Battery wiring

[Ka_sea_ta]

Cool... You might, however, want to consider routing the alternators to the house and use the ACR to charge (top off) the starter batteries. Staring engines doesn't take that much from starter batts, but a day or two on the hook will. It is more accepted to use the alts to replenish the house batteries when you are underway, saaaayyy, between anchorages. At least from all that I have learned about the subject.

I would disagree, just add the ACRs to each starting battery to charge the house bank, dead starting batteries are a show stopper, dead house bank is just an inconvenience... My reasoning is if the ACR fails the staring batts are still charged the inverse if the alt are connected to the house bank and the ACR fails then the starting batts can go flat...The other reason with twins you have two alts feeding a common load this can result with one alternator over or under charging ( this is why Balmar produces the center fielder ) . Another reason is unless you have secondary voltage monitoring you will only see the voltage of the house bank with the voltmeter on the engine gauges...

 

[dhays]

I would disagree, just add the ACRs to each starting battery to charge the house bank, dead starting batteries are a show stopper, dead house bank is just an inconvenience... My reasoning is if the ACR fails the staring batts are still charged the inverse if the alt are connected to the house bank and the ACR fails then the starting batts can go flat...The other reason with twins you have two alts feeding a common load this can result with one alternator over or under charging ( this is why Balmar produces the center fielder ) . Another reason is unless you have secondary voltage monitoring you will only see the voltage of the house bank with the voltmeter on the engine gauges...

I have never dealt with twins so I am unsure about the issue of two alts feeding a bank. It would seem to me that if you have have each engine alternator feeding its start battery and each of those has an ACR combining with the house bank, you still have the situation where both alternators are feeding a combined bank of both starts plus the house.

Again I don't know what I'm talking about with twins so maybe folks can help me out here but it seems to me that if you have some type of charge regulator for your alternators that feed your house bank, then either ACRs, Echo-chargers, or Duo-chargers to charge the start batteries, you will get the max charge on your house bank and always replenish the charge of the start batteries.

The Echo-charger or Duo-charger can't fail to combined bank (not sure it is likely with an ACR either) but if you are concerned about a failure to charge, then you can have a switch that would combine the two start batteries.

 

[kchace]

I have never dealt with twins so I am unsure about the issue of two alts feeding a bank. It would seem to me that if you have have each engine alternator feeding its start battery and each of those has an ACR combining with the house bank, you still have the situation where both alternators are feeding a combined bank of both starts plus the house.

Again I don't know what I'm talking about with twins so maybe folks can help me out here but it seems to me that if you have some type of charge regulator for your alternators that feed your house bank, then either ACRs, Echo-chargers, or Duo-chargers to charge the start batteries, you will get the max charge on your house bank and always replenish the charge of the start batteries.

The Echo-charger or Duo-charger can't fail to combined bank (not sure it is likely with an ACR either) but if you are concerned about a failure to charge, then you can have a switch that would combine the two start batteries.

Twin alternators feeding the same bank (assuming no special control) will both feed the bank until the bank's voltage during the charge starts to get close to one of the alternator's cut off voltage. At about that point, the alternator with the higher *voltage* output at that load, will do pretty much all of the remaining charging. If the bank can be split - as with say an a/b/combined switch - setting the switch so the banks are not combined will allow each alternator to charge that part of the bank at the alternator's best possible rate.

Ken

 

[kchace]

I would disagree, just add the ACRs to each starting battery to charge the house bank, dead starting batteries are a show stopper, dead house bank is just an inconvenience... My reasoning is if the ACR fails the staring batts are still charged the inverse if the alt are connected to the house bank and the ACR fails then the starting batts can go flat...The other reason with twins you have two alts feeding a common load this can result with one alternator over or under charging ( this is why Balmar produces the center fielder ) . Another reason is unless you have secondary voltage monitoring you will only see the voltage of the house bank with the voltmeter on the engine gauges...

