before anything drastic have you checked and cleaned all connections ?
Sent by David Birch. steam2birch@yahoo.com
Sent by David Birch. steam2birch@yahoo.com
you have to swap something to see if the problem follows. Prop or controller, whichever is easier.
From: marcdrachten <mevanderkuur@gmail.com>
To: electricboats@yahoogroups.com
Sent: Saturday, July 13, 2013 6:22 AM
Subject: [Electric Boats] Re: Wrong prop or engine?
Thanx for the replies,
The motor is fitted with a radice folding prop, same as the sistership. Replacing the prop should be easy, but if I can show the engine is faulty by logic reasoning I don't have to make extra cost for lifting the boat in and out and labour for swapping the prop.
The drop in amps after 12 seconds is system design and therefore normal system behviour, however it should start at 110 A and drop to 85 A instead of 83 A and drop to 55 A.
Marc
--- In electricboats@yahoogroups.com, "marcdrachten" <mevanderkuur@...> wrote:
>
> Hi,
>
> Recently I fitted our sailboat, a Hood 32, with a 2kW mastervolt podmaster. Just like they did on a sistership.
>
> On the sistership the system runs fine, on my boat the boat doesn't reach hullspeed where the sistership does. And the power used from the battery is well below of what it should be at full power. Now the discussion is, is it the prop, the motor or the controller that's faulty.
>
> The supplier expects the prop to be faulty, I think it's the motor. Any thoughts on how I can determine where the error lies without going into demounting and reinstalling the engine and prop?
>
> The engine draws 83 amps @ 27 V for 12 secs (system design) and then drops to 55 amps, measured on the battery. When I measure between the controller and the motor it draws 110 amps for 12 secs and then drops to 85 amps. I didn't actualy measure it, but I assume since amps are higher, voltage should be lower between the controller and motor. For as far as I can tell the motor doesn't reach it maximum rpm.
>
> What does this say about the prop or the motor?
>
> I would say:
>
> If the prop is too light, rpm should be high, amps lower than expected and boatspeed also lower than expected, what about voltage?
>
> If the prop is too heavy, rpm should be low, amps high and voltage normal, boatspeed unsure.
>
> What are your thoughts?
>
> 24v system with 5kW lithium battery
> 24v DC PM podmotor 2 kW with folding prop
>
> Sistership has same config except the batteries are AGM batteries.
>
> Marc
>
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