Electric Heli Voltage question

[Michael]

How do the number of volts used (battery volts) effect the electronics of an
all electric heli?

What does 7.2 volts do compared to 11.1 volts for example?

I'm thinking about buying an 11.1 volt 2200mah li-poly battery for my
Humminngbird V2 but am worried about burning it up in the process! LOL! If
you can shed any light on this stuff please let me know.... Century has a
disclaimer on their website stating that any battery greater than 8.4 volts
are used at customers risk, which made me wonder. Thanks!

- Michael

[Kevin R]

the problem is the amount of power the BEC & other circuits have to cope
with at 7.2 volts it has to drop the receiver and servo volts down to 4.8 or
6 volts and running at 11.1volts it increases the watts the bec is running
at by 50%
"Michael" <N0Spam_MShrader@Starband.net_N0Spam> wrote in message
news:7a26a$423bc9f0$943fd8a7$23949@STARBAND.NET...
> How do the number of volts used (battery volts) effect the electronics of
> an all electric heli?
>
> What does 7.2 volts do compared to 11.1 volts for example?
>
> I'm thinking about buying an 11.1 volt 2200mah li-poly battery for my
> Humminngbird V2 but am worried about burning it up in the process! LOL! If
> you can shed any light on this stuff please let me know.... Century has a
> disclaimer on their website stating that any battery greater than 8.4
> volts are used at customers risk, which made me wonder. Thanks!
>
> - Michael
>

[Michael]

Ok but which is good and which is bad, Kevin? I'm a computer scientist not
an electrical engineer! LOL!

- Michael

"Kevin R" <dontemailme@ntlworld.com> wrote in message
news:JER_d.74$Kt5.61@newsfe2-gui.ntli.net...
> the problem is the amount of power the BEC & other circuits have to cope
> with at 7.2 volts it has to drop the receiver and servo volts down to 4.8
> or 6 volts and running at 11.1volts it increases the watts the bec is
> running at by 50%
> "Michael" <N0Spam_MShrader@Starband.net_N0Spam> wrote in message
> news:7a26a$423bc9f0$943fd8a7$23949@STARBAND.NET...
>> How do the number of volts used (battery volts) effect the electronics of
>> an all electric heli?
>>
>> What does 7.2 volts do compared to 11.1 volts for example?
>>
>> I'm thinking about buying an 11.1 volt 2200mah li-poly battery for my
>> Humminngbird V2 but am worried about burning it up in the process! LOL!
>> If you can shed any light on this stuff please let me know.... Century
>> has a disclaimer on their website stating that any battery greater than
>> 8.4 volts are used at customers risk, which made me wonder. Thanks!
>>
>> - Michael
>>
>
>

[Kevin R]

a circuit designed for 7.2 volts with no tolerance for running a higher
voltage could be damaged or its life shortened think of it like running a
7.2 volt bulb at 12 volts it will work and it will be brighter but its life
will be shortened it all depends on what the speed controller and bec
circuits were designed for
"Michael" <N0Spam_MShrader@Starband.net_N0Spam> wrote in message
news:cc33a$423c44d5$943fd8a7$25711@STARBAND.NET...
> Ok but which is good and which is bad, Kevin? I'm a computer scientist not
> an electrical engineer! LOL!
>
> - Michael
>
> "Kevin R" <dontemailme@ntlworld.com> wrote in message
> news:JER_d.74$Kt5.61@newsfe2-gui.ntli.net...
>> the problem is the amount of power the BEC & other circuits have to cope
>> with at 7.2 volts it has to drop the receiver and servo volts down to 4.8
>> or 6 volts and running at 11.1volts it increases the watts the bec is
>> running at by 50%
>> "Michael" <N0Spam_MShrader@Starband.net_N0Spam> wrote in message
>> news:7a26a$423bc9f0$943fd8a7$23949@STARBAND.NET...
>>> How do the number of volts used (battery volts) effect the electronics
>>> of an all electric heli?
>>>
>>> What does 7.2 volts do compared to 11.1 volts for example?
>>>
>>> I'm thinking about buying an 11.1 volt 2200mah li-poly battery for my
>>> Humminngbird V2 but am worried about burning it up in the process! LOL!
>>> If you can shed any light on this stuff please let me know.... Century
>>> has a disclaimer on their website stating that any battery greater than
>>> 8.4 volts are used at customers risk, which made me wonder. Thanks!
>>>
>>> - Michael
>>>
>>
>>
>
>

[Michael]

Ok then I guess 11.1 volts would be bad connected to a Hummingboard designed
more for an 8.4 volt battery? :-\

Seems most of the Li-poly batts are 11.1 volts though dangit. :-|

I'm open to suggestions if anybody's got 'em. Thanks!

