Battery banks and fusing

[JK_Boston_Catalina310]

Not sure about all the fuss about fitting. I put the 6v batteries in and they fit where the old 4D's did. One thing I had to change was they are a tad higher so I had to re-design the bracing as the factory 2x4 would no longer fit over the top. Also had to make up jumper cables to make the 6V batteries into 12V banks.

That looks like bow to stern orientation which is the incorrect orientation on a sailboat

Also, do you have battery boxes?

 

[KZW]

I'm sure this has been covered many times , but here goes:
- Why are four 6V batteries better than the two 12V 4D batteries? The only advantage I see is it is easier to carry them onto the boat when installing.

 

[JK_Boston_Catalina310]

I'm sure this has been covered many times , but here goes:
- Why are four 6V batteries better than the two 12V 4D batteries? The only advantage I see is it is easier to carry them onto the boat when installing.

Read this from Maine Sail's website.

Bottom line is that 4Ds are not deep cycle despite what the sticker says. They are truck starting batteries. Same can be said for Group 24, 27 and 30 batteries, regardless of manufacturer. While 6V GC or 12V GC are actual deep cycle batteries.

 

[KZW]

Read this from Maine Sail's website.

Bottom line is that 4Ds are not deep cycle despite what the sticker says. They are truck starting batteries. Same can be said for Group 24, 27 and 30 batteries, regardless of manufacturer. While 6V GC or 12V GC are actual deep cycle batteries.

That answers my question. Thank you!

So the trick is to find golf cart batteries that total to the same capacity as two 4D batteries. Interesting problem!

 

[Stu Jackson]

So the trick is to find golf cart batteries that total to the same capacity as two 4D batteries. Interesting problem!

No trick at all. The 4D are most likely about 180 ah each. 4 GCs will get you 425 or so. Easy math.

 

[KZW]

No trick at all. The 4D are most likely about 180 ah each. 4 GCs will get you 425 or so. Easy math.

One assumes the four 6VGolf Cart batteries are about 106 Ah each. However, it takes two, in series, to get to 12V. So you end up with two 212 Ah banks, vs two 4D at 180Ah. You have a 18% increase in Ah capacity for the complexity of the extra wires, etc.

I presume you are using a 12VDC charger (meaning charging at around 14.2 VDC) going into the two in-series banks. Is that a good idea?

 

[Maine Sail]

One assumes the four 6VGolf Cart batteries are about 106 Ah each. However, it takes two, in series, to get to 12V. So you end up with two 212 Ah banks, vs two 4D at 180Ah. You have a 18% increase in Ah capacity for the complexity of the extra wires, etc.

I presume you are using a 12VDC charger (meaning charging at around 14.2 VDC) going into the two in-series banks. Is that a good idea?

GC-2 golf car batteries are 215 - 245 Ah's each.. Two 6V in series yields a 12V 215-245 Ah bank.

Four of them wired in series/parallel makes a 430-490 Ah bank....

 

[KZW]

No issues charging two in series from a 12 Volt charger?

 

[Stu Jackson]

Of course not, you've made a 12V battery (bank). That's the whole idea. No different than (2) 12V banks in parallel.

 

[KZW]

Stu,

Just asking. No two batteries are ever exactly alike. The internal resistance of one is always going to be a bit different then the other. One will always be able to deliver more current, under load, than the other in series. One will charge and top off before the other.

That being said, I presume the differences will be slight and all OK, as evidenced by many who have used such a battery bank.

Just trying to learn.

Cheers

 

[KZW]

Stu,

Just asking. No two batteries are ever exactly alike. The internal resistance of one is always going to be a bit different then the other. One will always be able to deliver more current, under load, than the other in series. One will charge and top off before the other. Back in the day, when I was young, I worked in a plant that made Sears Die Hard Batteries. One of my jobs was to test how well the burp valves worked by overcharging the battery in a chamber and igniting the vented hydrogen to ensure the subsequent fire didn't back into the cell being overcharged.

I presume the differences will be slight and all OK, as evidenced by many who have used such a battery bank.

Just trying to learn.

Cheers

 

[Stu Jackson]

You're right, of course. Learning is a good thing. But avoiding reinventing the wheel is also one of the great things about this forum and others.

When we first bought our boat in 1998, way before the internet was as widespread as it is today, all of us had to learn from (gasp!!!) books and magazines. We survived. The first thing I did after sailing my Catalina 25 for 13 years was to buy and read Nigel Calder's Boatowners Manual for Mechanical and Electrical Systems. I believe it's a must have for everyone with something bigger than a daysailor, especially with inboard diesels and other systems. He spends a LOT of time on electrical systems. Good investment if you haven't gotten it yet.

Maine Sail has discussed 6V batteries at length. I also developed our "Electrical 101" topic on our C34 website, which I've linked to quite often here on the C310 forum.

Lots of battery information here, too: The Ample Power Primer http://www.amplepower.com/primer/primer.pdf

Good luck, keep askin'.

 

[JK_Boston_Catalina310]

Stu,

Just asking. No two batteries are ever exactly alike. The internal resistance of one is always going to be a bit different then the other. One will always be able to deliver more current, under load, than the other in series. One will charge and top off before the other. Back in the day, when I was young, I worked in a plant that made Sears Die Hard Batteries. One of my jobs was to test how well the burp valves worked by overcharging the battery in a chamber and igniting the vented hydrogen to ensure the subsequent fire didn't back into the cell being overcharged.

I presume the differences will be slight and all OK, as evidenced by many who have used such a battery bank.

Just trying to learn.

Cheers

I know a lot of answers have been provided but saw one details missing.

To best deal with the issue you have pointed out, it is important that all batteries that are placed into a bank are done so at the same time. I know Maine Sail has pointed this out before but I don't have a link readily available.

So if you are going to replace your two 4Ds with four 6V GCs, then buy all four at the same time. Go a step further and make sure you have four with matching date codes.

When I did this at Sam's Club it took about 5 minutes of looking around to find the four newest batteries with matching date codes.

One other quick note. If we weren't going cruising and were just using our boat for weekends with the occasional 1-2 week cruise with her spending the rest of the time on the dock hooked up to shore power, I would not get all of these batteries. Why purchase 4 batteries when a good setup (i.e. alternator direct with ACR, battery monitor on primary, etc.), a primary bank of two 6V GCs of 230 Ah and a reserved bank of one 12V group 24 would be perfectly adequate for that use. You could save a lot of money, weight and space and still have more actually battery capacity and cycles then you do with two 4Ds tied up in parallel. As Maine Sail has pointed out, the 4Ds are only about 160 Ah when new and they are not true deep cycle. Which means in a real world you only have about 100-130 Ah of usable capacity from two 4Ds in parallel. You would get close to the same from the two 6V CGs in series.

Good luck and fair winds,

Jesse