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Old 29-10-2015, 09:28   #16
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Re: electrical repair works on the yacht

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Originally Posted by Tikka View Post
alexander, it's very simple . Any specialised shop, you pay a lot more sometimes double price. Any battery outlet sells lead acid - calcium batteries, they excellent for boat and half price than deep cycle. Generator, I only use Honda 1kW, perhaps you talking about engine alternator, any spare car parts outlet, simply all car alternators have build in regulator, just match the amperage depends how many batteries you intend to install. And finnaly all wiring on the boat is done by " thinned copper wire " from any electrical place. That's is my 40 electr. exp...hope it might help..
I need to agree with the gist of this. Some of the prices I see associated with some batteries is exorbitant. You can throw out a bunch of 8Ds for that amount of money.
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Old 29-10-2015, 15:39   #17
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Re: electrical repair works on the yacht

A true deep cycle battery - flooded 6 volt golf cart - will handle twice as many cycles as any normal 12 volt battery - group 24,27,31,4D, and 8D. The flooded golf carts are the lowest cost per AH of any other battery type. And they aren't very expensive.
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Old 29-10-2015, 19:00   #18
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Re: electrical repair works on the yacht

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Originally Posted by alexander_456 View Post


Thank you Ramblin Rod so much. Yeah, It will be first thing to do: the seacrh of a good marine electrician. In our days it is so easy to be cheated. I want to pay only for quality work.
I agree with his analysis.

What appears to be missing, so far, is what you want to do. You simply asked about parts.

Our experience, in boating and in business, has always been that even before you start to consider hiring anyone to DO anything or gets "parts" it is customary in ANY field of endeavor to develop at the very least a design criteria.

If you have that, would you care to share?
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Old 29-10-2015, 20:51   #19
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Re: electrical repair works on the yacht

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A true deep cycle battery - flooded 6 volt golf cart - will handle twice as many cycles as any normal 12 volt battery - group 24,27,31,4D, and 8D. The flooded golf carts are the lowest cost per AH of any other battery type. And they aren't very expensive.
Beware, a lot of folks have been sold a bill of goods on the virtues of golf cart batteries.

In physics, and especially energy conversion, you can't get sumthin for nuthin.

Everything else being equal, 2 group 27 deep cycles in parallel and 2 six volt golf carts in series, deliver about the same voltage and Ahrs.

The six volts have a little higher capacity but lower bulk density (less lead).

But here is the real rub, nobody but nobody should have just 2 six volts in their house bank. If one battery goes down, you can't operate anything off the house bank.

Whereas with 2 twelve volts, if one goes down, you can still run everything, just not as long between charges.

In larger banks, the same holds true, if you one 6 volt goes down, you have to take out 2.

In some cases, the benefit of the slightly higher capacity, is negated by the much more significant impact of a battery failure.

I'm not saying that 6 volt golf carts are bad, just that they are not as great as some have been lead to believe.
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Old 29-10-2015, 23:58   #20
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Re: electrical repair works on the yacht

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Originally Posted by ramblinrod View Post
Beware, a lot of folks have been sold a bill of goods on the virtues of golf cart batteries.

In physics, and especially energy conversion, you can't get sumthin for nuthin.

Everything else being equal, 2 group 27 deep cycles in parallel and 2 six volt golf carts in series, deliver about the same voltage and Ahrs.

The six volts have a little higher capacity but lower bulk density (less lead
The golf carts are true deep cycle batteries. The group 27's are starter batteries, whatever their label states. The golf carts will deliver roughly twice as many cycles as the group 27's. And you will probably pay a bit more for the golf carts but with their better cycling ability the cost/AH will be lower.
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Old 30-10-2015, 06:29   #21
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Re: electrical repair works on the yacht

Just saying that golf cart batteries are all great is misleading. I use a very large battery supply store and they had nothing called a golf cart battery. They had many that would work and he knew what I wanted and meant, but nothing "golf cart" and just saying use a "27" or "31" or other case size is confusing. Yes it's the same size bread box, but how much bread is in the box. Just throwing around a name does not mean much. Each has better or worse. Its hard to get honest numbers when each uses a different scale of use. Not trying to argue but trying to point out that its not that simple. What works for you, thats great, But for a person trying to do a proper battery bank it is very confusing to just throw out seemingly random numbers when each item has several different internal sizes. Most places that sell batteries don't have a clue about boats. Just my humble opinion. Thanks rant over.

