Sunday, May 27, 2018

[Electric Boats] Re: Shunt size

 

The shunt reducing the available voltage by 150mv or so should be insignificant.  But it would be worthwhile to check the shunt for heating which could mean a poor connection.  Shunts are generally large masses of brass/copper and be able to allow a large current without significant heating.  The 100A/100mV shunt has a resistance of 1milli-ohm and at 150A will produce 22.5W of heat which it has to dissipate.  Compare that to the motor at 150A/48V = 7.2KW. 

I think you said you have a 5KW system.  Maybe 7.2KW has something to do with the Sevcon overheating?  I don't know how well it does, but may be the problem.  How about the motor??

John

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[Electric Boats] Re: Shunt size

 

Hi John,


The Cycle Analyst is fine. The Sevcon Millipak gives 8 flashes which is an overheat fault I believe. It will motor around at 33 amps all day but to get more power I have to let it sit with no or very low amp draw for a minute or two before I can get more amp draw. Then that lasts a very short time. I'm wondering if the undersized shunt might be "choking" the system. 

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[Electric Boats] Re: Shunt size

 

150A through the 100A shunt is 150mv.  If your Cycle Analyst is expecting 100mv full scale it may not like that or minimally give undetermined readings.

Doesn't your Sevcon say why it is unhappy?

John

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Saturday, May 26, 2018

[Electric Boats] Re: Shunt size

 

No the shunt is probably not the problem. 100 amp ,100 mv means that there is a 100 mv drop at 100 amps. 

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Posted by: Brian Hall <mainfuse@gmail.com>
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Friday, May 25, 2018

[Electric Boats] my version of the African Queen total solar boat [2 Attachments]

 
[Attachment(s) from brucenoble@bellsouth.net [electricboats] included below]

Before and After pics

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[Electric Boats] Shunt size

 

I have a 100 amp 100mv shunt for my 5kw 48 volt system. I use it to feed a Cycle Analyst. At times I pull low to mid 100 amps (120-150amps). My Sevcon Millipak isn't happy when I use these higher amp loads. Could an undersized shunt cause issues?

Sent from my iPhone

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[Electric Boats] Charging Questions

 

I have some T105 batteries (6V, 230AH) I need to charge.  I have a Shcumacher SC-8020 charger that I have trusted and used in the past.  


Is it OK for me to join two T105's in series and charge them as one 12v battery using a standard charger?


Would it be OK for me to take two banks of series connected T105's and connect the banks in parallel to get 12V and use my standard charger?


Is charging banks of T105's any different than charging a "normal" battery?



Chris Curtis



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[Electric Boats] Re: Basic help with sizing

 

Thanks for your advice.  I picked up 4 X T105's today.  Initially I plan to use my trolling motor because I have it.  I modified it to create a remote head.   I'll need to create a tiller horn so I can steer.   I'll use the 4 batteries as a 12v pack and do some testing.  There is a small boat event close by next month called the howl at the moon cruise.  Its on Priest Lake in the Idaho Panhandle.  It will be a good place to test as I'll have a willing tow boat if needed.


If anyone is interested the boat is a converted sailboat.  A one of a kind prototype from a famous small boat designer.  For me, I already have a smaller version of a design by this person (Matt Layden, of Paradox fame) and there were things I did not like about the design as a sailboat.  One day while I was dreaming about boat designs I came on a Phil Bolger design called the Delaware Trawler and realized my e460 looked a small version of the boat.  Knowing I'd always chose my Paradox over the 460, I decided the boat would better serve me as a trawler when the weather was not ideal for sailing.  The builders website is still up if anyone wants to take a look.


I'll post later next month after I spend a long weekend testing the motor and its endurance.




Chris Curtis



---In electricboats@yahoogroups.com, <cpcanoesailor@...> wrote :

Hull speed for your boat is about 5.3 knots, so 4 knots is about 75% of that. I don't think a 50lb trolling motor will give the performance you want. If you change the prop, you could make it more efficient and get closer to your desired speed. A 100lb thrust motor would probably be appropriate.

