V drop through ROV cable
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Posts: 46,084
hey everyone,
the ROV that I started at the beginning of the summer is in its
water testing phase. We dropped the sucker in and it started to move
around and turn nicely. But it moved very slowly. I know that the two
30lb of thrust trolling motors can put out more power than they are
putting out.
= Each motor is rated at max 30A draw.
= I have them both hooked up to a deep cycle 12V battery that can put
out up to 60A.
= The 12 gauge cable between the battery and the motors is 115ft. The
resistance per foot of the cable is 0.0016ohms.
= So (0.0016 ohms)*230ft = 0.368 ohms total between the battery and
each motor. And since, 12V = (0.368 ohms) * I; I = 32.6A
So since over 30amps should be able to get through the cable to
the motors, I'm confused as to why they would not perform at top
speed. I have a 15A fuse on the + line to one of the motors, and the
fuse never broke... isn't this strange? The motors don't seem to go
faster when only one motor is run at a time either.. I have seperate
12gauge + and - lines for each motor, they aren't sharing. Any advice
would be great. Thanks!
the ROV that I started at the beginning of the summer is in its
water testing phase. We dropped the sucker in and it started to move
around and turn nicely. But it moved very slowly. I know that the two
30lb of thrust trolling motors can put out more power than they are
putting out.
= Each motor is rated at max 30A draw.
= I have them both hooked up to a deep cycle 12V battery that can put
out up to 60A.
= The 12 gauge cable between the battery and the motors is 115ft. The
resistance per foot of the cable is 0.0016ohms.
= So (0.0016 ohms)*230ft = 0.368 ohms total between the battery and
each motor. And since, 12V = (0.368 ohms) * I; I = 32.6A
So since over 30amps should be able to get through the cable to
the motors, I'm confused as to why they would not perform at top
speed. I have a 15A fuse on the + line to one of the motors, and the
fuse never broke... isn't this strange? The motors don't seem to go
faster when only one motor is run at a time either.. I have seperate
12gauge + and - lines for each motor, they aren't sharing. Any advice
would be great. Thanks!
Comments
>hey everyone,
>
> the ROV that I started at the beginning of the summer is in its
>water testing phase. We dropped the sucker in and it started to move
>around and turn nicely. But it moved very slowly. I know that the two
>30lb of thrust trolling motors can put out more power than they are
>putting out.
Sam -
Electric trolling motors come in 12 VDC and 24 VDC models. Are you sure
yours it 12 VDC AND NOT 24 VDC ?
Which brand of motor are you using ?
Bruce Bates
The resistance of the motor itself is 12V/30A=0.4 ohm
The combination of motor and cable would be almost twice that,
so your max current draw would be just over 15A.
Got an ammeter?
Original Message
From: "Sam" <hard-on@t...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, August 20, 2003 9:39 AM
Subject: [noparse][[/noparse]basicstamps] V drop through ROV cable
> hey everyone,
>
> the ROV that I started at the beginning of the summer is in its
> water testing phase. We dropped the sucker in and it started to move
> around and turn nicely. But it moved very slowly. I know that the two
> 30lb of thrust trolling motors can put out more power than they are
> putting out.
> = Each motor is rated at max 30A draw.
> = I have them both hooked up to a deep cycle 12V battery that can put
> out up to 60A.
> = The 12 gauge cable between the battery and the motors is 115ft. The
> resistance per foot of the cable is 0.0016ohms.
> = So (0.0016 ohms)*230ft = 0.368 ohms total between the battery and
> each motor. And since, 12V = (0.368 ohms) * I; I = 32.6A
> So since over 30amps should be able to get through the cable to
> the motors, I'm confused as to why they would not perform at top
> speed. I have a 15A fuse on the + line to one of the motors, and the
> fuse never broke... isn't this strange? The motors don't seem to go
> faster when only one motor is run at a time either.. I have seperate
> 12gauge + and - lines for each motor, they aren't sharing. Any advice
> would be great. Thanks!
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
>
Further thoughts--
Check for high resistance (Voltage drop) in your connectors and switches.a
If you don't have a suitable ammeter, and if the 0.0016 ohm / ft rating is
right, then 6.25 ft should be 0.010 ohm. Reading the voltage drop across a
6.25 ft section should give you 10 millivolts per Amp.
