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Old 02-11-2015, 09:03   #31
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Re: electrical repair works on the yacht

Quote:
Originally Posted by mitiempo View Post
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.
Yes 6 Vdc batteries are taller. This is why one needs to verify they have adequate space, and factor in the coast of replacing battery boxes when converting from 12Vdc to 6 Vdc batteries.

I can't speak to the "lab cycles" claim, as there is no indication of what these results mean or how they were obtained. Current Trojan specs do not include this data.

It could very well be, that the testing methodology favoured a 6 volt battery, skewing the results. For example, maybe a fixed discharge current value for all batteries. (Which would favour the batteries with a higher Ahr rating, that in fact would have the same Ahr rating of the comparable 12 V batteries, when put in banks of 2.) This is just supposition and one possibility, but the reason I don't trust data when I don't know how it was obtained.)

Back to reality vs supposition.

Here's what often happens.

An owner kills a house bank by neglect and misuse. On consulting a marine product retailer, they are sold on converting to 6 Vdc batteries, and educated on how to make batteries last longer.

They treat the 6Vdc batteries far better than they ever did the previous bank, and then assume / claim the 6 Vdc batteries are better. In reality, what is better, is their use and maintenance practices.

All you have to do, is ask any boat, with proper charging systems, and discharging / charging / maintenance practices how long their 12Vdc batteries last.

Daily use, 4-6 years is the norm, and 6-10 years for weekend warriors who are on float Monday to Friday.

Ask the same of 6Vdc battery users, under the same circumstances, and you will get the same answers.

How many times have I heard, "I switched from 12Vdc batteries to 6 Vdc batteries and they last a lot longer." With a little probing, I often find that they increased battery bank capacity substantially. They were much more diligent about checking and adding water. They were much more diligent about how deep the bank was discharged and how long it was left before recharging. In some cases, they upgraded from a temporary car battery charger (when they remembered to hook it up and recharge) to an automatic shore power charger.

In my experience, everything else equal, properly sized, maintained, and treated 12Vdc batteries, will last as long as equal quality 6 Vdc batteries.

Ramblin Rod
www.sheenmarine.com
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Old 02-11-2015, 10:04   #32
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Re: Electrical Repair Works on the Yacht

Alexander-
Do yourself a favor. Order a couple of highly acclaimed books, like Charlie Wing's book on boat electrics, or Nigel Calders. And there's a "12 volt bible" on the same subject as well. Since you are in Florida, you may be able to get them at your local library or through the interlibrary loan system (ask the librarian) quick & free, but they're worth buying.
These will give you a clear and comprehensive picture of how the whole system on a boat works, because if anything in the system is not optimal, you can eat up expensive batteries in a year or two, instead of the typical four years, and the potential eight years. (And Rolls brand battery users would say that eight years is still short.)

As to sources? Look for existing posts, there are many options. When it comes to wiring and cables, either you buy expensive tools, or hope your expert has them (ha) or just buy the cabling from genuinedealz.com a web supplier that gets nothing but praise for price and quality.

You may be surprised, but if you simply call up a couple of the larger battery manufacturers and say "I don't have a clue, you've got all this stuff, what will be best in a boat? And why is that?" you often will wind up getting someone on the phone who is glad to give you top advice for free. There are often considerations that no one really mentions. For instance, the biggest "industrial and commercial" battery users are probably fork lifts. And what do they use? Twelve volt batteries? Six volt? Nope, they use single 2.2 volt cells, so that when one fails, they just need to replace that one, not the whole bank. On a boat, that would also mean an awful lot of wiring, which is pointless, so it just isn't done. On a boat, you are constrained also by "Damn that's big and heavy!" and you often make a choice based on what you can list, move, and fit.

Check out the books, and the battery manufacturers. You won't regret it.
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Old 02-11-2015, 10:09   #33
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Re: electrical repair works on the yacht

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Originally Posted by ramblinrod View Post
...Shop for the electrician. The first question to ask, is "Through what organization did you receive your certificate? The second question is, "Can you please bring it with you to show me?

The person should bring a ticket they carry in the wallet (at all times) that indicated the "MARINE" organization that tested and certified them (examples include ABYC and NMEA...
You can't be serious.

It isn't all that hard to find out who the local pro's are--just ask around among local marine professionals.
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Old 02-11-2015, 10:12   #34
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Re: Electrical Repair Works on the Yacht

I don't think it has been mentioned, but its a lot easier to get a 6 volt battery on the boat, down the companion way, and into a tight cramped battery compartment. At least for me it is.

I'll stick with 6 volt batteries, thank you.

Also, Genuinedealz for wire, shrink, crimps, etc.

Marine Wiring, Boat Cable and Electrical Genuinedealz.com
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Old 02-11-2015, 10:47   #35
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Re: electrical repair works on the yacht

Quote:
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.
+1

There's no substitute for lead mass. A golf cart battery is just a generic term for deep cycle 6v battery usually with a capacity of 225Ahrs.

