My experience has been that pairs of 6 v golf cart batteries are good for hundreds of cycles more than 12 v deep cycles. MUCH HEAVIER, maybe because there is more lead?
Solar or Wind???
- Thread starter TaZ_Izzy
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I always kind to consider my Mac as a minivan, light and maneuverable. Yes, I can load it down so there's very little room to walk inside but that's not what I bought it for.
The only thing I really need 12 V for is my radio.
I have liquid candle lights, propane lights, dry cell lines and a five amp charger on my outboard.
I guess if I had lots of kids with lots of electronics that needed to be charged all the time and perhaps I would have lots of extra battery power.
Every electrical device that I have on the boat uses 12 V so that one 6 V battery is worthless.
I think that one 12 V battery trumps one 6 volt battery.
The only thing I really need 12 V for is my radio.
I have liquid candle lights, propane lights, dry cell lines and a five amp charger on my outboard.
I guess if I had lots of kids with lots of electronics that needed to be charged all the time and perhaps I would have lots of extra battery power.
Every electrical device that I have on the boat uses 12 V so that one 6 V battery is worthless.
I think that one 12 V battery trumps one 6 volt battery.
That might be true but what are the odds of it happening. We all drive around with only one battery in our car and don't give it much thought
. Worse case we pull start our outboard and go home or sail home or some place to get another battery,Sum
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That might be true but what are the odds of it happening. We all drive around with only one battery in our car and don't give it much thought
Sum
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Two 6v Batteries = Six 2V Cells
One 12V Battery = Six 2V Cells
I'll take two substantially more robust and longer lasting 6V batts over a single 12V batt every day of the week, if room allows..
I didn't make myself clear. I would rather have two twelve volt batteries as opposed to two six volt batteries. A battery selector switch allows several options along with an off position, not possible with twin 6 volt batteries.
I have been in large sailboats with huge battery banks made up of 6 volt deep cycle batteries and they all seem to have something in common. They all have battery selector switches so they can pick and choose which batteries they use.
The other thing that they have in common is one 12 volt battery used just for starting.
You Can, add a 20 gallon fuel tank, add a 40 gallon water bladder, add a waste holding tank and even added 25 hp motor but is it necessary to have the boat do what you wanted to do.
I have been in large sailboats with huge battery banks made up of 6 volt deep cycle batteries and they all seem to have something in common. They all have battery selector switches so they can pick and choose which batteries they use.
The other thing that they have in common is one 12 volt battery used just for starting.
You Can, add a 20 gallon fuel tank, add a 40 gallon water bladder, add a waste holding tank and even added 25 hp motor but is it necessary to have the boat do what you wanted to do.
Two 12 volt batteries:
Pro:
1. If one goes dead you still have one.
Con:
1. Not a 'true' deep cycle battery.
2. Harder to charge equally.
3. Inefficient charging if you do one at a time (slower overall to charge this way). Also it is hard to charge 2 batteries equally using 1-2-Both switch in the 'both mode' as then they are not connected in the proper way for an equal charge to both batteries. To have both charged equally you need to have them permanently tied together and wired properly. Of course if you do this you then take the chance they could be discharged accidentally together. If you are out mulitple days and recharging with solar you want your charging to be as efficient as possible. If you go in and have shore power this isn't as big a deal.
4. Not as robust as 6 volt deep cycle batteries.
5. Cost more for the same amp/hr capacity.
6. Normally have a shorter life span.
Two 6 volt batteries:
Con:
1. If for some reason one fails you have no elect. until it is replaced. For our boats if you have elect. start on the outboard you will have to pull start it and go get a battery.
Pro:
1. A 'true' deep cycle battery that won't be hurt as much by deeper discharges (still for the best life don't discharge below 50%)
2. Charge quicker than charging two 12 volt batteries one at a time.
3. Charge more efficiently if you are on solar than 2 12 volt batteries wired to a 1-2-Both switch.
4. More robust construction
5. Longer life span.
6. More amp hours for the dollar. (Note: the amp hour capacity for 2 six volt batteries is not the two added together but the capacity of one. Still most single 6 volt batteries have a higher capacity than 2 12 volt batteries do.)
