New battery bank questions

CC Rider

CC Rider

Member
My Cape Cruiser 23' came with a Group 24 battery on each of the 115HP Yamaha main, and on the 8HP Yamaha kicker (has electric start/tilt). There is a A-B-Both switch connected between the 2 batteries. These are located in the 23's horizonatal locker at the rear of the cockpit.
Everything on the boat is connected to the main's battery except a couple of Scotty downriggers which are connected to the kicker battery. There is a Guest 2-bank 10A charger on board.

Needless to say, I need to change this arrangement.

I want to install a couple of house batteries and re-arrange the sources for all the loads on board, especially the fridge, Wallas, and cabin lights. My thought is to put a set of new batteries under the V-berth platform (haven't cut the access holes yet, but will need to do this mod as well). I don't want to put any more weight on the already heavy stern.

Questions:

1. What type of batteries for the house bank? My understanding is they must be AGM or Gel due to gassing in the enclosed space. I take it that regulated-valve flooded batteries are not a good idea and AGM or Gel are the only choices? I would like to get about 200Ah of capacity. AGM's are sure pricey!!

2. I have purchased a new Mastervolt 12-25/3 charger which I intend to install soon. I am a little surprised to learn that one can't set battery types for individual legs of the charger. It's a global setting across the entire charger. I think that other chargers are like this as well. So, this brings up the question of what to set the Mastervolt battery type to. Likely AGM, even though there will be the Group 24's on the other charger legs.

3. I would like to charge the new bank via the main engine as well. My thinking is to install an ACR between the main's start battery and the new bank. Any harm in combining the start and possible AGM bank via the ACR?

Any advice appreciated...
Chris
 
Follow the KISS principle:

1. Keep all batteries the same - either wet flooded, gel or AGM
- keep one good AC/DC charger set to that type
- one Gr 24 engine start (per engine), one Gr 31 house loads
- long heavy cable run from bow on heavier Gr 31 will cost you amps,
I’d avoid this, make other weight redistribution
- get a solar panel to help charge the house battery only
- use the refrig for storage, not cooling

2. Install a Blue Sea System main 12V distribution 2 switch (ENGINE + HOUSE)
panel (OFF + ON+ COMBINED) with Blue Sea ACR (Auto Chrg Relay - auto
combines batteries when charging and separates batteries when discharging
protecting electronics when engine starting isolating HOUSE from ENGINE loads)

Aye.
 
Not Gel - Gel's make great house banks for those with sophisticated charging systems, but they require lower charging voltages that an outboard will not deliver.
 
cc rider,

I have a BEP 125 amp battery selector cluster ( start and house ) with the integrated VSR (voltage sensing relay) that automatically connects/disconnects the house based on the start battery voltage. It is 6 months old, I removed because my outboard has a dual charging output, so now each of my batteries have there own charging input. $ 50 dollars if your interested PM me.
The words about the gel, are correct. The AGM's can accept the higher outboard voltage output. The cabling will need to be large ! Needs to be sized in case you ever need to start the motor off the house that would be way up forward. I would not be surprised if it would not be 1/0 wire ( I have not looked at the chart), the big cable gets expensive.
 
I see this a bit differently than some of the others. You are going to have two banks. One is the group 24 batteries already on the boat. One is engine start and the other is kicker start--emergency engine start. Then the second bank is two group 31 AGM(to give you 200 amps) which you can place where ever you want. You are not gong to be starting the engines off this house bank-thus do not need to have heavy cables--only enough to carry the charging load. That is going to be no more than 30 amps. For 40 feet round trip, no more than 3% voltage drop AWG #4 wire will be fine. Be sure and fuse it at both ends! (use a Maxi fuse) You can put one voltage sensitive relay between the main engine start and the house bank. No problem running AGM charging off that VSR (ACR)--and the engine start being a group 24. When you replace it use a group 31.

The rule is not mixing batteries of different type,capacity or age in the same bank. There is a little risk of overcharging the group 24 which is the primary engine start, but this is minimal.

I would keep the down riggers off the trolling motor. You can use a separate VSR for the trolling motor--you don't want to "combine" it with the big house bank.

Now you change the wiring for the console--it comes from the new house bank--same for the refer, (forget what folks say in the depth of the winter in the North about using it for storage--one wants their beer cold!) Wallas, electronics etc. Put in LED for cabin lighting anyway. If you have a windlass, you power it straight off the house bank--short cable run. If you already have a cable run for the windlass, that may well be changed over to work for the new house bank--and save some $$.

Agree, gels are sensitive to voltage over 14.1, should never be run off unregulated outboards.

The Mastervolt charger is an excellent choice. Set one leg to the engine start, one to the aux start and the 3rd to the house. It will proportion out as needed. AGM setting will be fine.
 
Thataway, makes a good point. The chances of both start batteries being run down would be very small. Only you can make that call. And any future owner of the boat should be made aware of the specific limitation.
 
Just to be clear, I didn't mean that both starting batteries should be kept connected. The kicker will only be connected with the "1/2/off/all switch. The second combiner would charge it. Thus it would remain isolated for starting the kicker in an emergency (separate start battery--redundancy)--and to run the down riggers, mostly when trolling with that motor--which would preferentially charge its start motor, and secondarily charge the engine start--and maybe even the house bank. (Most combiners are bi directional.)
 
