LM18 Houston Tx

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fallguy1000
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Re: LM18 Houston Tx

Post by fallguy1000 »

Nice looking work. Eric, the ends of the cables should be rubber booted. This is cheap and easy to do. You can boot only the hots, but booting both when they are in close proximity is also not a bad idea.

https://www.waytekwire.com/item/23546/2 ... -Terminal/

They have 48 different kinds n colors.
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ericwensel
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Re: LM18 Houston Tx

Post by ericwensel »

I will get the covers and cover both + and -.

Two new pictures. A fairly big milestone. There should be no more gluing, filleting, cutting wood. The aft deck and the gunnel caps are glued in place.

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Image

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VT_Jeff
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Re: LM18 Houston Tx

Post by VT_Jeff »

ericwensel wrote: Fri Dec 31, 2021 10:19 pm There should be no more gluing, filleting, cutting wood.
Woot Woot!
There are only two seasons in Vermont: boating season, and boat-building season.

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ericwensel
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Re: LM18 Houston Tx

Post by ericwensel »

I have a fairly smooth cockpit area. Glass for the deck is cut and ready to put down. I am going to have to purchase a bit more epoxy so i ordered today.
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Starting to think about wiring. I sketched up a diagram. If anyone has any suggestions i would be happy to hear them. The big cables and switch are in place but no small gauge wiring.
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fallguy1000
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Re: LM18 Houston Tx

Post by fallguy1000 »

Well, lots of corrections on your wiring diagram tbh.

Let's just start with a fundamental confusion.

You show a 24volt bank and a 12v starting bank.

The motor only delivers 12v(13 or so), so you can't send 12 volts to the 24v bank. Nor do you have any way to charge the 24v bank.

Proper boat wiring requires that grounds are shared, so the house bank and the starter bank are supposed to be combined commons.

All positive wires require fusing or breakers. Trolling motors are generally breakered.

Terminal blocks are not used on the ground side. A bus bar is used.

And rather than using a terminal block for the hots; a fusepanel is far better.

The only time terminal blocks are used is if you need to stage and extend wiring. I have 3 terminal blocks in the Skoota. The hardtop cannot travel with the boat on the highway, so there is a tblock under for service disconnecting only. Two others in each hull are for disconnecting parts if we ever take the boat apart.

Your boat really needs no terminal blocks.

Start drawing only the two battery banks and motor and determine how you plan to charge the 24v bank.

Sorry if I seem harsh or have misinterpreted. Putting + and minuses on the batteries is important as well.
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Mojosmantra
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Re: LM18 Houston Tx

Post by Mojosmantra »

Curious about your deck glass because it appears that you plan to lap the seams. That may be the right way to do it - I’m not sure, but it seams unnecessary. My understanding is that the deck glass provides some stiffening but is mostly for abrasion resistance. It doesn’t seem like the lapped seams will do much for you other than add some additional fairing to the job. I could be wrong about that.

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VT_Jeff
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Re: LM18 Houston Tx

Post by VT_Jeff »

Mojosmantra wrote: Fri Feb 11, 2022 8:08 am Curious about your deck glass because it appears that you plan to lap the seams. That may be the right way to do it - I’m not sure, but it seams unnecessary. My understanding is that the deck glass provides some stiffening but is mostly for abrasion resistance. It doesn’t seem like the lapped seams will do much for you other than add some additional fairing to the job. I could be wrong about that.
I'd agree, Trent. Leave some small gaps at the seams and save a ton of fairing!

Also looks like biax, which may be overkill for abrasion resistance. The threads will add some work.
There are only two seasons in Vermont: boating season, and boat-building season.

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fallguy1000
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Re: LM18 Houston Tx

Post by fallguy1000 »

Overlapping seams is standard in all glasswork.

Where you place overlaps can help reduce fairing.

Skipping an overlap will almost always result in a surface crack down the line as the thermal expansion rates between glass/ply/glass will vary as the sun hits the deck and almost certainly crack the paint in an unglassed seam.
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ericwensel
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Re: LM18 Houston Tx

Post by ericwensel »

Thanks for the feedback from all, especially the wiring feedback. I am going to continue to post the schematic until i feel i have it correct.

I did not include the common ground between the trolling motor bank and the starter motor bank which is needed. I was trying to follow the schematic below which includes the common ground as you suggested. I have not found many schematics online of this configuration even though I think it is very common. I believe that the sketch i have now follows this configuration but if it is not right, i would be interested in hearing suggestions.
Image

As for the Terminal Blocks. I should not have used that term as it was incorrect. My intention is to use a fuse panel which also includes a common negative bus bar. These are represented on the new sketch as BB1 and FP1. I will have another bus bar (BB3) in the transom area.

I did not show fuses and breakers in the schematic initially but given the importance i now show. Of course in the fuse panel there are breakers for each load. See the revised sketch below.
Image

As for charging the batteries. I did not show this on the schematic but I have a three bank battery charger which i expect to hook up something like shown in the sketch below.
Image

Lastly, i thought briefly about not overlapping the seams on the deck since as stated its not necessary for stiffness. Nevertheless i overlapped everywhere else so i felt it was the right thing to do.

Thanks again for the suggestions.

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Re: LM18 Houston Tx

Post by fallguy1000 »

You still cannot charge a 24v bank as drawn. You will end up charging the bank unevenly and the battery life will be terrible. I experienced this very thing, for the record, thinking it would not matter. And my 24v bank died. Fortunately, the retailer ate one of the batteries, so the error only cost me $200.

Here is a picture of the error. You must send 24v to a 24v bank. The ground should also be on the ground of the 24v system to avoid loops. This is not easy. I have a loop in my system and can't figure out where now :(
7BC8A3E5-AABD-494A-94B0-6B397D0E2DF5.jpeg
7BC8A3E5-AABD-494A-94B0-6B397D0E2DF5.jpeg (163.76 KiB) Viewed 999 times


You need a 12v to 24v converter and you need to charge the entire 24v bank and discharge it at the same rate or you'll be sorry. Something like this one may work, but I am not specifying the current. Victron Energy Orion IP20 12/24-Volt 10 amp DC-DC Converter Non-Isolated, High Power https://www.amazon.com/dp/B01BF5BT6M/re ... 59W79SQEM7
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