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  1. #1
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    Default Battery, charging, isolation, inverting, switching questions

    looks like I need to post in small chunks
    Last edited by outobie; 07-07-2017 at 08:36 AM.

  2. #2
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    Default Re: why is my post not showing up

    Battery, charging, isolation, inverting, switching questions
    Hello I have a new to me 30 year old 27 foot Tiara with twin engines and no generator.
    I’d like to set it up for my needs and am looking for suggestions and answers to electrical questions.

    My objective is to be able to overnight on the hook and run interior fans, refrigerator, lights, and charge phones off of battery power and still be able to start the engines in the morning.
    I’d like to be able to charge any battery from either alternator. Does a battery isolator do this? I’ve seen isolators advertised like PROMARINER 1 ALTERNATOR 3 BATTERY ISOLATOR 70 AMP that seem to do this but its not clear to me if the alternator input is switched to all batteries. For example, if one of my alternators dies will the other still charge all 3 batteries?...if so how would I know if one of the alternators went bad?
    I’d also like to be able to switch any battery bank to start either engine in an emergency.

    Current setup is:
    Two gas engines
    o Mercruiser stern drive 5.7 L V8 Alphas carburated
    Two alternators
    o Each tied to it’s own battery
    Two starting batteries
    o Port battery also powers windlass
    o Starboard battery powers all onboard house loads
    30 year old permanent battery charger (no inverter)
    o Question: is it advisable to leave the charger on while on shore power or will it cook my batteries? Boat sits at the dock during week and runs about 4 to 8 hours every weekend depending on the weather.
    An on / off battery switch for each motor/battery
    An on/off switch for the windlass
    An emergency momentary parallel switch on the dash

    My first questions are about batteries. I’d like to leave the house bank on overnight to run things.
    1. How much battery do I need to run the fridge, 3 small fans and phone chargers?
    2. Is it ok to just let the battery run down overnight till it’s out of power
    a. Will that hurt the fridge?
    b. Will that hurt the battery?
    3. Should I add a dedicated 3rd house bank or beef up one or both of the current two batteries?
    4. Should I do a 2 battery setup and make one the starting battery for both motors and one the house bank?
    5. What kind of batteries?
    a. Lead acid, AGM, other?
    b. Run dual 6 volt batteries serialed to equal 12 volts?
    c. Deep cycle vs startup for house and starting batteries (I assume there’s a reason for the term “start up”.
    My next question is about inverters and isolators
    1. When and why would I want to run ACHs vs a multi bank isolator?
    2. Should I replace my old technology battery charger with a modern charger/inverter?
    a. Does my AC/DC fridge run more efficiently on AC or DC?
    b. It would be convenient to power on the electrical outlets for AC phone charging but I can also charge them on DC USB chargers…again is AC or DC more efficient?
    c. What’s better inverter for my intended use (or do I need one at all)? Sine Wave VS modified Sine Wave
    3. If I upgrade the charger can I leave it on all the time on shore power?

    next questions are on battery switches
    1. If the answer to the battery question is to set up a 3rd house battery bank, what is the recommended battery switch configuration that enables any of the 3 batteries to be switched to start either engine in an emergency
    2. This question is easier if two battery banks are used…I’ve seen Blue Sea sells this set up pre configured
    Lastly, I plan to install a multifunction battery gauge that measures volts and Amps and can be switched to read up to 3 banks of batteries.

    Thanks for reading this far and any recommendations you can offer.
    I’m sure to have follow up questions J

  3. #3
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    Default Battery, charging, isolation, inverting, switching questions

    .....
    Last edited by outobie; 07-07-2017 at 08:37 AM.

  4. #4
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    Default Re: why is my post not showing up

    Hello I have a new to me 30 year old 27 foot Tiara with twin engines and no generator.
    I’d like to set it up for my needs and am looking for suggestions and answers to electrical questions.

