G'day Ron, All
At 05:14 PM 15/05/2010, tie dye ron wrote:
>My doctor is getting me a new powerchair to replace my old Hoveround
>which carries my 450 pound fat butt all over our yard at a really
>fast pace. It is powerfull enough to plow a garden and a charge last
>4 continuous hours or more at top speed.
>it is a dangerous tank of a powerchair.
>I have an 18 foot deck boat with a 305 mewrcruiser in it right now.
>Would the motors be a viable engine to replace the merc? It doesnt
>have to go fast enough to ski but would it push my boat at an
>acceptable speed to go on a long day of fishing or cruising?
You have experienced torque with your power chair, as those chairs
use DC motors with permanent magnets, so give full torque right from
the get-go. The maximum horsepower is not that much, probably under a
half a horse, which is why you have good battery duration.
Your Mercruiser produces horsepower in abundance. At idle its' torque
and horsepower is probably only about as much as the power chair
motors, but as the revs start to climb, so to does both the torque
and the horsepower.
If you were to use something like the power chair motors to drive
your boat, you will probably get displacement hull speed in calm
water - about 4 to 6 knots (someone more familiar with your style of
boat may be able to estimate that better). You stand no chance of
getting the boat to plane. The windage of the boat is likely to be
the real problem, so if the wind gets up, you can't overcome the
force from the wind so end up going where the wind blows.
So "would they be viable?" only at low speed in sheltered waters.
That brings up the option of hybrid operation - use the chair motors
for low speed manoevering and trolling, etc., with the mercruiser or
a smaller replacement motor for travelling. That said, I still
wouldn't use the wheelchair motors for that, I'd start with a series
DC motor and higher voltage (probably 48 volts).
As to "a long day of fishing and cruising?", with any planing hull,
weight is the problem with an electric conversion. Light batteries
cost a lot, and even then range is still an issue. At present
electric is increasingly viable for short bursts of high power or few
hours of more moderate power (displacement speeds), beyond that the
costs start to really add up, and it becomes cheaper to start with a
hull form that is designed for best efficiency at the displacement
that the electric system places on it, rather than throwing extra
money into shoehorning an inappropriate system into an inappropriate hull.
Hope this helps
Regards
[Technik] James
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