I am just finishing such a conversion... trust me, it is more work than you would think...lots need to be modified... including you will need to put in under bunk storage near your power panel as you need access to route your wires... I built a small storage box under there and put one of my extra lazaret covers on there...worked well but took a bunch to build the box under the bunk area...it would be impossible to get your arm in that area without an access spot.

I bought my #1 (super heavy )marine battery cable from Gregs Marine ...I found him on EBAY and he sold me all my marine cable and fittings... my 22 it took 84' of cable...2 runs (up/down and around the panel) I mounted two Optima batteries... I made a partition between the porta pot area and the back of that area between the berths...then mounted the batteries and put a shelf just above the batteries for storage..worked kool.. now the porta pot sits perfectly in that area under the bed board...

I mounted two marine On/Off switches on the back side of my throttles...a really convenient spot.. inside and dry

The conversion took me several weeks to finish..as I redid it several times before I was happy... I really do like having the batteries up in the bow area.. My boat always sat lopsided and hopefully, I cured that.

Joel
SEA3PO
 
I have twin 40 Yamaha motors and they will eat each others voltage regulator if they are hooked to just one battery... I had to find that out years ago when we visited you....Wefings mechanic told me each motor needed to be wired to a separate battery ... The dealer we bought our boat from did not even put a battery switch in the circuit.. and wired the two batteries in parallel. (probably why he no longer sells C-Dory)
 
CC Rider":1la6jeep said:
AGM's are sure pricey!!
Click to expand...
FWIW,
Deka (Duracell labeled) g31 AGM's are $180 USD at Sam's Club. I've had great luck with them. My first Deka g31 AGM house bank lasted 11 summers.

I might skip the extra weight of the second starting batt. With the right switches and wiring, even somewhat lighter wiring from the house bank, if the main start batt were depleted such that it couldn't fire up a motor, switching the house batts into the circuit long enough to start should easily take care of it. I do that occasionally for the big diesel in New Moon, which needs far more cranking amps than your outboards.
 
And the 950 cold cranking amps sure is not bad either.... when I did my conversion I oversized everything...the battery cables were 3 sizes larger than Yamaha had supplied.. the runs were long and I did not want to loose amperage...

I laughed when I saw that Yamaha battery cables were plain copper and not marine quality...guess they think the motor will go south before the cables rot

My boat had lots of foam under the berths that I dug out...then when I finished my little storage box I foamed under it and around to cables to lock them in place....

While I was shopping at Greg's Marine I bought marine quality heat shrink tubing...wow is that stuff great... it is double thick and has some sort of adhesive that seals everything when you shrink it... All the stuff is the same quality and most the same brands as I was buying from West Marine...but half price..
 
Sad that a major motor manufacturer would use plain copper wire, and not tinned. Must be the extra cost, and out of sight out of mind !
I found that Cabela's had very good pricing on some of there labeled AGM's.
 
Thanks for all the replies guys, really appreciate the comments. (What a great site we have going here!)

Foggy; A solar system is a definite future addition, probably using flexible panel(s). I can't use the fridge for storage and not cooling cause I have a wife (aka Admiral) that won't go for that. Besides, cold beer and a place to have frozen bait is a good thing even though the fridge is the biggest electrical hog of all the loads.

NewMoon/Richard; Agreed, Gel is definitely out. I already destroyed a Gel by overvoltage charging it last summer. It was a used one, so I wasn't all that worried. But I did manage to kill it completely.

Bob; Thank you for your input. It parallels what I was thinking. The existing Gr. 24's can stay and do what they already do. The switch can already combine them for emergency cranking power for the main. The downriggers can stay on the kicker's battery. I have had no issues with this setup since I have owned the boat. The new house bank will consist of (2) Gr. 31 AGM's which I will mount under the V-berth and wire-in to the console's loads that should be sourced from a house bank. I think I will leave the windlass power as it is because I really only run the windlass with the main running anyway. This plan will keep the main's battery and the kicker's battery as separate circuits, the exception being an emergency start when the switch will be set for "both" to combine them temporarily. The only commonality to these and the new house bank will be the charger, and that should be OK I believe. I was concerned about the global AGM setting on the charger, but it sounds like it would be OK for the flooded Gr. 24's as well. It also sounds like my plan to put an ACR or VSR between the main start battery and the new house bank won't do any harm either.... which is great because it would be nice to not "waste" the charger output of the main if the start battery is charged up while running. The kicker can continue charging it's independent battery and in turn the connected downriggers.

Joel/Sea3PO; Yes, lots of work ahead, and a few "pucker moments" will be coming, they always do when cutting or drilling holes in boats.

NewMoon; I wish we had a Sam's club up here in Canada. That's a really good price, even in USD. Up here the average price of a Gr.31 AGM battery is around the $375 CDN range... ouch....! Hmmm, I wonder if they will ship to Point Roberts and I can cross the border to pick them up.... I will look into this because $750 CDN for AGM batteries up here is pretty steep.

Thanks again guys, I feel much better about this project now..

Chris
 
Joel/SEA3PO
Just looked at your album. Some great projects and ideas. Hope you'll post your new battery install--I can't quite visualize it.
Kea is a good looking boat too. What is her history/make etc?
Thanks,
 
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