- Michael

"Kevin R" <dontemailme@ntlworld.com> wrote in message
news:fT__d.2634$Kt5.1208@newsfe2-gui.ntli.net...
>a circuit designed for 7.2 volts with no tolerance for running a higher
>voltage could be damaged or its life shortened think of it like running a
>7.2 volt bulb at 12 volts it will work and it will be brighter but its life
>will be shortened it all depends on what the speed controller and bec
>circuits were designed for
> "Michael" <N0Spam_MShrader@Starband.net_N0Spam> wrote in message
> news:cc33a$423c44d5$943fd8a7$25711@STARBAND.NET...
>> Ok but which is good and which is bad, Kevin? I'm a computer scientist
>> not an electrical engineer! LOL!
>>
>> - Michael
>>
>> "Kevin R" <dontemailme@ntlworld.com> wrote in message
>> news:JER_d.74$Kt5.61@newsfe2-gui.ntli.net...
>>> the problem is the amount of power the BEC & other circuits have to cope
>>> with at 7.2 volts it has to drop the receiver and servo volts down to
>>> 4.8 or 6 volts and running at 11.1volts it increases the watts the bec
>>> is running at by 50%
>>> "Michael" <N0Spam_MShrader@Starband.net_N0Spam> wrote in message
>>> news:7a26a$423bc9f0$943fd8a7$23949@STARBAND.NET...
>>>> How do the number of volts used (battery volts) effect the electronics
>>>> of an all electric heli?
>>>>
>>>> What does 7.2 volts do compared to 11.1 volts for example?
>>>>
>>>> I'm thinking about buying an 11.1 volt 2200mah li-poly battery for my
>>>> Humminngbird V2 but am worried about burning it up in the process! LOL!
>>>> If you can shed any light on this stuff please let me know.... Century
>>>> has a disclaimer on their website stating that any battery greater than
>>>> 8.4 volts are used at customers risk, which made me wonder. Thanks!
>>>>
>>>> - Michael
>>>>
>>>
>>>
>>
>>
>
>

[Kevin R]

possibly but I have a honey bee that is sold on either 8.4 or 11.1 so it
depends on the design
"Michael" <N0Spam_MShrader@Starband.net_N0Spam> wrote in message
news:d9a21$423c8c33$943fd8a7$506@STARBAND.NET...
> Ok then I guess 11.1 volts would be bad connected to a Hummingboard
> designed more for an 8.4 volt battery? :-\
>
> Seems most of the Li-poly batts are 11.1 volts though dangit. :-|
>
> I'm open to suggestions if anybody's got 'em. Thanks!
>
> - Michael
>
> "Kevin R" <dontemailme@ntlworld.com> wrote in message
> news:fT__d.2634$Kt5.1208@newsfe2-gui.ntli.net...
>>a circuit designed for 7.2 volts with no tolerance for running a higher
>>voltage could be damaged or its life shortened think of it like running a
>>7.2 volt bulb at 12 volts it will work and it will be brighter but its
>>life will be shortened it all depends on what the speed controller and
>>bec circuits were designed for
>> "Michael" <N0Spam_MShrader@Starband.net_N0Spam> wrote in message
>> news:cc33a$423c44d5$943fd8a7$25711@STARBAND.NET...
>>> Ok but which is good and which is bad, Kevin? I'm a computer scientist
>>> not an electrical engineer! LOL!
>>>
>>> - Michael
>>>
>>> "Kevin R" <dontemailme@ntlworld.com> wrote in message
>>> news:JER_d.74$Kt5.61@newsfe2-gui.ntli.net...
>>>> the problem is the amount of power the BEC & other circuits have to
>>>> cope with at 7.2 volts it has to drop the receiver and servo volts down
>>>> to 4.8 or 6 volts and running at 11.1volts it increases the watts the
>>>> bec is running at by 50%
>>>> "Michael" <N0Spam_MShrader@Starband.net_N0Spam> wrote in message
>>>> news:7a26a$423bc9f0$943fd8a7$23949@STARBAND.NET...
>>>>> How do the number of volts used (battery volts) effect the electronics
>>>>> of an all electric heli?
>>>>>
>>>>> What does 7.2 volts do compared to 11.1 volts for example?
>>>>>
>>>>> I'm thinking about buying an 11.1 volt 2200mah li-poly battery for my
>>>>> Humminngbird V2 but am worried about burning it up in the process!
>>>>> LOL! If you can shed any light on this stuff please let me know....
>>>>> Century has a disclaimer on their website stating that any battery
>>>>> greater than 8.4 volts are used at customers risk, which made me
>>>>> wonder. Thanks!
>>>>>
>>>>> - Michael
>>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>
>

[Jennifer Smith]

Not true. There's 2s LiPo's out there, they only have 7.4 volts (which
is fine for your bird)