One rule of thumb is 1A for each pound of thrust at 12V. I'd suggest going with a higher voltage system, like 24V or even 48V, since that will divide the current draw by 2 or 4, so you don't need to use really thick wires and the associated connections. Also, your Peukert losses will be divided as well, so less wasted energy.

It sounds like you want to use your batteries as ballast, which works in your favour. So you can use reasonably priced heavy batteries i.e. lead-acid.

Power required vs. speed is quite exponential, meaning it takes very little energy to make the boat start moving, but each increase in speed (say 1/2 knot) takes more and more energy than the last increase. So if you want to go 4 knots, and you're operating at 75% of hull speed, the last knot to get there will require a fair bit of power. I've seen graphs of power vs displacement speed on this forum.

Let us know how you progress with your plans.

 

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Wednesday, May 23, 2018

Re: [Electric Boats] Compac 23 electric conversion (parting with)

 

Good question: Copied and recommended at https://www.facebook.com/groups/549111295238164/
ᐧ

Cheers,

Rob Kay
Mobile: 0792 2692493
Landline and ansaphone: 01236 823129

On 23 May 2018 at 19:38, millsy321@yahoo.com [electricboats] <electricboats@yahoogroups.com> wrote:
 

Hello Group,


I purchased a new (to me) larger boat and am selling my Compac 23 sailboat, which is located in NW Florida.  


This is a unique boat in that I replaced the original concrete ballast in the keel cavity with a combination of lead and (8) grp 31 AGM batteries set up into two banks of 24V.  The original work was done in 2007, and I replaced the batteries in 2011, running a Torqeedo Cruise 2 outboard for about 12 hours (at 2.6 Knots) continuously if needed.  The Torqeedo quit right after the 3-year warranty expired (don't get me started on this) and I since have reverted back to the original gas engine.


The electrical system includes a 24V charger, e-meter, DC-DC converter with seperate 12V AGM battery.  Everthing is per current ABYC with respect to overcurrent protection, conductor size, etc (I am a marine surveyor).  One of the 24V battery banks has been disabled as it will not hold a charge and all batteries are now going on 7 years so it is probably time to consider replacement (last time I used AGM batteries from an elevator company).


The interior is fitted out with a new grid strucure including bulkheads and other joinery with mahogany staving and trim, new cushions, new head, LED lighting, sliding icebox, and other features.  I also increased the hull shell thickness in the keel area tapering off into the tun of the bilge and glassed the inside of the hull/deck joint.  I added the factory bowsprit.  Hull and decks are spray-applied Awlgrip.  New loose-footed mainsail.


I am asking $10,000.00, including trailer.  I think that this would be a good fit and unique oppurtunity for someone interested in electric boats, and would be happy to send interested persons a Dropbox link with  photos.


Thanks & regards,

Chris




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[Electric Boats] Compac 23 electric conversion (parting with)

 

Hello Group,


I purchased a new (to me) larger boat and am selling my Compac 23 sailboat, which is located in NW Florida.  


This is a unique boat in that I replaced the original concrete ballast in the keel cavity with a combination of lead and (8) grp 31 AGM batteries set up into two banks of 24V.  The original work was done in 2007, and I replaced the batteries in 2011, running a Torqeedo Cruise 2 outboard for about 12 hours (at 2.6 Knots) continuously if needed.  The Torqeedo quit right after the 3-year warranty expired (don't get me started on this) and I since have reverted back to the original gas engine.


The electrical system includes a 24V charger, e-meter, DC-DC converter with seperate 12V AGM battery.  Everthing is per current ABYC with respect to overcurrent protection, conductor size, etc (I am a marine surveyor).  One of the 24V battery banks has been disabled as it will not hold a charge and all batteries are now going on 7 years so it is probably time to consider replacement (last time I used AGM batteries from an elevator company).


The interior is fitted out with a new grid strucure including bulkheads and other joinery with mahogany staving and trim, new cushions, new head, LED lighting, sliding icebox, and other features.  I also increased the hull shell thickness in the keel area tapering off into the tun of the bilge and glassed the inside of the hull/deck joint.  I added the factory bowsprit.  Hull and decks are spray-applied Awlgrip.  New loose-footed mainsail.


