Input on 12v battery / charging / wiring

[SpaceRnglr]

After completing a bunch of other project I have recently started to map out Elessar's battery and charging systems. It moved up the priority list as the "start" battery will not crank the nearly brand new Beta 50 diesel engine (I don't remember if it would last year...). That makes me nervous as I recently started using the fridge and will be doing several 2-3 day trips in the near future. I am hoping to use the boat over the next year or so to determine how much battery I need before I complete a more extensive upgrade (likely new batteries, all new wiring, and an inverter). My objective now is to do the smallest amount of work possible now to have a safe and reliable system that will allow me to get to know the boat better.

Elessar has 3x 180 AH AGM deep cycle batteries. Two are in parallel connected to "1" on the 1-2-Both switch and the 3rd battery is connected to "2". I don't know how old they are but believe they have been abused. It is possible even a new 180AH deep cycle battery wouldn't supply the 620 CCA required by the engine but regardless currently I have no start battery and have to use the house bank. Anyway, I have attached a wiring diagram of the current system.

My plan is shown on the second attachment and described below--comments appreciated:

1) Since the "start" battery is not a start battery and won't crank the engine anyway, i will simply leave the 1-2-Both switch in Both at all times. This will give me 540 AH (likely a lot less AH) house bank using all 3 batteries. I know the wiring is not optimized and will favor battery 2, leading to its early demise, I will fix that next year.
2) Buy a small emergency jump starter to start the engine in case the house bank voltage gets too low. I found a 800 amp pack locally that has good reivew--it should be OK to start the Beta. I know using the house bank for starting is a hotly debated topic--we can debate that next year when I do the more expensive upgrade. The only other option is to throw out a 180 AH AGM and replace it with a real start battery that may be made redundant next year.
3) Install a Balmar SG200--hopefully this will give me some idea of battery state of health and state of charge. Has anyone else hooked one up to a mystery battery system like this and can comment how accurate the SOH and SOC readings are. I'm going to buy one next year anyway, so no harm in giving it a try now.
4) Install fuses on the positive side using a new bus bar. Right now there are no fuses so this will be a safety enhancement. The terminal block I have my eyes on uses AMI fuses which are limited to 200A.
5) Install a negative bus bar to move the negative connections off the engine block. All that vibration can't be good for those wires...

Some questions:
1) The engine is currently connected to a stainless plate (maybe 5cm x 20cm) embedded in the hull as well as the engine block. Do I need to ground to two places? Wouldn't I be better using that plate as an isolated grounding point for the tanks / deck fills? All my thru hulls are TrueDesign composite so no help.
2) How to size the starter fuse? I am sure the cable is not designed for 620A continuous but also not sure if I need that big of a fuse anyway. Max AMI fuse is 200A so if that's not enough I will need to find a new bus bar / fuse holder.
3) The current batteries have automotive style lugs with clamp wire terminals. This makes it impossible to fit fuses on the batteries unless I replace all the cables (I want to put that off until next year). Should I attach a fuse on the bus bar that covers all three batteries? If so, how do I size it? Maybe it will need to be the same size (or larger) than the starting fuse from the previous question.

I know this was a long post, but all input is appreciated.

[billknny]

Originally Posted by SpaceRnglr

1) The engine is currently connected to a stainless plate (maybe 5cm x 20cm) embedded in the hull as well as the engine block. Do I need to ground to two places? Wouldn't I be better using that plate as an isolated grounding point for the tanks / deck fills? All my thru hulls are TrueDesign composite so no help.

You have a LOT of questions. Some of which show the need for some very basic learning. If you don't have a current edition of Nigel Calder's book Boatowner's Mechanical and Electrical Manual --get one! If you do have a copy, study it!

I am going to go to just one part of your, quoted above. And I have one thing to say, WTF????

Your engine block should be "grounded" only to the battery neutral. There is no reason to connect it to a "stainless plate (maybe 5cm x 20cm) embedded in the hull".

When you say "embedded in the hull", so you mean exposed to the water on the outside?