J

Michael wrote:
> Ok then I guess 11.1 volts would be bad connected to a Hummingboard designed
> more for an 8.4 volt battery? :-\
>
> Seems most of the Li-poly batts are 11.1 volts though dangit. :-|
>
> I'm open to suggestions if anybody's got 'em. Thanks!
>
> - Michael
>
> "Kevin R" <dontemailme@ntlworld.com> wrote in message
> news:fT__d.2634$Kt5.1208@newsfe2-gui.ntli.net...
>
>>a circuit designed for 7.2 volts with no tolerance for running a higher
>>voltage could be damaged or its life shortened think of it like running a
>>7.2 volt bulb at 12 volts it will work and it will be brighter but its life
>>will be shortened it all depends on what the speed controller and bec
>>circuits were designed for
>>"Michael" <N0Spam_MShrader@Starband.net_N0Spam> wrote in message
>>news:cc33a$423c44d5$943fd8a7$25711@STARBAND.NET...
>>
>>>Ok but which is good and which is bad, Kevin? I'm a computer scientist
>>>not an electrical engineer! LOL!
>>>
>>>- Michael
>>>
>>>"Kevin R" <dontemailme@ntlworld.com> wrote in message
>>>news:JER_d.74$Kt5.61@newsfe2-gui.ntli.net...
>>>
>>>>the problem is the amount of power the BEC & other circuits have to cope
>>>>with at 7.2 volts it has to drop the receiver and servo volts down to
>>>>4.8 or 6 volts and running at 11.1volts it increases the watts the bec
>>>>is running at by 50%
>>>>"Michael" <N0Spam_MShrader@Starband.net_N0Spam> wrote in message
>>>>news:7a26a$423bc9f0$943fd8a7$23949@STARBAND.NET...
>>>>
>>>>>How do the number of volts used (battery volts) effect the electronics
>>>>>of an all electric heli?
>>>>>
>>>>>What does 7.2 volts do compared to 11.1 volts for example?
>>>>>
>>>>>I'm thinking about buying an 11.1 volt 2200mah li-poly battery for my
>>>>>Humminngbird V2 but am worried about burning it up in the process! LOL!
>>>>>If you can shed any light on this stuff please let me know.... Century
>>>>>has a disclaimer on their website stating that any battery greater than
>>>>>8.4 volts are used at customers risk, which made me wonder. Thanks!
>>>>>
>>>>>- Michael
>>>>>
>>>>
>>>>
>>>
>>
>
>

[Michael]

Jennifer I didn't mean it as a *fact*, only that 11.1 was all I've been seen
so far. :-p

Since the Century "birdseed" batteries are 8.4 volts, have you seen any
Li-poly's anywhere that are 8.4 volts? Thanks!

- Michael

"Jennifer Smith" <jennifer@you-wish-you-knew.mine.nu> wrote in message
news:MdWdne7nXdQnB6HfRVn-3A@comcast.com...
> Not true. There's 2s LiPo's out there, they only have 7.4 volts (which is
> fine for your bird)
>
> J
>
> Michael wrote:
>> Ok then I guess 11.1 volts would be bad connected to a Hummingboard
>> designed more for an 8.4 volt battery? :-\
>>
>> Seems most of the Li-poly batts are 11.1 volts though dangit. :-|
>>
>> I'm open to suggestions if anybody's got 'em. Thanks!
>>
>> - Michael
>>
>> "Kevin R" <dontemailme@ntlworld.com> wrote in message
>> news:fT__d.2634$Kt5.1208@newsfe2-gui.ntli.net...
>>
>>>a circuit designed for 7.2 volts with no tolerance for running a higher
>>>voltage could be damaged or its life shortened think of it like running a
>>>7.2 volt bulb at 12 volts it will work and it will be brighter but its
>>>life will be shortened it all depends on what the speed controller and
>>>bec circuits were designed for
>>>"Michael" <N0Spam_MShrader@Starband.net_N0Spam> wrote in message
>>>news:cc33a$423c44d5$943fd8a7$25711@STARBAND.NET...
>>>
>>>>Ok but which is good and which is bad, Kevin? I'm a computer scientist
>>>>not an electrical engineer! LOL!
>>>>
>>>>- Michael
>>>>
>>>>"Kevin R" <dontemailme@ntlworld.com> wrote in message
>>>>news:JER_d.74$Kt5.61@newsfe2-gui.ntli.net...
>>>>
>>>>>the problem is the amount of power the BEC & other circuits have to
>>>>>cope with at 7.2 volts it has to drop the receiver and servo volts down
>>>>>to 4.8 or 6 volts and running at 11.1volts it increases the watts the
>>>>>bec is running at by 50%
>>>>>"Michael" <N0Spam_MShrader@Starband.net_N0Spam> wrote in message
>>>>>news:7a26a$423bc9f0$943fd8a7$23949@STARBAND.NET...
>>>>>
>>>>>>How do the number of volts used (battery volts) effect the electronics
>>>>>>of an all electric heli?
>>>>>>
>>>>>>What does 7.2 volts do compared to 11.1 volts for example?
>>>>>>
>>>>>>I'm thinking about buying an 11.1 volt 2200mah li-poly battery for my
>>>>>>Humminngbird V2 but am worried about burning it up in the process!
>>>>>>LOL! If you can shed any light on this stuff please let me know....
>>>>>>Century has a disclaimer on their website stating that any battery
>>>>>>greater than 8.4 volts are used at customers risk, which made me
>>>>>>wonder. Thanks!
>>>>>>
>>>>>>- Michael
>>>>>>
>>>>>
>>>>>
>>>>
>>>
>>

[Jennifer Smith]

Nope :) I'm using a 7.4v Lipo in my bird (which came with an 8.4v NiMH
too), and it seem to work fine. You could possibly go ahead and plug in
a 11.1v LiPo and use a circuit board to regulate it down to 8.4v - I
think they're available at many electronics stores, and not heavy either.

