Dual 6V battery setup - switch wiring/removal?

jviss · Nov 1, 2017

How are you planning to charge those batteries?
Are you planning on keeping a separate engine starting battery in addition to the 2 6V ones? (Not necessary in my view).

jviss · Nov 1, 2017

Hi TR,
First, it's my intuition that two golf cart batteries would be overkill for a 26' boat; quite heavy, and big. In addition, I doubt your 8HP motor's alternator is up to the task of properly charging these, and certainly not with a stock regulator, which is really just designed to top off a starting battery. This needs some research.

The 1-2-B-Off switch won't be necessary, but can be used as a simple ON-OFF.

I recommend starting with a load and use spreadsheet, as you seem to have done, intuitively. Laptops can be power hogs, as well as your coffee maker setup. Remember, though, that you have to put that juice back in. Are you at a dock, plugged in when not sailing?

Stu Jackson · Nov 1, 2017

jviss said:
The 1-2-B-Off switch won't be necessary, but can be used as a simple ON-OFF.

Just wire your new house bank to the 1 post of the switch, and use it as an ON OFF switch.

You should learn about the difference between using the switch as a charging source or just a use switch. These links are for more "complicated" boats, but the concept is the same.

OEM 1-2-B Switch Wiring History http://c34.org/bbs/index.php/topic,4949.msg30101.html#msg30101

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: http://c34.org/bbs/index.php/topic,6604.0.html

This is another very good basic primer for boat system wiring: The 1-2-B Switch by Maine Sail (brings together a lot of what this subject is all about)
http://forums.catalina.sailboatowners.com/showthread.php?t=137615

This is a newer primer for boat system wiring design with a thorough digram: Building a Good Foundation (October 2016)
http://forums.sailboatowners.com/in...dc-electrical-foundation.181929/#post-1332240

The Short Version of the 1-2-B Switch Stuff: http://c34.org/bbs/index.php/topic,5977.msg38552.html#msg38552 This is a link to the Electrical Systems 101 Topic, reply #2

centerline · Nov 1, 2017

the batt switch you have will work well for what you are doing... im a proponent of more amps is better than less, for a number of reasons that I wont go into at this time...
the boat will easily carry the extra weight... I had an extra 1,800lbs of gear in my 25 without any issue at all... so maybe it wont sail at the top of its potential, but it seems you are more of a cruiser type anyway.

the only issue you are facing is getting the batts charged back up after discharging them... the little motor altarnator wont do it, although if its run at a full throttle under power it will come real close to delivering its full potential output to the batts, minus any loss due to wire size/length resistance....

but.. with that capacity, and if you learn how to count amps that you use out of the bank, you should be good for at least 3-4 days, with using the coffee maker, radio and led lighting, at which time you need to return to shore power for a FULL recharge.... an inverter is a power robber, so when you have a basic 12v system, buying 12volt appliances would be the most efficient use of the available battery power..

a tangent here...an example is laptop computers, usually operate on 9 to 12 volts of power, but they use a converter to transform the 120vac to 12vdc.... there is some loss of efficiency due to the conversion which is dissapated in heat...
now take the laptop down to the boat and plug it into an inverter....which is an even larger % of inefficiency, and the power then runs thru the computer cord to the transformer, and converts it back to 12 volts to run the laptop...... this is silly but done all the time. in this case it would be better to purchase a 12volt power cord for the laptop and forgo all the wasted amps.... inverters and converters are wasteful but handy at times.. and sometimes necessary.

DONT use a little harbor freight charger for the task of recharging the batteries, but a good charger with high output capability, as the GC batts, especially when deeply discharged, need a higher amp input to keep them in good condition.... but if they are only being used down to around 25% of their recommended maximum discharge capacity, the 10-15 amp multi-stage chargers will work well... if you find you are taking them down past 50% of the recommended discharge capacity, or lower, a 30amp multi-stage charger will keep the batts in the best possible condition for the longest amount of time....

basically, the lower a battery is discharged, the higher amp input is needed to "condition" it back to is best potential...

jviss · Nov 1, 2017

Your use pattern is like a daysailer, and with that capacity should work fine, assuming you have a good charger - not just any charger!

However, I wouldn't wire the motor's alternator to the house, you could overheat it or even destroy it if the house bank is down significantly. I'd keep a tiny starting batter for the motor, contrary to what I said before, and wire it to the motor's alternator, too.

