Putting all the charging into the house bank

[tradrockrat]

Hi all - so here's the question:

Explaining it to me like I'm a child (my wife assures me this is the best way)

How do I get my alternator to charge the house bank ONLY?

Right now, I'm upgrading the electrical system and have decided that I want all charging sources to charge the house bank and I will use an Echo charger to keep the starting battery topped off.

It's really easy to do that with inverter / charger and solar, but the alternator is pre-existing, and charges the starting battery because - I think - it's wired directly into the starter.

So how do I switch the alternator to charge the house bank only?

It's a Perkins 4108, standard (not heavy duty) alternator, and probably was wired up in 1978.

Thanks!

[Rearsteer]

Alt output to your house bank. This will be the large wire that comes off the threaded post on your alt. It may have a rubber boot over it, maybe red in color. If your house bank is paralleled, as in positive to positive and neg to neg this should be a 12 volt system with 12 volt battery's. I use 6 volt battery's (bats) and run them in series, pos to neg on two that will make one 12 volt bat. You can do the same on two more 6 volt bats. If not wired up correctly, you can have some big problems as in blowing your alt diodes out, messing up your bats, even stating a fire. Get a copy of the "12 volt bible" and learn up on this stuff. There are also lots of info online on this subject. You will still need to charge your start bat and there are different ways to do this. Wiring can be tricky even for experience people. Read up and talk to your dock mates. Look for that guy or gal that always seems to be always messing around with there boat. That is if there boat works good LOL. Good luck and keep learning your boats systems. The more you know about your boat, the better off you will be in taking care of her. You will also operate her better when you know what she wants and needs.

[misssherry]

Some engines connect the alternator output to the starter and the starter is connected to the start battery. This avoids having two cables from the engine. You need to disconnect the alternator from the starter and replace it with a cable from the alternator to the house bank. Leave the starter/starter battery cable as is.

[GILow]

Both of the previous posts neglected to mention that you also need a negative feed from the engine block to the house bank.

This alone tells you this is a more complicated process than it first seems.

Then add that you need to consider how your galvanic protection will be affected by all this and you can see it might be worth getting someone trustworthy in to look over the system.

Many pitfalls. I don’t often advocate a professional or an expert, but I think it would be worth it in this case. There are just too many expensive modes of failure.

[Marathon1150]

This is a somewhat complicated question because much depends on how your boat is currently wired and the kind of alternator/regulator that you are using. The diagram below will provide some guidance but as the previous post suggests it would be worth having a couple of dock experts, or better still a professional marine electrician, have a peek at what you have and how to proceed. Grounding systems and other elements of boat electrical systems vary between boats.

We have a Perkins 4-108 but installed an externally regulated high output Leece-Neville 100 amp alternator and a Balmar ARS5 smart regulator. The power produced goes to the house bank (2 x Lifeline 4D AGMs) that in turn are connected to a Xantrex echo charger which charges the start battery.

We also have 4 solar panels and a Blue Sky charge controller and a wind generator that are connected through fuses directly to the house bank. We do not have an inverter wired into the system but we do have a multi-voltage Xantrex charger.

This diagram is not/not our boat but provides a general indication of the kind of system that you seem to want to set up. As the previous post suggests there are a few things that can go wrong and cause serious, expensive and potentially dangerous problems.



Here is a pic of the battery compartment. The blue top battery is an Optima spiral AGM used as a starter. The Xantrex echo charger is showing a green light. Its the easiest part of the system to wire and is generic. For everything else I sought professional advice and then locked everything into place with the two plastic wrapped steel bars in the photo.




I have also found Don Casey's book on boat electrical systems helpful - he provides excellent examples and diagrams.

[tradrockrat]

Thanks to all of you so far for these answers. It's really great, I appreciate it.

I like to think I'm pretty confident with electronics, but when things are pre-existing and I'm somewhere between the 3rd and God knows how many owner of this boat, electrical can be a mess. I seriously considered gutting the boat and redoing it from the ground up, but I just don't have the time to do that right now. What got me on this project was the fact that the alternator is definitely going somewhere like the starter this is new to me, and I just wanted to make sure that I could take the alternators output directly to the battery Bank, but the advice here has got me rethinking , and I may have somebody come in to take a good look at it before I do anything.

[smac999]

Originally Posted by GILow

Both of the previous posts neglected to mention that you also need a negative feed from the engine block to the house bank.

This alone tells you this is a more complicated process than it first seems.

Then add that you need to consider how your galvanic protection will be affected by all this and you can see it might be worth getting someone trustworthy in to look over the system.

Many pitfalls. I don’t often advocate a professional or an expert, but I think it would be worth it in this case. There are just too many expensive modes of failure.

The alt, engine, start battery, and house battery would already be grounded. Otherwise the Hiuse battery would not currently be charging. Which I assume it is. (Probably via a 1-2-all switch)

Moving the alt output wire has nothing to do with galvanic isolation.

[belizesailor]

Like a modern child: Google "Blue Sea ACR". Basically, it automatically does exactly what you want to do (as do other brands of "ACR").