J

Michael wrote:
> Jennifer I didn't mean it as a *fact*, only that 11.1 was all I've been seen
> so far. :-p
>
> Since the Century "birdseed" batteries are 8.4 volts, have you seen any
> Li-poly's anywhere that are 8.4 volts? Thanks!
>
> - Michael
>
> "Jennifer Smith" <jennifer@you-wish-you-knew.mine.nu> wrote in message
> news:MdWdne7nXdQnB6HfRVn-3A@comcast.com...
>
>>Not true. There's 2s LiPo's out there, they only have 7.4 volts (which is
>>fine for your bird)
>>
>>J
>>
>>Michael wrote:
>>
>>>Ok then I guess 11.1 volts would be bad connected to a Hummingboard
>>>designed more for an 8.4 volt battery? :-\
>>>
>>>Seems most of the Li-poly batts are 11.1 volts though dangit. :-|
>>>
>>>I'm open to suggestions if anybody's got 'em. Thanks!
>>>
>>>- Michael
>>>
>>>"Kevin R" <dontemailme@ntlworld.com> wrote in message
>>>news:fT__d.2634$Kt5.1208@newsfe2-gui.ntli.net...
>>>
>>>
>>>>a circuit designed for 7.2 volts with no tolerance for running a higher
>>>>voltage could be damaged or its life shortened think of it like running a
>>>>7.2 volt bulb at 12 volts it will work and it will be brighter but its
>>>>life will be shortened it all depends on what the speed controller and
>>>>bec circuits were designed for
>>>>"Michael" <N0Spam_MShrader@Starband.net_N0Spam> wrote in message
>>>>news:cc33a$423c44d5$943fd8a7$25711@STARBAND.NET...
>>>>
>>>>
>>>>>Ok but which is good and which is bad, Kevin? I'm a computer scientist
>>>>>not an electrical engineer! LOL!
>>>>>
>>>>>- Michael
>>>>>
>>>>>"Kevin R" <dontemailme@ntlworld.com> wrote in message
>>>>>news:JER_d.74$Kt5.61@newsfe2-gui.ntli.net...
>>>>>
>>>>>
>>>>>>the problem is the amount of power the BEC & other circuits have to
>>>>>>cope with at 7.2 volts it has to drop the receiver and servo volts down
>>>>>>to 4.8 or 6 volts and running at 11.1volts it increases the watts the
>>>>>>bec is running at by 50%
>>>>>>"Michael" <N0Spam_MShrader@Starband.net_N0Spam> wrote in message
>>>>>>news:7a26a$423bc9f0$943fd8a7$23949@STARBAND.NET...
>>>>>>
>>>>>>
>>>>>>>How do the number of volts used (battery volts) effect the electronics
>>>>>>>of an all electric heli?
>>>>>>>
>>>>>>>What does 7.2 volts do compared to 11.1 volts for example?
>>>>>>>
>>>>>>>I'm thinking about buying an 11.1 volt 2200mah li-poly battery for my
>>>>>>>Humminngbird V2 but am worried about burning it up in the process!
>>>>>>>LOL! If you can shed any light on this stuff please let me know....
>>>>>>>Century has a disclaimer on their website stating that any battery
>>>>>>>greater than 8.4 volts are used at customers risk, which made me
>>>>>>>wonder. Thanks!
>>>>>>>
>>>>>>>- Michael
>>>>>>>
>>>>>>
>>>>>>
>

[Nigel Heather]

Michael,

Voltage is the measure of the potential to drive current through a circuit.
The higher the voltage for the same resistive load the higher the current
and the higher the power delivered into the circuit. If the circuit is an
electric motor (or two) then they will probably generate more mechanical
power within the restrictions of their design.

Many people fly Hummingbirds with 3 Cell Lipos and most will say that it is
the only way to go if you want to turn your heli into something that
performs well. There are a couple of provisos though ...

(i) The Battery Eliminator Circuit (BEC) needs to be able to handle it
without buring out - it must be able to receive 11.1V rather than the
designed 8.4V and deliver 4.8V for to the servos and receiver. Basicly it
has to be able to handle a power equal to the current delivered to the RX
and Servos multiplied by (11.1V - 4.8V) - normally the volatge drop would be
(8.4 - 4.8) - in other words it must be able to disspipate an extra 75%
power (heat).
(ii) The Electronic Speed Controller (ESC) must be able to handle 11.1V
rather than 8.4V although this isn't usually a problem as most ESCs simply
pass through the source voltage without any voltage drop.
(iii) The motors must be able to handle it - they will be receiving 11.1V
rather than 8.4V (i.e. an 32% electrical power increase). This will result
in higher revolutions and torque leading to more mechanical power but will
also generate more heat and strain on the motors.

