Battery Design: Start + 4 6V T-105s

[SausalitoDoug]

First,

I have learned a ton from this forum. Thanks a bunch for all who contribute.

My current boat (Passport 40) is due for new batteries. I thought this would be good time to upgrade the entire electrical system. I've read everything here and thought I might solicit comments to my design. I've re-worked this about a bunch, but I think I've settled on something I can show.

My design is KISS compliant (I think). I opted for 2 on/off switch instead of a 1/2/Both/Off as I think it will protect the alternator better. I'm not sure about running the batteries in parallel? Will they fight to a discharging duel? I also want to only have one connection on the battery post, so I will utilize Blue Sea bus bars for distribution. Grounding/Neutrals are not shown, but will all run to a negative bus bar.

Thanks for your time,

doug_

[btrayfors]

Looks good to me on a quick viewing. You could lose one of the two ON-OFF switches shown next to one another, and just run a single large battery bank with an ON-OFF switch. That's the preferred way these days.

Also, to save a bit of $$$ you could use a Xantrex EchoCharge in lieu of the Balmar DuoCharge. Does the same thing, just has a limit of 15A which is more than enough to maintain the start battery.

Finally, don't forget the CPD's....circuit protection devices. You need fuses or breakers on the house battery circuit and, if you're paranoid like me, on the start circuit as well (even though that's not strictly required under the ABYC standards).

You may also want to wire the bilge pumps on the battery side of the switch, or direct to the batteries, so you could turn the switch off to all DC devices onboard while not disconnecting the bilge pumps. These require CPD's, too!

Bill

[sailingdog]

You also might want a ON-OFF switch on the starting bank, just in case. They come in handy when doing things like working on the engine or underwater on the prop... and can save you from getting chopped up by the prop or the engine when working on it.

[chef2sail]

SausalitoDoug,

I am doing the same upgrade. I beleive I am getting Lifeline 6V AGM from Tristates. They are 255 including the shipping.

My plan is to have one large house bank of the the 4 (6 volt) charged by a Xantrex2 40 and have the starting battery charged by A Xantrex echo charger.

Dave

[SausalitoDoug]

Thanks all for your input. I will redraw with updates and post another schematic tonight.

doug_

[SausalitoDoug]

Ok. Here's an updated schematic. I still might bring the parallel bus bar in front of the ON/OFF switch so that I can bring it closer to the battery.

Thanks again for all your help.

doug_

[sailingdog]

should have switches for the two bilge pumps too.

[k1vsk]

With some chargers, the eco charger or duo charger is unnecessary - If your charger senses each bank separately, it will also charge each independently (at least my Xantrex 40 does). If not, you may want to consider a better charger if you have not already bought one - the economics alone may justify it.

[jonlgauthier]

SausalitoDoug,

You may know this already, but the best way to wire four 6V batteries into one large bank is to have the positive cable on the + side of battery 1 and the negative bus cable from the - side of battery 4.

The attached diagram is from Magnum Energy's MagnaSine Inverter manual - I hope they don't mind...


This wiring arrangement will insure that current is drawn equally from both 12V-series pairs of batteries, assuming the cables are the same length. If you wire to the positive and negative of, say, the rightmost pair, then those two batteries will always be charged just a little better than the leftmost pair...

[SausalitoDoug]

Perfect. I couldn't find this diagram to save my life.

Thanks for the info Cap'n Jon!

doug_