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  1. #1

    Question correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger ?

    have a 34 ft silverton w/ 2 engines- installed 2 batteries for each engine ( starting & backup), 1 additional for house only total of 5 batteries
    1 battery switch for each engine, have 1- 3 bank on board charger
    installed a separate on/off switch for house battery connected to # 2 battery on port engine switch ( to allow port engine to charge when running if house bat goes low.
    battery charger positive leads 1,2,3 1 is to port bat, 2 to strbrd bat, 3 to house bat

    questions are ......
    1. should ALL negative posts need to be connected together ?
    2. should positive battery posts be connected together ( engine port 1 & 2 connected together- strdbrd 1 & 2 connected together)?
    3. if charger is connected to port bat 1 won't it charge bat 2 also if both battery positive posts connected together ?
    4. also doesn't this cause battery switch position 1 & 2 to be connected together ?
    5. should each battery positive ( talking 1 engine) be left separated & only charger connected to both ? but again if charger is connected to both
    positves then aren't I going back to # 4

    really appreciate help, this has been a challenge I think I'm close though thanks

  2. #2
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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    I would take the available space and dedicate this to more batteries that would increase the size and capacity of your HLBB (house load battery bank).
    IMO, you need only one cranking bank per engine. In fact, you can get by with only one cranking bank, and a very large HLBB if you set things up correctly.

    Blue Sea offers an array of ACR units that will bring your Port engine alternator into the charge loop for your Stbd HLBB.
    The 7622 Ml Series Heavy Duty Charging Relay w/ Manual Control, is 500 amp capable.
    I'm using this one on my own twin engine boat.



    I won't try to understand your current system without an existing schematic.
    Best to begin with a schematic... or a proposed new schematic and new plan.

    As for your questions:
    1. IMO, best to give each battery bank it's own independent Negative to the System Negative Common.... I.E., engine block. This creates redundancy.
    If you plan to install a battery monitoring system that incorporates a shunt resistor (such as the Xantrex LINK), the bank being monitored will need to make an independent Negative connection regardless.

    2. Need to first understand how you plan to isolate these banks, and whether you are using MBS's or MBSS's. (MBS = main battery switch On/Off....... MBSS = main battery selector switch 1/ALL/2/OFF)

    3. Not when the correct MBSS's are used and when turned OFF when the boat is unattended.

    4. Try to avoid selecting ALL/BOTH when charging. This combines battery banks.
    Let your charger sense each bank independently, and predicate the charge rate accordingly.

    5. Again, a schematic would be very helpful.
    There is no need for charger leads to make a direct battery connections. You'll have corrosion issues that can be avoided by not doing this. The rear of your MBSS is a perfect location for charge leads.

    This can be shown schematically if interested.


    Here are a few icons that can be arranged so that you can make up a schematic.
    Draft one up, and post it.
    We can then look at it, and make suggestions.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	MBSS Batt and Engine icons for making schematic.jpg 
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ID:	5412  
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  3. #3
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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Did we loose Meleconn here????
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  4. #4

    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    hi, I am here. will get a schematic to you all to help you help me. thanks ps where can i find those icons ?

  5. #5
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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Quote Originally Posted by meleconn View Post
    hi, I am here. will get a schematic to you all to help you help me. thanks ps where can i find those icons ?
    Well, glad that you're still on board here. And yes, we'll certainly help you work through this.

    As for the icons, just save the image to a folder, and then manipulate the images in a program that allows you to do some form of graphics work.
    I'm very low Tech, so I use Microsoft's Paint Program. It's rather crude and elementary, but it will do the job.

    There is a feature that allows you to outline, cut/copy/paste any portion of the image that you encompass within the outline.
    You can then move them around, modify them, etc.

    The colored lines representing circuits are the easy part.

    Or... move the icons around, print the page out, and manually draw your lines in, then scan it and re-save.
    Or.... tell me want you want to start out with, and I'll put one together for you.