Original Message
From: "Sam" <hard-on@t...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, August 20, 2003 9:39 AM
Subject: [noparse][[/noparse]basicstamps] V drop through ROV cable
> hey everyone,
>
> the ROV that I started at the beginning of the summer is in its
> water testing phase. We dropped the sucker in and it started to move
> around and turn nicely. But it moved very slowly. I know that the two
> 30lb of thrust trolling motors can put out more power than they are
> putting out.
> = Each motor is rated at max 30A draw.
> = I have them both hooked up to a deep cycle 12V battery that can put
> out up to 60A.
> = The 12 gauge cable between the battery and the motors is 115ft. The
> resistance per foot of the cable is 0.0016ohms.
> = So (0.0016 ohms)*230ft = 0.368 ohms total between the battery and
> each motor. And since, 12V = (0.368 ohms) * I; I = 32.6A
> So since over 30amps should be able to get through the cable to
> the motors, I'm confused as to why they would not perform at top
> speed. I have a 15A fuse on the + line to one of the motors, and the
> fuse never broke... isn't this strange? The motors don't seem to go
> faster when only one motor is run at a time either.. I have seperate
> 12gauge + and - lines for each motor, they aren't sharing. Any advice
> would be great. Thanks!
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
>
--- In basicstamps@yahoogroups.com, "Stu Wrenn" <swrenn@z...> wrote:
> Sam-
> The resistance of the motor itself is 12V/30A=0.4 ohm
> The combination of motor and cable would be almost twice that,
> so your max current draw would be just over 15A.
> Got an ammeter?
>
>
Original Message
> From: "Sam" <hard-on@t...>
> To: <basicstamps@yahoogroups.com>
> Sent: Wednesday, August 20, 2003 9:39 AM
> Subject: [noparse][[/noparse]basicstamps] V drop through ROV cable
>
>
> > hey everyone,
> >
> > the ROV that I started at the beginning of the summer is in
its
> > water testing phase. We dropped the sucker in and it started to
move
> > around and turn nicely. But it moved very slowly. I know that the
two
> > 30lb of thrust trolling motors can put out more power than they
are
> > putting out.
> > = Each motor is rated at max 30A draw.
> > = I have them both hooked up to a deep cycle 12V battery that can
put
> > out up to 60A.
> > = The 12 gauge cable between the battery and the motors is 115ft.
The
> > resistance per foot of the cable is 0.0016ohms.
> > = So (0.0016 ohms)*230ft = 0.368 ohms total between the battery
and
> > each motor. And since, 12V = (0.368 ohms) * I; I = 32.6A
> > So since over 30amps should be able to get through the cable
to
> > the motors, I'm confused as to why they would not perform at top
> > speed. I have a 15A fuse on the + line to one of the motors, and
the
> > fuse never broke... isn't this strange? The motors don't seem to
go
> > faster when only one motor is run at a time either.. I have
seperate
> > 12gauge + and - lines for each motor, they aren't sharing. Any
advice
> > would be great. Thanks!
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the
Subject and
> Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
> >
> >
> >
> >
I am interested in your ROV project. Please put me on your mailing
list for all testing and updates. Pictures and code would be a plus.
I am sure that there are others interested to.
Wish you luck. The ROV is my next planned project. I am working
on magnetometers and sub bottom profilers at the present.
Dick
Original Message
From: Sam <hard-on@t...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, August 20, 2003 9:39 AM
Subject: [noparse][[/noparse]basicstamps] V drop through ROV cable
> hey everyone,
>
> the ROV that I started at the beginning of the summer is in its
> water testing phase. We dropped the sucker in and it started to move
> around and turn nicely. But it moved very slowly. I know that the two
> 30lb of thrust trolling motors can put out more power than they are
> putting out.
> = Each motor is rated at max 30A draw.
> = I have them both hooked up to a deep cycle 12V battery that can put
> out up to 60A.
> = The 12 gauge cable between the battery and the motors is 115ft. The
> resistance per foot of the cable is 0.0016ohms.
> = So (0.0016 ohms)*230ft = 0.368 ohms total between the battery and
> each motor. And since, 12V = (0.368 ohms) * I; I = 32.6A
> So since over 30amps should be able to get through the cable to
> the motors, I'm confused as to why they would not perform at top
> speed. I have a 15A fuse on the + line to one of the motors, and the
> fuse never broke... isn't this strange? The motors don't seem to go
> faster when only one motor is run at a time either.. I have seperate
> 12gauge + and - lines for each motor, they aren't sharing. Any advice
> would be great. Thanks!
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>