JBoss

My Feedback: (1)

Hi
I am building a scale ship. It is a 36" long buoy tender.
I am going to power it with twin 12 volt 700 motors 1 1/2 or 2" props and will probably draw 30 amps peak at full power. I am not afraid to put in 2 batteries at 2-3 lbs each. The most powerful battery in that class I could find was the (power sonic) PS-670 6 volt 7 Amp Hours. Max amp draw is 21 amps only for 7 minutes and 70 amps for 7 seconds. Wire them to get 12 volts. Will this work or am I totally on the wrong track. How long will 14 amp hours last at 20 amps draw.

HELP am i all wrong here

JimB

Matt Kirsch

My Feedback: (21)

If you plan on running at full throttle all the time, I would recommend that you consider a different source of power. Lead-acid is cheaper, yes, but NiCd would be more suitable for 30A current. You could stack four 10-cell CP2400 packs in there in parallel, come out lighter, and be able to run full-throttle for the duration of the pack.

JBoss

My Feedback: (1)

Yes I understand that. This is a scale boat so high speed is not the norm however short bursts will be cool. Also this boat will be participating in tug of wars so a couple minutes full throttle at most. I am also looking for duration.

Thanks for replying
Jim B

CLICK HERE TO SEE A PICTURE OF THE WORK IN PROGRESS

JBoss

My Feedback: (1)

here is a pic of the engine compartment

Peter Khor

My Feedback: (4)

Couple of minutes of 30A won't do small Pb cells any good; as Matt mentioned, consider NiCad/NiMh packs instead. You can also look into D size and larger Nicads. For eg, 30A discharge curves:

http://www.battlepack.com/images/chart1.gif