    Try this one.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	MBSS Batt and Engine icons for Meleconn.jpg 
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ID:	5414  
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  6. #6

    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    back again... attached is a schematic I made of the existing 12 V wiring for batteries. # 2 batteries go down after 1 week of no use ( all systems except bilge pumps off), shore power connected to run charger.
    House bat is charged along w/ # 1 bats (all on charger).
    All bats are brand new, same type same, time. Should I put another charger just for the # 2 bats ? must switch to ALL, to start either engine, if no use for 2 + weeks. All new cables (# 2), crimped ends, switches, batteries.

    hope the attachment comes thru, not sure how to do it
    Attached Files Attached Files

  7. #7
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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    If your #2 batteries are dead after one week of sitting (with them being isolated) then : 1) they are deffective and should be returned for replacements or 2) your wiring doesn't match your schematic and you have another connection draining them down.

    Along the lines Rick is thinking, I'd eliminated the #2 batteries as dedicated starting units and use them in the house bank. you can use switches or high current relays to connect them to either engine for starting purposes, if desired. Also, the ACRs allow charging more than one battery off a given alternator without the need for a switch (which is usually installed incorrectly over 90% of the time).

    The other thing to worry about is how long the wires are which drives their size requirement...nothing worse than marginally sized wiring, especially on a boat.

  8. #8
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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Hey, good to see you back here. I like these electrical challenges.

    IMO, you are waaaaaay over-kill with each engine having two cranking banks. But again, this is IMOO... you're the one that we need to please.

    If your icons are an indication of bank size, your HLBB (house load batt bank) is rather small.
    Also, the way in which you bring the HLBB into the #2 terminal of your Port engine MBSS, creates a combined scenario.
    We should avoid combining unlike batteries (unlike = size, group, age, number of cycles, etc).


    As I see this, your O/B generator start batt source could share a cranking batt from the Port engine, rather than to use the HLBB. If your HLBB should become depleted, this bank may not fire up the generator.... whereas one of your main SLBB's (start load batt bank) will fire up the generator.

    If this were my set up, I'd do something like shown in this modified schematic of yours (see attached image).
    Your original image is first.... the modified image is second.

    I've removed "ALL" from the schematic, sense ALL is a result of the MBSS selection, not a terminal point.
    I've also removed all Negative battery connections. All battery banks should make an independent System Negative Common connection (I.E., the engine blocks).
    If you plan to install a battery monitoring system, such as the Xantrex LINK system, the HLBB must have it's own System Negative Common connection for the shunt resistor.
    The two engines will also be joined together via one large System Negative Common cable (not shown in my drawing).
    I have deliberately not shown any of these Negative cables nor their connections....... it would just make the drawing too complex to read easily.

    I"ve also taken your O/B Charger leads from any direct battery connections.
    Instead, I've routed these to the rear of the MBSS terminals where these will be more permanently installed.
    Schematically this is identical, but eliminates the typical "Rat's Nest" that we see at battery banks, also eliminates small terminal corrosion and the likihood of mis-connection and/or forgetting to re-connect during battery R&R.
    The Rat's Nest alone is a real pet peeve of mine! No need for anything other than battery cables ONLY at our battery banks.... IMO.
    Your call on that, but I'd certainly recommend doing this.


    BTW, with today's components available, the ACR (auto charge relay) is a better choice over that of a battery isolator.
    Isolators, if not already, are going the way of the buggy whip!

    My modification to your schematic is a suggestion only..... it's your boat, and like said, you're the person who needs to understand your system and be happy with it.

    With my own twin engine set up, I do not have a dedicated Stbd side cranking bank. I crank on my Stbd engine on the HLBB.
    I also have the Blue Sea 7622 ACR that is 500 amp cable, which momentarily brings in the Port side cranking bank.
    By eliminating a Stbd side SLBB, it saves space that is dedicated to a larger HLBB (6 volt golf cart style batteries.... more Amp Hours).
    My O/B Generator also shares the Port side cranking bank, of which is always held in reserve.
    Fingers crossed that I do not ever need a second cranking bank!
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Melenconn MBSS Drawing1.jpg 
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Name:	Melenconn MBSS Drawing 2.jpg 
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    Last edited by RicardoMarine; 09-11-2012 at 11:57 AM.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  9. #9
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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    I forgot to address your battery draining.
    Mark may be correct. First, do an open load test. See if there is any current flow between the charger leads and battery bank with the charger switched OFF.
    There should be no current draw.
    If there is current draw, the charger itself may be the culprit.

    Edit:
    Back to your battery management ..... banks, MBS, MBSS, loads, charging, etc, etc.
    We all want our systems to be fully functional and pretty much goof proof and we want good performance and a tad bit of redundancy.
    At the same time, we don't want them to be overly complicated and difficult to trouble-shoot.
    I've taken both the goof-proof and functional approach, and the KIS approach.......... KIS = Keep it simple.

