Do I have a dedicated start battery?

[stormalong]

Not one of the posts so far has asked how you use your boat.

If you are primarily a day sailor with the boat in a marina most nights what you have is adequate.

On the other hand, if you are a live aboard cruiser or keep the boat on a mooring the antiquated off/1/both/2 switch is not the proper way to manage your electrical system. With the off/1/both/2 switch you have to manually manage your battery power. If you have no alternative power source, such as wind and/or solar this old style setup will leave you in a fix some time or another.

Combining the batteries with the switch and forgetting to separate them after charging could leave you with no battery power when you need it. That is where a battery combiner helps you. When a charging source raises either battery to a preset level the batteries are joined and both get charged. When the charging source goes away the batteries are separated and only one will be discharged. One battery can be designated as the house battery and the other is strictly for engine start. You would not have to switch anything, or remember when to switch between batteries. In this setup one battery would be wired to the engine and the other to the house loads. And the engine battery can be a cranking battery, designed to provide a lot of power for a short interval while the other battery can be a deep cycle, designed to provide less power for longer periods.

There are other changes that need to be made for a "bullet proof" electrical system. One is a higher capacity alternator with a smart regulator designed to properly charge a deep cycle battery quickly. Without the proper voltage regulator your batteries will never be recharged properly and will die an early death. typical internal voltage regulators are not designed to do this job. Another is a passive charging source like solar to keep the batteries topped off without having to run the engine.

[DoubleD]

I appreciate all the posts and have learned more about battery systems on boats. The boat has a Heart Interface LINK 2000 monitor tied into both batteries. As stormalong mentions, how a boat is used is a big factor in requirements and use of a system. The boat is moored at a marina, so shore power is always available. For the next few years I will be using the boat for day sailing and weekend trips, with hopefully at least a few weeklong trips. I live in the US PNW and with it being fall now, my intentions are to use it through the winter, but we’ll see. I do have one flexible solar panel on the bimini, but don’t know the brand or rating. I haven’t tested the direct output at the panels yet. For the past couple weeks I haven’t plugged in the shore power and the solar seems to be keeping the batteries topped up. But as I mentioned I live in PNW and in a couple weeks don’t expect to see the sun until spring. So solar output will be unreliable. The 12v electrical load on the boat is fairly low in my opinion. Engine start of course, cabin lights, water pump, basic instruments, fans for diesel heater and charging cell phones, etc. When I brought the boat up from Seattle on a four day trip, with 22 hours total travel time, we motored 85% of the time due to lack of wind, so not a good real life battery load test. Again, thanks for all the input.
DD

[GrowleyMonster]

Originally Posted by stormalong

Not one of the posts so far has asked how you use your boat.

If you are primarily a day sailor with the boat in a marina most nights what you have is adequate.

On the other hand, if you are a live aboard cruiser or keep the boat on a mooring the antiquated off/1/both/2 switch is not the proper way to manage your electrical system. With the off/1/both/2 switch you have to manually manage your battery power. If you have no alternative power source, such as wind and/or solar this old style setup will leave you in a fix some time or another.

Combining the batteries with the switch and forgetting to separate them after charging could leave you with no battery power when you need it. That is where a battery combiner helps you. When a charging source raises either battery to a preset level the batteries are joined and both get charged. When the charging source goes away the batteries are separated and only one will be discharged. One battery can be designated as the house battery and the other is strictly for engine start. You would not have to switch anything, or remember when to switch between batteries. In this setup one battery would be wired to the engine and the other to the house loads. And the engine battery can be a cranking battery, designed to provide a lot of power for a short interval while the other battery can be a deep cycle, designed to provide less power for longer periods.

There are other changes that need to be made for a "bullet proof" electrical system. One is a higher capacity alternator with a smart regulator designed to properly charge a deep cycle battery quickly. Without the proper voltage regulator your batteries will never be recharged properly and will die an early death. typical internal voltage regulators are not designed to do this job. Another is a passive charging source like solar to keep the batteries topped off without having to run the engine.

A smart regulator is indeed a very good idea. A good stop-gap measure is good instrumentation for monitoring current and voltage, and an adjustable regulator to manage the charge algorithm manually. This can be as simple as a diode or two, switched in or out of the sense wire circuit.

I do occasionally see that someone has upgraded to a bigger alternator and had problems with belts wearing out too quickly. I mean just EATING those belts. If an alternator is run by a single vee belt, you are really very limited in how much mechanical load you can put on belt and pulleys. A serious alternator upgrade also calls for a pulley and belt upgrade. Two, three vee belts, or flat belt. You can run a lot of power with the right belt and pulley setup. There are a LOT of EP boats using a belt drive for propulsion, especially in the DIY crowd, because it is so simple to change the reduction ratio to fine tune for efficiency. And that brings up another point. An alternator definitely has a preferred operating speed, and of course a diesel auxillary is ran mostly at a particular speed chosen by the skipper, and the meeting of the minds is in the relative pulley sizes. DIY alternator upgrades should be done with a lot of study on the matter, before buying a bunch of stuff. Also it should be remembered that alternators fail. More specifically, regulators and rectifiers fail more than the alternator itself. Brushed alternators of course, the brushes can wear out. Sometimes the fix is simple, but the fast, RIGHT NOW fix is to change the alternator for a spare, so keeping a spare is one hell of a good idea. Alts and starters. I always have spares for those! Especially if the diesel doesn't have hand crank start capability and I don't have solar, or the weather is gloomy.

