No genset on my boat

Presentation said:
Just a tip; during the couple of minutes when your wife is using the hair dryer I would have the engine running that is connected to the house batteries. I can’t remember right now if the house battery charges off the starboard or port engine. Maybe someone else here remembers.
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Just curious, I have 2 cranking batteries, no deep cycle and thought of adding a 3rd (deep cycle). I was told that the alternator is not sufficient to re-charge the deep cycle unless you were running for several hours. If I change one of my cranking batts to a deep cycle and add the other deep cycle in series with the batt isolator seperating A (cranking) and B (2 x deep cycle) will this set-up recharge if not hooked to shore power? I was also told by the same individual at a nearby ship store that the deeps are good for about 140 minutes of 20v output??? All new to me and well out of my scope of comprehension but I'm willing to look in to this. Any thoughts?
 
You ask a complicated question. Yes, it will take several hours for a 60 amp alternator to recharge your 80% discharged deep cycles. That assumes you have a 60 amp alternator, you have a big battery or a number of batteries, and it/they is/are deeply discharged. Your reserve minutes depends on the battery(s) and the number of amps you are drawing. You can get well over 400 minutes of reserve at at 25 amps constant draw with two 6V golf cart batteries that cost $125 each. There isn't any one stock electrical item on your 12V system that would use >25A constantly. You probably wouldn't hit 25A with all the lights on and radio/TV. If you change your cranking battery to a deep cycle you might not have enough cold cranking amps to turn over your engine. Cranking batteries have immmediate bursts of big amps. Deep cycles have long reserves of low amps. It has to do with the surface area and thickness of the lead plates in the battery. You really need a cranking battery, unless you have multiples of deep cycles to add up to the amps to crank the big engine you have.
 
JuliaValentine said:
You ask a complicated question. If you change your cranking battery to a deep cycle you might not have enough cold cranking amps to turn over your engine. Cranking batteries have immmediate bursts of big amps. Deep cycles have long reserves of low amps. .
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Thanks, I plan to keep one cranking and change the other cranking to 2 deep cycle. BTW... you give complicated answers as well:smt101
 
JuliaValentine said:
The boat is in the showroom, so I can crawl around the bilge and learn where everything is. In '08, I'm replacing the house deep cycle with 2 6V golf cart batteries. The cranking batteries will be isolated from the house bank with the battery switches, so they will never be run down. Under way, I'll charge the house bank by switching to "both." On the hook, I'll swithc to "2." With the reserve I'll have, the house bank will not likely be exhausted overnight by running the DVD, stereo, lights, etc. I'll use the cooler instead of the fridge. No need for a big inverter and 4 more batteries. You all helped me sort this out.
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Two things:

#1) It sounds like you plan to ‘switch’ the battery switch after you have the engines running. Be warned. With the engine running if you get all contacts off, meaning there is no battery connected to the alternator for even a fraction of a second your alternator will need replacement. Do not go past “none” on the 1, 2, both, none battery selector switch.

#2) With out Air conditioning, the dedicated house battery will have enough power. What group is the house battery now? I cant imagine a single group 31 battery would not have enough power for one night of TV/DVD, anchor lights, refrigerator, miscellaneous lights, etc.

Common battery size codes (ratings are approximate)
U1 34 to 40 Amp hours 12 volts
Group 24 70-85 Amp hours 12 volts
Group 27 85-105 Amp hours 12 volts
Group 31 95-125 Amp hours 12 volts
4-D 180-215 Amp hours 12 volts
8-D 225-255 Amp hours 12 volts
Golf cart & T-105 180 to 220 Amp hours 6 volts
L-16 340 to 415 Amp hours 6 volts
 
dpvandy01 said:
Thanks, I plan to keep one cranking and change the other cranking to 2 deep cycle. BTW... you give complicated answers as well:smt101
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Using a deep cycle battery as a starting battery

There is generally no problem with this, providing that allowance is made for the lower cranking amps compared to a similar size starting battery. As a general rule, if you are going to use a true deep cycle battery (such as the Concorde) also as a starting battery, it should be oversized about 20% compared to the existing or recommended starting battery group size to get the same cranking amps. That is about the same as replacing a group 24 with a group 31. With modern engines with fuel injection and electronic ignition, it generally takes much less battery power to crank and start them, so raw cranking amps is less important than it used to be.



Also, Marine batteries are usually actually a "hybrid", and fall between the starting and deep-cycle batteries. Performance is a mixture between a pure starting and pure deep cycle battery. The plates in the marine battery may be composed of Lead sponge, but it is coarser and heavier than that used in starting batteries.
 
Presentation said:
Two things:

#1) It sounds like you plan to ‘switch’ the battery switch after you have the engines running. Be warned. With the engine running if you get all contacts off, meaning there is no battery connected to the alternator for even a fraction of a second your alternator will need replacement. Do not go past “none” on the 1, 2, both, none battery selector switch.

#2) With out Air conditioning, the dedicated house battery will have enough power. What group is the house battery now? I cant imagine a single group 31 battery would not have enough power for one night of TV/DVD, anchor lights, refrigerator, miscellaneous lights, etc.

Common battery size codes (ratings are approximate)
U1 34 to 40 Amp hours 12 volts
Group 24 70-85 Amp hours 12 volts
Group 27 85-105 Amp hours 12 volts
Group 31 95-125 Amp hours 12 volts
4-D 180-215 Amp hours 12 volts
8-D 225-255 Amp hours 12 volts
Golf cart & T-105 180 to 220 Amp hours 6 volts
L-16 340 to 415 Amp hours 6 volts
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It is very difficult to get the stats of the new boat batteries. It is my impression that a boat dealer is also a certified dealer for a particular brand of battery. My dealer is an Interstate Battery dealer. I believe, but could be wrong, that Sea Ray doesn't list the specs of the battery, because the dealer chooses and installs the battery. Dealers sell many different brands. There may be minor difference in battery needs per region. Maybe the dealer gets an allowance for the battery from Sea Ray. The dealer told me the boat comes with 2 engine cranking batteries and one true deep cycle house battery. The service manager said the house battery is a 110 Amp-hr 12V battery. Batteries are probably the most common item to fail on a boat. You can't have enough back-up when it comes to batteries IMO. It is cheap insurance.

Thanks for the warning on the battery switch. If I keep it on "Both" to charge the house bank under way, will the cranking battery become discharged by trying to even out with a discharged house battery?
 
Search this site for more info, but some experts have told me that you don't even want to mix new batteries with old ones let alone deep cycle with cranking batteries. I had the same plan initially as well. The problem is that mixing old with new will cause the new ones to get over-charged (burned?). The same problem happens when mixing deep cycle with regular.
 
Four Suns said:
I vote for shaving your wife...
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It doesn't need to be that drastic. We got our boat and my wife cut her hear to shoulder length and bought a ball cap. Hair cut $60. Ball cap $17.50, peace on the ship, priceless.
 
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geriksen said:
That is what we do in Texas.
Gen and A/C are a must down here.
We have installed them in twenty five footers and performance boats!
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What's the average charge for parts and labor on the install?
 
well, that is the problem
it usually runs around 10k by the time it is done
It is usally easier and cheaper to get a gen set installed when the boat is built
a good shop can do an installation that looks "factory" and works properly, it is just harder to do when the boat is already built.

sometimes, folks will want a generator and it makes more sense for them just to get another boat. however, if you would be buying another new boat and you like your current boat the 10k might be cheaper

some people like inverters but personally I don't care for them. running an A/C unit off one is just not practical. batteries are large and heavy and require frequent maintenance. the inverters themselves tend to be pretty tempermental as well.
 
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