What else, if anything, is connected to this plate?

Other than a battery negative, what else is connected to your engine block? If your engine block is being used as a "negative bus bar" for the whole boat that is a terrible system--for lots of reasons.

[SpaceRnglr]

Originally Posted by billknny

You have a LOT of questions. Some of which show the need for some very basic learning. If you don't have a current edition of Nigel Calder's book Boatowner's Mechanical and Electrical Manual --get one! If you do have a copy, study it!



I am going to go to just one part of your, quoted above. And I have one thing to say, WTF????



Your engine block should be "grounded" only to the battery neutral. There is no reason to connect it to a "stainless plate (maybe 5cm x 20cm) embedded in the hull".



When you say "embedded in the hull", so you mean exposed to the water on the outside?



What else, if anything, is connected to this plate?



Other than a battery negative, what else is connected to your engine block? If your engine block is being used as a "negative bus bar" for the whole boat that is a terrible system--for lots of reasons.

Maybe my post was too long, but I just want to point out that I didn’t install the current system. I am trying to make it safe and usable now and do a complete system upgrade next year once I know the electrical requirements of the boat better.

I will add a negative bus bar now as I know the vibration will eventually fatigue the wires and lead to failure.

The stainless plate I referred to is exposed to seawater with only the engine and tanks connected to it. I think the two should be isolated with the engine grounding through the prop and the second ground for other items like the tanks. I am having trouble finding anywhere that says the engine needs / doesn’t need a second ground and hence my request for feedback before I undo the current setup. I got your vote to disconnect, thanks.

I am studying Cader’s book now. Happy to admit I may have missed the section that covers the specific questions I asked... the electrical section is a lot to take in!

[sailah]

Read this in its entirety.

https://marinehowto.com/automatic-charging-relays/

I just did my boat from scratch and followed the schematic he posts at the end of the "foundation wiring". At first I needed to let it sink in but once I read the thoughts, it made sense. Then I studied the schematic and it made even more sense.

I used the schematic as the basis for my entire wiring job. All wiring back to bus bars, fuses on everything, properly sized cable, ensuring negatives are terminated back to buss. I basically copied it verbatim, although I don't have solar but I do have windlass. And I used a different Blue Seas battery switch. But other than that, pretty much identical.

One thing he talks about is bringing the loads back as close to battery as possible for things like alternator, charger etc. I discovered my boat wasn't wired like that and things like alternator were using house panel feed for charging, lots of shared common grounds. I went overkill and grounded all loads to negative buss (except panel loads). My panel was grounded to engine previously, so I butt crimped it and wired it back to bus. Then I ran a separate 1/0 ground from engine block to bus.

Def study the schematic and read some of the articles he writes. His rationale of doing things properly clicked with me so I decided to do it right. And it worked first time.

[smac999]

If a 180ah battery. (4d?). Can’t start an engine. I certainly would not combine it with other batteries. If it’s bad. It will just kill the others. Time to throw it out. A group 31 start battery will cost you $100. And give you a battery that works.

A jump pack is not going to jump a dead 600ah battery bank. It’s designed to jump a dead single battery.

[Tillsbury]

Get a start battery. A real one, not a deep cycle house battery. Keep it absolutely separate from the house bank. Keep it charged. It won’t be redundant next year as you’ll always need one. Do what you like temporarily with the house bank if you intend to replace it next year.

[Zil]

One of your questions. Put the catastrophic fuse as close to the battery positive as you can. That would be at the house bank and another at the engine battery if the cable runs further than just the starter.
On the house bank, take the positive from battery one and the negative from battery two. ie; opposite ends.