Okay theory over, where does that leave you.

Well in short,

(i) BEC
If your electrics are seperate (RX, Gyro, ESC/BEC are three sepearte
components) then you stand a good chance of being okay.
If you have a one of the all-in-one boards there is more risk. The
Hummingbird ones seem better than most and remember than Century sell a 3
cell LiPo as an upgrade. The cheaper units you get in Dragonflies, Jabos,
Aerohawks etc have a history of burning out on 11.1V.

(ii) ESC
Should be okay as a good ESC simply passes voltage on and therefore doesn't
have to disipate much power

(iii) Motors
Your main motor should be okay but probably won't last as long. If you have
a 480 rather than a 400 then so much the better. The stock tail motor won't
last long on 11.1V - Century sell a more powerful upgrade especially for
this but be aware that this is heavier and since you have a lighter battery
up front the heli becomes more challenging to balance.

I fly my HB with a 1300 2 Cell LiPo (7.4V). I wasn't sure what to expect
because it delivers less instaneous power than the birdseed. But in reality
it is superb. The loss of about 40g of weight more than makes up for the
lower voltage. Also the way in which LiPos deliver power is much more
smoother - they maintain the power until the battery is used, unlike the
Birdseed which delivers good power initially but then falls off quickly. My
HB literally leaps into the air with the 7.4 LiPo compared with the birdseed
and is much easier to fly as a result.

One thing though - I hinted above about Centre of Gravity. The LiPos are
much lighter and so place the LiPo in the same place as the birdseed will
leave it really tail-heavy. It's bad practice to add ballest to any
aircraft so you have two options - move the battery forward or get a heavier
battery. With a very light LiPo you will have to move it so far forward
that you will not be able to fit the canopy (even with a heavier LiPo this
is a challenge). So my advice would be not to go for a really light LiPo -
get a 1500mAh minimum (maybe even a 2100mAh) so that the ballest earns its
keep.

Wow that went on a bit, but I hope it helps.

Cheers,

Nigel

[Beav]

"Michael" <N0Spam_MShrader@Starband.net_N0Spam> wrote in message
news:cc33a$423c44d5$943fd8a7$25711@STARBAND.NET...
> Ok but which is good and which is bad, Kevin? I'm a computer scientist not
> an electrical engineer! LOL!

What'd happen to a CPU designed to run at 1.4v if you shoved 2.8v up it's
arse? I have a feeling something would become useless pretty quickly. Same
thing with ANYTHING electrical.

Most RC equipment will handle voltages in excess of their quoted number, but
there's a limit. I suspect your spped controller would get fried.


--
Beav

Reply to "beavis dot original at ntlworld dot com" (with the obvious
changes)

[Beav]

"Jennifer Smith" <jennifer@you-wish-you-knew.mine.nu> wrote in message
news:c4ednYp7W8EeXaHfRVn-2Q@comcast.com...
> Nope :) I'm using a 7.4v Lipo in my bird (which came with an 8.4v NiMH
> too), and it seem to work fine. You could possibly go ahead and plug in a
> 11.1v LiPo and use a circuit board to regulate it down to 8.4v - I think
> they're available at many electronics stores, and not heavy either.

Confused, I ask the following question. If you're running a 7.4v Li-pol and
Mike is running an 8.4v Li-pol, what exactly is the voltage of a single cell
Li-pol?


--
Beav

Reply to "beavis dot original at ntlworld dot com" (with the obvious
changes)

[Michael]

Thanks for shedding so much light on this subject, Nigel! That was very
informative.

So going for lower voltage (7.2V) and greater mAH sounds like the best way
to go then, correct?

- Michael

[Jennifer Smith]

Beav wrote:
> "Jennifer Smith" <jennifer@you-wish-you-knew.mine.nu> wrote in message
> news:c4ednYp7W8EeXaHfRVn-2Q@comcast.com...
>
>>Nope :) I'm using a 7.4v Lipo in my bird (which came with an 8.4v NiMH
>>too), and it seem to work fine. You could possibly go ahead and plug in a
>>11.1v LiPo and use a circuit board to regulate it down to 8.4v - I think
>>they're available at many electronics stores, and not heavy either.
>
>
> Confused, I ask the following question. If you're running a 7.4v Li-pol and
> Mike is running an 8.4v Li-pol, what exactly is the voltage of a single cell
> Li-pol?

He's running an 8.4v NiMH - not a LiPo. Since 7.4v LiPo is a 2S (2 cells
in serial) each single cell would have 3.7v.

