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[likeomg]

Hi guys,


what's the best way of controlling a small 12v water pump? what you'd maybe use on a tug boat to shoot some water?


I have a small 6-12v pump i plan to run on 3s lipo to act as my cooling pump, is the best way just to plug it direct into the lipo?


i think i have some brushed controllers from when the atlantic challenger was new, would it be a option to use this on a spare channel on the radio? it would just be a on / off flick switch as that's all i have spare..


or is there a better way? should i just plug the pump directly into the lipo?


Thanks guys.

[SailorGreg]

The best solution is to use a digital switch such as this one.  This will work off your transmitter switch and means you don't have to switch the pump on until you are in the water, and can switch it off if the boat is sitting afloat without moving for a while.  Of course, plugging directly to the LiPo will work, but then it is running all the time, from the moment you connect the battery until you unplug it.

Greg

[DaveM]

Do check that the pump is rated for continuous running. A lot of windscreen-washer pumps are rated only for short bursts.
DaveM

[chas]

2 other possibilities, use a water pick up next to the prop, no pump necessary, or uprate your motor so its not running so hot that it needs cooling.  Of course, I do understand that last option might not be practical in a model that pushes the boundaries.
Chas

[likeomg]

hi guys,


some background - this is my slow boat - the Atlantic Challenger, the motors are already stupidly overpowered for the boat but it's what I have...


twin Neu 1521 1y motors, probably on 3/4s maximum, in all honesty it really probably doesn't need any cooling but it's a project I quite like the idea of

the pump is a dedicated pump from prestwich models rather than a  car part, rather than drill the hull I've planned out a internal water-cooling system with a 1 liter fuel tank ill fill with icy water and then pump around the motors and controllers,


The switch from Greg is exactly what im looking for, will get one ordered


I'll also be running a TCS micro pump in my Exocet 150 with a water pickup but that will be a spicy setup...

[malcolmfrary]

Plugging anything that will run constantly into a LiPo can never be a good idea.  ESCs that say "LiPo Safe" usually cut power when the voltages gets low to avoid damage to the LiPo.  A motor constantly running will just carry on discharging until the LiPo is beyond help.  This is especially likely to happen during the "LiPo Safe" warning period.
Having to water cool a motor means that it is having more asked of it than it should deliver.  In a fast boat pushing beyond normal limits, OK, but any other time it is just introducing an unwanted path for water to enter the hull.
If the pump (as said earlier, continuous rated) has a DC motor, it can be driven via a switch or an ESC.  The switch could be a dedicated electronic switcher, it could be a switch operated by a servo.  If an ESC is used, depending on the type of pump, it might need either a forward only type, or be connected to the ESC output via a bridge rectifier.  Depends on whether the mechanical bit is or isn't bidirectional.

[chas]

Maybe I'm missing something, if so please correct me. The idea of a performance boat lugging round over 1 kg of extra weight confuses me. Surely a standard water pickup, as used for decades with I.C. powered models would save effort, money and weight.
Chas

[likeomg]

The switch that greg posted is exactly what ill be running, I just didn't know if they existed or where to get.


it will be a 2s 5000mah batt so unlikely a small pump would drain it anywhere near as quick as the motors will get through the same 5000mah,


and Chas, the Atlantic Challenger is a Graupner model that was designed around a 12v lead acid batt, weight isn't a issue, I've just increased performance slightly removing the reduction drive and moved from a relatively low power setup to something capable of motoring the thing around at a more desirable speed.


you aren't missing anything other than I really don't want to drill the hull,


on the Exocet we are talking about boats that are doing 120-150mph in SAW running and it's common place to have the pumps running to constantly cool. This challenger I estimate will be doing 30mph tops.

[likeomg]

originally the boat was


twin graupner 700BB turbos, 2 controllers and a 12v lead acid batt,


I have all of the above and the model is in beautiful condition


if you take a look at this thread, its the first boat posted


https://www.modelboatmayhem.co.uk/forum/index.php/topic,62812.0.html


It really doesn't need any cooling when I think about it but its a project I'd like to do. (water cooling that is)

[malcolmfrary]

it will be a 2s 5000mah batt so unlikely a small pump would drain it anywhere near as quick as the motors will get through the same 5000mah,

The point is that after the 5AH battery has been depleted and the ESC has either switched off or gone into limp home mode, the pump will still be running during the time that you are trying/hoping to get your boat back.  There will be nothing to stop it, and out on the water, stuff happens that causes a boat to just drift in.  NiMH recover well from that kind of thing, LiPo less so.

[likeomg]

Fully agree, that's why as above, i've ordered the switch


it would be unlikely on this boat for it to get stuck out, very unlikely to roll over and being a twin, i should always have at least some drive to get me back...


will try to remember and post some pics of the setup once completed..