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Old 30-10-2015, 11:30   #22
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Re: electrical repair works on the yacht

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Originally Posted by mitiempo View Post
The golf carts are true deep cycle batteries. The group 27's are starter batteries, whatever their label states. The golf carts will deliver roughly twice as many cycles as the group 27's. And you will probably pay a bit more for the golf carts but with their better cycling ability the cost/AH will be lower.
Perhaps the reason you were getting too few cycles out of Grp 27's is because you believe there is no such thing as a Grp 27 deep cycle and have been using Grp 27 starting batteries instead?

Battery manufactures (there are only a few that make the many different brand names) produce separate models of Group 27: starting, deep cycle, and combined start/deep. Each model has different construction.

If you look at batteries from the same manufacturer and product line, the difference in capacity and longevity of 2 x 6 volts vs 2 x 12 volts, is not that significant.

Take for example, Trojan, a respected brand of marine battery.

a) 2 x GRP 27 twelve volt are rated 230 Ahrs, 120 pounds, and 1680 cubic inches.

b) 2 x T105 six volt are rated 250 Ahrs, 124 pounds, and 1623 cubic inches.

Slightly higher rating (less than 10%) , slightly more weight (3%), and slightly smaller volume (3%), for a slightly higher bulk density (more lead).

This is the advantage of 6 volts vs 12's, slightly higher performance.

Now for the disadvantages:

1. Higher price (typically).
2. Less (and maybe older) stock at retailer.
3. Different dimensions.
4. Greater capacity reduction on battery failure.

On a single battery failure, if you have 2 x 6 volts you just lost 100% of your capacity (compared to 50% for 12 volts). If you have a 4 battery bank, with 6 volt batteries you just lost 50% capacity (compared to 25% for 12 volts).

This should be a consideration when choosing between 6 and 12 volt battery banks, but is often overlooked.

When rationally evaluated, the slightly higher capacity and bulk density may not be worth the cost and impact to the house bank if a battery fails, until one gets up to 6 batteries or more.

So when a customer is contemplating changing from 12 to 6 volts, I advise the real impact on battery performance, vs the additional cost of batteries, new boxes, wiring, and labour. With this information, many decide to spend their money on something else that will have greater impact on their vessel enjoyment.

I've had numerous owners I just met for the first time, proudly advise me that they just changed out 2 x 12 volts for 2 x 6 volts.

When I ask them how they will run house loads without depleting the starter battery, if a 6 volt failed, they look at me all confused. Suddenly a light bulb comes on over their head and the smile goes away. The answer is to leave the engine running until the bad 6 volt is replaced.

Again 6 volt batteries aren't bad, in fact they are pretty good, (but not nearly as superior as some are lead to believe).

To each their own.

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Old 30-10-2015, 11:52   #23
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Re: electrical repair works on the yacht

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Originally Posted by ramblinrod View Post
Beware, a lot of folks have been sold a bill of goods on the virtues of golf cart batteries.

In physics, and especially energy conversion, you can't get sumthin for nuthin.

Everything else being equal, 2 group 27 deep cycles in parallel and 2 six volt golf carts in series, deliver about the same voltage and Ahrs.

The six volts have a little higher capacity but lower bulk density (less lead).

But here is the real rub, nobody but nobody should have just 2 six volts in their house bank. If one battery goes down, you can't operate anything off the house bank.

Whereas with 2 twelve volts, if one goes down, you can still run everything, just not as long between charges.

In larger banks, the same holds true, if you one 6 volt goes down, you have to take out 2.

In some cases, the benefit of the slightly higher capacity, is negated by the much more significant impact of a battery failure.

I'm not saying that 6 volt golf carts are bad, just that they are not as great as some have been lead to believe.
I am not an advocate of either but double anyone runs two six volts? my guess would be a series parallel bank of four or two 12s.
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Old 30-10-2015, 15:37   #24
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Re: electrical repair works on the yacht

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Originally Posted by ramblinrod View Post
Perhaps the reason you were getting too few cycles out of Grp 27's is because you believe there is no such thing as a Grp 27 deep cycle and have been using Grp 27 starting batteries instead?

Battery manufactures (there are only a few that make the many different brand names) produce separate models of Group 27: starting, deep cycle, and combined start/deep. Each model has different construction.