We have just passed 8 years on our trojan T105s. 3 banks of 2 t105s in series.

6v volt batts in series to 12v is a reliable proven and very cost effective house bank option.

Keep em clean, keep em wet and keep em charged. This will maximise the life of any battery options. If you never run them below 50% charge you will maximise their life.

Sent from my SM-N900T using Cruisers Sailing Forum mobile app
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Old 02-11-2015, 20:10   #36
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Re: electrical repair works on the yacht

Quote:
Originally Posted by ramblinrod View Post
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%.
Losing a battery in a bank can happen but with properly cared for batteries it is rare. Properly cared for means watered to the correct level, clean tops and proper charging. The majority of long term cruisers are using 6 volt GC batteries and they use them daily for years. They know how long they last compared to 12 volt batteries.
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Old 02-11-2015, 20:25   #37
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Re: electrical repair works on the yacht

Quote:
Originally Posted by ramblinrod View Post

I can't speak to the "lab cycles" claim, as there is no indication of what these results mean or how they were obtained. Current Trojan specs do not include this data.

It could very well be, that the testing methodology favoured a 6 volt battery, skewing the results. For example, maybe a fixed discharge current value for all batteries. (Which would favour the batteries with a higher Ahr rating, that in fact would have the same Ahr rating of the comparable 12 V batteries, when put in banks of 2.) This is just supposition and one possibility, but the reason I don't trust data when I don't know how it was obtained.)

Back to reality vs supposition.

Here's what often happens.

An owner kills a house bank by neglect and misuse. On consulting a marine product retailer, they are sold on converting to 6 Vdc batteries, and educated on how to make batteries last longer.

They treat the 6Vdc batteries far better than they ever did the previous bank, and then assume / claim the 6 Vdc batteries are better. In reality, what is better, is their use and maintenance practices.

All you have to do, is ask any boat, with proper charging systems, and discharging / charging / maintenance practices how long their 12Vdc batteries last.

Daily use, 4-6 years is the norm, and 6-10 years for weekend warriors who are on float Monday to Friday.

Ask the same of 6Vdc battery users, under the same circumstances, and you will get the same answers.

How many times have I heard, "I switched from 12Vdc batteries to 6 Vdc batteries and they last a lot longer." With a little probing, I often find that they increased battery bank capacity substantially. They were much more diligent about checking and adding water. They were much more diligent about how deep the bank was discharged and how long it was left before recharging. In some cases, they upgraded from a temporary car battery charger (when they remembered to hook it up and recharge) to an automatic shore power charger.

In my experience, everything else equal, properly sized, maintained, and treated 12Vdc batteries, will last as long as equal quality 6 Vdc batteries.

Ramblin Rod
www.sheenmarine.com
Trojan's numbers reflect the real world accurately in my and many others' experience. The numbers are accurate as far as lab cycles go - as I posted expect half as many in the boat. I am sure they like to sell batteries other than T-105's.

Your experience is unique compared to the many living long term with 6 volt batteries. With thicker plates - all else being equal - any battery will last longer. 6 volt GC batteries have very thick plates compared to any 12 volt group 24, 27, or 31 battery. These 12 volts are really start batteries in one form or another. Any battery with a CCA rating is not a true deep cycle.
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Old 02-11-2015, 20:26   #38
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Re: electrical repair works on the yacht

Quote:
Originally Posted by ramblinrod View Post
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%.
But do you need 4 x 12VDC batteries for the same capacity as the 4 x 6VDC batteries? Or do you only need 2?

What sort of batteries are you comparing such that you get the same Watt hours out of a single 6 VDC battery and a 12 VDC battery?
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Old 02-11-2015, 20:34   #39
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Re: electrical repair works on the yacht

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Originally Posted by Terra Nova View Post
You can't be serious.

It isn't all that hard to find out who the local pro's are--just ask around among local marine professionals.
How does one ask a pro, who the pro is, if you don't know a pro to ask. If you do know a pro to ask who the pro is, you already know who the pro is, the one you are asking, so why ask?

If they don't have proper training, credentials, business ethics, and a history of satisfied customers, they may not be a pro at all, just a body who works on boats for hire.
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Old 02-11-2015, 20:41   #40
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Re: electrical repair works on the yacht

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Originally Posted by StuM View Post
But do you need 4 x 12VDC batteries for the same capacity as the 4 x 6VDC batteries?

Yes, everything else being equal.

Or do you only need 2?

What sort of batteries are you comparing such that you get the same Watt hours out of a single 6 VDC battery and a 12 VDC battery?
As I have stated, everything else equal 2 x 12Vdc Grp 27s, have about the same capacity (Ahrs) as 2 x 6 Vdc batteries.

