Six volt batterys

[Rooster 27509]

Anyone using six volt batterys on a C-Dory? ( for house power)

[Adeline]

I use a Group 31 tucked into the back of the port lazarette http://www.trojan-battery.com/GeneralDC.asp?Product=65 .

[Sea Wolf]

Rooster-

I think there's some confusion here.

Am I correct in assuming that you're asking if anyone is using two six volt batteries in series to get 12 volts for the House Batteries in order to get more reserve power (Amp/Hours)?

Joe.

[Rooster 27509]

Joe that is correct I'm looking into more A/H so if I need them I got em.

[Sea Wolf]

Rooster-

Thanks for the response!

If you're trying to get more A/H (Ah), you can do it several ways:

1 Just get a bigger size 12 volt battery. More battery, more acid, more lead, more Ah. Simplest if you have the space in the existing battery storage space. No new wires, only a bigger battery box, hopefully.

2. Add a second 12 volt battery in parallel to the one you already have. Doubles the size of your reserve. Add a 1/2/all switch to control battery selection. Requires more connecting wires, switch, and extra battery box. "Proper" installation here would require battery isolators and a battery charger with multiple charging circuits. Becomes expensive with the last two items.

3. Get two 6 volt batteries and wire them in series, making a big 12 volt battery. Requires only one new cable to link the two batteries together. Will also require new battery box(es). Total number of Ah is the same as either individual 6 volt battery, but at 12 v. Simple alternative if you have the space. We'll call this the "Big Double Six" or "mega-battery" below.

What it comes down to is if you want more Ah, you need more lead and more acid. And since this is going to be your house battery, you're going to run it down quite a bit, so use only deep cycle batteries. The bigger batteries you have, the less you'll run them down percentage wise, and they will therefore last longer, being proportionately discharged less.

So the "Big Double Six" looks good, basically. The only caution I would have is about the charging load on your outboard alternator, voltage regulator, and the rectifying diodes. To put this discharged "mega-battery" on line with the outboard and try to charge it all at once puts a really big load on the charging components. Try not to run it down too far, and charge it whenever you can with shore power and the 120 volt battery charger instead of the outboard.

Another couple of issues:

1) Be to be sure to connect whatever system you do develop together with adequate sized cable to prevent over loading.

2. Be especially careful to avoid surging as when a fully charged battery is connected to a discharged one. The currents can run into the 100's of amps and boil the acid in the batteries!!!

I faced this same dilemma when I added an engine mounted trolling motor to my new Yamaha 90 EFI last fall. Needing a lot of Ah, and considering the above issues, I elected to leave the two (Group 27 Deep Cycle) 12 v batteries (with switch) in place and add two more similar 12 v in parallel with another switch, so that any possible combination of batteries could be switched on or off. This allows he use of any one, two, three, or four batteries together as well as their selective recharging individually in any combination. Thus I can recharge batteries one at a time without overloading the engine's charging components. It also gives me 4 x 115 Ah = 460 Ah, which is needed when trolling for 6-7 hours.

Perhaps others will think of additional issues that would influence your choice in this matter.

So what do you think?

RV Batteries?

Big Boat Marine batteries?

Golf Cart Batteries?

Submarine Batteries?

Joe.

[Sneaks]

For RV'ing I prefer (and use) two 6 volt golf cart batteries wired in series. Relatively inexpensive at Costco/Sams, their useful lifetime seems to be much longer than equivalent parallel marine batteries and there's plenty of ampere hours. Mine are on their 5th year! Never got more than two years out of marine batteries in the same application. IMHO, there is nothing better for house batteries. Plus you don't have to be concerned with getting both new batteries from the same battery "batch". A concern that's real if one parallels 12 volt batteries. Any parallel batteries, for that matter.

Caveats for boat use:

Those puppies are heavy and tall, and they do not provide a redundancy factor. Redundancy will mean a 12 volt battery somewhere in the system. Battery boxes will be necessary and are difficult to find. They're lead/acid and messy compared to "maintenance free" type marine batteries.

I had my dealer install parallel starved electrolyte (AGM) batteries in the Jenny B. Both fit in the starboard lazarette but he had to "shorten" the battery screw terminals to do it. Not a problem! Three-way switch does it all.

After a career in submarines, I've had it with acid maintenance! Like Snoopy's Pigpen character and dirt, acid loves me. Around here clothes cost more than batteries in the long run.... I will use one AGM for house useage and the other strictly for engine start, but that's not a hard and fast rule unless I'm gonna be somewhere lonely, then the engine start battery isn't used for anything but starting (and the wallas)

[Rooster 27509]

Sounds like I best look into adding one more 12 volt battery and let the thoughts of using the larger 6 volts just drift away.


thanks to all
Jim