    My objective is to be able to overnight on the hook and run interior fans, refrigerator, lights, and charge phones off of battery power and still be able to start the engines in the morning.
    I’d like to be able to charge any battery from either alternator. Does a battery isolator do this? I’ve seen isolators advertised like PROMARINER 1 ALTERNATOR 3 BATTERY ISOLATOR 70 AMP that seem to do this but its not clear to me if the alternator input is switched to all batteries. For example, if one of my alternators dies will the other still charge all 3 batteries?...if so how would I know if one of the alternators went bad?

  5. #5
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    Default Re: why is my post not showing up

    I’d also like to be able to switch any battery bank to start either engine in an emergency.

    Current setup is:
    Two gas engines
    o Mercruiser stern drive 5.7 L V8 Alphas carburated
    Two alternators
    o Each tied to it’s own battery
    Two starting batteries
    o Port battery also powers windlass
    o Starboard battery powers all onboard house loads
    30 year old permanent battery charger (no inverter)
    o Question: is it advisable to leave the charger on while on shore power or will it cook my batteries? Boat sits at the dock during week and runs about 4 to 8 hours every weekend depending on the weather.
    An on / off battery switch for each motor/battery
    An on/off switch for the windlass
    An emergency momentary parallel switch on the dash

  6. #6
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    Default Re: why is my post not showing up

    My first questions are about batteries. I’d like to leave the house bank on overnight to run things.
    1. How much battery do I need to run the fridge, 3 small fans and phone chargers?
    2. Is it ok to just let the battery run down overnight till it’s out of power
    a. Will that hurt the fridge?
    b. Will that hurt the battery?
    3. Should I add a dedicated 3rd house bank or beef up one or both of the current two batteries?
    4. Should I do a 2 battery setup and make one the starting battery for both motors and one the house bank?
    5. What kind of batteries?
    a. Lead acid, AGM, other?
    b. Run dual 6 volt batteries serialed to equal 12 volts?
    c. Deep cycle vs startup for house and starting batteries (I assume there’s a reason for the term “start up”.

  7. #7
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    Default Re: why is my post not showing up

    My next question is about inverters and isolators
    1. When and why would I want to run ACHs vs a multi bank isolator?
    2. Should I replace my old technology battery charger with a modern charger/inverter?
    a. Does my AC/DC fridge run more efficiently on AC or DC?
    b. It would be convenient to power on the electrical outlets for AC phone charging but I can also charge them on DC USB chargers…again is AC or DC more efficient?
    c. What’s better inverter for my intended use (or do I need one at all)? Sine Wave VS modified Sine Wave
    3. If I upgrade the charger can I leave it on all the time on shore power?

  8. #8
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    Default Re: why is my post not showing up

    next questions are on battery switches
    1. If the answer to the battery question is to set up a 3rd house battery bank, what is the recommended battery switch configuration that enables any of the 3 batteries to be switched to start either engine in an emergency
    2. This question is easier if two battery banks are used…I’ve seen Blue Sea sells this set up pre configured

  9. #9
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    Default Re: why is my post not showing up

    Lastly, I plan to install a multifunction battery gauge that measures volts and Amps and can be switched to read up to 3 banks of batteries.

    Thanks for reading this far and any recommendations you can offer.
    I’m sure to have follow up questions J

  10. #10
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    Default Re: Battery, charging, isolation, inverting, switching questions

    better to ask one topic at a time in a given post.....

    The bullet-proof setup is separate batteries for each engine and then a 'house bank' sized to your needs. Seriously, I'd suggest getting some research done as everybody has there own opinions. Isolators are overpriced diodes on a heatsink and have a voltage drop to deal with....I'd say ACR (automatic charging relays) are a better deal but you need to have the same technology batteries for best results.....on new vs old chargers, if you have anything newer than the basic lead acid battery, then yes, you are better off with the new technology - your battery will know it....

    What ever way you go, may sure anything you touch is the 'good stuff' - if not change it....tinned marine wire, heat shrink lugs/terminals ends - properly crimped, and liquid tape is the minimum.....ty-wraps help keep it organized - and a good drawing will help for any future changes.....

    on inverters, sine waves are what the electric company gives you and that's what most devices are designed for...as a rule, you get what you pay for....

