Battery Advice?

[CamB25]

I'm starting to scratch out some schematics for the B25's electrical system. The boat will be powered by a single outboard and I have a bow thruster. Regarding batteries, I was initially thinking about three banks - start, house, thruster, but the boat will have very low house loads - stereo, bilge pump, live well pump, led lights, etc. Seems like a waste of battery power to have three. Can I get by with a two battery bank system - running the thruster off the house? It would save some cost in switches, ACRs, etc. The thruster's fuse rating is 300amps, but that's probably a locked rotor rating and not a normal draw...and it will see very intermittent use.

Following Bob Lico's lead with the Odyssey AGMs, was thinking about using 2 PC2150S batteries (1150CCA, 100Ah reserve) http://www.batterymart.com/p-odyssey-pc ... ttery.html

What material should I use for the battery box (other than fiberglass...I'm not making another mold!)?

thoughts? thanks!
Cam

[IRGuy]

Hi Cam...

Glad to see you are progressing with your project!

As far as battery boxes are concerned I built mine out of plywood with several coats of white pigmented epoxy, but if I was to build them today I would use PVC sheet, which I buy from a local building supply store in 3/8" and 3/4" thick 4'x8' sheets. It can be worked with standard woodworking tools, is resistant to sulfuric acid, can be glued with epoxy, takes screws well (predrill the holes), doesn't rot and doesn't need to be painted (although it can be). I have given up using plywood since I read Capt Patrick's suggestions about PVC. It is available in board and molding profiles in the big box building supply stores as "Azek" as well as some other names, but you can find where sheets can be found by doing a Google search.

I did a writeup for the B33 forum that described the engine room battery replacement and rewiring project I did several years ago. I suspect the hacker who attacked the forum a while ago nuked it, but if you want I think I can email a copy to you. It shows drawings I did for the two boxes I built.

[CamB25]

Thanks Frank! I would love to see the write-up. I'm getting down to the finishes stage in the project. I have an inside work location that makes it bearable to work in the heat. Might have her done within the year if my luck (and bank account) holds up.

Internet browsing has turned up the usual answers regarding the bow thruster...examples of every conceivable arrangement. Some have them isolated from the start and house banks, and the deep cycle thruster battery charges via separate battery charger at the dock. I have power at my dock, so this might be a good set-up for me. Electrically it is much simpler than integrating the 3rd bank into the house/start system. And I can step down to group 34 Odysseys for start and house, and use a cheaper deep cycle for the thruster.

work in progress

[IRGuy]

Cam...

I just found the file on my old computer.. but I don't have an email address for you.

IRGuy@aol.com

[Tony Meola]

Frank

Why don't you post it in a thread on this board. I am sure some others would like to see what you have done.

[Navatech]

Why don't you post it in a thread on this board. I am sure some others would like to see what you have done.

I second this proposition...

[IRGuy]

Gentlemen....

I would be happy to distribute my writeup but it is a long (6-8 pages with several drawings and photos) document and quite simply I do not know how to post it here. If anyone can help I am happy to share it.

[Navatech]

Gentlemen....

I would be happy to distribute my writeup but it is a long (6-8 pages with several drawings and photos) document and quite simply I do not know how to post it here. If anyone can help I am happy to share it.

What I would do is convert it to a PDF and then link to the PDF file... I could do that for you...

[Joseph Fikentscher]

I wired in a two bank setup. Bank one is the port starting battery. Bank 2 is the starboard starting battery and the house battery with a Blue Seas ACR. The onboard charger charges both banks while at the dock plugged in.
The starboard alternator charges the house battery and starboard starting battery when underway. The port alternator charges the port starting battery.

If you run the thruster off the house battery, and it is being kept topped off while underway, you should have sufficient battery life for docking with the thruster. Of course while at the dock and charging via the charger, you should have sufficient power while debarking.

I am assuming that you only really need the thruster while docking.

[IRGuy]

Navatec

OK.. but where do I put the file so everyone has access to it whenever they want?

[Navatech]

Navatec

OK.. but where do I put the file so everyone has access to it whenever they want?

Dropbox will work for a PDF file... Sendspace will also work but the file will be deleted after 30 days (so not good long term)... If you don't have a free Dropbox account yet let me email you an invitation (I get more storage for that)...

[CamB25]

I wired in a two bank setup. Bank one is the port starting battery. Bank 2 is the starboard starting battery and the house battery with a Blue Seas ACR. The onboard charger charges both banks while at the dock plugged in.
The starboard alternator charges the house battery and starboard starting battery when underway. The port alternator charges the port starting battery.

If you run the thruster off the house battery, and it is being kept topped off while underway, you should have sufficient battery life for docking with the thruster. Of course while at the dock and charging via the charger, you should have sufficient power while debarking.

I am assuming that you only really need the thruster while docking.

I am a little bit concerned about a "brown out" when using the house battery for the thruster. I need to do some math to estimate the run time of the thruster on an isolated deep cycle battery that is charged only at the dock. Other than doing a few thruster donuts for fun while underway, the thruster would see dock use only.

In this scenario I would have single Start battery (one outboard) and single House battery connected via a Blue Seas dual circuit plus switch (6011) and an ACR for charging underway. A single battery for the thruster with an On/Off switch - not connected to House or Start batteries. For dock charging, A blue seas P12 AC charger for charging all three batteries at the dock.

[Tony Meola]

Joel

Is there a way through the battery switch you can get either alternator to charge either bank of battery's? I am thinking that if one of the alternators goes bad, you will run the one bank down.

At least with Diesels when they are running they are running. Gas is another matter.

[Navatech]

I am a little bit concerned about a "brown out" when using the house battery for the thruster. I need to do some math to estimate the run time of the thruster on an isolated deep cycle battery that is charged only at the dock. Other than doing a few thruster donuts for fun while underway, the thruster would see dock use only.

In this scenario I would have single Start battery (one outboard) and single House battery connected via a Blue Seas dual circuit plus switch (6011) and an ACR for charging underway. A single battery for the thruster with an On/Off switch - not connected to House or Start batteries. For dock charging, A blue seas P12 AC charger for charging all three batteries at the dock.

I understand what you're trying to do but if it were me, I'd do one of the following:

A) Run the bow thruster off one of your starter batteries... Yes, it would be a long run of heavy gauge wires but as you (presumably) only run the bow thruster when you're running the engines most if not all of the power to run the bow thruster would come off the alternator...

B) Put in another battery... You're already using one engine to charge (through an ACR) two batteries (engine & house)... I'd connect the fourth (bow thruster) battery to the other engine for charging... Through an ACR... The ACR's will also function at the dock... IOW, when the engine batteries are sufficiently charged the charing power will be redirected to the house and the bow thruster batteries... In this case you only need a 2 bank charger... As an option, you can get a 4 bank charger and speed up the charging...

[Joseph Fikentscher]

Tony,

I would just put the battery switches on Both, or All. But would fix it as soon as I got back to the dock.