Trojan Boat Forum

Need some advice from you "wiring experts" I apologize in advance for the long post. I did this a few months ago, looked at it yesterday and thought to myself "what the hell was i thinking"! I want to clean this up so if you can follow me ill explain what I have. I will have three batteries total. center will be generator only port and stbd are house/starting. basically there is a negative/ ground bus bar at the bottom of the the pic under the solenoid , I'm replacing the two factory "push to reset" 60 amp breakers with blue sea 60 amp surface mount, ignition protected breakers that will mount on either side of the solenoid(you can see one of the old breakers on the right of the solenoid that I used for a temporary hook up to test everything). I have two positive dc leads that are the smaller gauge /faded wires entering through the gromet on the right (these are both temporarily connected to one breaker for testing) that handle all the house dc power and run back to the factory dc panel and are each connected to a breaker at the panel. the original dc neg for the house panel is entering through the closest hole on the left of the solenoid and is connected to the bus bar. the two green wires going to the bus bar are the from the ac panel . the white wire is the ground from the charger (the old charger showed white ground so I replaced in kind) and three 8ga red entering from the top right are the charger leads for each battery. the only addition to the factory wiring is a 4ga red and 4ga black that feed a blue sea fused distribution block I added to supply power to my instruments that I want to have continuous power to. I ran three separate grounds from the termination bar to each battery.
OK here is my new plan!
one neg lead from the bus bar to the 1st battery then continue it, jumping across to the next two batteries. positive leads from port and starboard batteries running to two individual battery switches (will mount on the outside of the battery box with connections entering from the inside) then run from the battery switches to the new blue sea breakers inside the box (bluesea 187 circuit breaker states "provided switching and circuit protection in one device, could this eliminate the battery switch?) I would then attach the port and starboard house power leads to their respective breakers as well as the lead to my added blue sea fuse block and then run a short jumper wire from the breakers to either side of the solenoid (as seen running from old breaker in the pic on the right) I would then run from each solenoid lug to each starter on the engines (the solenoid is so I can combine the batteries if needed to start the engines). the engine grounds will be run to the bus bar. The center generator battery will supply power only to the generator so I plan on using either a battery terminal mounted fuse , one of the inline terminal block fuse or another blue sea breaker??? All battery charger leads will be replaced with 4ga as per the new charger instructions.
should the neg from the gen battery be isolated from the other batteries and common bus bar ?
should I add battery switches or is the blue sea 187 switchable breaker good enough?
Am I missing anything or does anything concern you guys? I'm am striving to have an organized, safe, PRETTY battery box!
Thank you so much for even taking the time to read this.

Todd ,if you could make a diagram of your intended setup it may make it easier to critique--------just remember to take the neg off one end and the pos off the other end of your battery group if it is in parallel ----I would have the gen battery totally separate with no charger input if you only have three,and use a third battery as you are---total of four batteries---one house,two starts,one gen---of course it would all hinge on the room you have---Mike

How much power do you want to draw from your house bank at anchor?
I am not a fan of starting/deep cycle combo batteries.... they are a compromise. I like to have a stand alone house battery. The way my F32 was wired I compromised by putting the fridge, small inverter and stereo on my stand alone house battery leaving the lights, pumps on the starting batteries which are not a concern as I converted them ALL to LED. I also have one engine charging the house and/or it's starting battery using a switch and the other engine does it's starting battery.

You are not planning to connect the generator battery to the charger are you? I believe that most generators do their own charging of their starting battery while running.... so it's not needed and in fact is detrimental if both charger and genny are trying to charge the battery

Do you have the space to setup 4 batteries or even move the genny battery to near the genny since it only needs to be connected to the common grounds?
To answer one point all the battery negatives should be connected together... by daisy chain cables or by using a ground bus bar terminator. So your new plan works.
You did not mention fuses on the charging positive cables?
Are your battery switches easily accessed outside the engine room?

Feel free to laugh at my attempt of a sketch and my in-ability to post it without taking a picture of it!
I never liked the fact that the house draws off the starting batteries. You guys sold me on a 4 battery system. I can find someplace to mount a small starting battery for the generator. a few notes about my "picasso-esqe" sketch.
I left off the three leads from the charger as well as the ground. it says to fuse each lead with a 50amp fuse. whats the best way to do this?

although I would like to have battery switches outside of the engine room. since the switch needs to be close to the batteries the only effective way I know how to do this is with a remote battery switch ($150 each for blue sea systems pn7700)

My typical DC draw while on the hook consist of my Fridge (switchable ac/dc), radio (basic one, not external amps) Anchor light , cabin lights (switching to led bulbs) vacu flush but used only as needed. I've always used standard batteries. If I add a dedicated house battery is it worth going with a different type? (AGM etc?) if so I need to exchange my new charger for a different different one that can charge various battery types at once (my new one will different types as long as all 3 are the same)

Would you add a automatic charging relay so that one engine would charge the house battery but a low house battery would not drain that engines starting battery? or would you just use the genny or shore power to run the charger to maintain the house battery?