  11. #11
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    Default Re: Battery, charging, isolation, inverting, switching questions

    I'm having a hard time wrapping my head around how ti wire in the house battery with ACR...Click image for larger version. 

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    I found this diagram which I believe is close to what I want but it seems to be missing some detail...
    I'd like to find one similar which shows the alternator and starter wiring for an inboard (sterndrive)...
    Also looks like I could add a 3rd ACR to allow charging of all 3 battery banks from either alternator if one fails (had that happen before)

  12. #12
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    Default Re: Battery, charging, isolation, inverting, switching questions

    This link gives you a better picture of the set up you're looking for.

    http://www.ase-supply.com/v/vspfiles.../sp_marine.pdf
    CHawk 25 DLX

  13. #13
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    Default Re: Battery, charging, isolation, inverting, switching questions

    Quote Originally Posted by chawk_man View Post
    This link gives you a better picture of the set up you're looking for.

    http://www.ase-supply.com/v/vspfiles.../sp_marine.pdf
    Thank you that is just what I was looking for!!

    two more questions
    1.) in the 2 alternator, 3 battery scenario, if one alternator fails, would the working alternator charge all 3 battery banks? If so how would I know if an alternator has failed? Does the voltage gauge on the dash measure voltage at the battery or alternator output?

    2.) in the 2 alternator, 3 battery with switches diagram, id like to have emergency parallel capability to start either engine from the house bank...just add another 3 position switch?

  14. #14
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    Default Re: Battery, charging, isolation, inverting, switching questions

    First, I am by no means an expert on these wiring setups. Others on this forum know far more than I do. So here is what I think.

    I believe that the isolator switch should handle the situation where if one alternator fails, it will switch all charging to the other alternator.

    Boats are wired differently. On most older boats the voltage meter measures voltage off of the battery. However, on newer fuel injected engines, the voltage meter is often run off the ECU. I suspect yours would likely be coming off the battery, but you never can tell - it could be the alternator. So try to find the sender wire off the meter and trace it back to the engine and see where it goes. It should have a unique color code.
    CHawk 25 DLX

  15. #15
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    Default Re: Battery, charging, isolation, inverting, switching questions

    I'm old tech. Carburetor and analog gauges...

    It's reading system voltage from the main harness which in the current setup is just battery voltage

  16. #16
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    Default Re: Battery, charging, isolation, inverting, switching questions

    battery voltage less any existing voltage drop(s) in the various connector(s).....

    The isolators will usually handle the failure situation you described but depends upon the specifics. Using the ACRs, as long as there is true redundancy, yes.

    As far as the emergency bridging system, the mechanization will be driven by the amount of redundancy you want - bridging the starting batteries would only require an appropriately rated solenoid and a monmentary control switch....being able to bridge any two batteries would be a bit more complicated....

  17. #17
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    Default Re: Battery, charging, isolation, inverting, switching questions

    FWIW, most isolators use combinations of high current diodes....the ACRs are just voltage controlled relays that will 'parallel' a pair of batteries...both have pros and cons.....my preference is for the ACRs, in most situations, as they provide a simpler install...

  18. #18
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    Default Re: Battery, charging, isolation, inverting, switching questions

    Simplicity is certainly a good thing

    my thinking was that having one isolator was simpler than two or three acrs.

    ive been going back and forth on that

    now I just read there is a third option... to install a D.C. To D.C. Charger.

  19. #19
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    Default Re: Battery, charging, isolation, inverting, switching questions

    then go with your preferences....just understand all the trades so you can make the solution optimal for your needs....and don't be surprised to find other opinions.

    Haven't investigated DC-DC chargers but I'd think that's not only expensive but more complicated....

  20. #20
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    Default Re: Battery, charging, isolation, inverting, switching questions

    I have been performing Auto/Marine Electrical work for over 45 years.
    In my humble opinion, you would be over-complicating this by doing what you have described!


    NOTES:

    ...... most smaller 27-28 foot twin engine boats (whether single or dual station) will be set up for the House Loads being supplied by the Starboard Engine battery bank.
    ...... most all scenarios will allow the use of an ACR that will bring both engine alternators "IN" for the HLBB charge rate.

