Charging a 48V bank?

[Delmar]

This is likely not the case unless it's listed as a LRA (locked rotor amps) value or a surge.

The initial flow of current to a motor is typically 5X higher than its maximum operating current. The winding of the motor essentially have zero resistance until the flow of current induces a field that "pushes back" at the incoming current.

My 48V Yamaha golf cart nameplate lists the AC motor as 6.7 HP. When accelerating or climbing hills it will draw ~130A at the batteries. Steady-state cruising draws ~25A.

 

[BobR]

She has a single prop, offset, and tucked up along the keel. She has no prop-walk to speak of. She simply doesn't steer.

She was designed to have two props, and I think she really needs two props.

Setups like that never steer well. The prop wash only effects one side of the rudder and is so far away it isn't much force on that side. If you put an outboard on the transom it will steer under motor much better.

 

[OzSolar]

Elco makes inboard motors, IIRC.

They do make outboards.

 

[jdege]

The do make outboards.

When I looked at Elco, I was looking for pod drives.

I didn't think to go back and look again, when I decided to look for outboards.

Thanks for the pointer - some of these deserve consideration.

 

[400bird]

This is likely not the case unless it's listed as a LRA (locked rotor amps) value or a surge.

The initial flow of current to a motor is typically 5X higher than its maximum operating current. The winding of the motor essentially have zero resistance until the flow of current induces a field that "pushes back" at the incoming current.

This is a boat with a throttle. It doesn't go from 0 to 100% in an instant. The reason a well pump or air conditioning motor hit with a huge starting surge and LRA is because they are trying to go from 0 rpm to full speed in an instant.

A boat, car, or something with a VFD designed to ramp up RPM over time won't have a starting surge or LRA to worry about.

They definitely will have some extra acceleration needs vs cruise, as already mentioned.

 

[larsenf]

Why would they need to be removed in the off season? Building a pack from cells is the most cost effective per kw and allows you to more easily hunt for deals. If you use a victron multiplus-II 48v/3000 120 you get super efficent 110v on the boat and it will give you 35a charging which can be limited based on your shore power or generator rating and would integrate with their mppt solar controllers.

 

[jdege]

Why would they need to be removed in the off season?

Because there's not much that handles temps of -40 without damage.

 

[time2roll]

Because there's not much that handles temps of -40 without damage.

Not sure that is so much an issue if stored disconnected. Verify with the manufacturer.

 

[jdege]

The general cutoff is 0C for charging and -5C for storage.

And that they be stored around 50% charge, and to be cycled at least every six months.

 

[w7eryron]

Hello, I dropped in to just check it out and WOW!, ... I find another meadowlark boat owner looking at propulsion via Torqeedo. Some thoughts: I built my boat in fiberglass in 1982, waterlines are the meadowlark, topsides and interior have changed many times since then.
I put in one Cruise 4.0 (six years ago, with Trojan L16's, 1400w of roof solar panels, MidnightSolar Kid, replaced the standard sails with a small Chinese Lug rig) and usually run it around 700 to 1500 watts, travelling between 3 and 4 knots. My top speed is about 6.5 knots at 4,000w. No trouble steering. My experience confirms what someone wrote above: it costs a lot in increased wattage to increase speed only a little.
The Trojans do fine for hanging around my home waters on the Columbia River, but I have a dream of wanting to motor overnight up the coast of WA, and so I am looking for more capacity. Thus, I am currently planning on replacing the L16's with LFE's ... thinking of 6 of the 48v-100a EG4-WP batteries ... but still researching. That's why I came to this forum, to see what I can learn from you folks.

 

[jdege]

I wish I could provide you with data, but I haven't splashed, yet.

I ended up going with a pair of Elco's EP-9.9 outboards, powered by a pair of Epoch 48V 100Ah batteries. I'm just finishing building the motor mounts, I should be splashing later this week.

That's far more engine than I think I'll need, but I figured that since there's very little difference in range between a 3kW motor throttled to 1kW and a 5kW motor throttled to 1kW, aside from initial price, I might as well go with the more power even though I wouldn't expect to use it.

Two question:

• How did you hang the Torqued do from the transom?
• And where did you put the solar panels?

 

[w7eryron]

Torqeedo mount - I cut a centerline hole in the transom and hung it directly off the back. In a prior version I had mounted an outboard on the side just ahead of the transom and I found that the mount would scoop up water into the boat when I was at speed sailing (and also soak the motor) ... I didn't want to repeat that. I now have twin rudders alongside the motor.

Power/speed - I decided on only one motor after much calculations from formulas in Skenes Elements, and they proved to be accurate. I agree with your thinking on two motors, plus having the back up just in case of failure. I just couldn't afford the cost. And didn't need the power for most of my cruising. I normally ride with the current and thus at about 1000w from the motor and speed of the current I usually make 5 knots over ground, and that is plenty for me. The fastest I have ever been able to go under power is about 8.5 knots with a larger gas outboard, and I can think of few times when I would really need to go that fast. So far, it appears that about 1400w gives me the best speed/mileage/wattage sweet spot.

Solar panels - I cut off much of the original cockpit/coachroof and covered the resulting (large) hole with a stand-up-underneath roof. The panels are the roof. Now in my old age, I really like the headroom and being able to walk around. My boat now looks much more like the African Queen (with leeboards) from the Bogart movie than the original Meadowlark design.

Thanks for the note on the Epoch batteries. I will check them out too.

 

[jdege]

The primary drive behind my repower is to get two props on her, again. The existing single offset prop results in a boat that simply can't be steered at slow speeds.

I went with the Elco primarily because they use standard outboard chassis - the very same as Yamaha and Tohatsu. This means they work with many of the standard accessories. I will, eventually, be looking at replacing the actual props. A prop designed to put a dinghy on plane won't be the best choice for pushing a displacement hull at low speeds.

I'm mounting the motors on a pair of Panther lifting outboard brackets, bolted through wooden wedges I built to provide the necessary offset.

As for power, I was looking at their EP-5 and their EP-9.9. Theoretically the 9.9 has twice the power, but it only costs 10% more.

There's a lot to like about the Epoch batteries. They're IP67 rated, they have built-in heaters for cold weather charging, they have a Bluetooth app for monitoring, etc.