I know driving techniques and water cooling etc affect run times, but are there any other ways of extending run times.

Im thinking particularly of the case with my twin prop Sintra 700, which is run by two battery packs. Im sure I read somewhere that theres something that can be done with twin packs to extend the run times

Any ideas anyone

Otherwise Im looking for some boat upgrades - what recommendations are there for reasonably decent performance boats with decent run times off the batteries

You can run the batteries in series, which will give you more power, or, you can run them in parallel, which will give you a longer runtime. Also, theres another thing you can do called "throttle management". When your boat gets up on a plane you can let off the throttle enough to just keep it on a plane. This will make your run time longer.

or gear reduction i think that adds runtime but thats a lot of work to put in one of those custom to your boat

how would the wiring look for parallel connection ?

Or you can just run 3600+ mah ni-mh battery packs.........

Parallel wil only give you half the power you have now......I think you will get bored realy quick

Larger cells like rooski says [sm=thumbup.gif]

So I would need to upgrade the 2 motors and the ESC to use higher capacity batteries then ?

Running a 3000 battery caused a similar 540 motor to get very hot in one of my other boats [&o]

That's the way it works. Your motors WILL get hotter if you run them twice as long. There is no way around it. Even the best motors get hot on high mah battery packs. Your solution is simply to water cool your motor(s). It's so easy to do and helps a lot.

And to answer your other question, NO you won't have to ugrade your ESC as mah has nothing to do with voltage delivered. Mah is simply a measure of how long the cells will last in milli amp hours. Like fuel in a tank, 3000 mah battery packs last twice as long as 1500 mah battery packs (assuming the same quality and peak charging).

Lastly, if you don't already have one, you should use a peak charger (like a dynamite peak charger) to get the most out of your batteries. Make sure you are fully discharging your current batteries (ni-cd's) prior to re-charging so they don't get the "memory effect". If you move to ni-mh cells this is a non issue. Good luck.

thanks for that rooski.

I have a decent charger which charges both types of battery - thanks to the forum I discovered that only the nicads need fully discharging.

I thought I had read somewhere about the ESC controller which prompted the question - perhaps I misread, is it possible that certain ESC's will perform best with certain motors or are they pretty universal

Certain low turn motors (which you don't have) do draw a lot of amps and in the wrong set-up can catch fire...seriously. But your 540 motor is a 23+ turn unit so this is not an issue. Your motor is built for 7.2v / 6 cell packs so as long as you stay with the correct voltage your motor and speed control will be fine. However, if you double up your volts by running 2 7.2 packs in series, this gives you 14.4v. If your ESC and motors are not rated for that many volts then they will burn.

We don't have Sintra 700 boats over here in the U.S. I don't think but a UK website I looked at gave me some basic info on the boat (below). Unless you have changed out your original speed control, you have a "switch" in that boat and NOT an ESC. This is another reason you get short runtimes...because your boat is either at full throttle or off. For a better rc boating experience there are many great ways to upgrade your boat. If you don't want super speed, you could simply add a Pro Boat waterproof ESC for $39 USD and get true electronic proportional speed control.

Sintra 700 Specifications and features:

* Ready to run electric R/C High Speed Off Shore racer with radio.
* Sintra 700 R/C Boat - 'Ready To Run' Single Motor Version.
* Waterproof receiver box
* Well designed V-Hull keeps the boat smooth and stable even at high speed.
* Reliable for racing! Fully adjustable trim tabs and anti skid fins
* Micro switch on/off speed controller[:'(]
* High torque Maubuchi RS54OSH motor is included.

Thanks for the interesting info.

My Sintra is the twin motor, twin prop version powered by two battery packs. I must confess I hadnt looked that closely at the innards as I bought this as a ready to run.

My other boat an Interceptor runs a 15v ESC controller, ok there isnt room for two battery packs, but in theory then I could connect two 7.2v batteries up with this controller.

If the Sintra does not have the ESC controller (Ive got a gut feeling that the dealer said there was in this model), would it be best to get a 15v ESC, or would it be better to get a higher rated one - if so which should I go for, what are the implications for having a higher rated ESC controller than is necessary, again does it affect run times.

There is a reasoning behind this, in that I borrowed a Futaba battery checker yesterday to check my collection of NiCad and Nimh batteries. Most showed charging levels pretty much in line with what I expected, dependent on when last used / charged and all came in between 90% and 100% charged up.

What was more strange but Im told is not unusual, is that the battery voltages ranged from 7.1v on one of the Nicads, up to as high as 8.7v on 2 of the 3000 mAh Nimh batteries I have.

On this basis therefore if the 2 batteries which read 8.7v were installed together that gives 17.4v combined - presumably this would have implications for the ESC controller rated at 15v, or is that level of tolerance acceptable.

Thanks again
Andrew

The parallel connection is simple. Just get two male and one female tamiya connectors and wire like this..

you could buy more powerful bats like the new 3700

The simplest way to extend runtime is to move up in mAh batterywise.
As others have mentioned, this requires cooling on the motors, because they will heat up substantually more, damaging the magnets in the longrun.

Better is to upgrade to a more efficient motor, the 540 motors are only 65-70% efficient (at best), the rest of your battery power is converted into heat.

Make sure the entire drive train runs as smooth as possible, steering outdrives are nototious powersuckers, a straight shaft or a flex shaft is much more efficient, keeping everything lubed is another thing, stuffing the stuffing tube with stiff grease is not a good idea, as it causes tremendous friction.

Choosing the right motor for the job is a variation on the theme above, a 800 motor in your Sintra would be very powerfull, but the boat would almost sink due to the weight of the 20 cells this motor requires.

Being content with less topspeed can extend your runtime considerably, my 12 cell monohull runs eight minutes with a 700 Neodym motor and reaches 45 Km/h
A test with a 700 ferrite motor gave me about twenty minutes of runtime with the hull getting just on the plane, not exitingly fast for a fast electric, but definately an alternative in a MTB that struggles with two 540 motors which get hot, even watercooled.

All components are related to each other and changing one will affect the others.

Regards, Jan.