J

[Michael]

Hey Jennifer, what do you think about this one?
http://www.heli-world.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=MX-2LI2200&Category_Code=Batt

2200mAH! I may have to order one of these critters. >:-)

- Michael

"Jennifer Smith" <jennifer@you-wish-you-knew.mine.nu> wrote in message
news:BcydnQzxRcxKpaPfRVn-ug@comcast.com...
> Beav wrote:
>> "Jennifer Smith" <jennifer@you-wish-you-knew.mine.nu> wrote in message
>> news:c4ednYp7W8EeXaHfRVn-2Q@comcast.com...
>>
>>>Nope :) I'm using a 7.4v Lipo in my bird (which came with an 8.4v NiMH
>>>too), and it seem to work fine. You could possibly go ahead and plug in a
>>>11.1v LiPo and use a circuit board to regulate it down to 8.4v - I think
>>>they're available at many electronics stores, and not heavy either.
>>
>>
>> Confused, I ask the following question. If you're running a 7.4v Li-pol
>> and Mike is running an 8.4v Li-pol, what exactly is the voltage of a
>> single cell Li-pol?
>
> He's running an 8.4v NiMH - not a LiPo. Since 7.4v LiPo is a 2S (2 cells
> in serial) each single cell would have 3.7v.
>
> J

[NONNE]

Michael wrote:
> How do the number of volts used (battery volts) effect the
electronics of an
> all electric heli?
>
> What does 7.2 volts do compared to 11.1 volts for example?
>
> I'm thinking about buying an 11.1 volt 2200mah li-poly battery for my

> Humminngbird V2 but am worried about burning it up in the process!
LOL! If
> you can shed any light on this stuff please let me know.... Century
has a
> disclaimer on their website stating that any battery greater than 8.4
volts
> are used at customers risk, which made me wonder. Thanks!
>
> - Michael

11.1V 2200mah is too powerful for your Hummingbird V2, I think the
Hummingbird V2 only use the 8.2V battery, right?? If that is correct,
you only need the 7.4V li-ion battery ONLY.

7.4V 1800mah Li-ion battery reference:
http://www.hobbyjapan2000.com/store/proddetail.php?prod=LIPOBATC

[Jennifer Smith]

I've got a LiPo, this is a LiIon. Mine gives me easily 30 minutes flight
time.

For some more technical information about LiIon batteries (most of it
applies to LiPos too):
http://en.wikipedia.org/wiki/Lithium_ion_battery

J

Michael wrote:
> Hey Jennifer, what do you think about this one?
> http://www.heli-world.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=MX-2LI2200&Category_Code=Batt
>
> 2200mAH! I may have to order one of these critters. >:-)
>
> - Michael
>
> "Jennifer Smith" <jennifer@you-wish-you-knew.mine.nu> wrote in message
> news:BcydnQzxRcxKpaPfRVn-ug@comcast.com...
>
>>Beav wrote:
>>
>>>"Jennifer Smith" <jennifer@you-wish-you-knew.mine.nu> wrote in message
>>>news:c4ednYp7W8EeXaHfRVn-2Q@comcast.com...
>>>
>>>
>>>>Nope :) I'm using a 7.4v Lipo in my bird (which came with an 8.4v NiMH
>>>>too), and it seem to work fine. You could possibly go ahead and plug in a
>>>>11.1v LiPo and use a circuit board to regulate it down to 8.4v - I think
>>>>they're available at many electronics stores, and not heavy either.
>>>
>>>
>>>Confused, I ask the following question. If you're running a 7.4v Li-pol
>>>and Mike is running an 8.4v Li-pol, what exactly is the voltage of a
>>>single cell Li-pol?
>>
>>He's running an 8.4v NiMH - not a LiPo. Since 7.4v LiPo is a 2S (2 cells
>>in serial) each single cell would have 3.7v.
>>
>>J
>
>
>

[Nigel Heather]

Depends on what you want to do. But if you just want it to fly a little
better and for longer then I would go for a 2 Cell large capacity.

The guys who fly 3 cell are virtually all running with brushless set ups and
upgrades than have turned their little HB into a $600 machine.

I went for a 1300mAh GWS 2 Cell. It weighs 54g compared with 90g for the
birdseed. It fits reasonably neatly but I have seperates and have everybit
moved up to the front. Even then the canopy won't fit as designed so I have
it velcro'ed to the battery. Looks okay but it is about 5mm forward so
won't clip onto the rear post. With this hindsight I would have gone for a
larger capacity - a 1500mAh or higher.

Make sure you get LiPo and LiOn - LiOn are the poor relation.

Also make sure you get a discharge rate of at least 6C so you can
comforatably get power to the motors.

Cheers,

Nigel

"Michael" <N0Spam_MShrader@Starband.net_N0Spam> wrote in message
news:34045$423e1c72$943fd8a7$31556@STARBAND.NET...
> Thanks for shedding so much light on this subject, Nigel! That was very
> informative.
>
> So going for lower voltage (7.2V) and greater mAH sounds like the best way
> to go then, correct?
>
> - Michael
>
>

[Nigel Heather]

Michael,

Three things worry me about this one though I accept that my concern may be
unfounded because they are based on the lack of information.

(i) Li-Ion - not as good as LiPo - poor relation in terms of capacity per
gramme and in terms of discharge capability
(ii) No dimensions and weight - given Li-Ion are quite heavy and its large
capacity and the fact that it is packed in a tube rather than the foil
envelope this could be heavier than the birdseed.
(iii) No indication of discharge capacity. I reckon you need at least 8A to
power your hummer - so this would have to be a 4C or greater.

