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[Captain Flack]

I have tried the searches and it's driving me mad, so unfortunately I have had to post a new topic.
Twin 700 engines, no other markings, running on 7.2v turning twin brass props around 35mm ( as near as I can make out)
Anybody have any idea what ESC for a small Perkasa?  Either one ESC or twin on a Y lead, may even consider water cooling?
Not mine this time, I hasten to add.
Thanks to everyone who helped with my last query.

[malcolmfrary]

The main thing you need to know is how much current each motor takes under load.  Once you know that (either measure it with an ammeter or work your way through a bag of assorted fuses from the car spares shop) you have a starting point.  Double it for a safety margin, use the next rating up from that.

[Captain Flack]

Thanks for that.  I suppose I should have guessed that but I am always hopeful that somebody has a magic chart or something that will help.  I will probably try the ammeter first and then double check with the fuses.

[malcolmfrary]

Unfortunately there can't be a magic chart, because the motor drain is significantly affected by the loading. 
Case in point, at the lake tonight a couple of lads with a boat that had been set up by a buggy expert.  A very flash looking 280 size motor driving a 35mm 3 blade prop in a boat maybe 18" long.  Went reasonably fast until it stopped, with the solder melted off the motor tags.  Same motor with a more sensibly sized prop would probably leave the solder intact but give the hull an embarrassing turn of speed.

[Stan]

Hi Captain Pm sent

Stan.

[inertia]

Twin 700 engines, no other markings

This is the problem. Graupner used to market at least five different "700" sized motors, from the fire-breathing 8.4V BB Turbo to the smooth and torquey 720 BB Torque. Robbe also produced a few different ones and I dare say there are plenty of others, all with the same diameter motor can. Unless you know exactly which type they are then there's no way that the info you need can be given. Once that's been established go back to Malcolm's reply.
DM

[BarryM]

Once upon a time, long, long ago, when only dinosaurs and DM M'ducks roamed the earth, one motor supplier (Robbe??) used to have performance graphs on the packaging illustrating current draw, revs, wattage and voltage under various loadings. Unfortunately, this very handy practice was discontinued and disappeared along with the dinosaurs to leave us only with DM M'Ducks. I'm unsure if we got the best of the deal....

Regards,
Barry M

[Stan]

I am not sure if this will help. Fitted in my Robbe Schutze are two BB 700 turbo motors running  on 12 volts. Each motor is supplied by  a 15 amp speedo both motors are then fused using a Action double fuse holder.  A 10 amp rated fuse is fitted for both motors. if you check out Stan's Schutze build under warships and military I have posted pictures of the installation. Also enclosed tech sheet for Graupner speed motors. As stated in previous posts it may be trial and error. If you have multi channel set I would recommend fitting a speedo on each motor.

Stan.