Monday, February 8, 2016

Re: [Electric Boats] FW: New Member from Iceland--- a Note or two

 

Dominic,

I'm interested in a huge battery like Pwrwall, but doesn't the Tesla power wall have about 400 volts in its battery?   what voltage are you using in your motor and what the efficiencies getting down to that voltage? are you transforming directly down to say DC 48V or are you invering to AC 120V then through another step to your motor voltage?

Another question I have is what happens in an emergency situation...like if you are swamped by a rogue wave, or laid over by the wind...how will you deal with 400volts DC awash in saltwater kneedeep? or am I imagining danger where there is none because it would all ground out into the sea? 
 
                     Bill Hopen   -  www.billhopen.com
       Hopen Studio Inc -  227 Main St., Sutton WV 26601
          304 -765-5611                  billhopen@yahoo.com


From: "Dominic Amann dominic.amann@gmail.com [electricboats]" <electricboats@yahoogroups.com>
To: electricboats@yahoogroups.com
Sent: Monday, February 8, 2016 10:42 AM
Subject: Re: [Electric Boats] FW: New Member from Iceland--- a Note or two

 
Pardon for the zombie thread post here. I have been working a lot with LiFePO4 batteries of late (professionally in my role as an embedded software developer). As people by now would know even from their cellphones - fast charging is a reality. A good system can charge about 60% of capacity in an hour or less. As a battery approaches capacity, the current must be reduced, so the overall charge may be several hours, but it is quite possible to charge a system faster than it can be depleted in normal use. Another way of saying this is that you can charge a system about as fast as it can be depleted at peak use.

I am going to deploy a Tesla powerwall in my 30' Alberg sailboat. I already have a 5KW motor. The 7KWh battery pack will give me about 3 1/2 hours at a cruising speed of about 3.5 kn (2 KW), which I think is excellent, and the powerpack can be charged in about 4 hours (hey, anything less than a full night is just fine by me).

Once I have dispensed with the fuel tank, engine (already gone) and sundry hoses and connections, there is ample space for the powerwall and motor. I can install temperature sensor driven fans to ensure adequate ventilation, and cut offs to prevent overheat. I suspect the powerwall capacity and price is going to really propel the shift away from ICE in the sailboat auxiliary world - whether by using the Tesla product directly, or by the intense price competition it causes.


On 27 December 2014 at 10:03, 'cal' h20dragon@centurytel.net [electricboats] <electricboats@yahoogroups.com> wrote:
 
Watch the charger size, and recharge times possible with different battery types, and battery sizes.  I can not think of a system that would take a charging time of "less than one hour" without a pack melt down, or at least shorten the battery life enough to make some ( maybe not all ) batteries in the pack lose capacity too fast to be cost effective.  I have always used the thought that it takes just as long to recharge as it took to deplete the pack to that point.  Been there, burnt out a new charger that way, and be sure the dock cord is up to the amps as well, now I use a 10 gauge to 2/0 by 50  to 100 ft. foot cord as needed, not a regular one.  Dock power plugs needs a looking at also for fast chargers.
 
Both my boat wet cells, and my bike with lithiums have normally taken that long with the factory chargers, faster may be harmful for long term use.  Two packs, charged after each was used, is a good turn around if a bit heavier than we would like.  That way smaller batteries can be used, depending on run time of course.
 
Thanks,  Cal
 
 
 
From: ]
Sent: Friday, December 26, 2014 7:19 AM
Subject: Re: [Electric Boats] FW: New Member from Iceland
 
 
Thank you Hannou
 
for exellant advice I do admit that i had not counted legal costs as an considerable factor and I to my best knowledge there are just inspections fees if I have an boat yard do the hulls the electronics and electric propulsion I have certification to do most of that my self and then we have our seafaring certification authority to have inspections and seafaring certification. Here in Iceland we have basically the Norwegian / Scandinavian rule set so what is allowed there will in most cases pass here (depends though on the day-form of the inspector) all electric runs in boats her are double insulated an always demanded for the most expensive and highest quality of materials.
I have found Lithium Polymer batteries that are 6.5 KW/Ah per 40 kg that gives me approx 250 KG pr. 40 KW/Ah I how ever need to pair them up with some hefty chargers where I intend to charge them in less than an hour to have acceptable turn around time.
This is not so far from the 2 x 35 hp outboards + fuel and batteries may be 1 or 2 passenger penalty and approx same for emergent gen sets 10 -20% less passengers in trade off for silence an Eco friendliness, is may be acceptable but costs are running quickly up an making the endevaor less feaseble
 
2014-12-25 11:18 GMT+00:00 Hannu Venermo gcode.fi@gmail.com [electricboats] <electricboats@yahoogroups.com>:
 
I am analytical and look at numbers.
As such, the project is expensive but doable.

25 kWhr usable load needs a minimum 30 kWhr battery (similar size as a tesla), and with some margin 40 kWhr.
At 500 $ / kWhr, ==> 20.000$.
At, say, 100 Wh/kg, => 400 kg battery mass.

Thus, its technically feasible, since the motors will be small and light.
The extra battery mass is likely still doable.

I would suggest planning around 100.000$ for systems cost.
Note requirement for proper schematics, survey, a licensed marine engineers write-off on safety etc. as its a commercial vessel.
Perhaps double insulated cables.

In a fjord (Norway) the engineers costs and licensing will be reasonable.

All prices are in line for any other custom commercial, insured, build, in my opinion and in my experience.
Any custom build will have the same safety and licensing costs, anyway.

The last thing you look at, or should think about, is motors, controllers etc.
The first thing you look at is systems cost, legal, engineering practicalities, and any suitable "white-box" technology will slot right in.

All good engineering solutions are pretty much comparable, and any one will work.
The legal aspects are about 2/3 the total cost and work, and should be the overriding focus, in the initial business plan.

In the us, or here in spain, the legal aspects might easily cost more than the 100k budget I mentioned.
In scandinavia, not necessarily.

I can advise further, if there is interest.

On 24/12/2014 20:57, 'Myles Twete' matwete@comcast.net [electricboats] wrote:
 
Any feedback for this gentleman?
 
From: electricboats-owner@yahoogroups.com [mailto:electricboats-owner@yahoogroups.com] On Behalf Of Stefán Brandur Jónsson stefan@martolvan.is [electricboats]
Sent: Tuesday, December 23, 2014 9:11 AM
To: electricboats Moderator
Subject: Re: FILE - Welcome
 
Hi All
 
I'm Stefan from Iceland, I'm an electronics field engineer by profession and bit of an boat and energy efficiency enthusiast.
My latest project is an feasibility / business plan for an catamaran tourist boat for using in my fjord that is for the most part very shallow, I think that an electric Jet drive would be the best fit where I need to overcome currents up to 8 knots in graceful manner. are there any ones that have some good advice on motor, battery and controller choices. My goal is to go electric only on approx hour trip on approx 25 KW load (max power 2 x 28 KW).
Look forward to comments.
,_._,___

--   -hanermo (cnc designs)


 
--
Kveðja – Regards
Stefán B. Jónsson

Sími: +354-4781309 GSM: +354 8946541, skype: stefan.martolvan.is
Trúnaður /Disclosure



--


People are generally better persuaded by the reasons which they have themselves discovered than by those which have come into the mind of others - Blaise Pascal.

Dominic Amann
M 416-270-4587


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