looking to install dual battery setup

[bundy]

Hi all.

I have a 50hp Mercury 2 stroke and the battery has started to fail. I am looking to bite the bullet and install a dual battery setup but need some guidance. I would like to have it wired so that one battery can do the motor and the other do all other things.

The battery that is failing is a Quicksilver Marine Starting Battery 450 CCA 100 RC had it roughly 6 years.

I am not sure what size alternator is in the Mercury (16amp maybe?)

I had a look in Road Tech Marine today and the young bloke that was on couldn't really steer me in any direction but I came across these

http://www.roadtechmarine.com.au/productView.asp?ID=TEA784&CATID=57&form=CAT2&SUBCATID=294#2

http://www.supercharge.com.au/others/allrounder the MRV48 60AH

I already have a 1,2,1+2, off isolating switch installed on the boat simply to shut the battery off when the boat is parked up.

Would 2 x 60AH allrounder batteries be suitable for motor and house or should I go cranking battery for start and deep cycle for house?

Do you still use the isolating switch with the VSR or just use one or the other?

Any help would be greatly appreciated..

[Blood Knot]

Why not get in touch with our site sponsor Craig at Huett Marine - He will be able to advise or quote you.

Cheers

Blood Knot

[oz_brett]

I installed second battery 2 weeks after buying the boat new, both batteries connected to 4way switch then to house & motor together. I usually start & run on both kepping charged while I travel then flcik to either battery 1 or 2 while sitting or sleeping overnight (while sleeping clear light & sounder combo remain switched on all night) Lately (after 6 years) battery 1 is getting week so I use it for fishing & sleeping and Battery 2 or both for cranking but will be replacing battery 1 soon to avoid getting stuck.

Battery 1 is a standard marine battery, Battery 2 is an NRMA car battery both have CC550 for the 150 4stroke.

[bundy]

Why not get in touch with our site sponsor Craig at Huett Marine - He will be able to advise or quote you.

Cheers

Blood Knot

I have sent Huey a message thanks for the heads up.

Am still looking for advise from other raiders as well.

[imgoin]

I agree with oz_bret I have the same setup and it has saved me a few times now. All my accessories run of house battery leaving my start battery for starting only. A few years back my start battery packed it in while outside fishing thanks to the switch all I did was switch to emergency parallel and we where on our way back home. They can be a bit expensive for the set up but once installed you will never look back. My system is the bep vsr hope that helps.

[Testlab]

I drew this up this afternoon. Although this uses a normal four position battery switch (Off, 1 2 Both) you should always leave it switched to the starting battery (Batt 2) when in use and obviously Off when not in use. The DVSR (or VSR) will switch in to charge the house battery (Batt 1) when the starting battery has come back up to full capacity.

If the starting battery dies, select Batt 1 then change back to Batt 2 once everything is running.

The electrical isolation switch provides a quick means to isolate the electronics and lights. It should be turned off while starting older tech engines using battery 1.

I am happy to answer questions... but please note the fuse sizes will depend on wiring size used, the maximum load and the manufacturers recommendations.

Note, when using a mains battery charger the battery should be disconnected or else the VSR will turn on and an intelligent charger will be unable to work properly.

Please disregard the note in the top left corner about connecting the DVSR in(+) to the battery switch C terminal. I meant to delete that after I removed some additional circuitry. the VSR in(+) should go to the start battery (+)

Edited January 5, 2014 by Testlab

[bundy]

Thanks for your replies.

I'm leaning toward the setup that testlab has drawn.

This way both batteries are independent but can still use the house battery in an emergency to start the motor.

I have also come across this double pole switch whilst searching. Looks like you can wire it 3 ways house battery on, house and start batteries on (still independent) and emergency parallel.

http://www.bepmarine.com/home-mainmenu-8/product-778/pro-installer-dual-bank-control-battery-switch-copy-

[GaryO]

Or as a cheap alternative buy a jump start unit you can take out with you or use it in the car when your not fishing.

[Testlab]

The problem with cheap jump start units is they often simply can't provide enough energy to bring the flat battery to a high enough float charge to then allow the engine to crank and start. The deeper the discharge the greater the difficulty.

What I mean is the small capacity of the battery in the portable jump unit dumps its charge into the flat battery but it's not enough to start the engine. The bigger the flat battery the less likely a portable jump pack will be successful. Also many cheap packs have thin cables that don't allow enough cranking current, making this problem worse. That is, they dump their charge into the flat batt but the cables won't carry enough cranking current.

On old tech small capacity outboards a jump pack may still work because they are magneto ignition and don't have any voltage sensitive electronics, but on bigger sized outboards or those with high tech or electronic fuel injected engines if there is insufficient voltage because they won't start unless the voltage is above a predetermined minimum.

If you're going offshore, spend the money and do it right. If you're in sheltered waters and don't mind the inconvenience of the occasional flat batt then go with the cheap option and see what happens.

There has been an exhausted jump pack present for half of the jump starts I have done for people on the water in the last year.

[batfishing]

+1 on the cheap units.

It's not just the battery but the gauge of the wire, connections etc etc.

One of my guys bought one, a couple of years back, the 2nd time he went to use it, it wouldn't start his boat.

We pulled it apart, bought a quality US battery, and redid connections etc. it cost us more for the battery (wholesale) than the unit had originally cost him

Sent from my iPad using Tapatalk HD

[GaryO]

Absolutely testlab , you cant beat a dual battery for the best possible setup . But a jump start unit are a good option for people who dont venture far or have a small boat setup or find it daunting to set up a dual system .

Edited January 9, 2014 by GaryO

[spaners]

I don't know if you can still get them or not but a few years ago a mate of mine was into 4wd and he had a battery that had a reserve switch in it,so when the main battery went flat over night from leaving lights/etc on all he had to do was engage the switch and the flat battery had enough power in reserve to start the engine..just a thought.

[bundy]

Hi guys

Just an update for you.

I have installed the dual battery system as per Testlabs diagram. Once I had sourced all the parts needed it only took me 3 hours to wire, install and test.

The VSR kicks in when the start battery has reached 13.6V and then engages the house battery.

One problem I have noticed is sometimes when I turn the isolator switch to 1 (motor) there is no power at the ignition, but if I turn it to ALL and then back to 1 I then have power. I wonder if it has something to do with the VSR???? It doesn't happen all the time mostly when the boat hasn't been used for a couple of days.

Any thoughts???

[Testlab]

If the power to the ignition switch is separate to the engine harness is going to one of the batteries or to the same terminal as the engine starter cable (which should be the common terminal of the battery selector) or is it coming up the engine harness?

Most engines source the ignition switch power from the engine loom itself and then run it up to the switch and gauge cluster. This is why I didn't show any engine wiring on the diagram... because they are all different.

You do have the battery switch wired up properly... engine to the switch terminal? You might get the problem you describe if one of the batteries and the engine wiring was transposed. Other than that I don't know without seeing the engine installation manual.

(From your description you have the starting batt on Pos 1 and house on Pos 2.)

Edited January 16, 2014 by Testlab