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Author Topic: battery help please  (Read 1856 times)

martinbrewster

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battery help please
« on: September 12, 2011, 08:23:00 PM »

i have two7.2 3300mln batterys that i would like to conett together to run a 12 vol speed 600 is this possible? if so what size speed controller would you say is needed thank you martin
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DickyD

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Re: battery help please
« Reply #1 on: September 12, 2011, 08:43:44 PM »

If you connect two 7.2v batteries together you end up with either a 7.2v 6600mAh battery or a 14.4v 3300mAh battery.  :-))
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justboatonic

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Re: battery help please
« Reply #2 on: September 12, 2011, 10:00:24 PM »

Some esc's dont like two batteries in series so check before you buy. I dont know any esc's that wont work with two batteries in parallel.
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malcolmfrary

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Re: battery help please
« Reply #3 on: September 13, 2011, 09:51:31 AM »

In parallel, the motor will run in a calm and dignified manner.  In series, it will be nudging the safety margin built into its specification, and will need either a smaller prop or water cooling or both.
An ESC that is rated as "12 volt" by its maker is intended for a 12 volt SLA, and so is, or should be, good for the 14 and a bit that a fully charged one will deliver.  I would look very closely at the specifications if fitting a battery arrangement that was going to deliver nearer 17 volts when charged.  Maybe have a look at other threads in the forum.
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martinbrewster

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Re: battery help please
« Reply #4 on: September 13, 2011, 09:07:34 PM »

In parallel, the motor will run in a calm and dignified manner.  In series, it will be nudging the safety margin built into its specification, and will need either a smaller prop or water cooling or both.
An ESC that is rated as "12 volt" by its maker is intended for a 12 volt SLA, and so is, or should be, good for the 14 and a bit that a fully charged one will deliver.  I would look very closely at the specifications if fitting a battery arrangement that was going to deliver nearer 17 volts when charged.  Maybe have a look at other threads in the forum.
thanks for your help which would be better or last longer a 7.2 3300ml or a 12 vol 1.2 bearing in mind a12volt moter thank you martin
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malcolmfrary

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Re: battery help please
« Reply #5 on: September 14, 2011, 09:37:47 AM »

The bigger capacity (in this case, the 7.2volt) will last longer.  Because its a lower voltage, it will also probably seem much, much longer.
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Harquebus

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Re: battery help please
« Reply #6 on: August 19, 2012, 03:27:35 PM »

In parallel, the motor will run in a calm and dignified manner.  In series, it will be nudging the safety margin built into its specification, and will need either a smaller prop or water cooling or both.
An ESC that is rated as "12 volt" by its maker is intended for a 12 volt SLA, and so is, or should be, good for the 14 and a bit that a fully charged one will deliver.  I would look very closely at the specifications if fitting a battery arrangement that was going to deliver nearer 17 volts when charged.  Maybe have a look at other threads in the forum.

I find it interesting the differences between series and parallel wiring in motors and batteries:

PARALLEL MOTORS

Pros - Max power, high top speed
Cons - Half the run time of a single motor setup or dual motors in series, high amp draw needing heavy duty ESC

PARALLEL BATTERIES

Pros - Long run time, easy on electrics
Cons - Heavy

SERIES MOTORS

Pros - Long run time, lots of torque
Cons - Low top speed

SERIES BATTERIES

Pros - Explosive power
Cons - Heavy, requires heavy duty ESC

What happens with parallel motors on series batteries? I am but a novice...
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malcolmfrary

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Re: battery help please
« Reply #7 on: August 20, 2012, 10:09:13 AM »

Quote
What happens with parallel motors on series batteries? I am but a novice...
Each motor behaves as if it was on the higher voltage, i.e. it tries to spin a lot faster.  It also draws more current.  Two of them draw twice the current, so the ability of the battery to supply the current and the wiring and ESC to carry said current becomes an important limiting factor.

Quote
SERIES MOTORS

Pros - Long run time, lots of torque
Cons - Low top speed
Not necessarily lots of torque.  That depends on the design of the motor.  Generally, more poles = more torque but less speed. 
Power is a function of amps through the turns times the number of turns, but the more turns in a given space, the thinner the wire and thus fewer amps.  To get more power with a large number of thin wire turns requires higher voltage.
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