Sorry for all the questions. I would try to hire someone to help me get everything correct but after realizing how many "questionable and unsafe" things I've recently fixed that were done by "paid Professionals" I feel safer figuring it out myself!
I wish I could find a picture of the battery box before, rats nest would be an understatement!! and I paid a marina to sort it out LOL!

Todd , check out blue seas systems site, they have some schematics there that may help,I am guessing with some pricey stuff but anyway they have the fuse locations etc---- Mike

Read this guy:
http://www.stevedmarineconsulting.com/e ... x.php?p=13

Charger line fuses I used Blue-Seas Maxi Fuse Block.


Drawing looks good to me.
You could use an m-ACR for the engine to charge both start and house... or use an external smart regulator which will do a better job of bringing the house bank back than the m-ACR route.

I believe that by defining how heavily one uses the house then the other questions are easily answered.
AmpHr size of house. bigger the better (consider using golf cart style 6V twinned)
m-ACR or external smart regulator
i.e. short runs on the engine won't do much to refresh the house so genny will do that as you move from anchorage to anchorage.
AGM vs wet cell.. again if one is out a lot needing the house to be recharged quickly AGM does that.

I went AGM on house and then changed starting to AGM's when cash flow was OK.... in the interim I was charging wet cells as AGM's without any problems... especially as start batteries were often only lightly discharged.

Hi Todd,

In order to determine the capacity of the required house bank, take a look at every load that you may draw from it while on the hook. Your lights, toilet, fridge, etc will all have an amperage rating on them. Next, take the amp rating and multiply it by the amount of time that the load will be in use throughout the day for each individual load. For example, a refrigerator that draws 7 amps and runs for 15 minutes an hour will draw 1.75 amp/hours (7A x .25hr = 1.75 Ah) Multiply this by 24 hours and you require 42 amp hours for the fridge. Now add up all of the amp hours for a day and double it, this is the required house bank capacity. You should not drain your house bank down to less than 50% however some people prefer 60%. Draining the bank to less than this really taxes your charging system and reduces the life cycles of the battery bank. You can also size the house bank for multiple days on the hook however since you have a generator on board, you can use it to run the AC battery charger and top up the bank on a daily basis. I usually start my genny in the morning to make coffee and a tank of hot water, then let it run for a couple of hours to charge the house bank.

The house bank can be made up of a single large or multiple 12V, or It can also be made up of multiple 6V batteries wired in series depending on your requirements. My house bank is made up of 2 Trojan 6V T-105 batteries that give me a 230 Ah capacity.

As for charging the batteries off of the engines, somebody with twins may be able to better answer this question. On my single engine, I have a 70 amp alternator with the output lead hooked up to a battery isolator. The first lead from this goes to my cranking battery and the second to my house bank to that both battery banks charge while under way however they are isolated automatically when the engine is shut down. This can also be accomplished with an ACR as opposed to an isolator. For my generator battery, I leave the charging switch off on the generator and let third bank lead on my smart charger take care of it while on the hook or at the dock.

Battery requirement is a good place to start, then we can work our way up from there.

Hope this helps,

ABYC says to fuse within 7 inches of the battery. The only practical way I know to do that is with terminal-mounted fuse blocks. I used these when I re-did my charger:http://www.bluesea.com/products/2151/Du ... 30_to_300A

Some folks will call this heresy, but I use deep cycle batteries on both of my engine starting batteries. The generator gets a starting battery, but only because it never sees "house" loads. Deka actually says that a deep-cycle is suitable for moderate starting loads, which I'd say is the case for my 270's. If I was trying to start diesels or bigger gas engines, I might not go the same route. http://www.dekabatteries.com/assets/base/0149.pdf. For insurance, I usually use the parallel switch anyway, so that each of the allegedly not-for-starting batteries only sees half of the amperage draw that it otherwise would. I also put in the largest batteries that would fit in the box, which required a slight modification to the battery box lid. Two years, zero problems.

For a good treatise on batteries, you should read Nigel Calder's Boat Owner's Mechanical and Electrical Manual. I would steer away from AGM unless you need to mount them sideways or have too much money.

And there is no problem with a long post! What kills me is when folks ask "Why won't my engine start?" and provide no data. Information is good, because that's the only way to know what the heck you've done or what the symptoms are. I would say that more white space in you original post would improve readability.