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'My' conclusions: If you day sail chances are the one 12 volt battery that came with your boat is more than good enough. If you stay out longer periods you will have more capacity with 2 six volt batteries vs. 2 twelve volt batteries and more importantly if you are using solar panels to charge while out the charging will be more efficient with the 6 volt batteries which can be very important unless you have a lot of solar.
So take your pick. For us we have had 2 twelve volts batteries tied permanently together (charged via solar and discharged together) but will switch to 2 six volt when they are no longer good,
Sum
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Pro:
1. If one goes dead you still have one.
Con:
1. Not a 'true' deep cycle battery.
2. Harder to charge equally.
3. Inefficient charging if you do one at a time (slower overall to charge this way). Also it is hard to charge 2 batteries equally using 1-2-Both switch in the 'both mode' as then they are not connected in the proper way for an equal charge to both batteries. To have both charged equally you need to have them permanently tied together and wired properly. Of course if you do this you then take the chance they could be discharged accidentally together. If you are out mulitple days and recharging with solar you want your charging to be as efficient as possible. If you go in and have shore power this isn't as big a deal.
4. Not as robust as 6 volt deep cycle batteries.
5. Cost more for the same amp/hr capacity.
6. Normally have a shorter life span.
Two 6 volt batteries:
Con:
1. If for some reason one fails you have no elect. until it is replaced. For our boats if you have elect. start on the outboard you will have to pull start it and go get a battery.
Pro:
1. A 'true' deep cycle battery that won't be hurt as much by deeper discharges (still for the best life don't discharge below 50%)
2. Charge quicker than charging two 12 volt batteries one at a time.
3. Charge more efficiently if you are on solar than 2 12 volt batteries wired to a 1-2-Both switch.
4. More robust construction
5. Longer life span.
6. More amp hours for the dollar. (Note: the amp hour capacity for 2 six volt batteries is not the two added together but the capacity of one. Still most single 6 volt batteries have a higher capacity than 2 12 volt batteries do.)
=====================================
'My' conclusions: If you day sail chances are the one 12 volt battery that came with your boat is more than good enough. If you stay out longer periods you will have more capacity with 2 six volt batteries vs. 2 twelve volt batteries and more importantly if you are using solar panels to charge while out the charging will be more efficient with the 6 volt batteries which can be very important unless you have a lot of solar.
So take your pick. For us we have had 2 twelve volts batteries tied permanently together (charged via solar and discharged together) but will switch to 2 six volt when they are no longer good,
Sum
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Just for insurance I also carry a jump box you know the kind you can pick up for$50. I use it to charge the phone or power the radio. Also picked Duracell battery powered LED lighting at Costco 2 for $20 for cabin lighting. They last all summer but I only spend the occasional night aboard when to lazy to drive home after a day of sailing.
What about costs? Are 6 volt batteries competitive?
I know nothing about 6 volt batteries. Do they fall into the same category as 12 volt in terms of how they are built and by whom? Mainsail once gave a review of 12 volt batteries and one of his findings was that a cheap Walmart battery is as good as an expensive "marine" battery from West Marine (as long as it was looked after). I'm working on memory without checking the thread so I hope I'm not way off. So is there a better name in 6 volt battery's to zero in on or supplier?
I know nothing about 6 volt batteries. Do they fall into the same category as 12 volt in terms of how they are built and by whom? Mainsail once gave a review of 12 volt batteries and one of his findings was that a cheap Walmart battery is as good as an expensive "marine" battery from West Marine (as long as it was looked after). I'm working on memory without checking the thread so I hope I'm not way off. So is there a better name in 6 volt battery's to zero in on or supplier?
Where our boat is in Florida last year I could find Trojan T105's in the low $90 range and the other easy to find ones that are suppose to be made by Trojan are the Powertron 2000's and 2200's. They were $15-$20 less. I just called down there to the two places I knew of and they were already closed because it is Sat.. Because of all the golfers down there batteries seem to be cheaper than elsewhere.