Tyler Rippel said:
I am looking at less than $200 for 2 Duracell GC2 batteries from Sam's Club

Not all golf cart or deep discharge batteries are alike. Here's a good article:
https://marinehowto.com/what-is-a-deep-cycle-battery/

Jeff_B · Nov 1, 2017

Very Interested in this post as I have a new to me H260 and 2 GC 6volts that I just pulled out of my Mac 26, I have 2 x 12v at the moment one under the sink and one behind the rear berth, Id like to put the GCs both under the sink as they weigh a ton, and sell the 2 x 12vs with the Mac.
I run a 12v RV water pump to the two faucets and would like to add the Keurig feature through my inverter.
At the moment I keep it charged with a 30 watt solar panel but imagine I will have to really beef this up in the future.
Ive also found one of those 12v digital starters are worth their weight in gold when the starter battery runs down and you don't have a pull cord feature.
Can you post some pics on here once you get it completed.

Doug J · Nov 1, 2017

Tyler I did exactly what you are describing to my 26.
Here's a link to my mod in the mod section.
https://hunter.sailboatowners.com/mods.php?task=article&mid=15&aid=100055&mn=26

I have since added an 80 watt solar panel with charge controller. I have an 1800 watt inverter that came with the boat, but haven't really used it, tested it, but that's all. I do have a small 300 watt inverter that is plenty to power my 19" LED TV/DVD combo. I have a simple on/off battery switch. My 15HP Merc does not have electric start, wish it did.

I have pressure water, all LED lights, auto-helm, sound system, etc.

https://hunter.sailboatowners.com/mods.php?task=article&mid=15&aid=100074&mn=26

Doug J · Nov 1, 2017

Tyler Rippel said:
As far as 2 GC2 batteries being overkill - I get that, however, this setup should be way less money than even one 12V 120AH battery, and they are truly set up to deep cycle and live a long life doing it, whereas from what I understand, marine deep cycle 12V batteries are all more dual-use than actual deep cycle. I am looking at less than $200 for 2 Duracell GC2 batteries from Sam's Club and new marine battery boxes to fit their extra height.

Agree whole heartedly

jviss · Nov 3, 2017

I would find the manual for the charger. The "thing" is to make sure the acceptance voltage is good for flooded batts, and that it holds at acceptance until charging current diminishes to .5% of your bank Ah capacity; which I doubt it does. @mainesail may recommend a charger.

jviss · Nov 3, 2017

I am not an expert, but I think MaineSail has said that you really need to charge to near completeness at the acceptance voltage level, which is 14.4V; at 13.8 or 13.5, you're not really doing any serious charging. The idea here is to make the batteries last a ling time, so to fully charge them soon after they are discharged.

You are lucky to have shore power, and to be able to find room for those tall golf cart batts. They simply won't fit in the battery compartment of my 38' boat! So, I am doomed to lesser solutions.

Doug J · Nov 3, 2017

Tyler Rippel said:
Ok, this is what I have currently. Looks like I may be on the edge as far as the charger is concerned for the 2 GC2 batteries in series?

Should work fine! Also known as a Smart Charger. Stage 1 Initial bulk charge, Stage 2 starts to reduce amps, Stage 3 float to maintain 100% charge. Safe to leave at float for long periods of time.

heritage · Nov 3, 2017

Looking at your charger pic, what the heck is going on with the #2 full led?? Looks like a worm is crawling out of it.

centerline · Nov 3, 2017

the charger is not the best available, but its a lot better than some use... its totally acceptable for your use, but if you had multiple batteries in a series-parallel bank, then you may want something different.

I would be happy with it, as it has 2 legs of 12v @15amp each... it will take care of the batteries in a better manner than your habits of using them will...

but its your money and it needs to be spent on something, and a premium, top of the line charger is never overkill ;-)

Stu Jackson · Nov 3, 2017

jviss said:
and that it holds at acceptance until charging current diminishes to .5% of your bank Ah capacity

I am not familiar with any charger that does this, unless its the Sterling or ProNautics Ultra recommended by Maine Sail.

Wiring a new charger From Maine Sail:

http://forums.sailboatowners.com/in...ation-tips-considerations.136765/#post-880275 and

http://www.pbase.com/mainecruising/installing_a_marine_battery_charger

Dual 6V battery setup - switch wiring/removal?

.

.

.

.

.

.

.

.

.

.

.

.

Attachments

.

.

.

.

.

.

.

.