But if we use a battery and alternator system in our cars, because they both charge and recharge each other, why do this system not work on a boat, why do we need starter battery and deep cell battery? Please explain
Hope this is not a dumb one
- Thread starter hummingbirdbassist
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When you are in your car and running the wipers, radio, heater fan, you usually have your engine running, and it is charging the single battery under your hood. A sailboat does not have the engine running all the time to charge the battery, while you still need the 12 volts to power your radios, lights, etc. This will drain a single battery really quick, so you need the extra juice from several batteries. Running your engine will charge the batteries back up. I run 3 batteries in my boat, with solar charging and engine charging. This way i can anchor at night with lights on, radio, TV, etc. It's also good to have a second battery if you drain the only battery you have and you need to start your engine.
Lots of folks are concerned that they will draw down the batteries with "house" use .. to the point that they'll not be able to start the engine.
I have two deep cycles and no dedicated "start" battery.. I usually use one of the batts in an overnight and crank on the other.. then recharge both.. then the next night, I use the other one .. etc.. seems to work fine .. The problem comes when you have a lot of electrical drain and the normal alternator system can't completely recharge that battery .. so ya have to know your loads and keep track of what you are using .. and how it is going to be recharged.
I have two deep cycles and no dedicated "start" battery.. I usually use one of the batts in an overnight and crank on the other.. then recharge both.. then the next night, I use the other one .. etc.. seems to work fine .. The problem comes when you have a lot of electrical drain and the normal alternator system can't completely recharge that battery .. so ya have to know your loads and keep track of what you are using .. and how it is going to be recharged.
One works for us
Our only loads on the hook are the anchor light, cabin lights, depth gauge, and occasionally charging the phone.
Under way, the tiller pilot is a big draw, but we only use it when running the engine. We love to steer on the wind!
As I understand it, a starter battery is built to provide a lot of amps in a short time, while a house battery is made to provide lower amps over a longer period.
We like our boat simple! Both our bilge and sinks run off hand/foot pumps. If you load needs more than one battery, then you are better off tailor one to each function.
Our only loads on the hook are the anchor light, cabin lights, depth gauge, and occasionally charging the phone.
Under way, the tiller pilot is a big draw, but we only use it when running the engine. We love to steer on the wind!
As I understand it, a starter battery is built to provide a lot of amps in a short time, while a house battery is made to provide lower amps over a longer period.
We like our boat simple! Both our bilge and sinks run off hand/foot pumps. If you load needs more than one battery, then you are better off tailor one to each function.
Just to add to the comments. The two batteries are isolated from one another. The deep cycle battery runs all the equipment and lights on the boat. The start battery is just that, its only purpose is to start the engine. You could run the deep cycle down clear dead and the start battery would still crank up the engine. Once running, the engine will charge BOTH batteries.
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Replaced all the lights in my boat except the bow nav light and stern light with LEDs. Made a huge difference in the draw. Will be replacing the bow nav an stern light with LEDs this winter.
Ok, so I have 2 starter batteries, one 650cca the other 850cca thinking about using them in parallel and I guess now I need a deep cell battery! I want to be able to run what we want to at harbor, but what about shore power, do people not use shore power at dock, seems like that shore power would. Be the answer at harbor,,,,,,
Onecoolair, I'm saying I have 2batteries that I will use as some sort of battery bank and I need a deep cycle, but everyone is talking about using their setups at port and being able to run all gadgets and such, so why not just use your shore power plugs at night when at harbor and save all batteries period! Hope that explains my ramble better. Anyway things I need to do b4 spring, fix mast compression( any help out there give me a email, in Annapolis) get mixing elbow replaced on qm15, little wash/wax, bright work , fuels, water impeller, some other minor ifs and ands , then off the hard .
We use our H30 for mostly day sailing with occasional overnights. If you are not going to overnight you have enough batteries. First, if you are at the dock, the battery charger should take care of your charging needs. If you anchor during your daysails, run the TV or radio, don't have refrigeration, the two batteries you have should do, just replace one of the starting batteries with a deep cycle. Walmart has a Group 29 size that should work nicely. If you are planning on overnighting, you will need the additional battery. You should have a 1-2-ALL-OFF battery switch for any setup with more than one battery. Call the starting battery "1", the house battery(-ies) "2". Move the switch to 2 when you are away from the dock and plan to use TV, lights, etc. If you deplete your house batteries, you can then switch to "1" to start the motor. This is the simple explanation. You can get more complicated but this is the basic explanation of what is needed. Best thing is to talk to other people in the marina, they will be a great source of information and most likely willing to assist you in planning for your specific needs.
Jimmy
Jimmy
Trying not to make it more confusing, but a friend purchased a a/c to d/c converter to run 12 volt applications while at the dock. This requires more wiring and switching off of the batteries and onto 12 volt converted shore power. It worked well and saves using the boat's batteries while at the dock.