If you look at batteries from the same manufacturer and product line, the difference in capacity and longevity of 2 x 6 volts vs 2 x 12 volts, is not that significant.

Take for example, Trojan, a respected brand of marine battery.

a) 2 x GRP 27 twelve volt are rated 230 Ahrs, 120 pounds, and 1680 cubic inches.

b) 2 x T105 six volt are rated 250 Ahrs, 124 pounds, and 1623 cubic inches.

Slightly higher rating (less than 10%) , slightly more weight (3%), and slightly smaller volume (3%), for a slightly higher bulk density (more lead).

This is the advantage of 6 volts vs 12's, slightly higher performance.

This should be a consideration when choosing between 6 and 12 volt battery banks, but is often overlooked.

When rationally evaluated, the slightly higher capacity and bulk density.....
You are not comparing batteries properly really. The plates in the 6 volt (T-105 for example) are thicker than the group 27 - any group 27. The 2 group 27 batteries total 12 cells, the 2 T-105's total only 6 cells but 2 weigh even more than the 2 group 27's.. The cycling differences are evident in use, not just on paper.

The marine industry is way too small to develop a battery like the golf carts for itself, but the golf industry and associated use of battery operated carts was more than able. Any major golf course can tell you exactly how many cycles they get out of the 6 volt batteries in their carts. Many golf courses have hundreds of carts. None of them use 12 volt group 27 or 31 batteries. The reason is dollars - more cycles for the dollar from golf cart batteries.

I agree with Cadence - a bank of 4 golf cart batteries makes the most sense. My customers have anywhere from 4 to 16 golf cart batteries in series/parallel for house bank use.
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Old 31-10-2015, 11:16   #25
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Re: electrical repair works on the yacht

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Originally Posted by mitiempo View Post
You are not comparing batteries properly really. The plates in the 6 volt (T-105 for example) are thicker than the group 27 - any group 27. The 2 group 27 batteries total 12 cells, the 2 T-105's total only 6 cells but 2 weigh even more than the 2 group 27's.. The cycling differences are evident in use, not just on paper.

The marine industry is way too small to develop a battery like the golf carts for itself, but the golf industry and associated use of battery operated carts was more than able. Any major golf course can tell you exactly how many cycles they get out of the 6 volt batteries in their carts. Many golf courses have hundreds of carts. None of them use 12 volt group 27 or 31 batteries. The reason is dollars - more cycles for the dollar from golf cart batteries.

I agree with Cadence - a bank of 4 golf cart batteries makes the most sense. My customers have anywhere from 4 to 16 golf cart batteries in series/parallel for house bank use.
I'm not comparing batteries properly referring to manufacturers specifications, yet you are comparing batteries properly assimilating the needs of a golf cart at a golf course are identical to the needs of a lone cruising sailboat, anchored in the out islands??????!!!!!

If a battery fails on a golf cart, the club staff will drive up with a replacement cart in minutes, where there is a dedicated service shop probably less 1/2 mile away, where there are likely staff and replacement batteries on hand, just waiting for the occurrence, so they have something to do.

Again, 2 x 6 volt batteries have slightly higher Ahr rating and slightly higher bulk density. Not as significant as many are lead to believe. Capacity and life expectancy improvement is less than 10%.

Again, with 2 x 6 Vdc batteries (and I do see this in about 20% of sailboats that have just converted from 12Vdc to 6 Vdc batteries), if one goes down, you must isolate both, rendering the house bank useless until the defective battery is replaced.

Again, with 4 x 6 Vdc batteries (and I do see this in about 70% of sailboats that have just converted from 12Vdc to 6 Vdc batteries), if one goes down, you must isolate 2, cutting the house bank in half, until the defective battery is replaced.

Only 10% of the sailboats I see, that have just converted from 12 to 6VDC batteries, have 6 or more.

IMHO, until you move up to a house bank of 6 or more 6 Vdc batteries, the reduction of capacity on a battery failure is quite significant. For these reasons, (and the cost of doing so) I do not recommend converting from 12 Vdc to 6 Vdc batteries, unless the house bank consists of 6 batteries or more. (So in my experience and opinion, about 10% of the people who ARE changing from 12Vdc to 6Vdc batteries, are actually benefitting, as marginally as it may be.)

In almost all cases, those with a number of 12Vdc batteries, would benefit far more, by simply adding another 12Vdc battery (because you CAN add just one) for a fraction of the cost.