    See what you think, make changes to the schematic, and post again if need be.

    There are always several ways to skin the cat.... however, the furrier dealer will tell you that one cat skinner's pelt is better than the other's.



    .
    Last edited by RicardoMarine; 09-11-2012 at 11:53 AM.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  10. #10
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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Two batteries per engine is completely unnecessary. In my opinion, the perfect setup is each engine on its own isolated battery, genny on its own isolated battery, and an isolated house bank. I would treat this as a 4 bank application.

    Though I may consider charging the generator battery through the AC charger at shore to maintain a full charge at the dock, I’m not a big proponent of having the engines charging the generator battery. I feel while away from the dock, the generator should do a fine job of charging its own battery. If you use the generator often, as you should to help it last longer, there should be no reason for a dead battery unless it is failing in which case it should be replaced anyway.

    Though I’m big on ACRs, I have changed my wiring strategies based on monitoring the systems I’ve set up in the past. The biggest caution I would throw out there is that I do not install an ACR between an engine battery and a large house bank for example. I do not like paralleling an engine battery whose charge is typically not very depleted with that of a house bank that will most likely call for a high current charge rate be it from an alternator or AC charger. Unless the ACR is dual sensing and shuts off based on bank static voltage and not just based on the presence of a charge, I would not link a large bank with a single starting battery. A good example of a dual engine application for example IMO would be for one engine to charge the house bank, and the other engine to charge the two engine batteries (one per engine) using an ACR to keep them isolated otherwise. In this way, all banks are isolated, and the ACR is paralleling two battery banks that will typically call for the same rate of charge. If the genny battery is to be charged by an engine, again, I would install a second ACR to parallel the genny bank to the engine bank, not a large house bank. If you want redundancy or the ability to start an engine on a low battery, install emergency start solenoids. With a momentary push button at the helm, they are carefree no brainers when trying to get back home.

    PS; Go to the Blue Seas web site and read the specs and installation notes on the ACRs. Installation is not as simple as it may seem. The wiring part is easy but considerations must be taken into account with respect to AC and DC charging. For example; if you have 3 banks to be charged, and you hook up a 3 bank charger, typically you simply hook up each charging leg to each of the three banks. If however, for DC charging purposes you throw an ACR into the mix to charge two banks with one alternator, you are combining 2 banks when a charge condition exists. What needs to be considered is that this condition will also exist when charging with the AC charger which complicates things. Two charger outputs will be charging esentially the same bank as the ACR will again see a charge and combine. Though this may be ok with some chargers, in others, it will create a conflict and potentially shut down the charge completely. ACRs have also been reacting wierd under some "smart" charger cycles and have been undergoing some circuit changes as a result. The trick here is to know your equipment or the application you are applying new equipment to and wire accordingly.
    Last edited by WoodieMan; 09-11-2012 at 08:33 PM.

  11. #11
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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Woodie, I did consider what you are saying.
    The Stbd engine ACR will indeed parallel between the two cranking batteries...... and yes, this would split the O/B Charger output between the two batteries.
    These two batteries should reach full SOC quickly, and the charger should also cut back quickly.

    The other two ACR's are out of the loop when he will be using his O/B Charger.
    Reason: the two ACR's connect between the "common" terminals (Stbd and Port MBSS's) and will be functional only when these MBSS's are making a battery selection (i.e., when he is under engine power).

    Other than when he's on board and on S/P, and using his 12 volt power....., his MBSS's will be in the OFF position when leaving the boat unattended, and during O/B Charger use.

    I'll take another look, but I believe this will work.

    .
    Last edited by RicardoMarine; 09-11-2012 at 09:08 PM.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    It may be easy for you and I to follow Rick, but IMO may require too much thinking or second thought from an average boater with limited understanding of how the circuit actually works. I think you know how I feel about MBSS. "ON, OFF" battery switches to service the circuits or shut them off while away are best IMO. I don't like leaving room for bank selection; just something I've learned to prefer over the years based on failures I've attended to. Keep it simple right? I still see a way in your diagram for the system to parallel the large house with a single battery in the presense of a charge which IMO will shorten the starting battery's life unless the ACR disconnects when the starting battery reaches full charge, however, they typically stay connected as long as a charge condition exists which WILL be the case in an application where a typical house bank is in the circuit.
    Last edited by WoodieMan; 09-11-2012 at 09:49 PM.