Here's the problem of your thinking which will not work correctly . When joining batteries together to create a bank the batteries need to be of same same size, age and make. Make sure they are equalized. Otherwise the weaker battery will always draw down on the better battery causing early failure. One good starter battery is all you should need..correction lets call it a starter/reserve. Maybe you can use the extra starter battery in your truck or power boat?....Go with as large as you can go bank of deep cycle batteries as your house bank. The larger the bank of batteries the longer the life span of the batteries...at least that is what my experience has been. My last bank of optima s lasted almost 18 years. Larger boats like mine usually have two large house banks. When I had my Mac26 I had just one large house and one start/reserve..That's all I needed at the time. In my case now I have a 1/2/both/off make before break house selector switch...I have 4 optima s all the same age and size for bank one and another 4 optima s the same size and age for bank two. Since these two banks are of the same size and amp ratings I will sometimes when out cruising and off grid for a long time. I will first check to see that they are equalized and then run them on both. I then have one optima start/reserve battery ....I have a second dedicated 1/2/both/off switch next to engine and its "C" post is connect to 30 amp min. breaker right next to it along with a second heavy duty momentary button for emergency use. I no longer leave starter connected 24/7 to battery....position one is start reserve, position two is connected to the "C" common post on house bank selector switch. I use house bank to start engine, reserve is just that an emergency reserve. While plugged into shore power my protect4 battery charger keeps all three banks independently monitored and charged. That's both house banks and start/reserve . When off grid engine alternator charges the house bank I have selected. My echo charger a 12 volts to 12 volts charger is connected only to alternator. It keeps emergency reserve/starter topped off as needed while engine is running. It sees very little use but is there if ever needed.
I did this for my Alder Barbour 12 volt freezer and it works great! The unit I installed has the capacity to do more like lighting etc....But have not felt the need yet.
- Dec 30, 2009
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Hum, I look at it like this, no matter what toys I am playing with, my deep cycle battery house bank that is made to discharge and charge over and over is fine. Before I repowered it was a crapshoot when I turned the key, and I did not have the starter battery to worry about. Most boat inboards on our older sailboats have a thousand other ways to fu*k you by not starting, My boat weighs in around 17k, and when I push the started button I want to hear that diesel. I have had a couple of close encounters, with lets just say hard shallow objects when that old piece of sh*t would not start.A fresh dedicated started battery is a must for me..Red
Paul F-Hope that was a "marine" converter your friend used. I don't think it is necessary as the charger does the same thing. See this link for RV vs marine charger/converters.
Jimmy
Jimmy
http://www.cruisersforum.com/forums/f14/differences-in-marine-and-rv-inverters-chargers-38195.html
Forgot the link for above post-fogive the elder moment-Jimmy
Forgot the link for above post-fogive the elder moment-Jimmy
The difference between a car and a boat is that in a car, you always have the engine running when using the electronics for any period of time (lights, radio, etc), but on a boat we may run electronics for hours, or days without running the motor or being plugged into shorepower. That would be like leaving your car headlights on over night - you know what happens when you do that. You separate the banks (Starting and House) so that if, and when you finally do, drain the house bank, you still have the starting bank to start the motor and charge back up.
If you never, or at least rarely and for only short durations, use electronics unless your plugged in, or have the motor running, you should be fine with only a starting bank, but thats more a use case for a runabout power boat, or daysailor, not a cruising sailboat. Also, a starting battery isn't really made to be deeply discharged - It can do it a couple times, but will hurt it much more then a deep cycle which is designed for it.
Jimmy ......
For a long time I used my marine battery charger to run my 12v Adler Barbour freezer. 24/7 off the battery house bank. With a constant draw on the batteries. The battery charger would monitor and charge batteries as needed. This means that there was a constant working load or draw down on the house battery bank. Which the battery charger had no problem doing . But after having a ground failure on circuit board of 10 year old battery charger and freezer as well as other loads that totally depleted my battery bank 2 down to about 3 volts. When boat was left unattended for a few weeks.
After I repaired the grounding issue on battery charger I decided that the continuous 12 volt power supply was the way to go for me.
By using a 120 volt to 12 volt regulated continuous rated power supply while on shore power at the dock I believe this may help extend the life of my charger as well as house battery banks. The power supply I found is marine rated and is large enough that it can take and run other 12 volt loads.
So for me.... and my needs the new setup is working great and I have been quite pleased.
BTW...
My 8 year old four optima's on bank #2 have survived and are back to life. They readily came back to being equalized with the other four optima's on bank#1 ... So I have reason to be quite please with my choice of absorbed glass mat batteries. Which was not to difficult since my last set of optima's lasted about 18 years. In fact I still have one of these optima's left which my dad likes to keep on hand stored in the garage. In fact he had it out the other day (because the less then 2 year old duralast gold :cussing: in his truck totally died and he need to get to the store for the 3 year warranty free replacement of the duralast)... I believe the old optima's resting voltage was still at about 12.2 volts.
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