P-Dogg wrote:ABYC says to fuse within 7 inches of the battery. The only practical way I know to do that is with terminal-mounted fuse blocks. I used these when I re-did my charger:http://www.bluesea.com/products/2151/Du ... 30_to_300A

+1
I use one of these on the house lead to the panel and on the alternator lead at the isolator. They are rated for the required current capacity which means that it would take a major event ti trip them but hey, you never know.

Michael, thanks for all the info and the link. I just read the whole thing! looks like I have some home work to do. Mike, I was just looking at the blue seas diagrams, every thing is becoming a bit clearer. Paul , Thanks! whats the benefits of the 6 volt batteries vs a 12? P-dog, I have calders book, obviously its been a while since I read it. Time to study again! I previously ran two size 29 dual purpose batteries as my starting / house and a separate starting battery for the gen. I guess I'll do some work on figuring out my battery needs then figure out how to fit the correct size batteries (a bigger box may be needed)

blue seas almost makes it look easy!
http://www.bluesea.com/systems/46/Twin_ ... ttery_Bank

Thanks Again Everybody!

yorklyn wrote: Paul , Thanks! whats the benefits of the 6 volt batteries vs a 12?

Todd,

For me it's simply a matter of packaging. The two 6 volt batteries are easier to handle and position than a single 12 volt battery of the same Ah rating.

Looking forward to your battery wiring project! I hope you document and write it up like in your other thread. I have a similar wiring mess to tackle.
Is there a better replacement for the solenoid/relay in the battery box?
I have all my batteries out and am cleaning up the mess. Would like to replace the solenoid/relay.

Bimmerbill wrote:...Is there a better replacement for the solenoid/relay in the battery box?.... Would like to replace the solenoid/relay.

Why do you want to replace the solenoid, is it broken? In my opinion, for the purposes of paralleling two banks in an emergency, the solenoid works just great and has no continuos draw in standby mode. Unless you're upgrading your system with an ACR that has a manual paralleling option from the helm, there's absolutely nothing wrong with using the solenoid. An ACR will typically have a continous small draw which can be undesirable in some cases. While some ACRs also parallel automatically during start-up, that is not always desirable, especially when it is paralleling a start bank with a house or dedicated electronics banks that is sensitive to the sudden heavy loads when starting an engine. Having said that, using an ACR or any other devise to charge two different types of banks (start and house), is not recommended in my opinion, but inevitably it gets done all the time.

I notice in the diagram above that there are breakers in the starter circuit. I don't see any problem with doing that as long as the breaker is properly rated, but a breaker there is not required.

I plan on it Bill! check out this for a new solenoid
http://www.bluesea.com/products/categor ... -Solenoids

Big D , the breakers are part of the factory system.

I'm picking up a harbor freight hyd crimper tomorrow for making custom battery cables. I started trying to calculate my house loads but other than the fridge an few lights and a few other things I haven't a clue how to be anywhere exact ? I believe I may try plan "B".

everywhere I researched basically said "theres no such thing as having too much reserve power" , I am limited on battery space. I checked my records and my old set up was two group 29 dual purpose batteries @ 125 amps each that served as my starting and house batteries and a starting battery for the generator. I only remember draining them to the point of not starting 2 or three times in the 5 years I ran the boat. Obviously draining them below 50% is a bad thing.

My main dilemma is that the battery box is designed with room for two 13" 1/4 x 7" 1/4 (group 27 or 31?) on either side and a single space thats 10"1/2 x 7" 1/4 in the center. I can also create a space for an additional battery under the platform directly behind the existing box (like bobct did) .

idea#1
I can put two isolated starting batteries and the gen battery in the existing box and add a box to house two 6volt trojan t105 which would give me 225amp house bank. (should have room to expand the house bank) Although I hate to not utilize the larger spots in the existing box

Idea #2
Two trojan t-1275 + (150 amp hr each 300 total house) , single starting battery shared by both engines in existing in existing battery box. Separate gen battery. the gen battery could be connected to starting battery by solenoid for emergency starting?

idea #3 existing battery box is 25" 5/8 x 18" 1/2 . I Have 28 inches between my stringers and the existing platform is 24" long, Moeller marine makes a Double 8d battery box that 27.50L x 24.50W x 11.62H.

Then I have to figure out where the heck to put all of the solenoids, switches and fuses?!?!?

Paul wrote:

yorklyn wrote: Paul , Thanks! whats the benefits of the 6 volt batteries vs a 12?

For me it's simply a matter of packaging. The two 6 volt batteries are easier to handle and position than a single 12 volt battery of the same Ah rating.

It is my understanding that the golf cart sized 6V batteries have thicker plates to withstand frequent discharging......
Along with the fact that high AmHr 12V batteries are v heavy.... On my Trojan I went 12v and it weighs 160lb on the President I went with 6v and they are 60lb each.