Adding a third battery??

[SMELIKFIS]

Have a 03, 265 Express/twin F225's, want to add capacity to my house (starboard) battery bank. The boat currently has one house/start battery starboard, and one start battery port, both Group 27 dual purpose batteries (typical GW setup).
I have a factory installed two bank 5/10 amp charger.

All i really want to do is add capacity to the house system, not rework the switching, the current system has never let me down, (boat has over 1000hrs on it).

Here is what i propose to do:
Add another matching group 27 battery to the starboard bank, and connect + to + and - to-
Leave charger and everything else as is.

FYI, access to batteries is very limited, a group 27 battery or smaller will only fit thru the access hole, there is room for two and in battery area

Will this work and give the added capacity desired?

Thanks, Randy

 

[ocnslr]

While there are certainly better ways to set-up a "house bank", they would require changes in wiring and switches.

Yes, your proposal to add another battery in parallel with the current starboard battery will increase capacity.

It in not good practice to put a new battery in parallel with a non-new one.

Assuming your two current batteries are the same model and vintage, then I suggest you put the current port battery in parallel with the current starboard battery, and put the new battery in place as the port battery.

JMHO,
Brian

 

[seasick]

It's generally never a good idea to wire two batteries in parallel. Small differences in battery voltage between the batteries will cause each to 'fight' the other. One battery will be 'charging' the other or discharging the other. You need to change the wiring and add the appropriate isloator .


here's what happens: If one battery is a bit low, the charging system doesn't see it since the other good battery pulls up the voltage. The good battery is actually charging the bad battery even when the motor is off. So, the good battery gets run down and the bad battery never gets a proper charge.

 

[jekyl]

This is an interesting thread as I am in a similar situation with my 265.
I am looking to increase my amps also on the house/starboard side. However I have 2 relatively new marine start batteries on that side and I was thinking of getting higher amps via gel mat or other deep cycle battery/batteries. My new fridge seems to run the batteries down easily and I'm not sure if I'm charging them correctly?

I have an isolator switch on both port and starboard sides . The number 1 is used for the house batteries and the number 2 is start on the port side.

If I run the two house batteries switch on ALL does this mean I am running only off those 2 batteries or is the starboard battery now linked as well?

When I use my charger to charge the house batteries should I have that Isolator switch in the ALL position or the 1 position?

 

[fishingFINattic]

I am not sure you can get two Group 27's in that area -

I have four Group 24's in my 265 Express -

I dont buy into the fact the you shouldnt run two batteries in parellel - Sure there are small differances in voltage, but it my opinion that these batteries see a hard life being on the boat - so really two years is all I expect -

Running batteries in parrell is a common solution - not just in marine applications -

I have two batteries on the starboard side in parrell to support the house system (fridge, ect)

I have two one the port side - both isolated from each other -

I have upgraded to a three bank charger and the two in parrell are one bank, and the other two are each on there own bank - depending on my swith arrangement I can start either motor from either bank.

Tim

 

[seasick]

I am not sure you can get two Group 27's in that area -

I have four Group 24's in my 265 Express -

I dont buy into the fact the you shouldnt run two batteries in parellel - Sure there are small differances in voltage, but it my opinion that these batteries see a hard life being on the boat - so really two years is all I expect -

Running batteries in parrell is a common solution - not just in marine applications -

I have two batteries on the starboard side in parrell to support the house system (fridge, ect)

I have two one the port side - both isolated from each other -

I have upgraded to a three bank charger and the two in parrell are one bank, and the other two are each on there own bank - depending on my swith arrangement I can start either motor from either bank.

Tim

You should be able to get more than 2 years out of a decent battery.
We have many folks at my club that get 8 or more years out of their batteries. There are three things you can do to really hurt a marine battery: Overcharge it, number 1
Have it freeze ( cold + low charge)
Run low on electrolyte.
As I said earlier, if one battery is not up to snuff and it's in parallel with another battery, it will pull down the voltage which will cause the charging system to charge. The problem is that the second battery may not need a charge but it will get one anyway. The good battery gets cooked.
I know that parallel applications are common. It's just not a good idea from an engineering point of view.

 

[SMELIKFIS]

I can fit two group 27 batteries on either side, but I don't think I could get any larger battery thru the access hole.
As far as the parallel hook up, after more checking I know now this is a very common setup on midsize diesel trucks, sometimes with three batteries in parallel with no other devises used in the system.
I will be moving my matching port battery to the new two battery starboard house bank.
All I need to buy is one new dual purpose AGM group 27 battery for port, battery tray and two jumpers, est. $300.
I will post if I encounter any problems.
Thanks for the imput.
Randy

 

[seasick]

Parallel batteries are also very common in those megawatt car stereo installations.
Battery engineers prefer two 6 volt batteries in series to increase amperage over 2 12 volt in parallel but that might be difficult to do (finding 6 v marine batteries).
If you are going to parallel two 12 volts, the batteriers must be the same brand, model and age.