  13. #13
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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Quote Originally Posted by WoodieMan View Post
    I still see a way in your diagram for the system to parallel the large house with a single battery in the presense of a charge which IMO will shorten the starting battery's life unless the ACR disconnects when the starting battery reaches full charge, however, they typically stay connected as long as a charge condition exists which WILL be the case in an application where a typical house bank is in the circuit.
    Woodie, I'll take another look, you may be correct.
    Perhaps the two ACR's need to be moved over to the isolated terminal of that MBS.... not the Batt side.
    BTW, this particular one is an MBS (main batt swtich), not an MBSS!

    I'll take a closer look in the AM, and I may move these two over to the other side.
    That may make more sense.
    With the two engine alternators producing a charge, his house bank MBS will be switched ON anyway.

    If you have time, make some changes to it....... I'm sure that he's open to seeing a few more proposed schematics.



    .
    Last edited by RicardoMarine; 09-11-2012 at 10:20 PM.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Give this modified schematic a try. I rearranged the two ACR's interface with the HLBB MBS.

    The MBS and MBSS management is still relatively simple.
    When operating the boat, make your MBSS battery bank selection, and turn the HLBB MBS to "ON".
    With the Stbd engine, you'll have two cranking battery banks to select from.
    With the Port engine, you'll have only #1 to select (unless you were to find yourself with a low battery).

    The ACR being used on the Stdb side will indeed split the O/B Charger output to each bank.
    According to the Blue Sea ACR literature, this should work OK.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Melenconn MBSS Drawing 3.jpg 
Views:	7252 
Size:	46.3 KB 
ID:	5441  
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  15. #15
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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Quote Originally Posted by RicardoMarine View Post
    Give this modified schematic a try. I rearranged the two ACR's interface with the HLBB MBS.

    The MBS and MBSS management is still relatively simple.
    When operating the boat, make your MBSS battery bank selection, and turn the HLBB MBS to "ON".
    With the Stbd engine, you'll have two cranking battery banks to select from.
    With the Port engine, you'll have only #1 to select (unless you were to find yourself with a low battery).

    The ACR being used on the Stdb side will indeed split the O/B Charger output to each bank.
    According to the Blue Sea ACR literature, this should work OK.
    Nice setup. You guys must spend lots of time "off the grid". How about adding a circuit breaker protecting the wire going to the "house panel" buss. Many boats came from the factory without a house battery. They just split house panel with half of the breakers fed from the right engine & half on the left engine accessory feeds. The engine main fuse or breaker should have protected these feeds. Now that we are using a dedicated house battery we need to protect this wire.
    Just a thought,
    Lou

  16. #16
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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Lou, at this time we're simply narrowing down a battery management design.
    I have omitted items such as all System Negative Common cables, wire gauges, wire colors, fuses, breakers, etc. I'm certain that Melenconn understands that these will need to be inserted as required.

    Typically we'll see house loads being powered from the Stbd engine side (up to 30 foot hulls or so), or they will be independent such as what he shows in his original drawing.

    BTW, I'm not aware of any hull that seperates house loads and splits them up between Port/Stbd battery banks. HLBB's fair much better when they are one large bank, apposed to two smaller banks.

    .
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Quote Originally Posted by RicardoMarine View Post
    Lou, at this time we're simply narrowing down a battery management design.
    I have omitted items such as all System Negative Common cables, wire gauges, wire colors, fuses, breakers, etc. I'm certain that Melenconn understands that these will need to be inserted as required.

    Typically we'll see house loads being powered from the Stbd engine side (up to 30 foot hulls or so), or they will be independent such as what he shows in his original drawing.

    BTW, I'm not aware of any hull that seperates house loads and splits them up between Port/Stbd battery banks. HLBB's fair much better when they are one large bank, apposed to two smaller banks.

    .
    Rick, if that's the "simple" schematic I can't wait to see the detailed version. BTW, my 84 31' Chriscraft's panel came from the factory split between both banks.

  18. #18
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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Lou, I hear ya!
    It will be a lot more complicated once he gets all of the details incorporated into the schematic, if he chooses to do that. There's really no need to incorporate every gauge, color, fuse value, etc. detail, if he understands how the work is to be done.
    He did make a very nice looking schematic, so I have a hunch that his work will follow suit.