I got mine from http://www.rcflying.biz/PipsElectricPlanes.htm in
Singapore - cost me £16 ($29) including postage to the UK. This may not be
such a great deal in the US but for the UK its is quite a saving.

Cheers,

Nigel




"Michael" <N0Spam_MShrader@Starband.net_N0Spam> wrote in message
news:9b2bf$423e5dff$943fd8a7$14872@STARBAND.NET...
> Hey Jennifer, what do you think about this one?
> http://www.heli-world.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=MX-2LI2200&Category_Code=Batt
>
> 2200mAH! I may have to order one of these critters. >:-)
>
> - Michael
>
> "Jennifer Smith" <jennifer@you-wish-you-knew.mine.nu> wrote in message
> news:BcydnQzxRcxKpaPfRVn-ug@comcast.com...
>> Beav wrote:
>>> "Jennifer Smith" <jennifer@you-wish-you-knew.mine.nu> wrote in message
>>> news:c4ednYp7W8EeXaHfRVn-2Q@comcast.com...
>>>
>>>>Nope :) I'm using a 7.4v Lipo in my bird (which came with an 8.4v NiMH
>>>>too), and it seem to work fine. You could possibly go ahead and plug in
>>>>a 11.1v LiPo and use a circuit board to regulate it down to 8.4v - I
>>>>think they're available at many electronics stores, and not heavy
>>>>either.
>>>
>>>
>>> Confused, I ask the following question. If you're running a 7.4v Li-pol
>>> and Mike is running an 8.4v Li-pol, what exactly is the voltage of a
>>> single cell Li-pol?
>>
>> He's running an 8.4v NiMH - not a LiPo. Since 7.4v LiPo is a 2S (2 cells
>> in serial) each single cell would have 3.7v.
>>
>> J
>
>

[Beav]

"Jennifer Smith" <jennifer@you-wish-you-knew.mine.nu> wrote in message
news:BcydnQzxRcxKpaPfRVn-ug@comcast.com...
> Beav wrote:
>> "Jennifer Smith" <jennifer@you-wish-you-knew.mine.nu> wrote in message
>> news:c4ednYp7W8EeXaHfRVn-2Q@comcast.com...
>>
>>>Nope :) I'm using a 7.4v Lipo in my bird (which came with an 8.4v NiMH
>>>too), and it seem to work fine. You could possibly go ahead and plug in a
>>>11.1v LiPo and use a circuit board to regulate it down to 8.4v - I think
>>>they're available at many electronics stores, and not heavy either.
>>
>>
>> Confused, I ask the following question. If you're running a 7.4v Li-pol
>> and Mike is running an 8.4v Li-pol, what exactly is the voltage of a
>> single cell Li-pol?
>
> He's running an 8.4v NiMH - not a LiPo.

Back to the reading lessons for me then :-)

Since 7.4v LiPo is a 2S (2 cells
> in serial) each single cell would have 3.7v.

Indeed it would, but if he used three (coz 2 wouldn't be enough), at 11.1v
he'd be well over the capabilities of his current speed controller/motor
combo I'd hazard.


--
Beav

Reply to "beavis dot original at ntlworld dot com" (with the obvious
changes)

[Jennifer Smith]

Beav wrote:

>
> "Jennifer Smith" <jennifer@you-wish-you-knew.mine.nu> wrote in message
> news:BcydnQzxRcxKpaPfRVn-ug@comcast.com...
>> Beav wrote:
>>> "Jennifer Smith" <jennifer@you-wish-you-knew.mine.nu> wrote in message
>>> news:c4ednYp7W8EeXaHfRVn-2Q@comcast.com...
>>>
>>>>Nope :) I'm using a 7.4v Lipo in my bird (which came with an 8.4v NiMH
>>>>too), and it seem to work fine. You could possibly go ahead and plug in
>>>>a 11.1v LiPo and use a circuit board to regulate it down to 8.4v - I
>>>>think they're available at many electronics stores, and not heavy
>>>>either.
>>>
>>>
>>> Confused, I ask the following question. If you're running a 7.4v Li-pol
>>> and Mike is running an 8.4v Li-pol, what exactly is the voltage of a
>>> single cell Li-pol?
>>
>> He's running an 8.4v NiMH - not a LiPo.
>
> Back to the reading lessons for me then :-)
>
> Since 7.4v LiPo is a 2S (2 cells
>> in serial) each single cell would have 3.7v.
>
> Indeed it would, but if he used three (coz 2 wouldn't be enough), at 11.1v
> he'd be well over the capabilities of his current speed controller/motor
> combo I'd hazard.