I am asking $10,000.00, including trailer.  I think that this would be a good fit and unique oppurtunity for someone interested in electric boats, and would be happy to send interested persons a Dropbox link with  photos.


Thanks & regards,

Chris



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Posted by: millsy321@yahoo.com
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[Electric Boats] Re: Basic help with sizing

 

Hull speed for your boat is about 5.3 knots, so 4 knots is about 75% of that. I don't think a 50lb trolling motor will give the performance you want. If you change the prop, you could make it more efficient and get closer to your desired speed. A 100lb thrust motor would probably be appropriate.

One rule of thumb is 1A for each pound of thrust at 12V. I'd suggest going with a higher voltage system, like 24V or even 48V, since that will divide the current draw by 2 or 4, so you don't need to use really thick wires and the associated connections. Also, your Peukert losses will be divided as well, so less wasted energy.

It sounds like you want to use your batteries as ballast, which works in your favour. So you can use reasonably priced heavy batteries i.e. lead-acid.

Power required vs. speed is quite exponential, meaning it takes very little energy to make the boat start moving, but each increase in speed (say 1/2 knot) takes more and more energy than the last increase. So if you want to go 4 knots, and you're operating at 75% of hull speed, the last knot to get there will require a fair bit of power. I've seen graphs of power vs displacement speed on this forum.

Let us know how you progress with your plans.

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Posted by: cpcanoesailor@yahoo.ca
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Tuesday, May 22, 2018

Re: [Electric Boats] Basic help with sizing

 


I have an aluminum hulled Bolger Oldshoe sailboat. Also a sharpie hull. 5 foot beam. 11.5 feet long. Fixed full length keel (about a foot "high") in the center. I suspect the bottom of my hull is more curved than yours.. And the keel (7 inches wide) probably adds some drag as well.

250 lbs ballast. say another 50 for masts and rigging. 200 to 300 for hull. 2 people another 300. Gear another 50. Anchor and tools another 50. Ice chest and some more junk another 50.  So all up 950 to 1050 lbs.

I used a trolling motor for a bit. 50 lb thrust. Controller was dead so I ran it full out with motor connected directly to the battery. In very calm conditions...with a very modest headwind (and sails tightly furled)...that motor would push the boat along at 3.6 mph give or take.

So there are some real world numbers to work with.

However, with some rough conditions and some decent headwind...that 50 would barely move the boat...in those conditions it was more like 1 mph. Thats when the 2.5 hp outboard got bought. Though cruising with the trolling motor sure was sweet....may still rig that up again and only use the outboard when really needed.

IIRC (somebody needs to check me on this )....the 50 lb thrust trolling motor drew something like 50 amps at full power. So, for 4 hours you are going to need 200 amp hours (at least.....you really don't want to regularly draw your batteries all the way down...not good for them at all....you need to leave the last 25 percent or so in the batteries...and only use that rarely for emergencies.

Again, IIRC your typical Walmart/autostore deep cycle battery has about 100 amp hour capacity....so that is 2 batteries per day....4 batteries for 2 days....something like 60 lbs per battery....so 240 lbs worth of battery.

Again...rough numbers...will need to look up the specifics...but these are fairly close ballpark number.

If your hull is a bit "faster" than mine and you can stand to go a bit slower....under calm conditions you might get by with a 25 to 35 amp draw.

Hope that helps....did a lot of battery research earlier in the year...later today I'll dig up what I found...

take care

Buddy
On Monday, May 21, 2018, 9:31:35 PM PDT, yahoomail@curtisteam.org [electricboats] <electricboats@yahoogroups.com> wrote:


 

Hello All.  I have a microtrawler I'd like to electrify.  The boat is basically a sharpie hull, 42 inch beam, 15.5 feet in length, 7" draft.  She needs a total about 800 to 900 lbs to get her to her lines.  

My goal would be two consecutive 4 hours days at 4 kts without a charge.   I'm hoping a 50lb trolling motor and four T105 (220HA, 6V) batteries would possibly be enough. If not I could go with 6 or 8 T105's.  

I'm just looking for any "rules of thumb" that I could possibly use for sizing batteries, etc,


Chris Curtis



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