[sailcrazy]

FWIW, we made that change on our boat several years ago. We ran the fused (+) wire from the alternator to the (+)house bank bus bar (we use 6 Trojan T-105s, arranged as 3 12-v "batteries, then tied together via a (+) and (-) bus bar). Our solar controller and the windgen controller both feed that same bus bar via fused wires. When we run the genset, we also power the batt charger, which has 3 legs-1 for each "battery". We recharge our isolated conventional start battery, used for both the main eng and the genset, via a Balmar Duo-Charge. Sys works good!

[waterman46]

It's not rocket science, but if you want to DIY and don't have much background then do consult a good book on marine DC systems.

General approach:

The negative for the engine and the house battery should already be connected together at a negative bus, or in a very simple system, the house negative would be running directly to engine block. Your starting battery negative should already connect directly to engine block.

Switch off or remove + cables at house battery and starter battery before making any changes.

If you like the echo charger then just remove the alternator's connection to the starter and move it to the same point that all your other charging sources are connected to. Your echo charger should be connected there also.

You can also have a protection diode connected at the alternator from its 12V output post to its ground post. In case there is a wiring fault it may save the alternator diodes.

None of this will change any electrolysis situation you may or may not have.

[Stu Jackson]

OEM 1-2-B Switch Wiring History http://c34.org/bbs/index.php/topic,4....html#msg30101

1-2-B Considerations (New 2020 - Rodd finally got around to diagramming what I had done in the above link in 2009 )
https://marinehowto.com/1-2-both-bat...onsiderations/

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: http://c34.org/bbs/index.php/topic,6604.0.html

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: http://c34.org/bbs/index.php/topic,5....html#msg38552 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 http://c34.org/bbs/index.php/topic,9....html#msg70131

[Pete7]

Before going ahead, perhaps a question of why you want the alternator to charge just the house bank? Assuming the perkins starts straight away, it will actually use very few wiggly amps to start, so could be included, it won't hurt and be filled very quickly, then all the current will go to the house bank.

Also how are things like lights and the VHF wired on the boat? all from the engine battery or the house bank? You don't want to be sailing along and suddenly find a flat engine start battery because the auto pilot has drained it down.

You will need some provision for connecting the house to the engine start battery in an emergency.

We had the rotary 1/2/both/off switch fail so needed to replace the switches. this was a need solution with VSR, if a little pricey today:

https://www.bepmarine.com/en/716-sq-140a-dvsr

The only thing that doesn't go to the engine start battery is the solar, that's direct to the house battery bus bars. Yes bus bars are a neat way of wiring whilst you are in there.

[caffel]

Amen to Pete7.
For the child's point of view: switching alternator output from one load to another requires that the alternator's field be turned off during the transition. (otherwise the voltage can spike up and ruin the alternator's internal diodes) Special switches are made for this (incl ACR). However the actual install can be tricky if the alternator has an internal regulator, which is why you're getting such complex answers.
One childishly simple alternative hasn't been mentioned and you may wish to compare it for cost: add a second alternator! (for the house bank)
Typical engine alternators are not rated for the large loads required to bring up the house bank in less than 6-8 hours. (possibly the root cause of your question)
As a bonus this solution provides a worry free backup supply for starting the engine and no switches to look after.

[tradrockrat]

Thanks again for all the great answers and help.

to answer some of the queries:

I want to switch the alternator because I'm going to have solar, wind, alternator, and inverter/charger as the 4 ways to charge my batteries. Having them all charge the house bank with an echo charger to keep the starter charged just appeals to me.

I'm being overly cautions as I've never dealt with an electrical system like the one on my Tayana before - it's multiple previous owners has led to all the problems you can imagine - spliced lines, dead wires, half assed upgrades, and wiring anywhere from 1 year old to 42 years old.

For example - the shore power appears to go directly to the panel and the battery charger runs off an outlet - none of which are GFCI. Several bus bars are RUSTY!!!

So while it seems almost obvious to simply take the alternator wire off the starter and run it to the new positive battery bank busbar.... obvious doesn't mean safe necessarily

I'm updating a lot of the electronics - right now I'm trying to figure out how to run the shore power to a 30 amp breaker as per ABYC, then get it to inverter/charger while separating out some AC stuff that doesn't need to be run on the inverter AND clean up 42 years of old wiring. This might take a while, so my house batteries might need the alternator to charge them until I get it all worked out. - I don't live on my boat yet, and It's 3 hours away from me in Kemah (I'm actually on it right now - took a three day "work online and fix the boat at the same time" adventure...lol).

I know I could just turn my switch to all and charge it that way, but I have the echo charger and it was just an hours work to switch the alternator cable.

So, thanks to you all, I'm done with the alternator and moving onto the AC / Inverter / Charger / Panel.

Thanks again!

[Jim Cate]

FWIW, our setup is pretty much what you have described: alternator and all other charging sources go directly to the house bank, and an Echo charger tops up the start battery. Has worked well for over a decade now, full time anchor-out cruising.

I think your plan is very reasonable (of course!).

Jim