    Ah Chriscraft!
    If any company was to use unorthodox procedures, it would have been Chriscraft.
    Having your house loads split up is probably not a deal breaker, but it is certainly easier to manage one large HLBB, as apposed to two.
    The other issue is that a large single dedicated HLBB can be specifically Deep Cycle batteries, whereas split loads may be sharing loads with Cranking Batteries.
    Also there is much less risk of drawing one large bank down below 50% (or so).

    Ya got ta love the Chriscraft flywheel fwd/front crankshaft drive scenarios!

    .
    Last edited by RicardoMarine; 09-12-2012 at 10:11 PM.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Quote Originally Posted by rfdlou View Post
    ... panel came from the factory split between both banks.

    Have seen this several times on more than one brand

  20. #20
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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Interesting observation. I guess that you could say that this is one of those; If it ain't broken, don't try to fix it!

    BTW, do we need to coax melenconn back to his thread again? Just kidding!


    Woodie, what did you think of the change that I made to the two ACR connections to his house bank MBS?

    And by all means, if anyone else wants to modify the schematic..... please do so!


    .
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Again, the set up may be acceptable to some but I preffer not to do it that way. I still see a large discharged house bank paralleled to a start battery while charging, and I have a problem with that. I get the redundancy of having the two alternators charging the same banks, I just prefer to have that done ONLY if there is remote voltage sensing and the ACR opens once the start battery is charged not just when it no longer detects a charge – big difference. One also has to consider that in a typical application you’re dealing with charge wire size rated for perhaps a 65 amp alternator output, connect both alternators into the same circuit and I would not feel comfortable unless the wiring is rated for both outputs combined ie 130 amps – that’s a hefty charge wire, fusing, etc. Again, I also think the system requires too much battery switch maintenance to remember, and wouldn’t be an option to forget, it would be a must if the wrong charger were used. Essentially, we always advise not to mix battery types in the same bank; not good for the batteries while charging or discharging, but that’s exactly what this and similar circuits do unless the above option exists. In such a case, one must also consider that the ACR being used should isolate for the duration of the cranking to protect sensitive electronics hooked up to the house bank from surges. Not all ARCs have this feature. Just not as simple as we used to think it was when isolators were so prevalent. The wiring for most even as suggested by manufacturers was questionable IMO. ACRs, though great in some applications, do have limitations and considerations that need to be addressed when designing a system. I haven’t installed one yet but my next system design recommendation will likely involve “smart” isolators instead. Still looking into it, and considering where things could go wrong in the real world but I am liking what I see so far.
    Last edited by WoodieMan; 09-13-2012 at 06:21 PM.

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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Woodie, how about taking this schematic and making the proposed changes to it, so that we can better understand your take on this?

    Remember, when he's on the hook, engines OFF, his cranking banks and his HLBB voltage will be below the voltage at which the ACR requires in order to join banks.
    Blue Sea suggests that this is 13.5 volts.
    The 7622 ACR has a lock out feature via manual or via their remote switch.
    Switches can be located near our LINK system display, the helm, or anywhere we wish to mount them.

    Food for thought!

    Last edited by RicardoMarine; 09-13-2012 at 08:46 PM.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Let me simplify what I've found is essential for good battery life in a boat: Each battery needs to have its own dedicated charger, and one designed to maintain the battery correctly (ie: NOT a trickle charger that doesn't stuff off). With the above set up your batteries (and wallet) will be happy. I once tried to get awy with one charger caring for 2 batteries, and it destroyed one of them.

    Now, while under way, it doesn't seem to matter if one alternator charges two batteries for you're using current at the same time. Nor does the alternators seem to hurt anything for they are charging for a relatively short period (compared to sitting in the slip). I have a battery paralleling switch that allows my two alternators to work together, charging up to 5 batterie at once. This, too, has not been a problem and, on a cruise, I need them recharged after a night on the hook with the inverter running.

    Jeff

  24. #24
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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Jeff, today's multi-bank smart chargers are fully capable of charging and maintaining multiple banks..... yes/no?
    Would you say that the charger that destroyed one of your batteries was most likely defective?