    ..... I'd suggest using a Cranking Battery on the Port side..... and Deep Cycle batteries for the HLBB.

    You can accomplish most of what you need by doing the following.

    Set up the Port Engine with a dedicated SLBB (start load batt bank) only.

    Set up the Starboard Engine with a large HLBB (house load batt bank) made up from four (4) 6 volt Deep Cycle batteries. Do NOT attempt to separate this out...... this scenario works just fine!



    The Starboard Engine can safely crank from the Deep Cycle HLBB (been doing this on my own twin engine 28' SDN F/B for years).
    Here's the math in Amp Hours:
    Starter motor = approx 200 amp draw.
    A well tuned healthy Engine starts in 4 to 5 seconds of cranking.
    1 hour = 3,600 seconds.
    That is a current draw of approx 0.222222 Amp Hours, which is much less than what most of us think it would be.

    If concerned, the BlueSea 7622 ML ACR can assist.




    You can use a momentary solenoid switch to combine the Port Engine's SLBB to the Starboard Engine side during cranking for use in an emergency. This works in the reverse scenario as well.
    You can also use a BlueSea 7622 ML ACR to combine battery banks during cranking.



    As for using an Inverter..... please understand that by inverting DC current to AC current, there is a hefty cost in the form of "inefficiency".
    The problem is..... these Inverters are Amp Hour Hungry.


    This also means that what ever AH you consume while making AC current, must be replaced sooner than later if you want to take good care of your Batteries.

    In order to charge and replace the AH consumed, we need a healthy charging system.
    Engine Alternators are not as efficient as would be an O/B Generator and a 50/100 Amp Charger.


    I'm not suggesting to NOT use an Inverter..... but rather be miserly about the usage.



    Also..... one of the most important instruments for someone like yourself, will be a true Amp Hour monitoring system that incorporates a Shunt Resistor. These units allow you to see your Amp Hour capacity and your usage in Amp Hours....... not just voltage (which is actually rather meaningless).
    These are similar to a fuel gauge..... so to speak!





    Here is a twin engine schematic that you can look over.
    I show this using two MBSS's (main battery selector switch) ..... not BS (batt switch).
    MBSS = OFF -- #1 bank -- BOTH/ALL--#2 bank
    BS = OFF -- ON only.

    Second image is for icons if you care to put together your own schematic.


    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by RicardoMarine; 07-19-2017 at 09:19 AM.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP drives

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

  21. #21
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    Default Re: Battery, charging, isolation, inverting, switching questions

    Thank you this is very helpful!!!

    I understand all of you post except for this part below...I thought the acr distributed the alternator output to both banks for charging. How does it combine banks during cranking? I thought that was done with the emergency momentary parallel switch I have on my dash




    "You can also use a BlueSea 7622 ML ACR to combine battery banks during cranking."




  22. #22
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    Default Re: Battery, charging, isolation, inverting, switching questions

    .......................
    Quote Originally Posted by outobie View Post
    Thank you this is very helpful!!!
    You are welcome!

    I understand all of you post except for this part below... I thought the acr distributed the alternator output to both banks for charging.
    Quote Originally Posted by Ricardo
    "You can also use a BlueSea 7622 ML ACR to combine battery banks during cranking."
    That is correct. An ACR or VSR does just that once the voltage reaches 13.2 +/- . When the voltage drops, the contacts open.
    However, the 7622 ML does a bit more.

    How does it combine banks during cranking?
    Go to the BlueSea website, and find the 7622 ML.
    You should see the spec sheet of which will explain the options.


    I thought that was done with the emergency momentary parallel switch I have on my dash.
    That works also. I have this system as well.
    There is one issue with this;
    Let's say that the momentary parallel switch (a solenoid switch) is powered from the helm.
    The helm is powered via the hull harness.
    The hull harness power is dependent upom the HLBB.
    If the HLBB is the low voltage bank, it may not offer enough voltage to operate the solenoid.

