2 banks plus a starting battery am I right?

[madprops]

Hi,
I have bought all new batteries for my new to me sailboat, I already have the batteries and because of available space and battery type I have to go with a odd set up. I'm putting in one 300 AH bank, one 200 AH bank/starter, and one starter battery.

I have attached a photo of my wiring diagram, it doesn't include any fuses but I know I need them on just about everything. I have searched a bunch on this forum and on google, I would like someone to check my work to make sure i'm not way off here. I want to make sure that no matter what combination the battery selectors are turned to, I won't have any problems. I also want to make sure everything stays charged (I am going to have 800 watts of solar).

Here is my handy work so far.... Done in MS Paint so be nice

boat.jpg Views: 298 Size: 123.6 KB ID: 195704" style="margin: 2px" />

[john61ct]

Treat the two bigger sets as one big House, the two sub-packs in parallel. Fat wire top-notch crimped connections and fuses in between.

With a bigger bank you'll be drawing it down less as a % of discharge, shallower discharges lead to longer bank life and the bank will last longer. Plus actually get more Ah's out of a larger bank when compared with the same load, than you can on a smaller bank due to Peukert effect.

You could also put switches in between to take either out of the loop, but that gets more complicated.

http://www.sailnet.com/forums/showth...p?p=2051311866

http://forums.sailboatowners.com/ind...0#post-1346247

http://forums.sailboatowners.com/ind...-2#post-891581

http://www.cruisersforum.com/forums/....php?p=2863989

http://www.cruisersforum.com/forums/....php?p=2860503

[Jammer]

Sure, that will work.


I would dispense with the selector switch for the starter. Just leave it wired up to the start battery with a disconnect. If your start battery is dead you can jumper house to start manually, or your ACR may have an override of some kind (many do).


You could also get rid of the ACRs and just use manual switches. The ACR is really just a convenience, and they eventually fail.

[madprops]

Originally Posted by john61ct

Treat the two bigger sets as one big House, the two sub-packs in parallel. Fat wire top-notch crimped connections and fuses in between.

With a bigger bank you'll be drawing it down less as a % of discharge, shallower discharges lead to longer bank life and the bank will last longer. Plus actually get more Ah's out of a larger bank when compared with the same load, than you can on a smaller bank due to Peukert effect.

You could also put switches in between to take either out of the loop, but that gets more complicated.

http://www.sailnet.com/forums/showth...p?p=2051311866

http://forums.sailboatowners.com/ind...0#post-1346247

http://forums.sailboatowners.com/ind...-2#post-891581

Eliminating the 1-2-Both-Off Battery Switch - Page 3 - Cruisers & Sailing Forums

Combined for starting, or in need of a better system design? - Cruisers & Sailing Forums

How do I wire the two banks as one big house?

The 2 banks will be about 5 feet away from each other, and one of them is a solar style AGM bank and the other bank is a starting/AGM style. both banks are different brands of battery and they also have different Amp Hours. I was under the impression that you couldn't mix the two together in one bank?

If I have the Bank battery selector switched to both doesn't that do the same thing without having to wire the banks as one? and that way I can still charge them as 2 banks but use them as one bank.

There is a good chance i'm making this more complicated then it needs to be. A further explanation would be greatly appreciated.


I will be using all big wire, crimped connections, and fuses. Just looking at what crimper to order right now

[barnakiel]

Why 2 house banks in a 26' boat?


Why 500Ah house capacity on a 26' boat?


Our boat (and ours is bigger! by a whole foot!) is wired on one house bank and one starter battery. The house is about 100Ah. The relay is not ACR type, only plain banana QUALITY brand relay.



We do not use any 1-2-both-off switches.


1) skip the black wires, draw only the hot wires, this simplifies reading.


2) review the fuse panel area - it is wired to both + and - (???). This is safe but the fuses will burn immediately. ;-)


3) review the relays area - if these are automated and set at same V point, in some situations you will be depleting all three batteries at the same time.


My own attitude is to never deplete the house bank while starting. Just start from the engine battery and if this goes dead then manually switch to the house bank (a 1 or 2 type switch, no both and no off positions)



Also notice how you wired the sources you cannot charge one battery only. This is bad practice, if you want to quickly recharge the start bat only (e.g. with solar panels).


In other words, I would vastly simplify this, unless you have a good reason not to!



My 2 cents. Hope helps you a bit as our boats seem similar.



Cheers,
b.

[john61ct]

Originally Posted by madprops

How do I wire the two banks as one big house?

In parallel, but of course having already purchased may make that less possible.


> The 2 banks will be about 5 feet away from each other
NP

> one of them is a solar style AGM bank and the other bank is a starting/AGM style. both banks are different brands of battery and they also have different Amp Hours

Yes problem. OK, merge the latter with your Starter, call it Reserve.

Point is get down to 2 rather than 3 banks.

> If I have the Bank battery selector switched to both doesn't that do the same thing without having to wire the banks as one? and that way I can still charge them as 2 banks but use them as one bank.



> There is a good chance i'm making this more complicated then it needs to be.

yes, especially by buying before finalizing your high-level design.

Read those threads I posted, google for other relevant ones, post new topics to new threads before spending (wasting) more money.

[john61ct]

Originally Posted by Jammer

The ACR is really just a convenience, and they eventually fail.

Most might, but not all

Never seen, or even heard of one of these doing so

https://www.bluesea.com/products/762..._-_12V_DC_500A

Of course an exception or two just proves the rule 8-)

[roverhi]

Curious as well why such big battery amperage. Are you going with electrical propulsion?? That much battery storage will definitely affect boat trim on a small boat like yours.

