate it and you will very soon have a burnt out ESC !

When starting out in this hobby - common to have to replace a few items that are badly sized by sellers. Once you get a few models and set-ups under the belt - you get to instinctively feel what size you need. You also end up with spare ESC of various sizes on the bench !

Nigel
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Old Apr 06, 2015, 02:27 PM
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Quote:
Originally Posted by solentlife View Post
Slow down ... think a little about it.

When you read the specs on motor's - you look for a few items :

Max watts power output.

Maximum Volts (in LiPo terms that's 2S .. 3S ... 4S etc).

Maximum Amps

Prop range designed for.

Weight of motor.

You match with your model and you get a flyable machine.

Now as to ESC .... it is my usual way to see what max Amps are in spec and add 50% to that figure. That's my ESC size to aim for initially. So lets take this motor in this thread : 9A ... add 50% = 13.5A So IF the 9A is true, then a 15A ESC should be good enough in normal use.

What you need to do once you have the motor and it's gear is run it up with required prop on a Wattmeter. Read the REAL Amp / voltage results. Once you have the Amps figure at FULL throttle - then you add 50% to that Wattmeter reading to arrive at real ESC Amp size needed.

Reason you have 50% greater capacity in ESC than actual amps - is to avoid overstressing ESC by pushing it to limits all the time. You can go as high a rating as you like - but do not go down to minimum or less - ESC will not appreciate it and you will very soon have a burnt out ESC !

When starting out in this hobby - common to have to replace a few items that are badly sized by sellers. Once you get a few models and set-ups under the belt - you get to instinctively feel what size you need. You also end up with spare ESC of various sizes on the bench !

Nigel
Ok Nigel thanks for the explanation. Regarding batteries so if I buy a 7.4v lipo is ok yes?
Thanks
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Old Apr 07, 2015, 02:34 AM
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Quote:
Originally Posted by guruji View Post
Ok Nigel thanks for the explanation. Regarding batteries so if I buy a 7.4v lipo is ok yes?
Thanks
The size of battery depends on the model, prop, motor combination.

The small prop in the specs usually relates to maximum voltage recc'd for motor : 3S (11.1v), largest prop relates to lower voltage limit : 2S (7.4v). That is a usual understanding of such data. Each model will of course indicate variations on that, but is a good starting point.

So my reply is : What prop are you proposing to fit or is reccomended for the model? That is what will decide the battery voltage you select. So there is no way anyone can say yes or no to your question - we do not know what you intend to fit.

Nigel
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Old Apr 07, 2015, 02:48 PM
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Quote:
Originally Posted by solentlife View Post
The size of battery depends on the model, prop, motor combination.

The small prop in the specs usually relates to maximum voltage recc'd for motor : 3S (11.1v), largest prop relates to lower voltage limit : 2S (7.4v). That is a usual understanding of such data. Each model will of course indicate variations on that, but is a good starting point.

So my reply is : What prop are you proposing to fit or is reccomended for the model? That is what will decide the battery voltage you select. So there is no way anyone can say yes or no to your question - we do not know what you intend to fit.

Nigel
Ok so the 2S(7.4) is the right battery for me cause I bought this prop yes?
Specifications:
Product Name RC Airplane Propeller
Blade Number 3
Model GWS Style HD9050*3(Non-OEM)
Motor Shaft Hole Dia 6mm / 0.24"
Rotating Diameter 229mm / 9"
Pitch 127mm / 5"
Max Thickness 9mm / 0.35"
Material Plastic
Color Black
Net Weight 10g
Package Content
1 x Propeller
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