Help me with an electrical plan for a new hull please

[Smokeyr67]

Hi guys,

Sorry for the long winded title, but what I’m looking for is your input and opinions on the electrical rigging of my new hull.

I’m looking at running a Merc Pro XS 225, 3 x 12 inch screens, a 36 volt TM, 2 transducers, VHF and AM radios, 2 bilge pumps, 1 live bait pump and nav lights.

For reference this is the boat I’m talking about, but I’ll be getting a bare hull https://surfcoastmarine.com.au/boat-...ntier-rear-cc/

My first consideration is batteries.

The cranking battery will be an AGM of whatever capacity Merc recommends.

I’m looking at lithium for the TM (36v, 80 ish Ah)

Again, Lithium for the electronics 12v but I have no idea as to how many Ah I’ll need.

I’m planning on running either 8 or 10 gauge wire for everything except the motor - I’ll leave that to the pros.

So, that’s my plan, here come the questions.

1. To run all my electronics (3 screens etc) for up to 16 hours, how many Ah do you think I’ll need on the “house” battery?

2. Are then any cons to using larger wires ?

3. Can I charge the batteries from the alternator, if so what’s the best system to use?

4. Would I be better off placing my TM battery forrard keeping it close to the TM and having a long run from the charging source, or placing it aft keeping the wires to the charger shot?


As you can probably tell, I’m no genius when it comes to electricery, so all your advice will be greatly appreciated.

Thanks
Smokey

[Alumicraft145]

Wow nice boat!! My only input for this would be for the cranking battery... I used an optima d31 battery. Never had a problem. On one vacation the alternator went on my optimax. I saved my trip by charging the d31 every night. I currently have 2 optimas in boat that are 8 years old. Running great. I charge them with the optima charger which is really good.
The rest of the rigging is for everybody else.

[catdude28]

Pick your AGM for the Mercury from this list of Don Weed's recommendations. The bottom two are actually relabelled Northstar. In your location, you may have to do a little research if looking for a rebadged Northstar.

AGM BATTERIES: Suitable for ANY Alternator-Based Outboard Engine (DTS (All), Verado (All), Fourstroke (150+hp including the V6/V8 Fourstroke), Optimax (all) or (Alternator-Based 2-Stroke EFI engines ONLY)).

Label Brand	Part Number	Retailer	CCA	MCA	RC	Weight	Group	Technology	Manufacturer
Vmax	XCA31-1400	Various	1200	1400	205	78	31	AGM	VMAX USA
Odyssey	31M-PC2150	Various	1150	NR	205	77.8	31	AGM	Enersys
Northstar	NSB-AGM-31M	Various	1150	1370	220	75	31	AGM	Enersys
BPS Pro Series X-900	31	BPS/Cabela's	1150	1370	220	75	31	AGM	Enersys
Batteries Plus X2 Power	SLI31AGMDPM	Batteries Plus	1150	1370	220	75	31	AGM	Enersys

___________________

[Fishysam]

Wow nice boat!! My only input for this would be for the cranking battery... I used an optima d31 battery. Never had a problem. On one vacation the alternator went on my optimax. I saved my trip by charging the d31 every night. I currently have 2 optimas in boat that are 8 years old. Running great. I charge them with the optima charger which is really good.
The rest of the rigging is for everybody else.

Optima is now made in Mexico, apparently a drop in quality since then so be careful in the future.

batteries plus x2 agm is great and is not a prorated warranty. If it dies 47 months from purchase you get a new one for free.

if you are not looking at all three screens all the time put one or two to sleep this will help.

mono mention of livewells for 16 hours a day? If no pumps are running I bet this one battery will hold up for you. If your running pumps then you will want a house battery.

bigger wires cost more and weigh more thats all.

3- power pole charge looks to be a great device for on the water and at home.

batteries up front is harder on them as the ride is worse. But this is standard practice on many walleye boats and they know rough water. Charger leads normally say not to extend them ( I think this is because some of the features like over heat or something may not be able to understand the slight voltage drop or something)

[John Jones JTM]

You're pretty much have it going, except for wiring. You'll need 4ga to the outboard from the battery. Most outboards will come with they're own wiring harness. You should use 6ga from trolling motor batteries to the trolling motor. Be prepared to hardwire the trollingmotor to the batteries, making use of a junction block. I would not use 8ga wire for this, even though some charts show it to be ok on a 36V motor. At the batteries, you'll want a 60A breaker and I suggest one with a on/off lever that allows you to disconnect the trolling motor while charging the batteries are while not in use. There is some devices that allow for charging from from the outboard alternator, but for different reasons, I do not hang my name or hat on any of them. One of the reasons is that most don't run the outboard long enough except to deliver a surface charge that leaves as soon as you put a load on the batteries.
John

[Smokeyr67]

Hi guys,

Firstly, sorry for the delay in replying, I kept getting sidetracked.
Thanks for all your input, your advice is greatly appreciated.

Anyhow, I’m still waiting for the hull to be built (because I don’t want a complete ready to float package I’m not a priority) but I’ve adjusted my plans thanks to your ideas.

Firstly, I’ll let the Mercury dealer supply, fit and wire up their recommended AGM, and just use it as a starter and for running lights, UHF radio.

Next, for the TM I’ll pick up a 36 volt 100ah LifePo4 battery locally, fit it just forward of the console to give it a softer ride and run some nice fat cables to the TM on the bow. That’ll be about a 5 to 6 metre run (16 to 20 foot if my maths are correct) so not ideal, but I can cope with a little bit of voltage loss. I’m thinking of running this through a motorsports style battery isolator switch, for no other reason than the cool factor. Oddly enough, I have a 36v 100 amp version in my parts bin, not sure why, maybe I was thinking of building a racing truck?

For the “house battery” I’m looking for a 24v LifePo4 in around the 80 ah range to run 3 screens, 3 transducers (Max 2 screens and transducers at 1 time) anchor lights, live well, VHF radio and a couple of USB ports. I’m having trouble finding a 24v lithium battery the right size locally, I can find them up to about 40ah, from there they leap up to over 100ah, so I might end up using 2 x 12 volt batteries. I’ll mount these in the base of the console, wire them to a fuse box, then run the spiderweb of wires from there to the bits that need electrickery. I’m not sure if I’ll need a 24-12 step down for the screens, I still haven’t decided exactly what I’m putting in, so that’ll come later.

For charging I’m trying to wrap my head around the Yandina Trollbridge gear, unfortunately I’m no electrician so I can’t see how I could charge the starter battery (12v agm) the house batteries (24v Lithium) and the TM battery (36v Lithium) at the same time. I’ll have to send them an email and see if they can decipher my gibberish

Anyhow, thanks again for your help, sorry for prattling on , but I’m getting a bit excited about the prospect of fitting out the boat and I love to discuss my thoughts.

Thanks

Smokey

[billnorman1]

If I were to buy a bare hull from a factory I'd ask them to wire it, even though I have 50 years of wiring experience. Then I'd change anything I didn't like.

[Smokeyr67]

Bill, this is more than likely the last boat I’ll ever buy, so I’m going all out to make it as close to perfect as I can.

I’m making the deck, console, underfloor storage, hatches and the like myself just so it’s as close to perfect for me as possible.

Wiring’s just a part of that equation, but I’d rather run it myself so I can (a) keep it neat and tidy (b) know exactly what’s going where for future upgrades/maintenance and (c) so I can over spec everything, not just run the cheapest option possible.