    Our main concern is typically the HLBB (house load battery bank). The cranking banks usually recover rather quickly upon warm up.
    If you do the math, cranking amperage (in terms of Amp Hours) is relatively low..... unless our engines require excessive cranking.

    From your post, you may like having an ACR installed in leiu of the paralleling that you're doing. The Blue Sea 125 amp ACR's are not all that expensive. The Blue Sea 7622 Ml Series Heavy Duty 500 amp Charging Relay is a bit expensive.


    Side note:
    Among my most valued instruments is my Xantrex LINK 1000 battery monitoring unit, since we want to monitor our HLBB in Amp Hours, not necessarily voltage. The LINK system does this. The Nasa BM1 and BM2 do a nice job as well.
    Both use a negative return path shunt resistor to gather data that the head unit dispays in terms of AH used, and AH charged.
    Once zero'd in with the total bank AH, the system gives data similar to that of a fuel gauge.

    But I'm side tracking us..... so I'd best quit.


    Melenconn..... are ya still with us?

    More food for thought!
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    Last edited by RicardoMarine; 09-15-2012 at 09:11 AM.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Since meleconn hadn't been back for a few days, I fired a PM to him.
    Without his permission (and I hope that he doesn't mind)..... here's his reply.

    I replaced the 2 new batteries, for port 2 & strbrd 2, w/ 2 other new bats and it seems that solves the problem so far. Not sure if you got a chance to read my schematic that I sent. I installed 2 bats for each engine, as I wanted to make sure that I always have a separate backup starting battery available. Everything is new, but just to show how things go, the new backup bats were a good example of things going bad unexpectedly. Both alternators (new) for each engine can charge both bats ( for each engine).
    The house bat is connected, via separate switch, to the # 2 bat on port engine, so that if I can recharge the house bat, when port engine is running, when switched to # 2 bat only.
    Might seem redundant / overkill, but I belive in preventative not emergency repair situations if at all possible. I have been stranded before !!!
    The house bat is connected to the on board charger (shore power) and the charger is also connected to the on board generator.
    The only question / concern I have , is the # 2 bats are not connected to the onboard charger (120 V), & not sure if I should put in a separate on board charger for those 2 only for maintenace charging, or if the bats should stand up using normal engine charging ( alternate switching between 1 & 2 while running).

    Thanks for your input, let me know what you think.

    I did look at the schematic attachment in your post #6. I believe that is your most current image.... correct?
    That is the same image that I've been working from.



    Since our cranking banks are not depleted by many Amp Hours (during cranking), these normally fair well by being alternator charged while the engine is warming up.
    Typically, there is plenty of charge time while the engine is warming up.
    Any drain to these banks is a result of something that yet needs to be addressed (see post #9 again).
    That being said, I'll still maintain that your two banks per engine is over-kill. Your previous issue was very likely caused by something that you did not catch or identify as a drain..... or perhaps from not isolating this bank (via MBSS OFF position) while on the hook.

    If a seperate O/B charger is required, this can be a lower amp maintenance charger for cranking batteries.

    I'll also add that I believe you are underestimating the ACR's and their ability to bring both engine alternators into the loop for taking care of both #1 and #2 cranking banks (per engine) and also for the HLBB charging.
    The 7622 ACR is also capable of combing automatically for any cranking redundancy. Key word "automatically".

    Will your design work??? ..... yes, it certainly will.
    However, I've laid this out for you as to show how the ACR's can achieve your needs and without all of the MBS and MBSS switching..... but of course, this is IMOO.

    Would I use your schematic??? Quite frankly, no...., I would not.
    But again, this is just IMOO.

    If this were my boat, I'd use what I've drawn up, or a version very similar.
    I may keep the two cranking banks on the Stbd engine, but I'd remove one from the Port side.
    I'd take advantage of the Blue Sea ACR's to accommodate the charging of each, and to accommodate both engine alternators charging the HLBB.
    We can safely bring two alternators in for this.
    (perhaps reread post #8 again)

    Side note:
    While your boat is larger than my 28, our 12 vdc electrical demands may not be all that different.
    I have a refrigerator, cabin lights, electric head, furnace fan, system water pump, etc, much as what you do, and will/should be very similar in daily 12 vdc loads.
    I have one large HLBB on the Stdb side. Actually, 6 volt deep cycle batteries to gain the Amp Hour capacity.
    I crank the Stbd engine from this bank, but with the 7622 ACR feature involvement.
    The Port engine has a dedicated cranking bank.
    The Gen has it's own cranking battery.

