I think it all depends on how you use the house batteries. If they are permanently paralleled they will discharge and charge equally, and could be charged as one, but if they are on a battery switch that allows you to run one down without using the other you would need to charge them independently. The reason for that is because the higher voltage of the fully charged battery would trick the charger into thinking the discharged one was also fully charged. I think you would also want to make sure they were identical batteries of the same age.

 

im planning on running the group that is paralled together to run as 1 battery and have the starter battery seperated. will this work? will my charger charge the starter and the group at same time or will it stop once one is full as in the starter?

 

Yes, if your charger is a dual battery charger, that means it essentially functions as 2 discrete chargers that will treat the house and cranking batteries independently. It wouldn't hurt to check the specs of your charger and make sure that it can handle the charging load of the house bank or it may be very slow to recharge.

Polar Battery on Boundary Rd in Vancouver is a good resource, and you can get good prices on batteries and chargers without paying the "marine" markups!

 

The paralleled house bank (Bat A and Bat B) can be charged as one battery; run the positive charger lead to positive post on bat A and the negative charger lead to negative post on battery B. You could use an ACR (automatic charging relay) to charge the start battery without using a multibank charger. Best battery life would be obtained with a "smart charger", and separate charging of house bank and start bank. Temperature sensors add a safety feature if you're selecting a new charger.

 

SchockT, My boat has 10 amp Newmar with 4 terminals but only 2 are being used on the house bank. Way it was when I got the boat. Is it a bad to have one pos wire on each bank and 2 Neg on the common negative?

 

I don't see why you couldn't since it is no different than connecting the negatives to their respective battery's negative post. They are all electrically connected after all. My Xantrex 2 bank charger only has a single negative wire, and then a positive for each bank.

Of course the prudent thing to do is to read the manual for your specific charger!

 

Recommended reading for basic understanding of charging system:
Installing A Marine Battery Charger Photo Gallery by Compass Marine at pbase.com

 

No one has mentioned the more modern approaches.

A common setup these days is to have chargers only charge the house battery, then to charge the starting battery off of the house battery.

On my boat there 3 batteries in the same configuration as yours and 3 multi-phase chargers: shore power based one, alternator-based, and solar. All of these are charging the house batteries.

The starting battery is charged off of the house battery using a Xantrex Echo Charger.

The battery switch is a Bluesea 5511e which has 3 positions: Off, On, and Combine(Emergency). Off turns everything off. On connects the starting battery to the engine circuits, and the house battery to the house circuits. Combine will combine all circuits should I need to start the boat off of the house batteries.

The advantage of this setup is that my house and starting batteries are never combined (unless there is an emergency) and all batteries get the best quality charging possible. It also allows me to safely mix battery technologies, my house batteries are AGM while my starting battery is a wet cell.

My shore power charger is a Xantrex Trucharge 20+ that can handle two battery banks, but I only have one attached to it.

 

I beleive the ACR is the more modern day approach and accomplishes the same thing without having to buy the echo charger.

No one has mentioned the more modern approaches.

A common setup these days is to have chargers only charge the house battery, then to charge the starting battery off of the house battery.

On my boat there 3 batteries in the same configuration as yours and 3 multi-phase chargers: shore power based one, alternator-based, and solar. All of these are charging the house batteries.

The starting battery is charged off of the house battery using a Xantrex Echo Charger.

The battery switch is a Bluesea 5511e which has 3 positions: Off, On, and Combine(Emergency). Off turns everything off. On connects the starting battery to the engine circuits, and the house battery to the house circuits. Combine will combine all circuits should I need to start the boat off of the house batteries.

The advantage of this setup is that my house and starting batteries are never combined (unless there is an emergency) and all batteries get the best quality charging possible. It also allows me to safely mix battery technologies, my house batteries are AGM while my starting battery is a wet cell.

My shore power charger is a Xantrex Trucharge 20+ that can handle two battery banks, but I only have one attached to it.