I completely agree with your concerns. I was able to rationalize my own setup which has the alts directly connected to the house - in a few ways. One, is my start batteries are completely independent. So a single dead start battery can still allow me to start one engine and with a combined A/B house bank and ACRs closed will charge both start batteries. Two, I have a crossover that allows me to combine both engine start batteries in an emergency. Three, the Gen powered battery charger (with its own start battery) can separately charge the engine batteries. Four, I installed voltage monitors for both engine batteries and each half of the house bank, so I can verify that the start batteries are indeed charging properly and lastly, in my experience ACRs are pretty reliable.

Ken

 

[Ka_sea_ta]

I completely agree with your concerns. I was able to rationalize my own setup which has the alts directly connected to the house - in a few ways. One, is my start batteries are completely independent. So a single dead start battery can still allow me to start one engine and with a combined A/B house bank and ACRs closed will charge both start batteries. Two, I have a crossover that allows me to combine both engine start batteries in an emergency. Three, the Gen powered battery charger (with its own start battery) can separately charge the engine batteries. Four, I installed voltage monitors for both engine batteries and each half of the house bank, so I can verify that the start batteries are indeed charging properly and lastly, in my experience ACRs are pretty reliable.

Ken

So what is the advantage to directly wire the alts to the house bank?

 

[Ka_sea_ta]

I have never dealt with twins so I am unsure about the issue of two alts feeding a bank. It would seem to me that if you have have each engine alternator feeding its start battery and each of those has an ACR combining with the house bank, you still have the situation where both alternators are feeding a combined bank of both starts plus the house.

Again I don't know what I'm talking about with twins so maybe folks can help me out here but it seems to me that if you have some type of charge regulator for your alternators that feed your house bank, then either ACRs, Echo-chargers, or Duo-chargers to charge the start batteries, you will get the max charge on your house bank and always replenish the charge of the start batteries.

The Echo-charger or Duo-charger can't fail to combined bank (not sure it is likely with an ACR either) but if you are concerned about a failure to charge, then you can have a switch that would combine the two start batteries.

Dave, I just can't understand the advantage to feeding the alts to the house bank.. But I can see some disadvantages .. By the way the echo charger that I'm familiar with is limited to 10 amps, it's a little solid state device that has a transistor for the output, it has failed a few times over the years. I do use it to charge my dingy battery when underway. I'm not acquainted with a Duo Charger, how does it work? Thanks

 

[Alaskan Sea-Duction]

Good job Bob. I didn't have the switch issue you had, but I did have a similar batteries situation. I had 3 each 8D batteries in my ER and a 4D for the Genny. The 8Ds were my start batteries AND house batteries. The STBD side had the 3rd 8D in parallel. All four batteries were charged by an ancient 50amp charger. The charger would boil all batteries.


First thing I did was get rid of the charger and disconnected it to all batteries. I installed a group 27 battery for the Genny and new 8Ds for START only batteries for the engines. None of these batteries are connected to a charger.


I installed 2 banks of 6Vdc batteries for the house (bank 1 and bank 2). I have an inverter on bank 1. These 2 banks are connected to battery chargers.


I would recommend ACRs as suggested when you have engines running to charge the start batteries and house batteries.

 

[kchace]

So what is the advantage to directly wire the alts to the house bank?

There's a lot of ways to wire boats but for me and for the way my boat is wired and my usage patterns, my house bank is by far the most in need of a charge. I believe that wiring the output of the alts to those first and then to the start batteries through ACRs puts the most juice where its needed.

Ken

 

[dhays]

Dave, I just can't understand the advantage to feeding the alts to the house bank.. But I can see some disadvantages .. By the way the echo charger that I'm familiar with is limited to 10 amps, it's a little solid state device that has a transistor for the output, it has failed a few times over the years. I do use it to charge my dingy battery when underway. I'm not acquainted with a Duo Charger, how does it work? Thanks

The Xantrex Echo-charger is a very simple device that, as you say, provides a small amount of charge current (15amp). It does this by bleeding off a bit of the charge current that is being directed to the house bank and sends it to the start motor. IMO, it is perfect for charging a start battery or thruster batteries provided that the house and starter battery are the same type. It is simple and you are the only person that I've heard has had one fail.

The Balmar Duo-charger is similar in that it sends a charge to the start battery when the voltage at the house battery hits a certain voltage, such as when it is being charged. It will charge up to 30amps of current and can be configured to 4 types of charge profiles. The advantage of this is that your house can be wet cells and your start battery an AGM and each bank gets the charge profile that it needs.

