Charging Multiple Battery Banks

[nmit5903]

Looking for any help or thoughts on charging systems for multiple battery banks please. I have read threads which have been useful re the use of combiners and duochargers/echochargers and I think I have managed to fathom out a solution.

I have three battery banks - starter which is a cranking flooded lead cell X2; house - AGM batteries and a small ONAN genset starter battery which I am ignoring for the time being. I will probably just put it on a small independent solar panel and regulator for the ONAN.

The house batteries (array of 6V AGM's providing 690AH) are currently charged by a high output alternator via a Smart Charger that kicks in at 1500 revs. The starter is charged directly by another alternator.

Two 80W solar panels are connected to the house bank and starter, switched, via a regulator (old but works although it has no readout so not sure how effective the also quite old panels are).

Havnt fathomed out the wind circuits yet.

The solution I am thinking about is:

1. Replace the old solar charger with a Steca PR3030 with a readout so that I can monitor whats happening with the solar array (presently really no idea).
2. Remove the switch for the solar between starter and house and wire the Steca to the house bank.
3. Fit a Xantrax Echocharger between the house bank and starter banks.

Some questions that I am unsure about:

1. Will I have any problems with the fact that the starter battery is also charged by its own alternator?
2. Can I use a Xantrax echocharger between the house AGM's and starter flooded batteries.
3. Any other thoughts re better solutions?

[sabray]

Seems too complicated echo charge won't handle the 2 different charge profiles. At least as I understand the manual. Why not one house bank and a start battery. All the same battey type. Combiner and then a good solar wind regulator. A little less cramp. And yes Maine sail is not going to like that combiner but it has worked for me for more then a few years in Agm house batts. I'm
Lucky I guess.trick is to fully charge the house Agm.

[nmit5903]

Thanks. That was my concern re the two different types of batteries. Balmar duocharger does apparatnly but twice the price of Xantrax (and I like Xantrax). There is a lot of negative stuff written about combiners so I have tended away from them. Appreciate some like yourself swear by them and have had many good years usage.

The setup is inherited and far more complex than needs be. I have had electricians crawling over the thing and they are scratching their heads so am just taking a slow cautious apprach to simplifting, taking one thing at a time and see what happens.

[sabray]

I am really bad my start is a group 27 Agm. Topped up by combiner. Suppose to not be great for a start bat but it has worked every time for 6 years plus . Alternator has a boosted internal regulator for Agm profile. Solar goes through blue sky regulator. 110 is handled by xantrex inverter. All very basic and functions. Not up to some folks standards. Maine sail has the best site for really good info on how to do this better then me. Including best practice in tying in the batts. I like one house bank. Good luck

[smac999]

why do you need the echo charger? just let the 2nd alternator charge the start battery as is. the agm battery lasts months without draining. as long as you start the engine every few months you'll be fine.

I would get a 3 bank charger and allow all 3 batteries to charge at dock though

[nmit5903]

Boat is left for weeks at a time. Starter battery probably OK but I am more comfortable knowing that it will be in good shape when i arrive and start her up.

Rarely if ever put on shore charge unless alongside overnight. Kept on swing mooring.

[btrayfors]

nmit5903,

Your plan with the EchoChargers is just fine. No problem mixing AGMs and flooded batteries: they have almost identical charging profiles.

I wouldn't bother with a separate panel to charge the Onan's start battery. Just use an EchoCharge...either connected to the house batteries or the other start battery. As you know by now, start batteries require very little charging to keep them topped up, but it IS a good idea to keep them topped up, especially AGMs.

RE: your question #1 above, no problem. No conflict. The EchoCharge is a one-way voltage-follower device. When the engine is running and the 2nd alternator is charging the start battery, the EchoCharge just won't pass any current.

One thing to consider, though. Those AGMs in the house battery will take a heck of a lot of charging current. Depending on how you use the boat, size of alternators, etc., at some point you might want to consider using the 2nd alternator to boost charging current to the house batteries and let the EchoChargers handle keeping the start batteries happy.

Bill

[nmit5903]

Thanks Bill. That's very helpful and answered my questions.

[Andina Marie]

To get the best out of both alternators and reduce charging time, a Combiner160 between the two systems would be a major improvement over the echo charge.

They are bi-directional so which ever system has excess capacity available it will be delivered to the other alternator load.

They can deliver up to 160 amps continuous which is an order of magnitude higher than the 15 amp limit of an echo charge.

[mbianka]

With my 48 volt electric propulsion battery bank consisting of 4 12 volt 8A4D batteries in series having balanced batteries is important. I found the solution using a Dual Pro 4 (thought they make several configs) works for me:
THE BIANKA LOG BLOG: A QUESTION OF BALANCE
I have not charged my battery banks from an alternator in six years and the banks ( both 48 volt EP and 12 volt house) are still very healthy just by using it and a Honda 2000i for charging along with solar and a wind turbine.

[nmit5903]

There seem to be two schools of thought on the combiners and the ecochargers. On balance I am swayed towards echochargers for one reason - which is that the combiner process seems to be to equalise the two banks, which may involve draining one to charge the other.

Having said that - Bill - if your still there - I could also see some merit in the combiner approach with dual alternators. The house and starter alternators would effectively end up charging both banks through the combiner.

[nmit5903]

The dual pro 4 looks good as well however more costly than both the combiner and echocharger solutions. Also note it is limited to 10a per bank - not sure how it would work with the smart charger on the house bank?

[s/v Beth]

Wow this is complicated. I am glad I am such a simple man. I use one type of battery, and I have them on two separate circuits. One for house bank, then startup bank. I have a emergency joiner (just a switch with large wires, doesn't cost much.) Then I have all charging going into the house bank. When I am charging, from whatever source, I turn on the joiner- everything gets charged. When I am draining electricity without charging (passage making at night, anchoring out) I turn off the joiner. This way all charging mechanisms only need one controller.
Everyone is happy and I always have a fully charged battery to start with in the morning. Why do you need more complexity than that?

[nmit5903]

Ha ha. Sounds too easy!

[Andina Marie]

Originally Posted by nmit5903

There seem to be two schools of thought on the combiners and the ecochargers. On balance I am swayed towards echochargers for one reason - which is that the combiner process seems to be to equalise the two banks, which may involve draining one to charge the other.

Having said that - Bill - if your still there - I could also see some merit in the combiner approach with dual alternators. The house and starter alternators would effectively end up charging both banks through the combiner.

Our Combiners will NEVER take charge from one battery and deliver it to the other battery. All they take is the alternator output over and above what is going into the battery on charge. If the battery being charged by the Combiner is demanding more current than the alternator can supply it will cycle on and off to prevent overloading the alternator and preserve the charge in the starting battery.