Dual Battery system - what batteries

[Oceanic Dave]

Hi,

I currently have the Marine Pro 720 century batteries on my Victory. They are from 2012 so I am thinking of replacing them, the volts on the dash are sitting around 10-11. It charges when underway but then drops so I rather replace them.

I have read that it is a good idea to have one cranking battery and one deep cycle. The ones that came with the boat are both deep cycle. What would be the best way to replace these? I was thinking of just getting the same unless someone else recommends something else?

I have an etec 225 on the back.

Thanks!

[Crunchy]

Those Century Marine Pro 720 are a kind of a dual purpose - start and deep cycle cross over, they are very good batteries when maintained properly, it's what I have been running for many years without any complaints. Do you keep on charge when not in use?

[Oceanic Dave]

No I don't. I usually take the boat out a lot though, but this year it has been quite difficult. Next year will be a different story!

Yes I thought they were a bit of a crossover. I might just get the same!

[Dan5]

Get the same again or the Exide allrounder version...........maybe consider a small maintence charger also that'll keep em in good nick.

[Chimo]

OD

I just replaced two motor batteries and a house main and a secondary house, all still in use but it was felt that maybe it was time
What I replaced were 1st house,ACDelco Voyager, Oct 2005 2nd house another AC Oct 2002 Port motor ACDelco March 2003 Stbd motor ACDelco June 2010 and not too bad as it still holds 12 volt so its kept as a spare

Replaced all the above with 3 new HCM27SMF ACDelco High Cycle batteries. Two for start and one for house. Should do the job for another 10 years. Specs. http://odaustralia.com.au/index.php/acdelco-hcm27smf-sealed-maintenance-free-battery-marine-rv-4wd-boats-caravan.html

They (the AC Delco battery) seem to be rather cost effective and weight around 20 kgs each.

Cheers
Chimo

[Oceanic Dave]

That is a good price. I just found the above on special at BCF so went with them.

Now another question. Is it best to start with two batteries selected or 1?

When underway, charge both of them and when you stop and use your acc, just run of the batteries?

What is the best method here?

Thanks guys :)

[TruBlue]

Use crank to start
Charge both underway
Use secondary under anchor
Be careful that u don't leave both on and have a secondary that's way undercharged as when you switch to both they will equalise "drain your crank to charge the secondary"



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[Dogtoooth]

I recommend getting a pair of blue top Optima batteries AGM can mount them on their side, fully sealed. I wanted to buy local but their price was crazy and just a rip off. I will buy all my batts online for now on. Make sure you have always got a Ctek fitted to maintenance charge your batts when not fishing. You should get about 4 or 5 years out of them easy. Most are getting about 7 years.

[Chimo]

Fit an auto battery coupler ABC, so the house gets charged as you run the motor.

Use your accs and as the voltage drops the motor battery will be automatically disconnected and the power is only drawn from the house so you always have a fully charged motor battery to start and run the motor.

Fully automatic so you don't have to do anything and new users of family cannot strand you either.

C
C

[Oceanic Dave]

Use crank to start
Charge both underway
Use secondary under anchor
Be careful that u don't leave both on and have a secondary that's way undercharged as when you switch to both they will equalise "drain your crank to charge the secondary"



Sent from my iPad using Tapatalk


Thanks mate :)

[Crunchy]

Thats a lot of switching, while you are changing your battery set up a VSR mate, not hard to do and 'best practice' so to speak.

[Oceanic Dave]

Fit an auto battery coupler ABC, so the house gets charged as you run the motor.

Use your accs and as the voltage drops the motor battery will be automatically disconnected and the power is only drawn from the house so you always have a fully charged motor battery to start and run the motor.

Fully automatic so you don't have to do anything and new users of family cannot strand you either.

C
C

I haven't heard of this, I will look into it. Thank you!

[Chimo]

I can give you the name and contact details of the marine electrician on the Gold Coast who makes them and still has them if thats of interest. (Just checked and when I rang he was in a bilge doing stuff )

Cheers
Chimo

[Spaniard_King]

I can give you the name and contact details of the marine electrician on the Gold Coast who makes them and still has them if thats of interest. (Just checked and when I rang he was in a bilge doing stuff )

Cheers
Chimo

VSR does the same thing and is more cost effective $55

[Oceanic Dave]

Ok, I will look into both, than you.

[Robwhi]

Hi Dave

A VSR is definitely a far better option and we sell them just over the $40.00 mark and many places have them.

I prefer to put in a isolator as you can emergency start off the aux Battery if required but a little more expensive. We use a solid state sealed unit
as solenoid type as pretty useless in the marine environment


Cheers

Rob

[scottar]

If you do end up fitting a VSR, either make sure you get one that has a mechanical override or fit a paralleling switch - doesn't need to be a hugely expensive thing. There are as many ways to fit a dual battery system as there are of skinning the proverbial cat. None of them are right or wrong - (apart from hooking them up in series and smoking the lot) just different. You simply need to make a decision as to whether you want the system automated or totally manual. There are things to take into account with both of the main types of set up.

The most basic system is the single multiple position switch. How you manage your batteries with this is entirely down to you. Me personally (as this is what I have), I turn the battery switch to both, and unless I am anchoring up overnight, this is where it stays. The engine has access to double the CCA so that issues with electronics dropping out during starting or spiking are minimized and it charges both batteries at once. This system has run this way for in excess of 3 years now with no issue. Problems that can occur - if there is a problem I may flatten both batteries and be unable to start. Definitely a concern but as I run an E-Tec that can be rope started reasonably easily it is not something I lose sleep about. The second problem that I have seen (it is rare but I have seen it) is if you start the engine on one battery and then move the switch to the both position to charge both batteries. If your switch is getting a bit dicky due to whatever reason and loses electrical contact during this movement, stuff gets toasted in an expensive fashion.

There is a variation of this theme by using independent switches for each battery. With this system you can switch the second battery in or out without issue while the engine is running as the switch for the main start battery isn't touched.

The other way is to automate via a VSR or whatever other device your heart desires. With this there are really only a couple of things to consider. VSR's, just like any other electronic device, can and do fail - hence the previous comment on a manual override be it external or incorporated. The second thing is the actual wiring method utilized to install the unit. There are two ways essentially. The first sees the VSR's monitoring of the start battery disconnected if the switch for that battery is turned off. This method does not pose any chance of discharging your start battery while the boat is sitting at home not being used but means if you want to charge both batteries with one charger you will need to turn on the battery switch for the start battery.

The second is to have the VSR independent of the battery switches. This method will allow you to isolate the entire boat apart from the VSR and charge both batteries with a maintenance charger or solar set up. The downside to this is that if you forget to hook up the charging system or it fails, the VSR's electronics that monitor the state of the start battery will flatten it eventually.