Neither the Echo-charger and Duo-charger are combiners. ie when a Blue Seas ACR engages, the start and house banks are really just one large bank with one charging source. With the Echo-charger and Duo-charger the banks are still isolated but getting a charge current to the start batteries.

I like them simply because I would rather not combine a 50% SOC house bank with my start batteries. Instead I would rather run all my charge sources to the house bank and then use a small amount of that to keep the start batteries topped off.

Currently, I have a Duo-charger for my thruster batteries and for my genset start battery. I have an ACR for my starter battery but have a Duo-charger in place that I will likely switch to instead of the ACR.

 

[Ka_sea_ta]

I like them simply because I would rather not combine a 50% SOC house bank with my start batteries. Instead I would rather run all my charge sources to the house bank and then use a small amount of that to keep the start batteries topped off.

.

The issue I see with this is that in order to get your starting battery "topped off" is that your house batts have to get to the float charge state before any current flows to the starting batts. This because of the trigger voltage of the ACR. If you have a large house bank this could take several hours of run time...

In my case I have what I suspect is an unusually large house bank ( about 1800 ah ) charged with two 130 amp alts... it takes about 4 to 5 hours of run time to charge the house bank. if we were making short hops the house bank doesn't get completely charged.... If the charge path is house bank first then start batts, it could be that the start batts don't get completely charged

This is all minutiae anyway a well designed system would allow manual cross connect of batteries in an emergency.

 

[kev_rm]

Good job Bob. I didn't have the switch issue you had, but I did have a similar batteries situation. I had 3 each 8D batteries in my ER and a 4D for the Genny. The 8Ds were my start batteries AND house batteries. The STBD side had the 3rd 8D in parallel. All four batteries were charged by an ancient 50amp charger. The charger would boil all batteries.


First thing I did was get rid of the charger and disconnected it to all batteries. I installed a group 27 battery for the Genny and new 8Ds for START only batteries for the engines. None of these batteries are connected to a charger.


I installed 2 banks of 6Vdc batteries for the house (bank 1 and bank 2). I have an inverter on bank 1. These 2 banks are connected to battery chargers.


I would recommend ACRs as suggested when you have engines running to charge the start batteries and house batteries.

+1 agree this is the right approach to fix a common goofy setup. I would go so far as to say 8D too big for start in a lot of cases (including mine, twin 175hp..) The start battery size reached insanity here with The PO/PO's mechanic on my boat had rigged a combine switch to bond the 8D start to start a small 3cyl 8kw genny because of a bad solenoid and bad battery for genny. Just dumb.

I am still working on refactoring my setup, presently a 27 to start genny (working now with new solenoid), 8D start both ME's and 8D house, moving to group 31 to start either ME or genny (one battery for start.. period..) , and then maybe 1000Ah-ish from T-105 6v or equivalent interstate etc. Genny alternator and one ME will charge start batt other ME will charge house. Jumper cables/switches as appropriate when things don't work as intended.

Probably biggest three things I've learned is 1) use the right @!#!@ cable size for the load 2) use quality rated flooded batteries for deep cycle 3) use a charger that is FULLY adjustable for all stages on your house that will meet the battery manufacturers recommendation for rates and voltages.

 

[dhays]

The issue I see with this is that in order to get your starting battery "topped off" is that your house batts have to get to the float charge state before any current flows to the starting batts. This because of the trigger voltage of the ACR. If you have a large house bank this could take several hours of run time...

The way the Echo-charger and Duo-chargers work, is they will start to charge the start battery as soon as there is a charge supplied to the house bank.

 

[Ka_sea_ta]

The way the Echo-charger and Duo-chargers work, is they will start to charge the start battery as soon as there is a charge supplied to the house bank.

You sure about that? The lowered internal resistance of a discharged battery will lower the apparent voltage of the battery and charger ( the source) below 13 volts until the internal resistance of the battery increases unless these devices increase that voltage so that is above the ambient voltage of the battery that you're trying to charge, no current will flow.

