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[martinbrewster]

Hl,  do i have to use a lipo to power a brushless  motor

[rmaddock]

No, but many ESCs will expect a LIPO.

[dodgy geezer]

Expanding a little on rmaddock's perfectly correct answer:

The electricity is the same, so it will power the motor 'the same'. However, a Li-Po is capable of putting out quite a lot of amps, and the brushless motors are generally wound to expect this. So if your replacement source is hi-amp, fine, but if it is two AAs then you will find the motor dropping in power quite quickly....

rmaddock points out that brushless ESCs expect Li-Pos. That means that they are often programmed to expect a battery which starts at a bit over 4v per cell, and mustn't be allowed to drop much below 3v. So the ESC will switch off at that point, leaving you with a lot of juice in your big lead-acid battery (if that's what you're using) and no way to get at it.  ESCs can often programmed to accept different battery types - but it's a fiddly job depending on the ESC....

[john s 2]

Please also remember that discharging a (pb) lead acid cell at a very high rate is not good for it.Also depending on the esc used you could discharge it more than is good for it. As a matter of interest a pb cell has a life span of no more than 300 full cycles. In a car the battery Floats But in a model it is cycling.John.

[rayna]

 
Interesting. A question that I hope "Dodgygeezeer" might answer for me on this thread.
Hobby King have a remarkable cheap ESC (no reverse) Product TGY-20A which is a 20 amp esc for brushed motors and in the specs suggest 2-3 cell Lipols (11.7 volt) or Ni MH bsatteries.
Question is: Is it an option to use a 12volt gel cell as supply where drive is standard Robbe geared motor in a Happy Hunter tug.
If yes i am quite sure that a servo and DPDT switch could handle reversing.
thanks
Rayna

[HS93 (RIP)]

you can use any battery type if you can join enough potatoes  together it will do ( for a second or two), what type of boat do you intend to put it in they are used very successfully in big boat and tugs where there is a low drain so gel cells are fine if you want speed look at a min of Nimh of Lipo. reversing speed controllers are cheap these days , also speed controllers that enable you to run nice and slow and brushless are far more efficient than brushed

Peter

[rayna]

 
as I said in this case I want to put them in Robbe Happy Hunter a medium size twin screw tug. You say ESCs are cheap but Mtronik and Electronise are 20 quid plus. The ones I am talking about (Hobbyking) are $5 US each plus post. Though as I said also they are forward only.
Rayna

[sailorboy61]

$5 is cheap, and we all love a bargin - but if it looks too cheap then it probably is, in the end you only ever get what you pay for, especially if it's made in China!

[dodgy geezer]

Interesting. A question that I hope "Dodgygeezeer" might answer for me on this thread.
Hobby King have a remarkable cheap ESC (no reverse) Product TGY-20A which is a 20 amp esc for brushed motors and in the specs suggest 2-3 cell Lipols (11.7 volt) or Ni MH bsatteries.
Question is: Is it an option to use a 12volt gel cell as supply where drive is standard Robbe geared motor in a Happy Hunter tug.
If yes i am quite sure that a servo and DPDT switch could handle reversing.
thanks
Rayna

Naa.... I would get someone who knows what he's talking about.....

1 - what Robbe geared motor? They do little 280 type things, but Robbe also go up to 710s.  Looking at the reviews for this thing people are happy using it for 400s, but I can't see anyone using it on a 540. I wouldn't go bigger than one 450 per esc...

2 - I think the voltage would be fine - 3 Lipos is 12.5v when fully charged.

3 - The only problem I found with the little ESCs I bought is that they were hard-wired to turn off when the voltage dropped to a lipo min of 6v when I was using 7.2v. Which means your battery still has a fair bit of poke in it, but can't use it. However, I note that these ESCs have a jumper to set for 'NiCad' use - so maybe that's not an issue with these. You might like to compare the ones I got, which are here: http://www.r2hobbies.com/eng/proddetail.php?prod=rcps51601

I might buy some of these - they look better than the ones I have! But the standard Cheap-China warning applies - these will have had no quality control, so you can't complain too much if there's something wrong. Hobby-King reviews suggest that they will replace things, but it will be a lot of work to send back a low-cost item and you might prefer to take the hit...

[RaaArtyGunner]

as I said in this case I want to put them in Robbe Happy Hunter a medium size twin screw tug. You say ESCs are cheap but Mtronik and Electronise are 20 quid plus. The ones I am talking about (Hobbyking) are $5 US each plus post. Though as I said also they are forward only.
Rayna

Rayna,

More important than the cheap price is the capacity of the ESC. 

There is commentary on this forum and I know of someone personally, who bought several of these cheap, 300 amp ESC's, only to have them burn out at less than the rated amperage. 
Which in this instance was about one tenth of what was claimed. 
So at the end of the day the "dearer" ones are cheaper.

[RaaArtyGunner]

Whilst the original question was about lipos and brushless motor, commentary is now about using brushed ESC's with brushless motor.

Am I wrong, but don't you have to use brushless ESc's with brushless motors, irrespective of the power source??????????

[JB]

Am I wrong, but don't you have to use brushless ESc's with brushless motors, irrespective of the power source??????????

Errrm...Yes..you are not wrong!   

Brushless motor needs a brushless ESC.

JB.

[cuppa]

One thing to keep in mind when buying a 'generic' cheap ESC is that most of them are designed for aircraft use, have small heatsink plates, and rely on airflow for cooling.

To keep costs down I used a cheap Turnigy ESC in the Piranha but I made up a simple watercooled plate to ensure it did not overheat.

All I did to fit it was to cut away the speed controller's heatshrink covering the existing heatsink plate and then added the home made watercooling plate making sure there was plenty of heat conducting paste between the controller and the new plate.