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[Phantom_Maloo]

G'day guys,
I've purchased the Aquacraft Bristol Bay RTR model to get me on the water whilst i build my first kit. and i just have a question about batteries. The instructions call for a 7.2V 1500mAh NiCd battery pack. However i have a Venom R/C 7.2V 4200mAh NiMH that i use in my Tamiya 1/16 Tanks. Could i use this battery in the Bristol bay? I don't want to run the risk of melting anything.
Cheers,

[Netleyned]

No problem at all.
It is the same voltage.
In fact it is a much higher capacity and being NiMH does not have the
memory problems of a NiCad.
You will also get nearly three times the run time with the 4200mAH pack.


Ned

[Phantom_Maloo]

Thanks very much 

[pompebled]

You will also get nearly three times the run time with the 4200mAH pack.

This can be an issue, if the prop/motor combo tends to cause heat build up in the motor, three times the runtime may cause overheating problems.

As an example: I only ran my Dickie Harbour tug once with the stock battery, which lasted about 15 minutes, no problems except the very short range of the stock radio.
After converting to hobby grade radio stuff (a servo for the rudder and a proper ESC), I installed 8000mAh 2S Lipo and went for a test run.

After an hour and a half of continuous running the boat, I connected the batteries to the charger to see how much juice the stock motor had consumed, when I noticed the 'electrical smell' in the hull.
Inspection revealed a deformed motormount and a motor that had been severely overheated, turning the copper windings blue...

The 380 motor was replaced with a 540 type (five pole) and a small computer fan was placed on top of the motor, connected in parallel to the motor connections.

The boat has been running for up to four hours continuously full throttle without any sign of overheating.

So keep in mind to check for overheating when making long runs!

Regards, Jan.

[Netleyned]

I didn't mention continuous running as unless you take your boat for a long walk along a canal or river most models are run for short periods with stops for talking to the other guys at the lake.
No one in our club sails a model continuously unless its a yacht.

Ned

[pompebled]

Hi Ned,

As there's no local club where I live, my outings with modelboats are indeed long walks along the canals that surround our town.
Previous to melting the motormount in my tugboat, I never ran a 'RTR' boat for such a long period of time.

My scratch builds don't suffer from overheating, as the propulsion is chosen with long runs in mind.
My sailyacht even outruns me, runtime wise...

Regards, Jan.

[Phantom_Maloo]

I used to run this battery in my tamiya tanks and i'd get bored long before it even got close to being flat. I can't see me sailing it for more than 30minutes at "scale" speed