 

[stone beach]

On the aspect of sharing start batteries...if everything gets "flattened"...by who knows what event...I like the comfort of being able to start the genny. I think it deserves its own starting means.

 

[dhays]

You sure about that? The lowered internal resistance of a discharged battery will lower the apparent voltage of the battery and charger ( the source) below 13 volts until the internal resistance of the battery increases unless these devices increase that voltage so that is above the ambient voltage of the battery that you're trying to charge, no current will flow.

I am not sure about it and could easily be wrong. Never trust me on electricity.

 

[BruceK]

On the aspect of sharing start batteries...if everything gets "flattened"...by who knows what event...I like the comfort of being able to start the genny. I think it deserves its own starting means.

Sure does. My genset battery even has its own solar panel.

 

[Tom.B]

I would disagree, just add the ACRs to each starting battery to charge the house bank, dead starting batteries are a show stopper, dead house bank is just an inconvenience... My reasoning is if the ACR fails the staring batts are still charged the inverse if the alt are connected to the house bank and the ACR fails then the starting batts can go flat...The other reason with twins you have two alts feeding a common load this can result with one alternator over or under charging ( this is why Balmar produces the center fielder ) . Another reason is unless you have secondary voltage monitoring you will only see the voltage of the house bank with the voltmeter on the engine gauges...

A 1-2-B-Off switch would easily resolve that issue. A house bank... ANY house bank... can start an engine. It takes just a quick dump of energy for just a second or two and your going. Look at it this way, you can always start engines with house batteries, but start batteries can ever work as a house bank. I would always want my largest capacity bank as full as I can get it.

In bulk mode, having two alternators going to a single bank is a non-issue. They don't cancel each other out or one won't burn up the other one. They act as one alternator. They sense voltage and not current and batteries will take what they need.

If you want to anchor out for any length of time or day after day, you must have your alternators wired to your house bank. Plain and simple. Imagine taking 100 AH out in a day or two on the hook. Wouldn't it make far more sense that while you are underway that you are charging your house bank at 60a or more and not relying on the ACR to pass that? Or worse, a trickle charge? Like I said, starting batts have it easy, whereas a house bank has to do the heavy lifting. Let the alternators earn their keep and have you arrive at an anchorage with a fully charged house bank.

 

[Ka_sea_ta]

A 1-2-B-Off switch would easily resolve that issue. A house bank... ANY house bank... can start an engine. It takes just a quick dump of energy for just a second or two and your going. Look at it this way, you can always start engines with house batteries, but start batteries can ever work as a house bank. I would always want my largest capacity bank as full as I can get it.

In bulk mode, having two alternators going to a single bank is a non-issue. They don't cancel each other out or one won't burn up the other one. They act as one alternator. They sense voltage and not current and batteries will take what they need.

If you want to anchor out for any length of time or day after day, you must have your alternators wired to your house bank. Plain and simple. Imagine taking 100 AH out in a day or two on the hook. Wouldn't it make far more sense that while you are underway that you are charging your house bank at 60a or more and not relying on the ACR to pass that? Or worse, a trickle charge? Like I said, starting batts have it easy, whereas a house bank has to do the heavy lifting. Let the alternators earn their keep and have you arrive at an anchorage with a fully charged house bank.

To me my most important bank is the starting bank, not the house bank like I said it's a show stopper if fails. It's nice to arrive at the anchorage with fully charged house bank, but it's better to be able to leave the anchorage.

 

[Tom.B]

To me my most important bank is the starting bank, not the house bank like I said it's a show stopper if fails. It's nice to arrive at the anchorage with fully charged house bank, but it's better to be able to leave the anchorage.

I don't disagree that the start bank is important, but not using the full power of your alternator on the bank that needs it the most is wasteful. But as not to be repetitive and argumentative (and as an ex moderator... I know that is against the rules) let's just say that our priorities are different and let the readers decide where THEIR priorities are.

 

[dhays]

This is a thread where it would be nice to see CMS weigh in.

