How am I supposed to wire Batteries properly?

[Stu Jackson]

Originally Posted by smac999

with a single swtich there is no separation of house and starter loads. both are on the common post coming from the same battery selected. unless you have multiple switches. I put the add a battery kit onto a lot of sail boats and they all work great.

your comment on sail vs motor makes no sense. all the electrical is identical and both will have the same issues. the only difference is power boats will have more charging time from alts.

the power boats I work on go the same places, drop anchor for the same amounts of time, and have similar power draws as the sail boats I work on. electriclly they are no different.

I did say: ..."but if you read the links I provided earlier, there are various wiring and switching diagrams that address completely separating starting and house loads."

Maine Sail & I simply disagree with you about the application of the dual circuit switch in sailboats. Did you bother to read the link I provided? It explains in detail just why it is NOT a good idea. And also why it does work for boats that start and stop their engines much more often than sailboats and have much smaller house banks.

For the OP, this discussion about the merits and demerits of this Blue Sea concept has been going on for quite some time. Those of us who have been investigating sailboat electrical systems for many years have written quite a bit about with good reason. I have given you a link to a long article by a trusted marine electrician (Maine Sail) who posts here and on many other boating forums. Some other people think it's just fine. We simply disagree, with what we believe is good reason.

Your boat, your choice.

[reed1v]

Originally Posted by SteveInMD

1/2/All battery switches are old school. These days one large bank is considered the best way to go. It's less hard on the batteries to have All on all of the time, draining them 1/2 as far down. Just use a simple On/Off switch rather than the 1/2/All. Add a separate starting battery if you can.

Good idea but for the problem that if one cell goes bad, it can drain the entire bank.

[Clivevon]

Instead of a 1-2-both-off switch, these days you can use an automatic electrical relay switch which means both the engine and domestic banks are connected when the engine is running, but separated when it is not. Make sure the relay switch is big enough to handle the charging current from your alternator.

For wiring together multiple batteries to make one big battery for the house (domestic) bank, look at this site:

SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank

Your batteries will last longer wired as suggested here.

Hope that helps.

[mitiempo]

Originally Posted by Stu Jackson

Maine Sail & I simply disagree with you about the application of the dual circuit switch in sailboats. Did you bother to read the link I provided? It explains in detail just why it is NOT a good idea. And also why it does work for boats that start and stop their engines much more often than sailboats and have much smaller house banks.

Stu

I used to feel the way you and Mainesail do about the dual circuit switch but now I feel it is, while not the best choice, better than a 1/2/both switch that is most often used incorrectly. My first choice is 2 separate switches - one for engine starting and one for house loads, with a third crossover switch for starting with house bank or using engine battery for house loads if needed.

*Others may not understand the powerboats you are referring to are smaller boats with one battery in each bank.

[btrayfors]

I agree with mitiempo, and have done installations with 3 ON-OFF switches, such as this one:



Here's a circuit diagram which works very well and utilizes a single ON-OFF switch and a traditional 1-2-Both-Off switch which also provides the COMBINE feature for emergencies:



Bill

[NorthCoastJoe]

A simple Battery Isolator would do the job.

All grounds to a engine block,

Alt + goes to isolator, then isolator outputs go to each battery.

This is commonly used on rv and campers to keep starting battery and house charged. The starting battery gets priority in charging when it is fully charged then the house battery gets full alternator output.

The only switch if you want one would be a on/off for the house battery.

https://www.batterystuff.com/battery.../bi303306.html

I have used them for over 20 years with no problems.

[btrayfors]

Originally Posted by NorthCoastJoe

A simple Battery Isolator would do the job.

All grounds to a engine block,

Alt + goes to isolator, then isolator outputs go to each battery.

This is commonly used on rv and campers to keep starting battery and house charged. The starting battery gets priority in charging when it is fully charged then the house battery gets full alternator output.

The only switch if you want one would be a on/off for the house battery.

https://www.batterystuff.com/battery.../bi303306.html

I have used them for over 20 years with no problems.

NCJoe...

What works in an RV environment may not be appropriate in a marine environment. Why? Because isolator diodes drop the voltage enough to ensure that -- without special precautions and circuitry -- the batteries will never reach a full charge. Generally, the voltage drop with most isolators is on the order of 0.4 volts.

