4 six volts better than 2 twelve volts

[rsn48]

So I read the article above, glad I did, and it supported what I said in my original opening post. Since most 12 volt "deep cycle" batteries are frauds, at least the golf cart 6 volt batteries are better. This is good news for me, not because I'm about to purchase golf cart batteries but it boosts my opinion of the guy who recommended the 6 volt golf cart batteries over the 12 volts. He's been in the marine repair business for decades and he stands to make no money from me - and he knows it - as my boat is in refit in Comox and he is an hour drive down the road from there, but we have had a somewhat similiar past and he likes to help me out with his wisdom. He was the one that told me my boat was most likely a Grenfell design. I sent pictures into a volunteer organization that lists all the boat builders (almost all of them) in British Columbia that has and does built boats in this province. They, upon seeing my photos, agreed it was most likely a Grenfell design.

With retailers I'm going to rely on, or rely on their advise, I will often test them with a question I already know the answer to. So in my hobby which 99 % here aren't familiar with model railroading in N scale, I asked a retailer in Gas Town in Vancouver if N scale engines had fly wheels like HO engines. He told me in "N" scale there are no engines with fly wheels - wrong answer - you can imagine how much business I gave him. His primary business was snagging American tourists off the cruise ships who were looking for a model railroad store fix.

So the purpose of my original thread was to find out if the advise from the chap advising me was reliable and it is. So 6 volt versus 12 volt where both are true deep cycles, probably not that much a difference. But 6 volt (golf cart batteries) versus fraud 12 volt batteries - a big difference which is what he told me.

[lewisa]

I am on 5th set of Trojan T-105 golf cart batteries, each of which has been good for a minimum of 5 years. At about $100 per battery, they are an excellent value and each set of two gives 225 AH. I use 2 sets of 2 batteries in a single bank for both starting (Perkins 4-108) and house. I don't use a lot of electricity (LED lighting and only occasional reefer use), so even a single 225 AH bank would be fine.

The Trojans are very reliable and have never given my any trouble as long as I maintain the fluids and connections regularly. They reside in Blue Seas battery boxes that each house two 6V batteries.

When it comes time to replace them, they are easy to lift and transport -- something I couldn't do by myself with 4D or 8D batteries. AGM's would be nice, but I can't justify the significant extra cost.

[SailorPat]

In my cruising sailboat, my “House Bank” of batteries is made up of six (6), golf cart deep cycle 6volt batteries; wired up 2 at a time to make 3, 12 volt batteries — as far as my smart charger sees them. This system has worked fabulously for eighteenths years. The batteries last about five years before replacement.

I recommend this set-up for capacity, ease of charging, and ease of battery replacement.

[Group9]

Certainly better on your back when changing them out.

[stormalong]

Where do you get these $100 Trojan T-105s? They are $200 each here in the Pacific Northwest, My bank is now ten years old and I need to replace them this spring.

[Pizzazz]

Could we agree on some points and move on? May be make it a sticky? This is what I got from the discussion and personal experience:

1. Golf cart batteries are best value for money. Interconnecting 2, 4, or 6 batteries is not a problem but if you need bigger capacities then it makes sense to look at bigger batteries.

2. The value for money is not so much dependent on the brand but on pure economics, the golf cart market is much bigger than the marine market.

3. A problem with golf cart batteries is that if one goes bad, it quickly destroys the other one in the pair, so you have to replace both in the pair. Watch out for that.

4. From personal experience, I have golf cart batteries for house and a 12V for starting. I abuse my batteries as much as possible (I just get a kick out of discharging to 20% and using them as if they were lithium’s). I have difficulty destroying the house bank in less than three years, but the starting battery (it was some dual use crap battery). I can typically murder in less than a year. So, now I need to replace the starting battery. Should I get a pair of golf cart batteries for $200 or should I buy a proper deep cycle 12V battery for $240? I think the choice is obvious, no?

SV Pizzazz

[MarknLori]

Can anyone explain why it is a problem to connect two twelve volt units in parallel? When I say twelve volt units I am referring to a pair of 6 volt batteries connected in series.

[stormalong]

Originally Posted by MarknLori

Can anyone explain why it is a problem to connect two twelve volt units in parallel? When I say twelve volt units I am referring to a pair of 6 volt batteries connected in series.