 

[ghost]

I took out two 8d starting batts, replaced with a single smaller starting batt for both engines and used the left over space to increase my house capacity to around 1200ah with extra house batts which are all agm. My dual alternators feed the single house bank, and I do use a duo charge to keep the starting batt
up. The safety of my starting batt is its isolation. It can not be run down accidentally. Backup to that is a very large house bank that is likely to not be depleted, because my potential charging is always maximized and let's be honest I'm kind of obsessive about every ah that comes out of it. Watching amp loads is 2nd only to the efficiency of the ice maker. Backup to the house bank again is a diesel D.C. Generator that can be hand cranked to start, but will provide 180 amps.

Took a bit of thinking through, but it's all automatic. I don't have a single battery switch, because a human can forget and screw the up. The design work goes into the automation, daily running is nothing more than watching the amp hour meter to decide when to run the generator.

 

[psneeld]

it becomes a cyclic argument depending how the boat is set up.

Many cruisers here have engines that can be started with a half depleted house bank or a partially depleted start battery.

through the years I have seen many gravitate to the 3 way punch....actually 4 ways with some effort.

A big enough house bank that could easily start one engine even pretty way down (obviously not dead), a big enough yet stipp reasonable size start battery that can crank a good bit before being dead, and a genset that can charge either the start battery back up quickly or put enough into a house bank to start a main...plus the genset battery to jumper over or move to the main.

So really...one can set up and use all kinds of complicated ways to do this....but I use one simple start/stop batt switch that either connects or separates the house bank of 6 golf carts to the start batt and alternator.

The switch is turned off when I check the engine compartment at the end of the day and turned back on after the morning start and all looks well down below.

I wait till after start because I have blown the fuse at the house bank that protects the fairly long run back to the switch near the engine. Too many cranking amps for the 125A fuse.

 

[stone beach]

I took out two 8d starting batts, replaced with a single smaller starting batt for both engines and used the left over space to increase my house capacity to around 1200ah with extra house batts which are all agm. My dual alternators feed the single house bank, and I do use a duo charge to keep the starting batt
up. The safety of my starting batt is its isolation. It can not be run down accidentally. Backup to that is a very large house bank that is likely to not be depleted, because my potential charging is always maximized and let's be honest I'm kind of obsessive about every ah that comes out of it. Watching amp loads is 2nd only to the efficiency of the ice maker. Backup to the house bank again is a diesel D.C. Generator that can be hand cranked to start, but will provide 180 amps.

Took a bit of thinking through, but it's all automatic. I don't have a single battery switch, because a human can forget and screw the up. The design work goes into the automation, daily running is nothing more than watching the amp hour meter to decide when to run the generator.

Please post (or pm me if you prefer) details of your hand crank gen. Thanks

 

[psneeld]

So far in boating, electrical systems, especially the more complicated are...seem to fail as much as the humans. And of course that depends on either the system, the human, either/or, or both....


Again...with 4 options for starting an engine...not sure that someone forgetting a switch is all that big of a deal.


For me, worst case scenario....forgetting to connect a partially depleted house bank gets a pretty good charge back from the solar array...so technically...


If people are SOooooo worried about amp hours.... I really have a 7 pronged attack if I need to get the engine started.....in addition to the 4 I already mentioned....There is the solar, the emergency 1000 Honda and the mast winch battery up on the flybridge.


Then ...if really desperate and in a reasonable cruising area that I usually do cruise....I can get a jump from Sea Tow. 8 different ways to get my engine started and that still doesn't include a good Samaritan.


So relying on one switch that isn't really that big of a deal ....I would hardly worry about occasionally forgetting to combine them up with the flick of a switch right where I check the engine after starting anyhow. I could also rig an idiot light at the panel if it were that big of a deal. And of course I could buy something automatic. But that priority hasn't bubbled up enough to displace the next six pack....


But I digress...there are many ways to wire a boat...some are dangerous, some are confusing, some really don't work so well, some make troubleshooting a nightmare, some are manual and work well and some are automatic and work well. Any of them can be a problem at any moment...there are no perfect ways.


Just the one you are the most happy with.

 

[dhays]

So really...one can set up and use all kinds of complicated ways to do this....but I use one simple start/stop batt switch that either connects or separates the house bank of 6 golf carts to the start batt and alternator.

The switch is turned off when I check the engine compartment at the end of the day and turned back on after the morning start and all looks well down below.