Should a cell go bad and short, the other battery will feed a lot of amperage into the lower impedence (shorted) battery. The high currents can cause fires. If I were to go the parallel route, I would install a disconnect switch for the second battery and keep it disconnected when the boat is not used.

 

[Hookup1]

Extra battery

Like the other posts I don't like parallel battery setups.

If your have the room why don't you put a larger deep cycle battery in for the house and a battery switch? The switch could be either a ON/OFF or a A/BOTH/B/OFF to the engine battery.

If you need a charger look at the ProMariner Sport 3-bank models. Easy install, great product and great price.

 

[jekyl]

Something different that has happened last 2 trips is when i go to start the starboard motor with the house batteries ....nothing happens and i have to go turn the switch to all and then she fires up easily.
These batteries had just been charged fully at home and i have just taken off all the terminals and given them a good cleaning, as well as spray.
I have just bought a cheapo led indicator for checking the batts. and it showed they were great after they had been charged 2 days ago.
Am I looking at a faulty isolator switch? a or both faulty house batts?
Or smething else that I have not considered?

 

[seasick]

The only way to really test a battery is with a load tester. You can lug the batteries to ana auto store like Pep Boys and they will load test them for you. perhaps you can borrow a load tester from a friend.
If the batteries are OK, the next place to look is a bad connection, either loose or more likely corroded. Battery switch could be bad, a voltmeter will tell you. measure the voltage after the switch when cranking and measure the voltage before the switch when cranking. There should not be a lot of difference, a tenth of a volt or so.
The same approach works for connections. measure the voltage at the battery before and during cranking. The open voltage should be 12.5 or better and the cranking voltage at the battery should be no less than 11 volts or so. If it is, move up the line and measure voltages. At some point, you will find the excessive drop.
Remember that ground wires and connections are just as important. If you trace voltages on grounds, you want to see very little voltage drop but instaed of 12 volts at the battery, you should see 0 and as you move along the ground wires, you will see a little voltage. If you start to see a few volt jump, you have a bad connection or cable.

By the way, a battery with a bad cell will still measure the correct voltage with no load but will fail a load test.
Good luck

 

[ocnslr]

My "bullet-proof" battery set-up has two starting batteries and a house bank.

Each starting battery goes to a regular battery switch, so either or both batteries can be set to either engine. These switches are just left "opposite" so each engine is one its own battery.

The house bank is two dual-purpose batteries in parallel. It feeds the house through a separate On-Off Perko switch, and the usual 40-amp breaker. No cross connect to the engines.

The three-bank battery charger separately charges both starting batteries and the house bank.

Each starting battery is charged by the engine it is set for on the switch.

The auxiliary charging leads from BOTH engines go to the house bank. Either or both engines will charge this bank underway.

This system was set up when we repowered 37 months ago, and the dual-purpose batteries were six-months old at that time. They are still in excellent condition, and YES, they are in PARALLEL.

Brian

 

[BobP]

Brian, you can paralell the aux charge feed from both motors to the one common aux bank set? That's OK to do by Yamaha ?

Do you have each aux feed fused?

 

[ocnslr]

Brian, you can paralell the aux charge feed from both motors to the one common aux bank set? That's OK to do by Yamaha ?

Do you have each aux feed fused?

Yes. I designed this system with the Yamaha certified technician that did my repower from a single to twins.

No fuse.

No issues.

No problems.

685 hours on the F150s since Nov 2005, with this set-up and the same batteries.

Shore power always on, powering the factory-installed Charles charger. (Refrigerator has been on since Fall 2002, except when boat on the hard for a few days for bottom work. Good time to defrost..)

Brian

 

[BobP]

I recall when you repowered, it's been that long (?)

And both aux batts are hard tied to eachother , no isolators or relays in there?

 

[ocnslr]

I recall when you repowered, it's been that long (?)

And both aux batts are hard tied to eachother , no isolators or relays in there?

Bob,

For your first point, I could say "Time flies when you're having fun", but probably more accurate to say "When you're over the hill, you pick up speed"....

And yes, the two batteries in the house bank are hard wired together, AND the two auxiliary charging leads both lead directly to that bank.

Bob