It isn't a problem. It's done all the time. I've been doing that for 30 years and never had a problem. Only issue is to do it with brand new batteries so that they are matched. Replacing individual batteries in the bank ends up with the stronger battery continuously being drawn down by the weaker one(s).

[Shaneesprit]

You don’t get anything for free, double the volts is half the Amps and obviously the same the other way, 6V batteries only have half the amps when you connect them as 12 Volt for your boat or anything else.
In effect not getting anything for free, so the battery weight will be the same, for a given power output.
I use 2 small 12Volt sealed batteries ( about the same size as a car battery ) for small loads and 1 x 12Volt battery for the Engine, with a dual charger,
Charging is more important, so Shore power ( I have it but never I never use it ) charge both sets from the Engine and both from the Solar panel ( just one 148W )
That panel keeps everything topped up even in the UK with no little sun.
Most important is to reduce DC loading with modern equipment and LED lighting.

[Cheechako]

My understanding is the 6v are typically made with thicker plates as they are designed for deep discharge and recharge like golf carts. Thicker plates last longer. Batteries are all about plates. Want to tell good batteries from poor ones? Weigh them.

[john61ct]

Originally Posted by stormalong

Where do you get these $100 Trojan T-105s? They are $200 each here in the Pacific Northwest, My bank is now ten years old and I need to replace them this spring.

The Deka's (post #5)are IMO just as good, possibly better sometimes, within range of factory QA.

[john61ct]

Originally Posted by Cheechako

My understanding is the 6v are typically made with thicker plates as they are designed for deep discharge and recharge like golf carts. Thicker plates last longer. Batteries are all about plates. Want to tell good batteries from poor ones? Weigh them.

Yes true but simplistic.

Many industrial types are just as heavy per AH but designed for other purposes.

Deep cycling storage is just one specific use case, and GCs are the cheapest per AH that fit.

And more to the point essy to find near you, since last-mile shipping wipes out that value proposition.

[john61ct]

Originally Posted by Shaneesprit

I use 2 small 12Volt sealed batteries ( about the same size as a car battery ) for small loads

May be fine for you, but not what is being discussed here.

50-100AH per say is often "small" loads for a House bank, and that requires proper batts for deep cycling use **if** you don't want to replace the bank frequently.

Now many people choose the latter approach, don't care if it costs them more long term.

Which is fine, long as it's an informed decision, not out of ignorance.

[Beau.Vrolyk]

Originally Posted by rsn48

Was talking to a chap and told him of my possible battery acquisitions. He recommended I get 4 six volts, two wired in parallel, rather than 2 twelve volts. He said the 6 volt jobbies were better as part of battery function was dependent on size and the two 6 volts would offer more usage than an equivalent one 12 volt. Checking to see if this is true.

RSN48,

There really isn't enough information for anyone to make a reasonable comparison here.

First, to make things even remotely even, you'd have to compare true deep cycle batteries only. No CostCo type 27 car batteries vs a Trojan 6v Golf Cart battery. If you do the later, you're comparing apples to oranges. The answer will be obvious, Trojan wins.

Second, for a given battery chemistry, the sizes in cubic inches are the same. there is no free lunch. With the exception that multiple 6V batteries will have more external case material between the batteries than half as many 12V batteries. This is the first place that another difference shows up. Because most 6V batteries are build for golf carts, most of them are taller than large 12V batteries. The taller batteries might not fit in your boat.

Third, there is a LOT of talk about true deep-cycle vs just pasting a "Deep Cycle" sticker on the side of an 8D truck battery. You need to go to the Trojan and Rolls web sites and read up on what you're buying when you buy a true deep-cycle battery. They are physically different from CostCo car batteries in important ways which will directly effect the life span and maintenance. You need to understand these differences before making a decision or your run the risk of buying the wrong sort of battery.

Finally, like many things, you generally get what you pay for. The Trojan deep-cycle batteries are dramatically better than the much cheaper batteries you can buy in auto parts stores and discount shops. Again - there is no free lunch.

You don't need a deep-cycle battery to start your motor. However, you really DO need a deep-cycle battery for a typical cruising life-style when you only want to run your engine or generator once or twice a day. Regular batteries are simply not designed for that job, they are designed to start your car or trunk and then immediately be re-charged while you drive. It's a completely different job.

[Zil]

Two six volt batteries have 6 cells. Two 12 volt batteries have 12 cells, so that is not a comparison. 4 six volt GC2 batteries are better than any two 12 volt batteries in the similar size foot print.