    In my schematic, I have shown a means of manually combining (using both MBSSs) for such an event.



    .










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

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

  23. #23

    Default Re: Battery, charging, isolation, inverting, switching questions

    This thread is perfect for what I am trying to do on my boat. I have a 1987 37ft Silverton with the wiring torn out right now. My boat was wires very similar to what you mentioned with only one difference I can tell that I have a Bank #1 DC panel running off the Port Engine and a Bank #2 panel running off of the Starboard engine.

    I was planning to do a three battery setup with two ACRs but I like your diagram a bit better as its fewer parts (one less ACR) and I already have two perko MBSS.

    My question is on the parallel solenoid that is in my boat currently. Can / Should I just remove that and cap the wires coming from the switch at the helm if I opt to use your two battery diagram attached above? It makes sense that with a low voltage situation the switch may not work anyway.

    Is it safe to assume that I should move the main Bank #1 Wire feed over to the new HLBB as they currently come from each individual battery?

  24. #24
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    Default Re: Battery, charging, isolation, inverting, switching questions

    Quote Originally Posted by russ_scotchandiron View Post
    This thread is perfect for what I am trying to do on my boat. I have a 1987 37ft Silverton with the wiring torn out right now. My boat was wires very similar to what you mentioned with only one difference I can tell that I have a Bank #1 DC panel running off the Port Engine and a Bank #2 panel running off of the Starboard engine.
    See below. That would help me understand your scenario.

    I was planning to do a three battery setup with two ACRs but I like your diagram a bit better as its fewer parts (one less ACR) and I already have two perko MBSS.
    I would ditch the Perko MBSSs...... The contacts are too small and the contact spring pressure is weak.

    My question is on the parallel solenoid that is in my boat currently. Can / Should I just remove that and cap the wires coming from the switch at the helm if I opt to use your two battery diagram attached above? It makes sense that with a low voltage situation the switch may not work anyway.
    Your call on that.
    Although a bit more complex, you could power the momentary switch from each bank using diodes for separation.
    This way the bank with the higher voltage will operate the solenoid.

    Is it safe to assume that I should move the main Bank #1 Wire feed over to the new HLBB as they currently come from each individual battery?
    Using the icons that I posted in post #20, could you be more specific by perhaps putting your own schematic together and posting it?

    I would be glad to look at it and make a few comments.


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

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

  25. #25

    Default Re: Battery, charging, isolation, inverting, switching questions

    I could make a new diagram but my plans at this point were to more or less copy your diagram.

    What would be a suitable replacement for the perko?

    Based on your diagram wiring up the parallel switch at the helm seems redundant if I can combine the batteries manually using the MBSS. I’d rather just eliminate that switch from my dash and just seems out of date anyway.

    My original plan was to have a dedicated cranking battery for each engine and one house bank. This scenario however requires more switches and ACRs.

  26. #26
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    Default Re: Battery, charging, isolation, inverting, switching questions

    .............
    Quote Originally Posted by russ_scotchandiron View Post
    I could make a new diagram but my plans at this point were to more or less copy your diagram.

    What would be a suitable replacement for the perko?
    BlueSea offers a good unit.
    My personal preference is the old black Cole Hersee M705 MBSS.
    While these are old school, they are extremely well built.
    They have an O-ring sealed removable rear cover that offers access to the contact area for checking/cleaning, etc.


    Click image for larger version. 

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    Here is a later version.... similar to the M705.
    You can see how the rear cover can be removed.

    Click image for larger version. 

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    Based on your diagram wiring up the parallel switch at the helm seems redundant if I can combine the batteries manually using the MBSS. Id rather just eliminate that switch from my dash and just seems out of date anyway.
    That works also.
    However, with a momentary helm switch and the combing solenoid, we can combine banks immediately in the event of time constraints.


    My original plan was to have a dedicated cranking battery for each engine and one house bank. This scenario however requires more switches and ACRs.
    If your engines fire easily and quickly, there is no reason why you cannot use the HLBB for the Starboard Engine to crank on.
    This reduces your battery banks down to only 2.

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

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

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