Re: [electricboats] 15 KW DC l electric conversikon

Graeme,

By the way, if you're planning to burn about 1000A for a long time, a Honda 2200 generator would do fine to provide that (it defeats the purpose of the "green" effort, but at least you still have an electric motor.

If you do that, you could reduce the size of your battery bank significantly (saving a LOT of $$ if you're planning on Lithium).  Size the bank sufficiently for short outings, and use the generator any time you'd be out over an hour or so?

Just a thought.

John

On Sunday, February 9, 2020, 06:45:42 PM CST, Graeme Ross <graemealross@gmail.com> wrote:

 John  Thank you very much for the info. I think that this will work out perfectly. I will get a small generator to extend range for emergencies.   

On Sun, Feb 9, 2020 at 3:30 PM john via Groups.Io <oak_box=yahoo.com@groups.io> wrote:

Graeme,

I ran some experiments on a a Catalina 22 with a Torqeedo 4R - which is probably the closest recorded data you may find with that motor...

At 4 to 4.5mph, I was burning 800-1000W.   At 48V, that's around 20A.

Your range will depend heavily on your battery chemistry.   If you are using AGM or Lead Acid batteries, assume maybe 50% of your rated amperage - so a 130A bank might get you 65AH, so you should comfortably be able to get 3 hours of cruising, assuming you limit yourself to 1000W - which will hopefully push your boat close to 4mph.

Does that help?

Here are the test numbers from a run with the 48V Torqeedo on the C22:

You can see how the required power increases dramatically above 4.5mph.  Hull speed for a 22' boat is about 6mph, if I did the math right...

Power            Speed

160w                2mph

500w                3.3mph

800w                4.0mph

1000w              4.5mph

1500w              5.3mph

2000w              5.8mph

3000w              6.5mph

On Sunday, February 9, 2020, 01:12:19 PM CST, Graeme Ross <graemealross@gmail.com> wrote:

Sorry I meant 130 amps

On Sun, Feb 9, 2020 at 1:25 PM Graeme Ross via Groups.Io <graemealross=gmail.com@groups.io> wrote:

Hi I bought a Torqeedo 4.0 with 4 12v 30 amp batteries. The boat is a 23ft Bayfield sailboat weighing 3500 lbs . I am wondering the approx. range I can get at 4 knots. The hull speed is 6 knots.   Thank you Graeme Ross