However, if you have a single 12Vdc battery failure, you can isolate it, and use all others. If you have a 6Vdc battery failure, it and the one it is connected in series to, has to be isolated, you lose the capacity of 2 batteries until you can replace the bad one.
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Old 02-11-2015, 20:46   #41
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Re: electrical repair works on the yacht

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Originally Posted by ramblinrod View Post
As I have stated, everything else equal 2 x 12Vdc Grp 27s, have about the same capacity (Ahrs) as 2 x 6 Vdc batteries.

However, if you have a single 12Vdc battery failure, you can isolate it, and use all others. If you have a 6Vdc battery failure, it and the one it is connected in series to, has to be isolated, you lose the capacity of 2 batteries until you can replace the bad one.
6 volt GC batteries vary from 220 to almost 250 AH. The ones I sell are 242 AH.

Please show me a group 27 battery that is 110 AH or more.
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Old 02-11-2015, 20:55   #42
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Re: electrical repair works on the yacht

Quote:
Originally Posted by mitiempo View Post
6 volt GC batteries vary from 220 to almost 250 AH. The ones I sell are 242 AH.

Please show me a group 27 battery that is 110 AH or more.

First place I looked at Trojan:

Trojan SCS200 12V Deep Cycle Battery - Superior Cycling Series
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Old 02-11-2015, 21:00   #43
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Re: electrical repair works on the yacht

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Originally Posted by StuM View Post
But do you need 4 x 12VDC batteries for the same capacity as the 4 x 6VDC batteries?

Yes, everything else being equal.

Or do you only need 2? No, 6Vdc batteries typically have twice the Ahr rating (lets say 250 Ahrs), but only half the working voltage of their comparator 12Vdc batteries (lets say 125 Ahrs).

Therefore, if one puts two 12Vdc batteries in parallel you have 12Vdc with 250 Ahrs of capacity. Or if you put two 6 Vdc batteries in series, you have 12 Vdc with 250 Ahrs of capacity.


What sort of batteries are you comparing such that you get the same Watt hours out of a single 6 VDC battery and a 12 VDC battery?
Batteries aren't typically rated in Watt hours, but this can be easily calculated, a typical Grp 27 at 12Vdc x 125 Amp hrs = 1500 Whrs, whereas a typical 6Vdc x 250 Ahrs = 1500 Whrs

(As mentioned, in reality the two 12 Vdc batteries in parallel will have slightly lower Ahr capacity than two 6 Vdc batteries in series.)

However, if you have a single 12Vdc battery failure, you can isolate it, and use all others. If you have a 6Vdc battery failure, it and the one it is connected in series to, has to be isolated, so you lose the capacity of 2 batteries until you can replace the bad one.

In summary, for this very reason, changing from one 12Vdc battery to two 6Vdc batteries is a really bad idea, changing from two 12Vdc to four 6Vdc batteries doesn't gain enough to overcome the additional failed battery isolation drawback. Only when one is changing from a larger system yet, should a conversion from 12Vdc to 6 Vdc even be considered, but the benefit is very marginal at best. For the cost of the change over, there are probably a lot of other boat improvements that would represent a greater performance benefit (like adding just one more 12Vdc battery, which one can't even do with 6 Vdc batteries, as they have to be added in pairs).
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Old 02-11-2015, 21:14   #44
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Re: electrical repair works on the yacht

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Originally Posted by StuM View Post
Exactly, in this case, 2 x Trojan SCS200 12Vdc batteries have a capacity of 230 Ahrs (2 x 115).

In comparison, 2 x the 6Vdc batteries connected in series, as sold by Militempo, have a capacity of 242 Ahrs. A grand total increase of 12 Ahrs (5%), at the cost of changing wiring and battery boxes, and having to isolate 2 if one goes down. It's just not worth it, IMHO.

For far less cost, the boater could add one more 12Vdc battery, and increase capacity by 115 Ahrs, (33%). Now that's a real performance improvement and good value.
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Old 02-11-2015, 21:25   #45
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Re: electrical repair works on the yacht

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Originally Posted by StuM View Post
Exactly!

2 x Trojan SCS200 12Vdc batteries, connected in parallel, deliver 12Vdc and have a capacity of 2 x 115 = 230 Ahrs.

In comparison, 2 x the 6Vdc batteries that mitiempo sells, connected in series, deliver 12Vdc and have a capacity of 1 x 242 Ahrs.

This is only a 5% increase in capacity. For this marginal gain, one has to change out the wiring, boxes, and live with having to take out 2 batteries if one fails.

In comparison, if rather than incurring the cost of converting from 12Vdc to 6Vdc, one simply added another 12Vdc battery, connectors and box (for less cost than the conversion), they would increase capacity by 115 Ahrs, or 50%. That is a significant improvement and in my mind, much better value for money spent.
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