This exacerbates the battery-unfriendly situation on many boats, where the charging voltages are too low anyway. For example, a good quality deep-cycle battery like the Trojan T-105 requires 14.8-15.0 VDC absorption voltage. Most alternators don't put out more than 14.2-14.4 VDC. Insertion of an isolator in the circuit would drop the charging voltage to 13.8-14.0 VDC.....too low for effective battery charging, especially in sailboats where the motor isn't run full-time.

That's why for some years now the general recommendation by almost all marine electricians is to NOT use battery isolators. Rather, the preferred method these days to to run ALL charging sources directly to the house batteries and use an ACR or voltage-follower device like the EchoCharge or DuoCharge to automatically maintain the start battery which, anyway, requires very little charging.

Bill

[reed1v]

Betrayfor has it right. BTW here is a tip in case your batteries do run low and you are stuck with not enough from either to turn over the engine. Run them in series. The extra voltage often is enough to get starters to turn over. Diesel starters normally can withstand the extra voltage for short bursts. And they will turn over fast. Have done this several times from ancient batteries when parallel or individually would not work.

Just be sure all other electronics hooked into your power system are turned off, otherwise you will fry them.

[SteveInMD]

Originally Posted by btrayfors

I agree with mitiempo, and have done installations with 3 ON-OFF switches, such as this one:

Attachment 123886

Here's a circuit diagram which works very well and utilizes a single ON-OFF switch and a traditional 1-2-Both-Off switch which also provides the COMBINE feature for emergencies:

Attachment 123887

Bill

This is a great setup. Go this route if you can.

[nigelmercier]

Originally Posted by sailorchic34

Run the negative terminals to the engine...

Very dangerous as a general statement. May be applicable in this context, but many engines must be isolated from the negative.

[mitiempo]

Originally Posted by nigelmercier

Very dangerous as a general statement. May be applicable in this context, but many engines must be isolated from the negative.

The best connection on the engine for the negative is starter negative.

[Golden Echo]

The best and easiest way to do this is to have all the negative called from your batteries end at a buss bar somewhere in your engine compartment or anywhere there is easy access. Have all negatives connect there and the have a single line connecting that to your engine. Make sure you get a buss bar that can handle the amperage of your bank. You are correct in wiring your alternator directly to your house bank, but make sure you fuse the positive wire within 7 to 12 inches from the battery. The fuse should be 140% of the rated capacity of your alternator. I know there are grammatical errors here. I can't stand this damn auto correct. I want to tell you more but I'm too damned frustrated!!!!

[leftbrainstuff]

Originally Posted by Ebtvision

I'm rewiring my boat (27" Newport) shortly and need some clarification on how to wire the batteries. It'll be a starting and house battery (regular kind not gels or anything), going to a 1/2/All switch.

I'm not exactly sure where the negative terminals will go.

The positives of each battery will go to the appropriate positive terminals of the switch, how should I be connecting the negative terminals to my distribution panel?

I have a blue sea breaker panel with a negative bus bar and grounding bus bar. Somehow I need to get both battery negative terminals to the negative bus bar? And at the same time also get both battery negative terminals to one grounding wire to the engine bolt? I'm not quite clear on this.

----
note: I was planning on wiring the alternator to the house battery so that it removes the risk of one of my kids hitting the switch while motoring, etc.

I'd suggest you spend some time reading Calder and others.

You should start with a schematic. This way you can experiment before you start building.

You're looking to minimise cable runs, keep runs similar lengths. You also need to add bus bars for power takeoffs, trenches, panel cutouts, etc, etc.

Once you have your schematic share it on this forum. There are many good sparkies here.

Sent from my SM-N900T using Cruisers Sailing Forum mobile app

[Cheechako]

There's nothing wrong with your 1/2/all switch idea. Especially on a small boat with two simple batteries. You don't need the complication of 3 separate switch housings and related cabling on that boat.

[nicholson31]

If I can add another question regarding Batt wiring which may be of benefit to the OP,
how important is connecting the -neg and pos+ from alternate terminals, i.e neg from batt 1 and pos from batt 4, my case a 4 Batt house bank ?
Starter Batt is separate bank.

I have just discovered that my 4 12v Batts feed from the neg and pos posts from batt 1 and not alternate post of batts 1 and 4.
Not a big issue to run another wire lead but will leaving this configuration cause a significant imbalance between the batts when charging and/or during loads or should I change??