T-Pain Is On A Boat: Re: [Electric Boats] New member, new boat, Dowsizing question

Tuesday, May 5, 2015

Re: [Electric Boats] New member, new boat, Dowsizing question

Thanks Curtis.

Your point about inertia struck a design cord on a boat designed for comfort rather speed. Like James Bond...I prefer my happy hour beverage stirred not shaken.

When it comes time to change the battery I may try going to a single bank of 8 Trojans to see the how much impact it has on the motion. If it is too lively I will add the addition weight and batteries and report back to the group on its impact.

Mike

On Tuesday, May 5, 2015 6:28 AM, "Ned Farinholt nedfarinholt@comcast.net [electricboats]" <electricboats@yahoogroups.com> wrote:

Mike,

Yes, it would cause an error. However, you can bleed off the 5 volts with a load or just let them settle for a little while. They will drop down to 13 volts pretty quickly. I now have lithiums so it is not a problem for me. I had considered using a hot water heater element in a section of 3" stove pipe, clip leads, and thermally insulate handle to load the pack for a few seconds to knock off the surface charge. A 4 kw 240v element would draw about 1 kw at 70 volts and probably pull the bank down in a few minutes; no real loss in stored energy. Of course with 6 volt cells you could just use 9 rather than 10 and lessen the problem.

Ned

On Apr 30, 2015, at 11:15 AM, Michael Dellario dellariom@yahoo.com [electricboats] <electricboats@yahoogroups.com> wrote:

Thanks Ned
It makes sense that the Cruise 2 will not give me much other than a lighter wallet.

Your suggestion of higher voltage battery pack seems to make sense but I noticed the Cruise 4 but I noticed they have a High Voltage error message at 65v.
Do you think10 Trojans charged to say 14v (70v) kick the this error code off?
Like I said I am still learning.
Mike

On Wednesday, April 29, 2015 3:26 PM, "Ned Farinholt nedfarinholt@comcast.net [electricboats]" <electricboats@yahoogroups.com> wrote:

Mike,
If the goal is to reduce weight, you can remove half the trojans keeping the voltage at 48 volts, or what I would do is use 9 or 10 of the trojans in series for about 60 volts. The Cruise 4 runs better at 60 volts than at 48 since it uses less current for the same amount of power, thereby creating less heat. The Cruise 4 is rated by Torqeedo at 65v. The Cruise 4 will perform just like to Cruise 2 but more efficiently. The significant weight loss with the Cruise 2 purchase would be in your wallet.
Hope this helps.
Ned

On Apr 24, 2015, at 1:40 PM, dellariom@yahoo.com [electricboats] <electricboats@yahoogroups.com> wrote:

[Attachment(s) from dellariom@yahoo.com [electricboats] included below]
Hi all
I am new and just purchased a (one off) electric boat someone else built by converting a Venture 17 sailboat to an electric launch. He added a Torqueedo Cruise 4 with 16, 6v Trojan 105's (450AH) . The 1000lb battery weight is concentrated in the center of the boat to replace the ballast of the centerboard. He did some creative fiberglass work to move the Cutty Cabin to the aft end which houses a small day head and some resting bunks and converting the forward area into a lounge like the Duffy design. I love the concept of an all day electric boat that makes provision for both battery and bladder needs.

However, I wonder if it is overpowered and wonder if when it comes time to replace the batteries if I could replace the Cruise 4 (8hp-48v system) with a Cruise 2 (5hp-36v system) and reduce the batteries to 6(-620 lbs) or 12(-248 lbs). This would reduce the weight and hopefully increase efficiency? I am however concerned about power reduction and effect on ballast that may be needed to maintain stability. I am obviously not an engineer and hope someone can give me some insight on how to calculate this conversion.

Current Boat specifications are:
-Estimated weight 500lbs (without batteries and extra little things taken off boat). Original displacement 900lbs
-Length 17ft , Length at Water Line 15ft, Beam 6.5ft, Draft 18in,
-Max Engine size rating 10hp,
-Current speed is 6.5 mph max with an efficient cruise at 5mph with a Torqueedo calculated range of 80 to 100miles.

Any suggestion on how to calculate how much power is needed?
Thanks

Mike