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[john1951]

My Deans Marine Royal Marine trawler is powered by 4 AA batteries.
           What length of running time can I expect from them ?

                                                                               John                                                                           

[DickyD]

What motor and what prop, what amperage batteries ?

[john1951]

Motor is a modified servo, the prop is a 1" diameter 3 blade, but I have no idea as to the battery amperage, just that they are the usual 1.5 volt rechargeable.

                                                                                              John

[malcolmfrary]

With a similar setup in a converted Lindberg trawler, I get a good hour and a bit.  A lot "depends" - higher capacity AAs last longer, constant flat out will shorten run time.  Its a mile round "my" lake, and it will take me for a walk round, then allow a reasonable time to mess about when I get back to the start.  I was using 1000mAH cells, that capacity being the state of the art at the time. Newer ones are likely to be much higher.

[john1951]

Thanks Malcolm, mine are 800mAH, so I think an 1 hour would be about right at Trawler speed !
                                                                                                Cheers      John

[stallspeed]

Motor is a modified servo, the prop is a 1" diameter 3 blade, but I have no idea as to the battery amperage, just that they are the usual 1.5 volt rechargeable.

                                                                                              John

John,If a 2kgcm servo has a 300:1 gear then its motor has a stall torque of 7gcm.
Compare that figure to some more familiar motors.

[dodgy geezer]

.....  I was using 1000mAH cells, that capacity being the state of the art at the time. Newer ones are likely to be much higher.

Current top-end NiMH AAs are speced at about 2500mAh. But you can buy 1000mAh ones at half the cost...

[DickyD]

Current top-end NiMH AAs are speced at about 2500mAh. But you can buy 1000mAh ones at half the cost...

That'll be because they last less than half the time then.

[DickyD]

Current top-end NiMH AAs are  2900mAh £4.75 for four at Component Shop.

http://www.component-shop.co.uk/html/body_aa.html

[dodgy geezer]

That's a very good buy. The shipping is low as well.

I have some Sony batteries specced at 2800mAh, but I'm a bit suspicious of whether you actually get these high figures in practice. Still, they are probably well over 2000mAh....