Note though that the 105's are rated at 225 amp/hr for the 20 hour rate and the 2000's at 210 amp/hr and the 2200's at 216 amp/hr...
http://www.trojanbattery.com/pdf/TRJN0111_ProdSpecGuide.pdf
http://www.safe-start.com/vendors/powertron-golf-batteries/
...so the 105's cost more but also have more capacity.
Now if we look at the 12 volt batteries the Group 27 are rated at 85-105 Amp hours so even two of the very best 27's are going to be 210 amp/hrs max. We have the 27's in the Mac now.
The group 24's that a lot of people use are even worst at 70-85 Amp hours, two of the best are only going to be 170 amp/hrs.
Look for Maine Sail's 6 volt battery thread as he has more data on different manufacture's batteries. I think Sam's Club has some that he likes but where the boat is I could get the Trojan's for about $10 more than the Sam Club batteries.
Before buying anything make sure it will fit where it needs to go
,Sum
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FWIW, I originally had the SAMs 6v batteries. This time I am trying out Trojan T105s instead. Not a huge price increase but what I am not comfortable with is that SAMs batteries may be manufactured by different suppliers under the Energizer brand name. Something to that effect at least. Assumption that Trojan may have better quality control.
Or so I had read and heard when deciding last season on my replacements. So far happy with my Trojans. Give it another season and they will have outlasted the two seasons I got out of the SAMs energizers.
Or so I had read and heard when deciding last season on my replacements. So far happy with my Trojans. Give it another season and they will have outlasted the two seasons I got out of the SAMs energizers.
Why complicate things on a small simple boat? If capacity is an issue use a single group 4D deep cycle. Most are rated at 160 AH - roughly the capacity of two smaller batteries. No switches, no charge monitoring - simple.
I have been asking people about battery reliability and the majority of problems (that I was told) relate to multiple batteries and not staying on top of charging and discharging (usually repeated discharge to totally flat). Also corrosion on the batter selector...
One big battery, one simple and visual charge/discharge monitor (not a voltmeter and chart) and charging that matches use (generally much less required than people think).
We use this arrangement with a 120 AH single battery and never shore charge. We are out for 3 to 5 days at a time and use all our instruments, lights and entertainment systems.
If I ever did run out of power and had no solar, the engine has a 6 amp alternator that can run the radio and instruments just fine.
Chris
I have been asking people about battery reliability and the majority of problems (that I was told) relate to multiple batteries and not staying on top of charging and discharging (usually repeated discharge to totally flat). Also corrosion on the batter selector...
One big battery, one simple and visual charge/discharge monitor (not a voltmeter and chart) and charging that matches use (generally much less required than people think).
We use this arrangement with a 120 AH single battery and never shore charge. We are out for 3 to 5 days at a time and use all our instruments, lights and entertainment systems.
If I ever did run out of power and had no solar, the engine has a 6 amp alternator that can run the radio and instruments just fine.
Chris
Sam's uses two main suppliers. Deka/East Penn and Johnson Controls. About half the states have the JCI product and the other half have the Deka.. East Penn is in Pennsylvania so no surprise that when shipping lead most of the Deka product winds up in Eastern states..
The Deka / East Penn is the better product and is avaible in these states: AL, CT, DE, FL, GA, IL, IN, KY, MA, MD, ME, MI, MS, NC, NH, NJ, NY, OH, PA, RI, SC, TN, VA, WV
Chris two 6 volts are simplicity, no switches except for a main on/off. The two 6's have 225 amps vs. the 160 you mentioned. Take that to 50% and you are at 112 vs. 80. For some of us with a fridge and say me with the CPAP machine that is big. For you with light loads no need so don't do it, but at some point you might want to stay out longer and have a fridge then you might want to reconsider
. Once you get behind on the battery charge it is hard to catch back up, the reason we still had to run the generator a couple times during our longer trips. 30 minutes on it at 20+ amps would be like running the outboard for a couple hours.Myself I'm just trying to give options to people who want to stay out longer or who have bigger energy needs
,Sum
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Let's not forget that Sumner put his comments in perspective...he is rigged up for 30-day trips a long way from home...big fuel tank, fridge, and extra ground tackle, just to name a few things. For that, he is obviously looking for the max possible combination of longevity and power capacity in a package that still fits on his boat. That is probably not at all the norm among the MacG crowd.
