need high output lead acid
09-02-2003, 03:36 AM
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need high output lead acid
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
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
09-02-2003, 03:19 PM
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30 AMPS??
I would doubt very much that you will ever get close to pulling 30 Amps out of a 700 motor in your set up.
We race with 700 motors on 12 cells in LSH class and do not see numbers that high.
I would bet that if you put in those 7Ah batteries the boat will not even pull 15 Amps on start up. ( your heaviest draw point)
You did not say exactly what voltage the motors were, but you may find that a 2" prop will be too big if you are going direct drive.
Some low pitch 2" props might work well. You need to let the motor get up in to its RPM range to work properly.
Peter
We race with 700 motors on 12 cells in LSH class and do not see numbers that high.
I would bet that if you put in those 7Ah batteries the boat will not even pull 15 Amps on start up. ( your heaviest draw point)
You did not say exactly what voltage the motors were, but you may find that a 2" prop will be too big if you are going direct drive.
Some low pitch 2" props might work well. You need to let the motor get up in to its RPM range to work properly.
Peter
09-03-2003, 12:52 PM
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Leaning towards 12v
Thanks for the info. Glad to hear that I will be drawing much less amps then the motor chart shows. I am leaning towards 12 as I understand they are a bit more efficient. Also I am looking for a gearbox. Probably 2:1 that will also shorten the drive chain. Motor shaft input and drive shaft input on same side. Basically a V drive setup. If I do end up going direct Drive do you reccommend a 1 1/2" prop with 3 blades.
Thanks
JimB
Thanks
JimB
