Sorry... another 6 volt battery question

[sgfrye]

Our 2 Wally World 12 volt deep cycle batteries have served us well the past couple years on our TT. Wife and I don't boondock but our fridge is residential and has worked well on 9 to 10 hour trips on the road. Also use fresh water tank and water pump when on the road. Only reason I'm considering switching them out for 2 6 volts is because it's time to replace our pontoon boats deep cycles. I have them powering a trolling motor on the pontoon for fishing and some electronics. They are still in good shape always maintened with charging and fluid checks. My question is what are good mid range priced 6 volts to add to the camper? Not looking for high end or cheap ones. Basically would be powering residential fridge, water pump and one slide to move out and in to access fridge on lunch breaks. Nice to have more battery storage if camp ground power went out for awhile.

[theoldwizard1]

mike-s wrote:
A GC2 battery is 6V and typically over 200 Ah (the common Trojan T-105s are 225 Ah, but current Interstate/Costco ones are labeled 160, which is the low end).

Where did you pick up that information ? Everything I have read is that the Interstate/Costco GC2 batteries are 225Ah.

[ktmrfs]

while talking advantages, 6V do have at least one disadvantage. the fewer number but thicker plates don't do well if you have high current draw, like an inverter for a microwave. Voltage drop can be a problem with the inverter. As long as the draw is in the 30-50A range/bank your ok, but I and others have found that a single GC2 bank needs around 80% SOC for a 800-1000VA load. 12V on the other hand do much better under these conditions.

But when looking at "useable" capacity for reasonable draw 6V wins hands down. Even trojan 12V deep discharge are spec'd for at most a 50% DOD. But the T-125 series trojans show a 500+ cycle life discharged to 75% !!!

So a 250AH 12V bank has around 125 "useable" AH, while a pair of 6V GC-2's has about 175 "useable" AH. My first set of Trojans saw this 75% ish DOD 30+ times/year along with many other discharges to 50% or less and were still lasted me over 10 years.

[ktmrfs]

garyemunson wrote:
Arranging a hold-down for 6 volts can be a challenge. I use these hold downs with threaded rod run at a 45 degree angle. My tray has a lip one side that the bottom of batteries rest against. The hold down goes on the far side of the battery and the rods run towards the lip.

https://www.golfcartking.com/yamaha-gas-battery-hold-down/

A watering system is also helpful as many RVs don't provide much access from the top to check water level.

https://www.amazon.com/Flow-Rite-RV2000-Pro-Fill-Battery-Kit/dp/B001FCAXT0/ref=sr_1_2?ie=UTF8&qid=1538652441&sr=8-2&keywords=battery+watering+system

several mfg make boxes designed for 2 GC-2's either mounted lengthwise or side by side. nice polyethelyne boxes.

[ktmrfs]

Chinolbz wrote:
Sorry ktmrf. You can double the voltage or double the amps, not both.
4 6v = 250ah. Chino

nope you can do both

two 6v in series =12V @ 250AH

parallel up 2 of this combo =500AH

four 6v (2 6v series banks in parallel) =500AH

[jplante4]

In addition to more capacity, 6 volt golf cart batteries have thicker plates and can take more cycles than a 12v RV/Marine "deep cycle" battery.

[garyemunson]

Arranging a hold-down for 6 volts can be a challenge. I use these hold downs with threaded rod run at a 45 degree angle. My tray has a lip one side that the bottom of batteries rest against. The hold down goes on the far side of the battery and the rods run towards the lip.

https://www.golfcartking.com/yamaha-gas-battery-hold-down/

A watering system is also helpful as many RVs don't provide much access from the top to check water level.

https://www.amazon.com/Flow-Rite-RV2000-Pro-Fill-Battery-Kit/dp/B001FCAXT0/ref=sr_1_2?ie=UTF8&qid=1538652441&sr=8-2&keywords=battery+watering+system

[mike-s]

Chinolbz wrote:
Sorry ktmrf. You can double the voltage or double the amps, not both.
4 6v = 250ah. Chino

ktmrf was correct.

A GC2 battery is 6V and typically over 200 Ah (the common Trojan T-105s are 225 Ah, but current Interstate/Costco ones are labeled 160, which is the low end). We can use 250 Ah for discussion.

When you put two in series, you get a 12 V battery at 250 Ah. If you put two in parallel you get a 6 V battery at 500 Ah. If you put 4 in series/parallel, you get 12 V at 500 Ah.

Or, maybe you're thinking a GC2 is only 125 Ah. That would be way off base.

[Chinolbz]

Sorry ktmrf. You can double the voltage or double the amps, not both.
4 6v = 250ah. Chino

[ktmrfs]

Unless you plan on doing a lot of boondocking and a lot of camping each year go for Costco/Sam's club GC batteries. IMHO you can't beat the bang for the buck. 1/2 to 1/3 the cost of Trojan or Deka, maybe not the same life but should be pretty close if taken good care of and kept charged.

[ktmrfs]

Bill.Satellite wrote:
Keep in mind that you will need to swap our your 2 12V for 4 6V batteries. If the math makes sense, they are good batteries.

I'll disagree. 2 12V in parallel around 150-200AH. 2 GC-2 in series 200-225AH.

I run 4 T125's that 550AH, WAY more than any typical pair of 12V marine batteries one would likely have on a trailer!

[Boon_Docker]

camperdave wrote:

Bill.Satellite wrote:
Keep in mind that you will need to swap our your 2 12V for 4 6V batteries. If the math makes sense, they are good batteries.

No, dual 6v batts are a common and almost direct swap (just a bit taller) for dual 12v. You just wire in series instead of parrallel.

You should have about the same Amp Hour with a pair of 6 volt as you would with a pair of 12 volt.

[camperdave]

Bill.Satellite wrote:
Keep in mind that you will need to swap our your 2 12V for 4 6V batteries. If the math makes sense, they are good batteries.

No, dual 6v batts are a common and almost direct swap (just a bit taller) for dual 12v. You just wire in series instead of parrallel.

[sgfrye]

Artum Snowbird wrote:
Many of us use Costco 6 volt batteries. I have had excellent luck with them.

They are taller than the 12 volt batteries, so be sure you have the vertical space.

Traditionally, deep cycle batteries and marine batteries are designed to run a slow discharge for a long time. If your pontoon boat batteries need to be deep cycle, or if they are suited better to a starting battery depends on the usage in the boat. I have used truck batteries in my boat for years as they just start the motor and are not drained down slowly. They also have a 7 year warranty compared to 18 months for a deep cycle marine battery.

Yes agree
I have cranking battery for motor and use deep cycle for trolling motor and electronics

[Bill_Satellite]

Keep in mind that you will need to swap our your 2 12V for 4 6V batteries. If the math makes sense, they are good batteries.

[Artum_Snowbird]

Many of us use Costco 6 volt batteries. I have had excellent luck with them.

They are taller than the 12 volt batteries, so be sure you have the vertical space.

Traditionally, deep cycle batteries and marine batteries are designed to run a slow discharge for a long time. If your pontoon boat batteries need to be deep cycle, or if they are suited better to a starting battery depends on the usage in the boat. I have used truck batteries in my boat for years as they just start the motor and are not drained down slowly. They also have a 7 year warranty compared to 18 months for a deep cycle marine battery.