Quote:
Originally Posted by 2nd Runway
Hello
New here and My first post/question
I have a lewmar 12 volt pro fish 1000 horizontal windlass, a 32 volt house bank (several 16 volt batteries in series and parallel) that is within 5 feet of my windlass.
This is a li-ion battery bank and the voltage of each individual battery will never go above 16 volts.
I have also noticed that a lot of race car guys are using 16 volt batteries on 12 volt starters.
What is the consensus of running a 12 volt windlass on a 16 volt battery?
Will it harm the windlass motor or just make it run a little faster?
Your thoughts appreciated
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Modeling what you do on what race car drivers do not a good plan. After all, if they had to replace a starter motor every 20 starts (about 40 seconds of total motor run time!) they would not care. You wouldn't even have your
anchor up once.
Doing what you suggest is a bad idea for lots of reasons. As others have pointed out, center tapping a battery bank, especially with a big load like this is a TERRIBLE idea. But let's leave that---and look at the motor.
Just because other posters can not think of why this wouldn't
work, doesn't mean it will.
Issue #1: Your motor's
brushes will wear out in short order. The no-load speed of the motor will increase, and this increases the mechanical wear on the
brushes, but also the higher voltage means longer lasting and more stable arcs every time the brushes move across a gap in the commutator, this is actually the bigger issue. Although this is a real problem, I seriously doubt the motor will last long enough to for you to notice.
The
current draw of a DC motor is a complicated thing. When running "at speed" the motor generates a "back EMF" that reduces the
current draw. So contrary to intuition, the faster the motor runs the less current it draws. This is why lower voltage is also an issue, the lower motor speed means more current.
So running at steady, no load speed, the motor will run faster at a higher voltage, and will draw about the same amount of current. It will run faster, but will produce no more torque. So, in a simplistic view of the world, the motor could run at the higher voltage and no load a long time without issue. But the world is not so simple.
So here is issue #2: The problem is when the motor is loaded up, even on startup. The higher voltage will cause it to draw more current, up to 30% more based on the voltage you propose. Since heat generated is proportional to current squared, the motor will generate 70% more heat than it was designed for in its windings when loaded, or when starting.
Since the average windlass motor is very poorly cooled, frequently starts and stops, and is frequently heavily loaded, I would predict a very short life from your motor windings. How short? I do not know know... maybe minutes? Maybe days? maybe if you find the actual motor manufacturer and ask?
It's a strange setup, such a small windlass on a
boat with a 32 volt battery bank, but it is what it is...