Mixing it up?

[Hoohaa]

Hi.
We have a 3 battery system, Battery 1 (Led Acid) is for the motor and batteries 2 & 3 are house. 2 & 3 are new Led Acid and 1 is a physically huge battery which is in good condition but older.

We like to run our fridge & freezer while on board. which will sometimes slowly bring the house batteries down to as low as 11 volts during the day. Depending on wind and the sun.

Charging is through an old 60 watt solar panel and a new D400 Wind generator.

So. Thats or system in a nutshell.
I already have spare
1 - Led Acid "Century N70T 11549 AH75.
1 - LifeLine GPL 27T 20 amp per hour.

I have the room to add both of these to the bank. What are the potential problems if I mount and wire them in?
Will it have a significant effect on the performance of the existing bank batteries?

[Badsanta]

you can have as many batteries as you want in one bank. I would keep one start battery and everything else in one house bank and I would not run them down to 11 volts. you need more info than I can provide.

[delmarrey]

If you use a combiner to isolate the old from the new, it'll equalize the charging system so it doesn't get over worked or ruin the newer batteries.

[Hoohaa]

Thanks for the replies guys.

Originally Posted by Badsanta

you can have as many batteries as you want in one bank. I would keep one start battery and everything else in one house bank and I would not run them down to 11 volts. you need more info than I can provide.

What would be considered a reasonable voltage to let it run down to before I start the motor to charge things up?

delmarrey
I will try and google the combiner.
You may have noticed that I am electronically challenged.

Thanks for the help.
If I was not to use a combiner what would be the long term effect on the two new batteries?

[forsailbyowner]

They would suffer being drained constantly to the votage of the lowest battery and die a premature death. I don't let my batteries get below 12v without shutting stuff down and taking measures to regain charge. I'd up the solar and separate the new from old.

[Hoohaa]

Originally Posted by forsailbyowner

They would suffer being drained constantly to the voltage of the lowest battery and die a premature death. I don't let my batteries get below 12v without shutting stuff down and taking measures to regain charge. I'd up the solar and separate the new from old.

OK That gives me a guide to work with.
My banks are already separated, its just a matter of increasing the size of the house bank without doing any damage to the existing batteries.
I just got back from the shops where I tried to get myself a "combiner" but wound up looking at well meaning but confused faces, so I am back again doing some more research.
At the moment I am planning to mount the batteries and wire them in sequence with my existing bank and talk to a marine electrician about isolating them at a later date as it appears there will be no short term effect on my existing bank.
I must already have some sort of duel system set up, so I may be able to utilize it if it has the capability.

Is a combiner the same as a "duel battery system"? or am heading down the wrong track?

[Hoohaa]

Originally Posted by forsailbyowner

They would suffer being drained constantly to the votage of the lowest battery and die a premature death. I don't let my batteries get below 12v without shutting stuff down and taking measures to regain charge. I'd up the solar and separate the new from old.

Just quickly.
What should I charge them to?? 13..14 volts?

[delmarrey]

Originally Posted by Hoohaa

Thanks for the replies guys.

What would be considered a reasonable voltage to let it run down to before I start the motor to charge things up?

delmarrey
I will try and google the combiner.
You may have noticed that I am electronically challenged.

Thanks for the help.
If I was not to use a combiner what would be the long term effect on the two new batteries?

Here are a couple links that will give you a bit more info on batteries and combiners. I think part of owning a sailboat, that one spends time on, is being an amateur electrician. These will get you started.

http://www.cruisersforum.com/forums/...ity-94243.html

Combiner Information

[forsailbyowner]

I made the attempt of combining batteries first time around before buying a whole fresh bank. It didn't go well. On the first trip it dropped voltage drastically quickly. Turns 1 cell shorted and sucked the whole system down. Then tried to locate the bad cell in 8 batteries. I figure I spend about $100 a year to keep in batteries. That's 8 sams club batteries every 5 years.
Instead of looking at voltage I check the specific gravity to determine battery state of charge. My charge sources don't include shore power source so if I get low it will sometimes take 3 days to charge in energy conservation mode.(Fridge off at anchor). Generally as I know it a battery needs 14.x to reach full charge. But 14.x doesn't mean full charge. Mine will sometimes get to 15 or more when nearing full charge in full sun. I'm way simple in my setup. I am the controller and adjust my usage to the power avalable. Nothing happens fast with 8 batteries. I carry around 600 watts of solar and 400 watt wind gen which is currently down. I found out I don't keep up with the charge while underway without wind gen. Losing the windgen from the system made it necessary to shut fridge down while sailing. Nav lights,radar,plotter, autopilot etc....

[sailorboy1]

I think it doesn't what you do as far as comining into banks if you are going to keep drawing the batteries down to 11V. I doubt your batteries are going to last!

You need larger capacity so that you aren't regularly downing below 50% charge. You also in your use going to need more solar etc. and to be able o get the batteries fully charged regularly (like at least weekly) if you want them to last.

[ranger58sb]

Batteries within a given bank should all be same size, type (flooded lead acid, AGM, cell...), and age.

-Chris

[sailinglegend]

Originally Posted by ranger42c

Batteries within a given bank should all be same size, type (flooded lead acid, AGM, cell...), and age.

-Chris

They don't all need to be the same size.

Recent research by Lifeline Batteries has proved that a bank can be made up of different capacities and that the life of the batteries is not compromised, as long as they are all the same make and the same age. This goes against most previous guidelines, but Sabre yachts, which use Lifeline AGMs, regularly ship with different sized batteries to be able to get the maximum capacity from all the available space.

[Hoohaa]

Originally Posted by ranger42c

Batteries within a given bank should all be same size, type (flooded lead acid, AGM, cell...), and age.

-Chris

Yes. This is what I have heard. I allready own these two different batteries, so am trying to find out what will happen if I wire them in sequence? Short term? Long term?
I can go and buy new batteries but it seems like a waste of the two that I allready own. Is it really an unknown quantity? If so, I don't have much too loose by giving it A go.

delmarrey
I am still trying to get my head around the links, thanks.

[David M]

Batteries in the same bank do not have to be the same size, just the same type. You would not want to mix a standard lead-acid with an AGM for example.

A hydrometer can be used to detect a bad battery cell.

It sounds to me like you need more capacity in your house bank. You definitely need to isolate your start battery from your house bank with a battery combiner.

The further down you run your battery voltage, the lower their life, even for a deep cycle battery. There is no hard number for this....lesser is better. Eleven volts is at the level of battery abuse.

[ranger58sb]

Originally Posted by sailinglegend

They don't all need to be the same size.

Recent research by Lifeline Batteries has proved that a bank can be made up of different capacities and that the life of the batteries is not compromised, as long as they are all the same make and the same age. This goes against most previous guidelines, but Sabre yachts, which use Lifeline AGMs, regularly ship with different sized batteries to be able to get the maximum capacity from all the available space.

That's very interesting! Although I've not heard that from any other manufacturer... I could certainly get onboard with Sabre's approach, given the way our available battery space is laid out. Is that research on Lifeline's website somewhere?

Thinking out loud here: I wonder if it's something about Lifeline's AGMs being OK for equalizing.... whereas other AGMs are apparently not. Can't imagine the chemistry is all that much different within equiavalent technologies. OTOH, an individual cell in a 245-ah 8D is sized differently than a single cell in a 100-ah Group 31. Hmmm.....

More info on this would certainly be welcome!

-Chris