Still, if that is what the customer wants, I will change out all batteries, boxes, and wiring, from 12Vdc to 6 Vdc for them, (after all, it is their boat.)

Another disadvantage of 6V batteries is that the cells are larger, causing greater likelihood of dry plates, when the vessel is heeled.
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Old 31-10-2015, 11:30   #26
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Re: electrical repair works on the yacht

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Again, with 2 x 6 Vdc batteries (and I do see this in about 20% of sailboats that have just converted from 12Vdc to 6 Vdc batteries), if one goes down, you must isolate both, rendering the house bank useless until the defective battery is replaced.

Again, with 4 x 6 Vdc batteries (and I do see this in about 70% of sailboats that have just converted from 12Vdc to 6 Vdc batteries), if one goes down, you must isolate 2, cutting the house bank in half, until the defective battery is replaced.
I agree that a 2 6V bank is a poor idea compared to 2 12Vs.

The second paragraph is a specious argument. If there are two 12V batteries in a house bank, it's either 4 6V or 2 12V, right. So if one 6V or one 12V dies, half your capacity is gone anyway. No difference at all.

What's the point then?
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Old 31-10-2015, 15:37   #27
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Re: electrical repair works on the yacht

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Another disadvantage of 6V batteries is that the cells are larger, causing greater likelihood of dry plates, when the vessel is heeled.
You should really do an bit of research on 6 volt golf cart type batteries.

They are taller for a reason. There is more room below the plates so the sluffing of material is less likely to shout out a cell.

There is more room at the top so the plates remain covered with electrolyte when a golf cart is parked on a hill.

Both are advantages to a cruising sailor.
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Old 31-10-2015, 15:49   #28
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Re: electrical repair works on the yacht

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Capacity and life expectancy improvement is less than 10%.
I'm not sure where you are getting your information but it certainly is not from a respected battery manufacturer.

These 2 charts come from Trojan Battery. They list all their batteries at the time the list was created and show all specs including lab life cycles in the far right column. In the real world cycles would probably be about half those listed.

The 6 volt batteries survive more than twice as many cycles as the 12 volt batteries. The Trojan T-105 is the leader with 754 cycles compared to for example the SCS225 - one of the better 12 volt deep cycle batteries available - at only 300 cycles.





As I stated these are lab cycles and I would expect about half or less in the real world. The point is the comparison between batteries, 6 volt vs 12 volt in particular.

Trojan is one of only a handful or major battery manufacturers in the US - Crown, Deka/East Penn,and Johnson Controls are others. Trojan has the largest research facilities for batteries in the US.
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Old 31-10-2015, 17:31   #29
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Re: Electrical Repair Works on the Yacht

Golf cart batteries are sold all over the US. They are typically the best value for money for a 6V deep cycle battery. Plenty of cruisers have good results with them.

Any battery rated in CCA (cranking current Amps) are starting batteries. They have little lead, dont like to cycle and wont last long as a house bank.

Any battery likes to be charged. Flooded lead acid like to be wet. (Filled with distilled water)

A good rule of thumb on sizing is to never drop below 50% charge. Recovering charge over 80% by generator is inefficient. Solar is great for recharging house batteries. So you can practically use just 1/3 of rated capacity.

Sounds like you need some rules of thumb before you start spending money.

We have 6 x Trojan T105s. They are grouped in 3 banks of 2. They are 8 years old and going well. They are starting to use some water but that's typical for older batteries.

Our 6 Trojans give us 675 Ahr of capacity. We have 280 Watts of solar. We tend to consume 100Ahrs a day on the cook. Therefore we can get 2 days of use with no recharge and not violate the 1/3 of capacity rule.

We need to add another 120W solar panel to recover our daily consumption.

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Old 02-11-2015, 08:16   #30
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Re: electrical repair works on the yacht

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I agree that a 2 6V bank is a poor idea compared to 2 12Vs.

The second paragraph is a specious argument. If there are two 12V batteries in a house bank, it's either 4 6V or 2 12V, right. So if one 6V or one 12V dies, half your capacity is gone anyway. No difference at all.

What's the point then?
Nope. Everything else equal, in both cases you have 4 batteries. If one 6 Vdc goes down, you need to isolate 2, cutting your house bank in half (50%). If you have 4 x 12Vdc batteries (for the same initial capacity) if one goes down, you only need to isolate 1, decreasing your house bank by only 25%.
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