 

I have an ACR from Blue Sea have yet to install it. rewire the engine panel (per Maine Sail)

 

No need to do anything to the engine panel. Blue sea has suggested wiring diagrams on their package and on their website. Study those and the excellent suggestions from Mainesail on wire terminations and related topics and you should be ok. I'm sure the crew on SNet will provide more than enough suggestions. Here are some pics of the installation:
http://plus.google.com/photos/103384431781172187499/albums/5894271531755244321?banner=pwa

 

Seaduction, I got a "You do not have permission to view this album." on your link

I need to rewire my engine panel because the Amp meter is connected from the switch and then to the starter; a bad thing in the older Universal diesel panels.

 

Sorry, I posted some photos here on my profile page to sort of show what was generally done.

 

I agree that the ACR is a simpler but not better solution than the Echo Charger. It also isn't that much cheaper ($146 vs $96 with no account at my local store).

The ACR works by combining all batteries together when there is a charge, but keeping them isolated when there is not.

The Echo Charger is a DC-DC charger that charges the starter battery from the house batteries. It only charges from the house batteries when they have >13v (so normally only when they are themselves charging).

 

There are a lot of misunderstandings out there about Echo's, Duo's (B2B's) and ACR/VSR relays. I suppose I need to write an article on this subject...

Echo Pro's:

*Easiest installation and least additional installation expenses if charge sources already flow to HOUSE bank.
*Simple
*Can mix some battery types, but not all
*Ideal & simple for just keeping a small start battery "topped up"

Echo Cons:

*Voltage drop
*Limited to 15A max
*Is a one-way device
*Could, in-theory, potentially over charge a "start" battery if house bank stays at a high absorption for a long enough period of time (never seen it, likely due to the voltage drop).
*Reliable
*POS factory fuses & poorly executed crimps MUST be replaced
*Voltage limited to 14.4V and non-adjustable (Trojan's & US Battery prefer higher charging voltages than 14.4V)
*WILL-NOT do float independently of the house bank. The manual lies and misleads owners to believe it will. It is simply a voltage follower and follows the house bank minus any voltage drop.
*All charge sources MUST be wired to the HOUSE bank if not already wired as such. This little tid bit can make an Echo or Duo charger cost a LOT more than an ACR installation.

ACR Pro's

*Bi-Directional - current can flow equally both ways
*Bi-directional voltage sensing - turns on when either bank is charged
*Significantly higher current capability
*Both banks are charged at the SAME voltage thus both banks reach absorption, float etc. at the same time.
*Impossible to have one bank with a higher voltage than the other for more than the first few seconds
*Extremely reliable
*Large studs (Blue Sea ACR's) allow MRBF bank fusing to be installed on ACR if close enough to bank
*Completely sealed/potted unit
*Better choice when owners decide to "alternate" house banks (this is not advised but people do it)
*Great choice for windlass or thruster banks (more available current)

ACR Con's

*Requires more expense because wiring is significantly larger gauge
*Requires more expensive fusing
*Not the best choice for mixing battery chemistry
*Requires running alt to house bank if banks are of unequal sizes
*Requires the "start isolation" feature to be wired if solar or other change sources exist

The Echo is very often the easiest to install but not necessarily always the best choice. I install boat loads of both B2B's and VSR's it just depends upon the application.

 

"Requires the "start isolation" feature to be wired if solar or other change sources exist"

Guess I need to explore that MS.

 

There is a terminal on the BS ACR that you wire to the starter solenoid wire or start button. When the starter is engaged it drops the relay so you don't pull more than 120A through it.

99.5% of them I see installed never connect this wire, even factory installations on boats that factory ship with them, and I have never had a single failure of a Blue Sea ACR. That said I do use the SI feature when there is a source that could have the banks at "combine" voltage...

On my own boat, for experiments sake, I never connected SI feature and the relay survived many hundreds and hundreds of starts without any failure. They are well built relays..

 

Ah.. ok. so Charging input from just about anything like solar, wind, should always connect to.......?

 

House bank.. Solar, wind, alt etc...