    It's very safe to suggest that our engine demands are extremely similar, if not almost identical.
    If our HLBB demands are not similar (yours being greater), the fix is very easy..... just increase the Amp Hour capacity of your HLBB.

    Given this...., we are pretty much apples to apples in this regard.

    I have had zero issues doing this.
    My battery management is also very simple and easy to understand.


    But again, I want to be clear that this is your boat, and that you need to the one who is happy with the arrangement, not me.


    If you were to want extreme simplicity, something like this could be used.
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    Last edited by RicardoMarine; 09-19-2012 at 12:30 PM.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    ..."Jeff, today's multi-bank smart chargers are fully capable of charging and maintaining multiple banks..... yes/no?
    Would you say that the charger that destroyed one of your batteries was most likely defective? "

    Sorry to confuse the issue. You want ONE bank of a charger per battery. I have a dual bank charger, and it takes care of two batteries. The other three bateries all have their own dedicated chargers.

    I wrecked a battery by having one bank of a charger charging two batteries. Not good!

    Jeff

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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Quote Originally Posted by fastjeff View Post
    ..."Jeff, today's multi-bank smart chargers are fully capable of charging and maintaining multiple banks..... yes/no?
    Would you say that the charger that destroyed one of your batteries was most likely defective? "

    Sorry to confuse the issue.
    1..... You want ONE bank of a charger per battery.
    2.... I have a dual bank charger, and it takes care of two batteries.
    3.... The other three bateries all have their own dedicated chargers.
    4.... I wrecked a battery by having one bank of a charger charging two batteries. Not good!
    Jeff, if you have three battery banks on board, and if you want O/B Charger capabilities via only one charger, then you need a three bank charger.

    In response to 1 thru 4, I'm a bit unlcear as to what a bank means to you.
    To me, a bank can be a single battery, or it can be multiple batteries.

    1.... ONE bank of a charger per battery...... or per battery Bank ?
    2.... two batteries... or two battery banks?
    3.... Again, batteries or battery banks?
    4.... If one charger lead was being directed towards two unlilke batteries, this can occur. However, if the bank is made up of "Like" batteries (i.e., age, group, size, amp hour capacity, brand, etc.), this would be unusual, IMO.

    I've always used mutiples in my HLBB, and with exception to an old ProMariner charger , I have never had an issue with my Xantrex 3-stage Smart Charger/Inverter.


    .
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    I've found that--even with identical batteries--you can't get away with ONE bank charging two batteries. One if them will steal more juice from the other and go blat-oh!

    Jeff

  29. #29
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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    Quote Originally Posted by fastjeff View Post
    I've found that--even with identical batteries--you can't get away with ONE bank charging two batteries. One if them will steal more juice from the other and go blat-oh!
    Jeff, again, I may not be following you. Can you please suggest to me how we can have a multiple battery bank (be it multiple 12 volt batteries in parallel, or be it multiple 6 volt batteries in series, 2 batts each group) and yet install battery charger leads independently of the bank's parallel or series interface with each other?

    Multiple 12 volts in parallel, or multiple 6 volts in series (groups of two each), simply make up one large 12 volt battery.
    The charger and/or engine alternator sees this as one large battery.

    We'll see multiples in our marine HLBB's, Golf Carts, long haul truck tractors, Motor Homes, RV's.
    If the bank is healthy, I just don't see issues occuring often.

    I don't disagree that unlike batteries (unlike age, group, capacity, number of previous cycles, etc.), whereby one battery is failing, can bring havac to a battery bank.

    BTW, I have never replaced only one battery in a multiple battery bank. If one needs to be replaced, they all get replaced, and the date code is the same, as well as all else.
    Perhaps my experience is quite different from yours.

    .
    Last edited by RicardoMarine; 09-20-2012 at 07:14 AM.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

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    Default Re: correct wiring for dual engines-dual batteries each 1 house battery switch each -3 bank charger

    I keep the Perko battery switch on positon # 1 or # 2, which isolates the batteries from each other. A dual bank charger then takes care of the two batteries. While on a long cruuise, however--and after using the inverter all night--I switch the Perko to 'Both' and let the alternators recharge everything. Normally, that would no be a good idea, but for a few days only it doesn't bother anything.

    Jeff

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