I wait till after start because I have blown the fuse at the house bank that protects the fairly long run back to the switch near the engine. Too many cranking amps for the 125A fuse.

So you in effect have a combiner that is controlled by you. Where does your alternator output go, your start or your house?

I also agree with you that there is generally no one right way to set things up. Just different ways with different advantages and disadvantages.

 

[psneeld]

I normally have it going to my start battery.


The combiner switch could be left on and the battery switch on the start battery could be shut off If I wanted to do it that way...but the combiner switch is the usual customer.


If I get lazy enough, I might replace the combiner switch with a continuous duty solenoid and an idiot light at the dash....but for the want of reaching down to it from the saloon after starting and doing a quick post start look...it is no big deal

 

[Island15]

You guys have forgot more about this than I know.
I really need some basic help, here is what I have on my 76 CHB 120 Lehman, 55amp alt, two 8d lead batteries as well as one group 27 start battery for the gen.

I would like to add a start battery just for the main engine. I want it separate so I don't have to worry about running the "house batteries" down.

What is the simplest way to give me peace of mind, I hear it hard to push start a boat

I have a three bank Protech 1240 charger that is working great I see no reason to change it out

 

[Ka_sea_ta]

The simplest way is to add an appropriately sized, same chemistry as the existing batteries battery. connect the the ground to the existing grounds. move the cable from the starter to the new starting battery, you probably want to add a disconnect switch from the starting battery to the starter. Wire an ACR between the new starting battery and the existing 8ds... If you have an existing 1,2,both, off switch it probably separates the 2 8ds if so switch it to both if you don't have that switch connect the positive terminal of the 8ds together.... If you want you can put one of the charger leads to the new starting battery, but the ACR will allow the charger to feed the start batt, just as it will allow the alternator to charge the house bank... That's it the ACR will isolate the start batt and house batts once the charging source is removed... Blue seas has a lot of good info on using ACRs

 

[Tom.B]

So for the record, CMS helped me out with the design if this. He didn't technically sign off on the final design, but I kept a running evolution of the ideas on his forum. Pretty sure any glaring problems would have been pointed out by him and the members there... Anyway, below is the, somewhat, final layout I did on Skinny Dippin'. The only difference in what the real-world solution ended up being is that I have not added a separate Genset battery. running it does require a custom profile on the battery, but that isn't a big deal at all. There are also more than a couple of buss bars, senor wires, and fuse blocks not pictured.

8-6V GC2 Batteries
3-Group 27s Dual Purpose as start bank
60A smart charger
Blue Seas ACR
2-1/2/Off/Both switches
2-60A standard issue Volvo alternators

So one 3-way switch controls the source of engine starting power and the other the house power. Easy to install, understand, and operate with very few point's of failure.

I hope this helps... Let me know if you have any questions.

 

[Lou_tribal]

So for the record, CMS helped me out with the design if this. He didn't technically sign off on the final design, but I kept a running evolution of the ideas on his forum. Pretty sure any glaring problems would have been pointed out by him and the members there... Anyway, below is the, somewhat, final layout I did on Skinny Dippin'. The only difference in what the real-world solution ended up being is that I have not added a separate Genset battery. running it does require a custom profile on the battery, but that isn't a big deal at all. There are also more than a couple of buss bars, senor wires, and fuse blocks not pictured.

8-6V GC2 Batteries
3-Group 27s Dual Purpose as start bank
60A smart charger
Blue Seas ACR
2-1/2/Off/Both switches
2-60A standard issue Volvo alternators

So one 3-way switch controls the source of engine starting power and the other the house power. Easy to install, understand, and operate with very few point's of failure.

I hope this helps... Let me know if you have any questions.

May I dare to ask why you need to select what is the house bank? Usually starting batteries are not intended to be used as service batteries if I am right. I clearly understand the value of the switch to select what to use to start so in case of a flat starting battery you can either start only on house or combine both but I do not see the opposite way.

On my own the OP did the mistake of letting the switch on Both once and woke up with a flat starter battery. After that he changed the wiring so the switch is only used to select start between starter or both but never the starter can be used as house. I still need to check his wiring in spring as I am curious, I may discover some odd things