What Chris describes is more along the lines of what I will be doing, and from what I read on here, probably what most of the boats are set up for, daysailing, weekends, overnights, maybe a week out, with marinas not too far away. For me, a single 12V is probably going to be all the power i carry, as i don't have much equipment on the boat besides the stereo and VHF, a little hummingbird, and a speedo. Yes, lights too. We plan to use the cooler just like we did when camping, no fridge needed. Flashlights and moonlight in abundance...
The point is simply that i can see where different setups could easily justify going with large capacity batteries, and i can definitely see the place for one 12V as the "simple" solution.
I'm getting a lot out of this discussion.
What Chris describes is more along the lines of what I will be doing, and from what I read on here, probably what most of the boats are set up for, daysailing, weekends, overnights, maybe a week out, with marinas not too far away. For me, a single 12V is probably going to be all the power i carry, as i don't have much equipment on the boat besides the stereo and VHF, a little hummingbird, and a speedo. Yes, lights too. We plan to use the cooler just like we did when camping, no fridge needed. Flashlights and moonlight in abundance...
The point is simply that i can see where different setups could easily justify going with large capacity batteries, and i can definitely see the place for one 12V as the "simple" solution.
I'm getting a lot out of this discussion.
Thanks, I thought I did that more than once but it must of been lost on some and no way would we dump the fridge but for sure one isn't for everyone,
Sum
Well.. just pointing out that when I see the pictures of Sumner’s solar panel on the back of the boat and that gas generator.. I cant help to think to myself that if he did get rid of the fridge, he could get rid of that generator and probably get by with 50 watts of solar (I said ½ earlier, should have said ¼).
But.. I know Sumner likes having that fridge and doesn’t mind the tradeoffs.
Regarding the battery capacity, we should also be considering how deep the batteries get cycled. If you look at the ratio of daily amp hours used to battery capacity, in the case for Chis’s boat, its probably about 20 / 160 = .125 I.e., for Chris, his daily use is about 12.5% of the battery capacity.
For Sumner case, I think he said he uses 35 + 9 + 10 = 54 amp hours (fridge + cpap + computer). If he had two golf cart batteries with 225 amp hours capacity, this same ratio is 54/225 = .24. I.e., for Sumner’s case, his daily use is about 24% of the battery capacity.
So Sumner is still cycling the batteries a lot harder than Chris even though he has more capacity (24% vs. 12.5%). It’s another interesting thing about having a fridge. In order to get the same 12.5% ratio of daily use to capacity that Chris has, Sumner would really need 432 amp hours. This points out another interesting thing about having a fridge. You either will be cycling your batteries a lot deeper or you need a lot more capacity.
But.. I know Sumner likes having that fridge and doesn’t mind the tradeoffs.
Regarding the battery capacity, we should also be considering how deep the batteries get cycled. If you look at the ratio of daily amp hours used to battery capacity, in the case for Chis’s boat, its probably about 20 / 160 = .125 I.e., for Chris, his daily use is about 12.5% of the battery capacity.
For Sumner case, I think he said he uses 35 + 9 + 10 = 54 amp hours (fridge + cpap + computer). If he had two golf cart batteries with 225 amp hours capacity, this same ratio is 54/225 = .24. I.e., for Sumner’s case, his daily use is about 24% of the battery capacity.
So Sumner is still cycling the batteries a lot harder than Chris even though he has more capacity (24% vs. 12.5%). It’s another interesting thing about having a fridge. In order to get the same 12.5% ratio of daily use to capacity that Chris has, Sumner would really need 432 amp hours. This points out another interesting thing about having a fridge. You either will be cycling your batteries a lot deeper or you need a lot more capacity.
Every Tuesday is food truck day, and is best time to check out generators. Last week the organizer put up some music. I thought he was running off batteries so went to see what he got. I didn't hear this generator until I was close enough to take the attached picture. Almost silent. Couldn't believe it. It is also very small. If you want fridge and ample power for long trip, that's the way to go.