[Ballsnall]

Originally Posted by stormalong

Not one of the posts so far has asked how you use your boat.

Maybe because the op asked a specific question regarding his dual battery set-up and battery switch operation. If the op wants to change his electrical and charging systems then I'm sure your advice will be very beneficial to him once he describes what his objectives are regarding , usage, cost, power requirements, charging sources, available space, total current system components etc. Until then, I think his question has been answered extremely well be several posts already.

Your advice to upgrade his alternator & regulator etc is all a bit premature if his current system is adequate for his current needs at this time.

[OndinePLC]

My 1985 Caliber 33 has a selector switch on the panel which determines which of the two similar batteries (or both) connects to the panel and house loads.
It has a second selector switch in the battery compartment which selects which battery/combo connects directly to the starter + terminal via heavy short direct-run cables.
I don't know if this was standard or a retrofit.
Normally in the marina the motor switch is off, so nobody can start the motor and a short in the starter/solenoid cannot start a fire (as happened to me once on a different boat at anchor).
Both batteries are the same type and size, I use the newer one for the starter as it probably is capable of giving more maximum current to crank the engine faster. The house battery amp-hour capacity is more important than its max. amp capability.
The anchor windlass breaker is connected straight to the starter battery, inverter to the house.

The alternator and charger connect to both batteries through diodes. The wind and solar chargers connect to the house battery.


One of these days I might install a third similar battery in parallel with the house battery.
Simple but effective and economical for this size of old boat.


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[GrowleyMonster]

Originally Posted by OndinePLC

My 1985 Caliber 33 has a selector switch on the panel which determines which of the two similar batteries (or both) connects to the panel and house loads.
It has a second selector switch in the battery compartment which selects which battery/combo connects directly to the starter + terminal via heavy short direct-run cables.
I don't know if this was standard or a retrofit.
Normally in the marina the motor switch is off, so nobody can start the motor and a short in the starter/solenoid cannot start a fire (as happened to me once on a different boat at anchor).
Both batteries are the same type and size, I use the newer one for the starter as it probably is capable of giving more maximum current to crank the engine faster. The house battery amp-hour capacity is more important than its max. amp capability.
The anchor windlass breaker is connected straight to the starter battery, inverter to the house.

The alternator and charger connect to both batteries through diodes. The wind and solar chargers connect to the house battery.


One of these days I might install a third similar battery in parallel with the house battery.
Simple but effective and economical for this size of old boat.


.................................................. ............................................


True sailing adventures by Cris Robinson;


A Small Slip and Desperate Deliveries



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Not bad. My guess is it is a retrofit. Two battery switches might confuse a first time boat owner, is all.

What are your thoughts on installing your third battery near your windlass, so you have a shorter cable run for that occasional but large load? That's what I will be doing, when I ever get around to installing one of the TWO windlasses that I have for this boat.

[OndinePLC]

Originally Posted by GrowleyMonster

Not bad. My guess is it is a retrofit. Two battery switches might confuse a first time boat owner, is all.

What are your thoughts on installing your third battery near your windlass, so you have a shorter cable run for that occasional but large load? That's what I will be doing, when I ever get around to installing one of the TWO windlasses that I have for this boat.

Not on this size boat. The windlass is 12V, 1000watt, with a 100 amp breaker which has never tripped in use. The cable run is 40 feet and I selected a cable size (#6 if memory serves) to give about 1 volt drop at 100 amps.
I always run the engine when using the windlass so the alternator takes most of the load and the battery terminal voltage is around 13.5V, providing a windlass voltage of12V or more.
I use the motor to take the strain off the chain and electrics when hauling anchor.


I prefer to have all my batteries in one space with adequate hydrogen ventilation, keeping weight out of the ends of the boat.


On other punters bigger boats with longer cable runs, more powerful windlasses, more batteries and maybe also bow-thrusters, I have installed bow batteries, but for my personal preference small is beautiful and the simpler the better.

[stormalong]

Originally Posted by GrowleyMonster

What are your thoughts on installing your third battery near your windlass, so you have a shorter cable run for that occasional but large load? That's what I will be doing, when I ever get around to installing one of the TWO windlasses that I have for this boat.

I never liked the concept of a battery forward.

Using heavy wiring to the house bank means that with the engine running the alternator can provide a lot of the power to the windlass.

A battery is heavy. The bow is the place of most motion on the boat. A battery forward must be extra secure to handle the motion in rough weather. You already have a lot of weight forward: anchor(s), chain and windlass - not a great place to add weight.

You are better off adding another battery to your house bank. Then the power can be utilized by all the boat's loads and reduce your depth of discharge of the house bank.

This topic has been discussed many times on many cruisers forums. Both camps seem to be intractable.