Not a big fan of AGM batteries. They are great if you keep them charged up but that's not usually the case with a cruising boat. Okay if you are hooked to shore power or have too much solar/wind charging capability. Other than that they'll live at less than optimum charge which negatively affects AGM's way more than lead/acid batteries. Golf Cart batteries are way cheaper $95 dollars at Costco last time I checked) and very tolerant of extreme abuse which to me make more sense unless you have money to burn.

[Q Xopa]

Originally Posted by john61ct

Most might, but not all

Never seen, or even heard of one of these doing so

https://www.bluesea.com/products/762..._-_12V_DC_500A

Of course an exception or two just proves the rule 8-)

For me an ACR is more reliable than a 'manual' switch. I find this man fails regularly.

[madprops]

Originally Posted by barnakiel

Why 2 house banks in a 26' boat?

Why 500Ah house capacity on a 26' boat?

2) review the fuse panel area - it is wired to both + and - (???). This is safe but the fuses will burn immediately. ;-)


3) review the relays area - if these are automated and set at same V point, in some situations you will be depleting all three batteries at the same time.

My own attitude is to never deplete the house bank while starting. Just start from the engine battery and if this goes dead then manually switch to the house bank (a 1 or 2 type switch, no both and no off positions)

Also notice how you wired the sources you cannot charge one battery only. This is bad practice, if you want to quickly recharge the start bat only (e.g. with solar panels).

In other words, I would vastly simplify this, unless you have a good reason not to!

My 2 cents. Hope helps you a bit as our boats seem similar.

Cheers,
b.

Sorry I forgot to update my profile. I am the proud new owner of a 39 foot steel cutter. It needs a bunch of welding above the waterline but that ok because i'm a certified welder.

The ground to the fuse box was just my way way of saying i know everything hooked up to the box needs to be grounded

Could you explain your point number 3 a bit better i'm not sure I understand that?

I am only going to use the starting battery for starting, the others would be used if something happened to the starting battery. and even so i have a booster pack on board that can jumpstart a 10L diesel engine

Thanks for your help and taking the time to respond.

[madprops]

Originally Posted by john61ct

Most might, but not all

Never seen, or even heard of one of these doing so

https://www.bluesea.com/products/762..._-_12V_DC_500A

Of course an exception or two just proves the rule 8-)

I was looking at those, but I was hoping to not spend 275 USD on one, especially because I need 2

[madprops]

Originally Posted by roverhi

Curious as well why such big battery amperage. Are you going with electrical propulsion?? That much battery storage will definitely affect boat trim on a small boat like yours.

Not a big fan of AGM batteries. They are great if you keep them charged up but that's not usually the case with a cruising boat. Okay if you are hooked to shore power or have too much solar/wind charging capability. Other than that they'll live at less than optimum charge which negatively affects AGM's way more than lead/acid batteries. Golf Cart batteries are way cheaper $95 dollars at Costco last time I checked) and very tolerant of extreme abuse which to me make more sense unless you have money to burn.

forgot to update my profile, I have a 39 foot steel cutter now. I picked those batteries because they were almost free and I had to either take them they would have been given to someone else. Since all the ones on my boat are dead I thought I would take them.

I can have up to800 watts of solar and right now the only thing that needs power is lights. I'm going to add a 12v fridge, chart plotter, auto pilot, and there is a hot water tank and pressure water (also charging phones/cpu and other stuff). So I don't think I will be drawing them down to much, I could add 400w of wind if I needed to.

I have only hooked up to shore power once in the last 2 months and it was only for a day, I'm on the hook 99.9% of the time and I have just been using the foot pump for water.

[madprops]

Originally Posted by john61ct

In parallel, but of course having already purchased may make that less possible.


> The 2 banks will be about 5 feet away from each other
NP

> one of them is a solar style AGM bank and the other bank is a starting/AGM style. both banks are different brands of battery and they also have different Amp Hours

Yes problem. OK, merge the latter with your Starter, call it Reserve.

Point is get down to 2 rather than 3 banks.

> If I have the Bank battery selector switched to both doesn't that do the same thing without having to wire the banks as one? and that way I can still charge them as 2 banks but use them as one bank.



> There is a good chance i'm making this more complicated then it needs to be.

yes, especially by buying before finalizing your high-level design.

Read those threads I posted, google for other relevant ones, post new topics to new threads before spending (wasting) more money.

I did read the threads thank you for posting them, I saw two of them before.

The batteries were basically free so no money wasted. its not great that i have 3 different types of batteries on board but as long as I can come up with a plan to hook them all up ill be ok (I can also get 80% of my wire for free)

I don't think there is a good way to get down to 2. another poster said to just wire in the start and just have one selector, I think i'm going to do that. it would make things a bit easier.

Do you know of a way that I can split my alternator charge between two banks? If i could have the alternator charge the starting battery and the large bank I would only need one ACR. So far the alternator split charges i have seen only put out 10 or 15 amps to each bank, If there was one that did 30 amps x 2 that would be perfect

[madprops]

Originally Posted by Jammer

Sure, that will work.


I would dispense with the selector switch for the starter. Just leave it wired up to the start battery with a disconnect. If your start battery is dead you can jumper house to start manually, or your ACR may have an override of some kind (many do).

You could also get rid of the ACRs and just use manual switches. The ACR is really just a convenience, and they eventually fail.

Thanks for the tip, new plan is to only have one selector switch. and leave the starter battery hooked up. I have a boost pack that will work on the motor if the starter battery fails.

Do you know of a way to get the alternator to split its charge evenly between two banks? If I could do this I would only need 1 ACR.

[john61ct]

OK, free changes things.

"Splitting" alt output is best done direct wiring it to the biggest bank or the one deep cycled most ideally, then using ACR / VSR / combiners to open the parallel connections only while a charge source is active.

Much better than using manual switches.

Look for a voltage setpoint all three are happy with.