Water cooling Cordite ss1

[riggerman]

For the cordite ss1 i solder 1/8'' brass tubing to the 2 motor terminals to draw a bit off heat away from the brushes do's anyone water cool the magnets ? i used to braze water jackets out of .010'' brass shim stock but after several seasons they would develop leaks and i would roll jackets from 5/32'' aluminum tubing but noticed that in fact in close inspection there is very little contact between tube coil and magnets to cool.Just interested to know what other boaters are doing to cool magnets .

 

[AlanN]

I am surprised to see that Jay T hasn't answered this one yet....it's not the mags but the brushes that need the cooling. Solder on some brass tubes and replace every so often.

Or...

Just let water leak in and keep it all cool! :lol:

 

[BoatDoc]

i only got my LSH boat set up a few weeks ago and ran it the first time at the Sardine Classic. no cooling at all to the motor, and all the temps were under control. that was with a 47mm prop and Jeti 600 esc. cooling the can probably won't do much good because of the torque ring. i know many cool the brushes and swear by it, so i won't contradict them. but i know that mine runs just fine without cooling. i think the comm temp on my motor was 125 after the 2nd heat. ambient temp was at least 85 degrees. the esc was 95 degrees after 7 or 8 laps, it only has a single cooling tube.

 

[Paul Pachmayer]

Hi Guys,

I don't bother cooling anything on a 700BB setup. Used to do the brush cooling thing but I don't any more and haven't had any problems.

Paul.

 

[David Kingston]

Most of the guys down under (australia) cool their brushes.

I myself cool the whole lot in my LSH.

We have some hot days - i think it helps to cool the motor. ESC i dont worry about.

I have seen some racer put a computer cooling fan on the motor after you run it.

Cooling may help if you intend on running longer than a race duration.

david

 

[jayt]

I guess the issue from an engineering point is - what part of the motor is degraded by getting too hot? Will the can or magnets be damaged? Not the magnets used in the SS-1 and similar, and the can certainly won't be damaged. The endbell? Not likely. Brushes? They are designed to run hot and are well air-cooled by the motor fan. Soldering something onto them can result in reduced spring tension - a bad thing. The commutator? Yes, that is the weakest part of the motor, but there is no way to effectively cool it except by circulating air - which the better 700s do. Keeping the interior air of the boat cool would be the best way to safeguard a 700 motor, but that would be more trouble than it's worth. Water cooling is usually a bandaid covering up a bigger problem, and IMO it simply isn't needed on a typical 700 motor run in a reasonable manner. B)

 

[Andrewg]

Jay

approximatley how many amps or amp hours in a "reasonable"? They seem to "go away" with a run on 18 cells

Using the dyno tests I had done on these motors at 10v and allowing a few percent efficiency improvement with the increased voltage the heating losses total 151w at max efficiency ie 42amps

On 16 cells which is how we use them the losses approach 177w

The fans are extremely effective but I wonder if the water cooling doesnt add a margin of safety to the brush arms? I think I just found an interesting experiment to do with the eagle trees

 

[jayt]

Andrew, most vendors list a maximum of 16 cells for their HiPo 700s, but is running at the maximum rating with a big prop "reasonable"? Probably not - most racers here tend to use 12/14 cells and I was really refering to LSH racing. Water cooling the motors does not effect heating losses, it just removes a small amount of heat from the motor can - which is the part least effected by the heat. Obviously BL motors don't have this much of a problem since the heat generating portion of the motor - the windings - are on the outside where water cooling is much more effective. With air-cooled arms the best solution by far would be an outside air venting system. This is a break in the normal paradigm, but it may be the best way for anyone brave enough to try it. B)

I tend to see water cooling the brushes in the same manner I see using a wire wrapping to secure the power leads to the motor tabs - in an effort to keep the wires from falling off when the solder melts.....the problem is not the solder. :lol:

 

[Andrewg]

Jay

thanks I was interested to get your thoughts

Agree completely on the magnets I just like to keep things cool - I would free the thing if I had a really easy method

If those arms were not sprung (and I know building workers all over the world must be leaning on those motors and taking them down to near stall conditions) I dont think I would be as cautious.

Having said that I have only ever seen the arms damaged using props that suit 12 cells on 16 or 18 cells.

We run mostly X645 X646 M447 maybe the odd Y547 on 12 cells

On 16 cells X442 and X437/3s seem popular - on hydros I have seen X643's used but IMO its pushing ones luck - happpy to hear contrary advice