hotjava66

I have a similar set up as you. I run 3 batteries, 1 group 31 deka marine to run the stereo and accessories, and one starting battery for each motor. I have never run down my stereo battery in a normal days use (4-6hours) and can switch to either of my starting batteries if I need to.

russellhorn

Cant say enough good things about my Odyssey batteries http://www.odysseybatteries.com/ . I would burn through 2 batteries that came with the boat at night and pray the motor would turn over in the morning...left me stranded twice. Switched to Odyssey and can get by easily on one by itself plus no problems turning the motor over the next day. This is where I bought them http://www.odysseybatteries.com/batteries.htm . BTW I use the 34M-PC1500 and they are made in the good ole USA

GTOFFSHORE

Running the gen in bilge is bad idea. You will have to run lines for exhaust to be safe. More batts are the answer but have to be right ones. Ody batts are dekas relabled. They are all made by the east penn batt company. Even napa marine batts are DEkas. Size matters as well as whats inside. Dekas will truly work miracles for you.

Irishtornado

It won't work Wayne. You'll be dead in 3-4hrs. You recall having to jump me right? I'm running 2 Kinetic 2400's and 3 Optima Blue Tops. I'm looking into the honda generator to power my shorepower when tied up.

Baja_man

After further advise I think I am just going to run 4 batteries....3 for stereo and 1 for starting. I cant see putting any more than that in just for the stereo. I will just have to charge every night.

The Honda generator would probably be the best for you. should be able to keep up with no issues. I know someone last year did it at Jobbie from the group.

Baja_man

MC or anyone really,

Does anyone have any experience with BatCap?

http://batcap.net/Home/tabid/36/Default.aspx

Are these just another "Kinetic" or similar brand?

wjb21ndtown

Does anyone have a schematic on how to properly wire the battery switches? It is a complete mystery to me! My switches don't seem to ever completely isolate ONE battery, even if I have both switches set to one or the other. It's maddening!

Also, Baja, with their wealth of wisdom and foresight, thought that it would be a great idea to put the switches in the engine compartment (where you can't get to them if the batteries are dead and the hatchlift won't open), so I'd like to relocate them. However, at this point in time I don't dare touch them because I have no clue how to re-wire the damn things properly.

JohnSchiavarelli

I have been running 2 JL 600/4, 1 JL 750/1 and 1 JL 300/4 (Old School) off 2 group 31 Interstate bats for years.. (before the MHD amps from JL I had many different AMP configs). The key is to charge them with a GOOD charger after the day is done.

here is the kicker.. You cna get re-mans from interstate.. $35 bucks a piece.. Cannot beat that price..

billat908

Maybe not.

Perhaps you need better batteries rather than more batteries.

At 3 amps, your stereo is a low current draw, and a deep cycle battery is best suited for this. Consider a pair of 6 volt golf cart batteries in series. This will give you 225 amp hours of capacity, and about half that of use. That means over 100 amp hours before they need recharging. 100 amp hours works out to 33 hours of stereo operation. Does that fit your usage? You can discharge deeper, of course, but it shortens their life.

These batteries can be charged at 20% of their rating, which is 45 amps, but when down to half, they will likely draw less than that. Probably around 12%, which is the textbook value.

You have two ways to go. Charge them on shore like fisherman charge their trolling motor batteries. Or use your alternator.

However, the engine alternator will be in parallel with the starting battery, so it will read the internal resistance of that battery, and charge accordingly. I don't like parallel charging. A lot of cruisers don't, either. They charge and discharge their batteries in separate banks.

A work-around it to use a battery switch to allow you to start the engine on the starting battery, and switch over to the deep cycles to run and charge. The alternator will then give the deep cycle batteries what they want. You must be sure to use the type of battery switch that does not interrupt the circuit. Most alternators do not like output interruption.

You may say, "What if I forget to switch back?". What happens is that you will try to start your engine with the deep cycle batteries. The results of this will depend on your engine and its tune. I have started my 502 with a medium size motorcycle battery when I had the GM mini starter. With the reverse-rotation Mercury/Delco starter, it took more juice, but the pair of Trojan T0125s did it quite well, even though it was not my normal practice. Costco's golf cart batteries perform less well under heavy loads, but four of them will spin a 502 quite nicely.

If you do light off your engine with the deep cycle batteries, just let it run and charge them until you shut down. An ammeter would help you a lot to keep a handle on things. I use a TriMetric 1020 to keep track of my deep cycle battery situation. It monitors drain and charging and acts as a gas gauge for the battery.

The alternator will do a good job getting the deep cycle batteries up to about 85%, then will charge much slower. It will take a long time to get them completely and fully charged with the alternator. A bigger alternator won't help much. The deep cycle batteries will benefit from a good long charge from a shore charger after an outing to bring them up to a completely full charge. This assures full capacity next time out and prevents sulfation, resulting in a long life.

If you want to use just one battery, a Minn Kota 12 volt trolling battery is very good.

mcollinstn

Dude,

Caps are for increasing the amount of available current to a high current draw setup. They don't extend usable battery life, they just supply LOTS of current for momentary needs. This is NOT what will get you additional runtime.

And somebody mentioned that your stereo draws 3 amps? That's flat wrong unless you are running only a headunit at low volume levels. From what you've already said before, your low runtime is a secure indicator that you are drawing a good bit of juice at your usual volume levels.

Golf cart batteries are great. But with flooded lead-acid technology, you gain storage capacity with additional plate area. This is a direct correlation to the mass of the lead, and the weight of the batteries. If you have a great source for golfcart batteries with 2 year free replacement warranties, then go for it. Otherwise my vote is to stick to "bang for the buck".

Nobody provides a decent warranty on a deep cycle battery while all auto stores give 2 and 3 year free replacement warranties on their "gold" or "premium" starting batteries.

Treat a starting battery well (don't discharge it below 10.5 volts, recharge promptly to a properly calibrated float voltage, and don't overheat them) and they will last very well in a marine application.

Best wishes.
MC