Power Requirements for basic boat setup?

[Ed]

Hoping Charles and others will chime in and help me.  I got a Raymarine Element 7HV Chartplotter/Fishfinder for Christmas so now I'm trying to figure out power for the system(s).  Nothing out there shows the draw of the Element so I'm assuming a .46 AH draw like a lot of other chartplotter/depth sounder combos. The only other draw will be charging iPhones and led running lights. Looking at Lithium battery vs AGM.  I like this 20AH sealed battery https://www.amazon.com/dp/B09L1ZXXMV/?coliid=I3ON6OSX292M70&colid=8VTO6UUJUN6F&psc=1&ref_=lv_ov_lig_dp_it but for half the price Wally World has a nice AGMYou cannot view this attachment.  https://www.walmart.com/ip/EverStart-Premium-AGM-PowerSport-Battery-Group-Size-TX30LA-12-Volts-385-CCA/49988420. What do ya'll think?  No charging circuit on the motor, no desire to get solar panels but need to have power for 6 hours a day for 4 days running.

[Charles Brennan]

Ed, You're putting up some pretty dismal math.
Went to Raymarine site and dug up your manual.
https://www.raymarine.com/en-us/support/raymarine-user-manuals
Says your unit averages 16.8 watts which works out to 1.4A (Not .46A like you guessed.)
LED nav lights (the USCG rated ones anyway) are .2A times 2  (combination bow and stern) for .4A
Your iPhone charger has two flavors: Fast-Charge for 2.4A or snails pace at 1A
6 hours a day times 4 days works out to 24 hours, you're trying to draw current from a battery.
Your Lithium choice is 20 A/Hr and your Wally World AGM choice is 30 A/Hr.
Most efficient discharge rate for 20hrs (From full to flat, on which mfg. A/Hrs are rated) is 1A for the 20 A/Hr and 1.5A for the 30 A/Hr.
Total current draw is either 4.2A or 2.8 A depending on iPhone charger choice. That gives you around 1 day at high current draw or approximately 2 days at low current draw.
Just based on the numbers, your worst case usage would necessitate a 100A/Hr battery, an absurdly large battery for your new boat. 
(And why I am such a fan of solar charging arrays; Urchin can cruise indefinitely, on current draw versus solar replenishment.)

Coupla factors to mitigate that somewhat:
1) You didn't state how much night running you might be doing.
2) You didn't state if you'd be using the chart plotter all the time, or not.
3) You didn't state how many iPhones you intend to re-charge.
4) Lithiums have one helpful trait that AGM's don't: They don't drop voltage until nearly depleted.
Voltage drop will freak your iPhone charger, although the chart plotter should be OK (wide operating voltage range) & LEDs don't really care.
Me, personally, I wouldn't even consider the AGM in your application.

To get all that you want, for as long as you want, (based on info provided thus far) I would recommend a 50 A/Hr Lithium battery, even despite the eye-watering cost.
It has 1/6 the weight of a 100 A/Hr lead/acid.
Another way to look at it, is 9 pounds for the 30A/Hr AGM, versus 11 pounds on the 50 A/Hr Lithium for half again the energy.

Hope this helps,
Charles Brennan

[Ed]

Thanks Charles, you're always helpful.  Thanks to your numbers, I'll probably bite the bullet and get a 50 or 100AH Lithium.  Now if it would only get warm for a few days so I can remove all the wiring 2 PO's before put in for his Ham radio/myriad of outlets up forward/double wooden battery box in the bow/non-functioning depth sounder, radio plugs, and tiller pilot plug.  Then I get to epoxy/gelcoat all the holes, before installing a rudimentary electrical system for the chart plotter and charger(s).  I'll go with a set of AAA running lights that will replace the existing, wired female fixtures from the factory since the light sticks didn't come with the boat.  I haven't gone night sailing since I had my Potter 19 in 2004.  This is how I feel sometimes fixing up another boat.
You cannot view this attachment.

[Charles Brennan]

Ed, Before you run out and overbuy something, ask yourself this question:
Why would a guy calculate worst case performance at 100 A/Hr and then specify a 50 A/Hr battery?
I get accused of overly wordy posts and sometimes I shortcut my explanations and it can cause problems or misunderstandings.

Engineers figure out worst-case/best-case scenarios to get a feel for a solution that is somewhere in the middle.  They are always looking for the "hump" in the Gaussian Curve.
For example, if you want to know what kind of water to remove from a boat, they will ask you how much water coming in, into how big a volume, so they can calculate whether you need a sponge, a 5 gallon PVC bucket, or an 8-inch intake pump hooked to a 500hp diesel engine.  It's all a matter of scale.

In the Real World, you rarely get a worst-case scenario. (Rarely get best-case either, but that's another soapbox discussion entirely!) 
In the case you cited, you wouldn't really be using your phone charger all the time; you'd charge the phone for an hour or so and it would last you possibly, the rest of the day.  Makes a big difference in total current draw, although designing for worst-case would require that calculation.
So while worst-case is indeed 100 A/Hr, best-case might be around 20+ A/Hr; but I doubt you'd see that even in 1 trip in 10.

Same deal with your Nav lights.  I run a lot at night and you didn't say how long your cruises were for.
I have used portable Nav lights and universally despised them.  One of my biggest problems is remembering to take out the alkaline batteries and the next time I go to use the lights, it's a big corroded mess.
On my RIB Short Ribs when I tired of the aggravation, I hard-wired my nav lights and ran them to a 12 volt plug that I plug into a battery jump pack, since my previous motor had no charging system.  Keep a little silicon grease on the metal bits and I've had no problem for the past 20+ years.