[moseriw]

[moseriw]

[Stu Jackson]

OEM 1-2-B Switch Wiring History Alternator/Batteries & "The Basic" 1-2-B Switch BEST Wiring Diagrams

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: Basic Battery Wiring Diagrams

This is another very good basic primer for boat system wiring: The 1-2-B Switch by Maine Sail (brings together a lot of what this subject is all about)
http://forums.catalina.sailboatowner...d.php?t=137615

This is a newer primer for boat system wiring design with a thorough digram: Building a Good Foundation (October 2016)
http://forums.sailboatowners.com/ind.../#post-1332240

The Short Version of the 1-2-B Switch Stuff: Electrical Systems 101 This is a link to the Electrical Systems 101 Topic, reply #2

What are ACRs, Combiners & Echo Chargers? (by Maine Sail) [scroll to the top]
http://forums.catalina.sailboatowner...d.php?p=742417 and Battery isolator / voltage regulator / batteries

Making Sense of Automatic Charging Relays (2019)
https://marinehowto.com/automatic-charging-relays/




And an energy budget is easy to make. Don't wait a year, there's nothing to figure out.


The All-Important Energy Budget:
Energy Budget


These links come from: Electrical Systems 101

[stormalong]

One tip on starting the Beta 50. ALWAYS use the preheat. When doing the first start of the year preheat for 20 seconds rather than the usual 10.

This will make starting much easier and save a lot of wear and tear on the starter motor.

[Mike Banks]

NEVER try to start a diesel using the house bank. They are normally different kinds of batteries entirely. Keep the starting batteries entirely separate with their own separate charging systems so that you will ALWAYS be able to start your diesel.

I nearly lost a vessel once on a lee shore, when I was not aware that the starting system was being used as the house system. They had used tractor batteries, not the usual deep-cycle house system and an entirely different separate starting system..

I was able to start the engine, but only because I knew how to jury rig a starting system. This happened on a lee shore in a gale. For most people it would have been a fatal mistake, and it was a very close thing, because the engine started on the last gasp of a dying system.

I have learned a lot in the years since then.

NEVER BET YOUR LIFE, HOWEVER INADVERTENTLY, ON THE ASSURANCES OF OTHERS EVEN IF THEY HAPPEN TO BE REGISTERED MARINE SURVEYORS.

Check EVERYTHING yourself.

[SpaceRnglr]

Thanks for the inputs everyone. MaineSail's various posts and MarineHowTo.com are great--I had seen them before but not all the links posted in response. I need a week or so to digest the various links, but I can already tell they are spot on with what I need.

As for the immediate future I will:
1) install a new start battery of 94 ah and 620 cca or larger (as advised by Beta)
2) remove wire that grounds the engine to the hull mounted grounding plate--it is not needed and could be harmful.
3) use the 1 2 Both switch in its traditional manner. Normally set to "1" for house bank use, when starting move to "2" and let run a few minutes after starting, then move to back to "1" (being careful NOT to pass through "off" while the engine is on).
4) install fuses ASAP
5) install an AVR ASAP to help prevent human error with the 1 2 Both switch. Once installed I can start from the house bank (assuming it provides enough amps)
6) install Balmar SG200 battery monitor so I theoretically have some idea of the SOH / SOC of the house bank.

Can anyone advise if my plan for a 200a starter fuse is correct? Bussman fuses seem to show they can take 5x their rated load for up to 0.1 seconds and ~2.5x for up to a full second. I think the largest 200A AML fuse should be OK for my 620 cca starter motor. The engine is new and in the tropics so it starts very fast every time. The wiring all seems to be 0 gauge or larger (~10mm diameter conductor) so 200a is smaller than the recommended max 325a fuse size.

Latest drawing for the temp system attached, with changes from current system in red. Mostly so I know what parts to order but comments appreciated.

Next year I will decide if i can live without a genset, decide AC/DC water maker, decide how big of a AC battery charger to buy, replace the house bank, replace or properly terminate all wires, wire alternator to house bank, connect start battery directly to starter with parallel switch for house bank (emergency use), install inverter & AC wiring, install more solar 600w+... The list goes on. Last year I started a similar "simple" replacement of the diesel fuel tank that resulted in me replacing all the tanks and upgrading more or less everything below the cabin sole. I can easily see this "simple temporary" fix going down the same path, but at least everything I am fixing now is useful no matter what direction I take on everything else.