A Battery Discussion; 6V vs. 12V

[ian ashton]

It seems like many of us are planning to do the 6 volt swap over winter, and others have questioned it, so I figured I’d share my rationale for making the switch.

For comparison sake, I chose to compare 2 of the easiest to obtain ‘golf cart’ 6 volt batteries (the Interstate GC2-XHD UT (formerly the u2200), and the Exide GC135) to the Deka DC24 and DC27, which are deep cycle marine Group 24 and Group 27, respectively, and available under many different private label brand names.

https://forum.moomba.com/attachment.php?attachmentid=18679&d=1382120311

Looking at the chart, you’ll find that 2 of the 6 volt batteries will be equal in capacity, weight, and cost to 3 of the Group 24, and like 2.5 of the Group 27s.

For me, putting 4 batteries in my boat (3 house, 1 start) will be more work than I want, so the easy choice was to get the 2 best performers I could.

Also important to note, the above chart shows MSRP - I was not able to locate a source for the Interstate batteries (which MMANDLEY is using) so I researched and located the comparable Exide, and was quoted $119 ea, further enforcing that this is the best choice for my needs.

[cab13367]

Ian, I went with two Group 29 125AH marine deep cycle batteries from Costco, cost about $90 each, for my stereo bank. If you are looking to get the most play time out of two batteries, I don't think you can beat this option. And it's less expensive to boot.

[MLA]

The GC's will take far more punishment. This is an advantage for those spend considerable time every weekend playing the system whale at anchor.

[mmandley]

I prefer the 2 Golf cart batteries i run. Running 4 big amps when we stop to swim and hang out i never have to worrry about my batteries.

Also the other big reason to change was due to when we take a lot of our trips in the summer i have no way to charge the batteries other then the engine. My stereo fare exceeds my Alt output when im cranking hard. Anyone who has spent any time in my boat knows my stereo only has 3 settings.
Off
Loud
So Loud you cant hear the person next to you shouting.

The other day i noticed i was cranking the stereo so hard the RPM guage was bouncing 400 RPM and the engine was running a consistent speed. LOL.

Also with the Pro 20 charger on board, i just switch off the batteries with my selector switch plug it in at home and it charges normally. No other modifications needed.

[David Analog]

It can be hard to compare specs from battery brand to brand to brand. For example, I don't believe the specs on some of the Walmart offerings. The amount of lead is a major determining factor in performance, which can't be cheated. I tend to trust the specs when the battery weight closely corresponds as a ratio to the amp/hour capacity. There seems to be a uniform relationship with all the quality brands shown in Ian's graph so it looks legit to me.
Not included is the Deka group 31, which generally is a 15 to 20% increase in capacity over a group 27 and a nice bump over a group 29.
Various battery types (cranking, deep cycle) exchange short term peak discharge for long term continuous discharge. More plate surface area versus thicker plates. Each makes a compromise in favor of an opposing performance benefit. For large stereos played at rest for long periods, its tough to beat what golf cart batteries have to offer.

[gus 08 mobius lsv]

i'm no audio guru but looking to revamp my stereo in the near future ... but what makes a 6 v golf cart battery better then a 12 v marine grade battery.

[clarkely]

I run two 6volt on my camper......... Inn the camper having a good converter for recharge is key.... Not sure how it works on the boat..... As far as trickle and not over heating. And over charging....

Sent from my SGH-T999 using Tapatalk

[rdlangston13]

i'm no audio guru but looking to revamp my stereo in the near future ... but what makes a 6 v golf cart battery better then a 12 v marine grade battery.

You can't just run one golf cart battery, you have to run two of them in series to generate 12 volts. This set up is better than two 12 volts wired in parallel due to the durability of the GCs being discharged and recharged so much. The two GCs also provide more amp hours than the two standard 12 batteries for extended play time with the engine off. Or at least this is how I understand it.


Sent from my iPhone

[zabooda]

A Cat battery if you have the room and the price $290. Not uncommon in motor homes. Nice compliment to a killer stereo system.



PART NUMBER: 153-5710
Length (in): 20.47
Width (IN): 8.58
Width (MM): 218.0
Height (IN): 9.76
Height (MM): 248.0
Weight - Wet (LB): 119.0
Weight - Wet (KG): 54.0
Terminal Type: SAE Posts
Maintenance Type: Maintenance Free
Grid Type: Calcium Lead Alloy Grid Design
Accessible Vent Caps: Accessible Vent Caps
Application: Starting
Battery Type: Wet
Volts: 12
Group Size: 4D
CCA: 1400
RC Mins: 425
AMP Hr Cap @ 20 Hrs: 200
Length (MM): 520.0

[David Analog]

i'm no audio guru but looking to revamp my stereo in the near future ... but what makes a 6 v golf cart battery better then a 12 v marine grade battery.

A cranking battery has more plate surface area and more perferation. This provides a faster discharge. It's good for starting and the transient demands of music but bad for durability when deeply cycling a battery.
At the other extreme is a deep cycle golf cart battery with thicker plates but less plate surface area. This deep cycle design will tolerate deeper discharges without degradation but isn't intended to release energy as fast.
So there are definite advantages and disadvantages to both depending on the application. But as stereos have become larger and used at rest for long durations with deeper discharges, most will prioritize maximum reserve time and longevity.