Battery Orientation

TortolaTim · January 28, 2020, 08:43:14 AM

I'm replacing the batteries (as well as most of the rest of the electrical system this winter) and have digested a ton of great info so far from this site. I'm kicking around going with 3 Lifeline AGM GPL31XT's for the house bank. The only way I think they will fit in the stock battery compartment is as follows...Is there any "no-no" as far as storing batteries like this, ie. slightly different length cables paralleling them, and different orientation? In my crude diagram, starboard is up.

steveg · January 28, 2020, 12:16:50 PM

Tim, a parallel set up allows one battery with a lower voltage to bring down the others until the voltage is equalized. The big problem would be if one battery has a short, then it would drain all the other ones down. If it goes unchecked, then the remaining two would sulfate the batteries if not caught in a reasonable time.

Steveg

Jim Lucas · January 28, 2020, 02:33:29 PM

I just finished a complete electrical upgrade to my MKII. I went with three Firefly AGM's and easily fit them side-by-side with room to spare. Not sure of the location difference of batteries in the various year/models... so maybe no help here, just sayin...

Ron Hill · January 28, 2020, 02:59:22 PM

Steve : You have almost the same setup as I have.
The only difference is I wired the single (for & aft) battery into BAT 1 position and the other 2 batteries (together) into BAT 2 position on the Perko Battery selector switch.

Have had that battery setup for 15+? years and it has worked well. Somewhere on this site I posted a picture.

A few thoughts

Ron Hill · January 29, 2020, 02:50:00 PM

Steve : My AGMs were group 27or 29? 105/110 AH. I was able to have the 2 side by side batteries in boxes, but the single battery I had to make a heavy clear plastic cover to protect the terminals.

A few thoughts

KWKloeber · January 29, 2020, 06:58:36 PM

Tim To answer your specific questions...

Being AGMs, the orientation makes no difference -- unlike flooded cells where the orientation does make a huge difference.

While it's ALWAYS preferable to balance installations by keeping cable lengths equal (and naturally short as possible) your difference is not feet but inches, so (presuming the cables are not WAY undersized) there is no issue with length.

I don't run AGMs but I know that they are easily killed with improper charging, so something to consider (not knowing what improvements you have ongoing.) Not to put any pressure on but Winter is 1/3 gone!

TortolaTim · January 30, 2020, 05:44:24 AM

Ken, thanks for the great info. I was thinking the same thing, but I wanted to make sure. Actually, after intensive re-review of this site and consideration of how I use the boat, I've decided on the 4 GC house, and single dedicated start battery setup. They are about 1/3 the cost, and if down the road I decide to upgrade to something different, it won't be too big a deal. I'm modeling my system upgrade to closely resemble Jon W's fantastic schematic for his design, biggest difference being that I like the "2 battery switch layout"and will modify it for that.
I have an ext reg 105A alternator, SG200, and SI-ACR on order from Mainesail, and am planning on adding solar this year too so I can start spending some nights away from the marina.
Couple of questions, the boat lives at the dock, so has plenty of time to recharge. Currently installed is a Xantrex TruCharge 40. Are these units still considered sufficient for such a design, or should I consider upgrading? I haven't really thought about an inverter, but might want to add one in the future. Anything I should consider right now that would make a future addition of an inverter more seamless?
You're right about winter 1/3 over! Holidays are finally behind me, and I have a 12 day break from the airline job, so I'm planning on "living" at the marina for the next week and immerse myself in boat projects before I have to leave town again!
As always, thanks again for all the great advice. It's much appreciated!
Tim

KWKloeber · January 31, 2020, 02:24:25 PM

Tim

You really have to budget out what your energy use is expected to be, which will determine how many amp hours you need to replace, over how many hours she's plugged in. For longevity sake its good to keep the charger working at half its rating. 40 isn't a lot of amps capacity of you are using the heck out of your maximum available amp-hours and using her every day, but if she's sitting week long that's different. A VERY general rule of thumb is 10% of your usable amp-hours (ie, 10 amps for every 100 ah of battery - again VERY general, everyone's needs are different.)

TortolaTim · February 03, 2020, 05:25:51 PM

Regarding the "2 Switch Option" for wiring the batteries. Does the cable from the #2 post on the ON/OFF/Both to the OFF post on the ON/OFF switch (or starter) get a fuse?

mark_53 · February 03, 2020, 07:20:15 PM

Quote from: TortolaTim on February 03, 2020, 05:25:51 PM
Regarding the "2 Switch Option" for wiring the batteries. Does the cable from the #2 post on the ON/OFF/Both to the OFF post on the ON/OFF switch (or starter) get a fuse?

No, since that wire is not energized until the switch is closed, then it's protected by the fuse at the battery.