Adding batteries to an existing bank

[Zanshin]

My new boat has a house bank of 4 Jeanneau batteries, each with 110amp hours. Although I tend not to use much power for lighting with my LEDs, I find that the DC powered refrigerator and freezer eats a lot of power and necessitates my charging the system daily. I would like to increase this capacity by adding another 4 110amp hour batteries. I will then also upgrade my charger from a 50amp one to a bigger one (my genset is sufficiently sized to allow that) and find a more powerful alternator than my current 80amp one.

I've recently installed a Xantrex Link 10 monitor and can see how adding that last 15% of charge to the battery takes significantly longer, so an increase in capacity would help my keep an efficient load cycle going.

The original batteries are 2 years old and still working well buy they have no manufacturer name - plus I probably wouldn't find them for sale here in the Caribbean.

What factors should I consider when adding batteries? I think that using the same technology is important, but should I also go for 4 x 110AH or is it OK to add 2 x 220AH? Space is not that great a consideration, as I have room in the battery compartment to stack more batteries on top of the originals and can box & strap them in.

[xort]

Are the existing batteries wet cells? How is the SG reading? Voltage when resting up to snuff?

all the experts say not to mix new with old. Perhaps you could set up a second bank with the new batteries. Eventually, you could replace all the new and old and then combine the 2 banks at that time.

Can you contact Jenneau and ask what make the batteries are?

[captainjay]

Zanshin I just had the 45DS out for a week that we have at CYOA. It has a 12 volt fridge and freezer as well. Jeaneau put five house batteries in the boat from the factory. The owners had two more added and a 120 amp alternator at Bay Yachts before it came down to us. They simply added them to the current bank. I found that overnight with both the fridge and freezer running the total bank would drop by .5Volts. I think in the long run based on what I have seen in the charter fleet the larger batteries hold up better.
I would look at putting in a selector switch for two banks. I would buy two of the larger batteries for your new bank and plan on replacing your four older batteries with two of the bigger ones when they die.
Jay

[Zanshin]

The batteries are sealed ones and their voltage is in the green; plus I can see with the Xantrex that they are accepting charge quite well. For the 2 years that these batteries have been installed they were used only for a short while (one ARC crossing and a sailing week or so) prior to my getting the boat.
I am hesitant to split the house bank into 2 separate ones, as that would take away the loading advantage of a large house bank (50-80% of 880AH would give me 264AH to play with while using full charge).

I did send a mail to Jeanneau inquiring which brand they used but haven't heard back.

[xort]

I agree that one bank is better. I thought of the 2 bank idea if the old batteries would be a mismatch to the new batteries. You could suffer through the 2 bank solution until it came time (hopefully 5 years later) to replace them all. Then combine them all.

Considering the existing ones are in good shape, what's the worst that can happen?

[Zanshin]

After thinking about combining batteries and having to resort to 2 house banks if I wanted additional power, I've decided to keep my batteries as they are and add either wind or solar immediately so that the system can at least keep up with the refrigeration power demands.
Thanks everyone.

[Selkirk]

Originally Posted by Zanshin

....... I find that the DC powered refrigerator and freezer eats a lot of power and necessitates my charging the system daily........

I am certain that the problem can be solved, but you may not want it when you price it out. After all, forklifts can run all day on batteries, why can't your boat?
My solution is to do without refrigeration....

[k1vsk]

A lot of us are of the view that doing without refrigeration isn't anymore realistic on a boat than it is in our home.
Having said that, mixing old and new batteries, although generally not recommended, is not always a terrible thing to do - it is a generality and there are exceptions, among which is primarily the consideration of how mis-matched they would be in the sense that the internal resistance should be similar, capacity ratings should be similar and obviously the technology should be similar.

Mixing old and new batteries can be done and only requires some due diligence to what you are mixing.

[erps]

I am certain that the problem can be solved, but you may not want it when you price it out. After all, forklifts can run all day on batteries, why can't your boat?

Are there any forklift operators out there that can give a little information on their lift's battery bank and amp consumption? Just curious.