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Author Topic: Two Batteries?  (Read 2074 times)

grace

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Two Batteries?
« on: March 09, 2014, 01:29:37 AM »

three people have told me now that,
if your running twin screw,two esc's you should have a battery for each system.... why?
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NFMike

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Re: two batteries?????
« Reply #1 on: March 09, 2014, 02:05:43 AM »


three people have told me now that, if your running twin screw,two esc's you should have a battery for each system.... why?
Because those three people all think that is the case.
I don't think that, and I'm pretty sure there'll be a few more to agree with me.

One battery for both will work too.

There are some pros and cons to both ways, but they aren't particularly significant really. Overall a single battery is likely to be cheaper and simpler. Two separate batteries may be useful when space and/or weight distribution are problematical.

Mark T

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Re: two batteries?????
« Reply #2 on: March 09, 2014, 09:59:39 AM »

Why not try a P103 by Action - It could be your solution but you don't say how many amps you are running


http://www.action-electronics.co.uk/pat.php
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rmaddock

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Re: two batteries?????
« Reply #3 on: March 09, 2014, 10:02:57 AM »

The only reason would be if the discharge rate of one motor at full power was more than 50% of the maximum discharge rate of the battery.

I.e. if you have a 1700mah battery and each esc/motor pulls an amp (1000mah) then you have the potential to overpower a single battery.
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Netleyned

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Re: two batteries?????
« Reply #4 on: March 09, 2014, 10:19:25 AM »

Might be a good idea if using lipos.
If one esc shuts down on low voltage
the other might enable you to limp
back to base.


Just a thought.


Ned
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Colin Bishop

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Re: two batteries?????
« Reply #5 on: March 09, 2014, 10:20:01 AM »

As rmaddock says, as long as the battery is up to supplying the combined current draw of the two motors then you only need one.

Basic electronics!

Colin
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roycv

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Re: two batteries?????
« Reply #6 on: March 09, 2014, 10:31:35 AM »

Hi I hve a twin screw boat with 2 esc's and two batteries, which works well. 
It also works with one battery powering the 2 esc's and also I can connect the two batteries in parallel and they power it OK.
I know there can be problems with parallel connection but when I am running on a smaller pond I am going slower so with two batteries in parallel the discharge current is less and the run time is longer.
I also run the receiver from one of the esc's

Just as an aside when planning the power train in a model boat I look out for offers.  In the above model it has 2 off 9.6 volt 1.6 AH batteries,which were very cheap.  So I used 2 x 12 volt Pittman ex computer motors, well tape decks actually, which must be close to 50 years old now and they run as sweet as can be.  Current consumption on full speed is 3/4 of an amp per motor and it gives my HDML (36" loa) a very good turn of speed.
I work on the basis that if the battery gets hot that is power not going to the motors, my ones run very cool.

good luck,
Roy
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John W E

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Re: two batteries?????
« Reply #7 on: March 09, 2014, 11:38:26 AM »

hi there
 
Food for thought here;  it is true that we can run into problems using 2battery and 2 speed controllers - there is a lot of things that have to be taken into consideration though and the easiest way is to keep the explanations of it simple.   
 
If we think of the speed controller being in 2 parts - i.e. front part and back part.
 
Front part - it receives a signal from the receiver and basically this signal in the front part is telling us what the 2nd part should be doing.  So the front part of the controller controls interprets the signal.
 
Back part - this deals with the heavy amperage after its been told what to do by the front part.
 
These circuits in the speed controller are connected electrically - normally on the negative side and this negative line in turn goes back through to the receiver through the wires.
 
Therefore if running 2 speed controllers through the wiring, they will obviously be connected together and the receiver makes the loop.
 
When connecting the 2 batteries together supplying the 2 speed controllers the batteries negatives are also connected to the negatives on the speed controller side of the wiring.
 
Any difference in battery voltages could effect the speed controllers - through this built in circuit.
 
I hope this is understable  :D :D 
 
aye
 
John
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davidm1945

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Re: Two Batteries?
« Reply #8 on: March 09, 2014, 12:23:37 PM »

Hi All,
    I am a novice when it comes to the electrickery side of our hobby, but I use two batteries and two ESCs in my RTTL because I assumed that this would extend the run-time over one battery and one ESC (two motors obviously). Was I wrong in this assumption?
 
Dave.
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malcolmfrary

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Re: Two Batteries?
« Reply #9 on: March 09, 2014, 01:00:30 PM »

Hi All,
    I am a novice when it comes to the electrickery side of our hobby, but I use two batteries and two ESCs in my RTTL because I assumed that this would extend the run-time over one battery and one ESC (two motors obviously). Was I wrong in this assumption?
 
Dave.
Think of electric energy (stored current in the battery) as fuel.  If you fit one two gallon tank, will there be any difference if you fit two one gallon tanks instead?  If you fit two two gallon tanks, you get a longer run, but it weighs more.  If you have two motors with two controls, two power supplies, each capable of handling its motor, does make a lot of sense.  But then again, so does one bigger or more capable battery and a distribution system.
Any battery has a maximum rate at which it can safely and/or reliably deliver its stored current.  Think of this as being the equivalent of a fuel pump and pipework.
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davidm1945

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Re: Two Batteries?
« Reply #10 on: March 09, 2014, 08:29:08 PM »

Many thanks, Malcolm, a very clear explanation.


Dave.
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Buccaneer

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Re: Two Batteries?
« Reply #11 on: March 11, 2014, 07:43:53 PM »

I have made all the combinations of 1 or 2 batteries and/or motors, albeit in Tugs and working boats. With 2 batteries I have always used an Action P103 and then, for both 1 and 2 motors, feed it into an Action P92 Power Distribution Board. This keeps the wiring down to my level as all the power goes in one side and all the power comes out the other! The P92 may be considered expensive at 24 but with 3 fuses built in and connections for auxiliary circuits it works for me.

John
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Peter Fitness

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Re: Two Batteries?
« Reply #12 on: March 12, 2014, 03:25:19 AM »

I have 2 boats each with 2 motors and 2 ESCs running off one battery, and another boat with 2 motors and 1 ESC also off one battery. In each case the battery is a sealed lead acid (SLA), and both set-ups work fine.


Peter.
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