Agreed, although I don't know what the tolerances on these circuits are. I
sure won't try :)

J

[Jennifer Smith]

Nigel Heather wrote:

> Michael,
>
> Three things worry me about this one though I accept that my concern may
> be unfounded because they are based on the lack of information.
>
> (i) Li-Ion - not as good as LiPo - poor relation in terms of capacity per
> gramme and in terms of discharge capability
> (ii) No dimensions and weight - given Li-Ion are quite heavy and its large
> capacity and the fact that it is packed in a tube rather than the foil
> envelope this could be heavier than the birdseed.
> (iii) No indication of discharge capacity. I reckon you need at least 8A
> to power your hummer - so this would have to be a 4C or greater.
>
> I got mine from http://www.rcflying.biz/PipsElectricPlanes.htm in
> Singapore - cost me £16 ($29) including postage to the UK. This may not
> be such a great deal in the US but for the UK its is quite a saving.
>
> Cheers,
>
> Nigel

Good points, and thanks for the link :) I'm always collecting links... pack
rat that I am ;)

J

[SkyCaptian]

So everyone agrees that the 7.4 V Lipo will work correctly on the Hummingbird? I'm in the same bost as everyone else and don't want to upgrade mine to a $500+ bird but want more flying time.

[Jennifer Smith]

SkyCaptian wrote:
> So everyone agrees that the 7.4 V Lipo will work correctly on the
> Hummingbird? I'm in the same bost as everyone else and don't want to
> upgrade mine to a $500+ bird but want more flying time.

It works for me anyway. I don't have a Hummingbird, I have one of the
Dragonfly clones - but these birds are pretty much all the same. The
battery I'm using is a 2s Thunder Tiger 2200mAh, and I can easily fly
for >30 minutes. The only thing I am a little worried about is that the
main motor gets very, very hot (so hot that I cannot touch it) and
there's no room for a heatsink. It's cheap though, so I'll see what
happens :)

J

[Beav]

"Jennifer Smith" <jennifer@cathouse.mine.nu> wrote in message
news:v6KdnXDdn4F1pqLfRVn-1A@comcast.com...

>>
>> Indeed it would, but if he used three (coz 2 wouldn't be enough), at
>> 11.1v
>> he'd be well over the capabilities of his current speed controller/motor
>> combo I'd hazard.
>
> Agreed, although I don't know what the tolerances on these circuits are. I
> sure won't try :)

Neither would eye.


--
Beav

Reply to "beavis dot original at ntlworld dot com" (with the obvious
changes)

[Michael]

What would be the result if I took 2 of these 2s 7.4 packs and tied them
together in parrallel? The voltage would remain the same being in parrallel,
but the mah would be nearly doubled and they'd provide much better usable
ballast wouldn't they?

- Michael

[Jennifer Smith]

Michael wrote:
> What would be the result if I took 2 of these 2s 7.4 packs and tied them
> together in parrallel? The voltage would remain the same being in parrallel,
> but the mah would be nearly doubled and they'd provide much better usable
> ballast wouldn't they?
>
> - Michael

Theoretically correct. You will have to be careful that the packs are
exactly the same charge though, else you'll have an imbalance which
might have some "interesting" side effects.

In theory the batteries should balance themselves, but I've heard
because of the specific properties of LiPos they don't do that.

J

[Nigel Heather]

Second what Jennifer says - but it is really important with LiPos - they
need to be precisely balanced - you really need to buy a balancing circuit
to run LiPos in parallel - this technique is used by plank fliers who need
big AMPs for their motors.

If LiPos are mistreated (charged incorrectly, discharged too much, run
unbalanced) they can catch fire and because the chemical reaction generates
its own oxygen, a LiPo fire is very difficult to extinguish. LiPo fires are
nowhere near as common as the alarmists make out but at the same time you
shouldn't take un-necessary risks.

Cheers,

Nigel

"Jennifer Smith" <jennifer@you-wish-you-knew.mine.nu> wrote in message
news:2b2dnf--27kGEd3fRVn-qQ@comcast.com...
> Michael wrote:
>> What would be the result if I took 2 of these 2s 7.4 packs and tied them
>> together in parrallel? The voltage would remain the same being in
>> parrallel, but the mah would be nearly doubled and they'd provide much
>> better usable ballast wouldn't they?
>>
>> - Michael
>
> Theoretically correct. You will have to be careful that the packs are
> exactly the same charge though, else you'll have an imbalance which might
> have some "interesting" side effects.
>
> In theory the batteries should balance themselves, but I've heard because
> of the specific properties of LiPos they don't do that.
>
> J

[arie]

don't use your bec system anymore, and use a smaller pinion gear
greatings A.Redert

"Michael" <N0Spam_MShrader@Starband.net_N0Spam> schreef in bericht
news:7a26a$423bc9f0$943fd8a7$23949@STARBAND.NET...
> How do the number of volts used (battery volts) effect the electronics of
> an all electric heli?
>
> What does 7.2 volts do compared to 11.1 volts for example?
>
> I'm thinking about buying an 11.1 volt 2200mah li-poly battery for my
> Humminngbird V2 but am worried about burning it up in the process! LOL! If
> you can shed any light on this stuff please let me know.... Century has a
> disclaimer on their website stating that any battery greater than 8.4
> volts are used at customers risk, which made me wonder. Thanks!
>
> - Michael
>