So with the additional information provided in your reply, if it were me trying to achieve what you describe, here is how I would do it:
1) Stick the battery in an ammo box to make it easy to take on and off the boat to recharge.
Something like this:
https://www.harborfreight.com/tactical-ammoutility-box-64113.html
I'd stick some 12 volt sockets maybe 3 sockets, appropriately fused in it.
You're going to need to put the battery in a box anyway to meet USCG requirements.

2) Hard-wire the nav lights and bring the wire ends to 2) 12-volt plugs.
While you could easily parallel them together, keeping them separate allows you to plug in stern light only, to use as an anchor light.  Plug in both to use running lights.

3) Get a 12-volt fast charger for your iPhones to plug into one of the 12-volt sockets.
Alternatively, you could get one of these gadgets and bypass iPhone boat-power, entirely.

https://www.stealthangelsurvival.com/products/4-solar-panel-power-bank-pro-20-000mah-with-4-built-in-cables-qi-wireless-charger-stealth-angel-survival?variant=39793159143518&currency=USD&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gclid=EAIaIQobChMIiO-f74eH_QIVi9-GCh2BoAnmEAkYAyABEgKjs_D_BwE

It has 4 solar panels to replenish the 20 A/Hr hour battery by laying it on the deck wherever.
Suspenders and belt solution: This gadget AND a 12-volt iPhone charger, so you and Becky each has a dedicated iPhone replenishment device.  I know that my wife refuses to cruise with me, if she can't call the grand-babies every SINGLE night.

4) 12 volt plug on the chartplotter to plug into the ammo box.
Keeps every thing simple and easy to use and even allows for some of those worst-case scenarios, by doing a little manual energy management (i.e. plugging and un-plugging 12-volt plugs).

Hope this provides some insight,
Charles Brennan

[Ed]

Great information Charles, thank you.  I'll buy you a Bushwacker on the FL 120, if we both end up going, at Juana's (of course I'll drink all the Planter's Punch you send me way too).  I like how robust the iphone charger solar bank is but there isn't an out of the way place to put it.  Becky pointed out that I've already got a solar charging thingie for the phones in the electronics box, duh.    I'll look into a flexible solar panel with a decent controller that will fit on the aft bimini, a set and forget rig while on the water, to recharge a 20ah or 50ah lithium battery.  I'm pretty responsible with stowing stuff in my electronics box without batteries in them and since running lights would only be used in an extreme emergency for us, I'll give them a shot first.  The ammo box looks like a great idea, didn't someone else just post something about that?  If I go with the 20AH lithium  I can bungie it to the mizzen mast tube inside the boat with no problems since it comes in a sealed waterproof case.  I'll search the archives for your recommendations for a flexible solar panel.You cannot view this attachment.

[Charles Brennan]

Ed Glad to hear you're considering solar replenishment!
(BTW, what took you so long?!?)
With the additional information from your last post we can now use the following parameters:
Nav lights are off the table.
iPhone charging thingies are already in the electronics box and off the table.
This vastly simplifies things.
So, I would recommend a 23 A/Hr Lithium battery like this:
https://gmienergy.com/DL12-23?sku=DL12-23&gclid=EAIaIQobChMI3LTarq6M_QIVahKtBh00nQTvEAQYAiABEgLoTvD_BwE

Fed by a controller like this one:
https://www.amazon.com/ExpertPower-Intelligent-Controller-Adjustable-Control/dp/B071RHBRTJ/ref=sr_1_2_sspa?crid=10W0E2A24GE5P&keywords=ExpertPower+30A+PWM+Solar+Charge+Controller&qid=1676080601&sprefix=expertpower+30a+pwm+solar+charge+controller%2Caps%2C90&sr=8-2-spons&psc=1&smid=ATW4RRWB3JMSM&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyMUxJT1JYQ001V0RKJmVuY3J5cHRlZElkPUEwNzcwMzgwQ1JPMUw4TVVGUlg5JmVuY3J5cHRlZEFkSWQ9QTAxNDU1ODkySDQ2VlNaSUI2WDhZJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

Powered by a solar array like this one:
https://www.sunpoweredyachts.com/product-page/sunpower-e-flex-50watt-panel?gclid=EAIaIQobChMIvIGEwaeM_QIVYhpMCh0fKQMnEAQYASABEgL57vD_BwE

On Urchin, I tied 4 nylon lines to the grommets in the 4 corners and the 4 ends to 4 bronze swivel snaps.

Looks like this on top of the Bimini top:
You cannot view this attachment.

On the underside of the Bimini top I attached stainless steel eye straps pop-riveted to the underside of the Bimini top  tubing that look like this:
https://www.shopsoundboatworks.com/products/wi151sistste

Looks like this underneath:
You cannot view this attachment.
(Looks like there's only three, but the 4th snap is very short and attached to back rear corner on the Bimini top frame.)

Put some kind of bulkhead connector from the solar panel cable running alongside the Bimini frame to make it easy to remove or set the solar panel.  On Urchin, I'm using a trolling motor plug and bulkhead connector, but you could use practically any easily obtainable connector and plug for your area.
The battery, controller and perhaps a few 12 volt DC accessory sockets could all be mounted in the ammo box and have a simple electrical system that could accommodate your chartplotter/finder virtually indefinitely.
https://www.harborfreight.com/tactical-ammoutility-box-64113.html

Hope this helps,
Charles Brennan
 

[Ed]

Great!  I have been looking/shopping for all of this and you saved me the trouble of ensuring compatibility.  I can put stuff like this together but have no practical knowledge for system design.  I just ordered it all, including a 3amp charger for the battery so it's topped off before leaving the house.  Thank you big-time for your help Charles.You cannot view this attachment.