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Author Topic: battery advice  (Read 290 times)

Dragginourbedaround

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battery advice
« on: July 31, 2017, 11:32:16 AM »
I need to replace my house batteries. I have 2 group 31s and I'm thinking of replacing them with 2 golf cart GC2s. We rarely boondock, but will be boondocking for 12 days at the Albuquerque Balloon Fiesta in October. After reading Gary's Choosing a Battery for Your RV in the library it looks like the golf cart batteries are the better choice. The ones at Sams club are less expensive ($65 ea.vs $75 for the 31s on sale Sunday). Since we don't boondock very often should I stay with the 31s or go with the GC2s? Not much difference in cost.
Gene

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2011 Honda Fit

kdbgoat

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Re: battery advice
« Reply #1 on: July 31, 2017, 12:01:09 PM »
Are the amp hour ratings equal? Are the 31's a true deep cycle, not a dual purpose marine battery? If the answer is yes to both, the only advantage to using the 31's over the GC2's is if one battery should fail, you can still get 12 volts out of the other. Total battery failure is uncommon though. You save $20 for the GC2's, but you have to remember that they are wired in series, where the 31's are parallel. Will you be able to use one of the existing cables to series the GC2's?
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Dragginourbedaround

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Re: battery advice
« Reply #2 on: July 31, 2017, 01:22:58 PM »
 The difference in actual amp hours is negligible. 210 vs 215 I believe . The 31s are marine batteries. I don't know if I have enough cable for wired in series.
Gene

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2011 Honda Fit

kdbgoat

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Re: battery advice
« Reply #3 on: July 31, 2017, 01:40:07 PM »
If the 31's are marine, I'd go for the GC2's.
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Dragginourbedaround

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Re: battery advice
« Reply #4 on: July 31, 2017, 01:52:16 PM »
Thanks
Gene

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kdbgoat

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Re: battery advice
« Reply #5 on: July 31, 2017, 02:13:20 PM »
No need to thank me, that's just my opinion. Hopefully the Wiz will see this thread, and get us both straight.
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blw2

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Re: battery advice
« Reply #6 on: July 31, 2017, 02:27:40 PM »
yeah, the commonly considered rule of thumb for marine batteries is to not discharge more than 50%
With a true deep cycle golf cart type the manufacturer (at least Trojan) says that they can be pulled down a lot lower
so if both batteries are roughly the same capacity.... the usable capacity of the deep cycle will be more.
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Arch Hoagland

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Re: battery advice
« Reply #7 on: July 31, 2017, 05:20:00 PM »
Two things before you buy.

1. Measure physical size of old battery and make sure new ones will fit.

2. Take a picture BEFORE you disconnect anything.

After you buy make sure batteries are full of water and use an anti-corrosion spray on the terminals.
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prfcdoc

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Re: battery advice
« Reply #8 on: July 31, 2017, 05:56:54 PM »


Take a picture BEFORE you disconnect anything.

But if changing to 6 volt don't hook them up exactly like the picture. 😊
Bob & Kathy
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8Muddypaws

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Re: battery advice
« Reply #9 on: July 31, 2017, 07:45:05 PM »
In addition to taking a picture label every battery post with a number and every cable with the number of the post it goes on.
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John From Detroit

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Re: battery advice
« Reply #10 on: August 01, 2017, 06:51:45 AM »
Two Group 31's means you have about 260 Amp Hours of battery but if they are MARINE/deep cycle you can only use a small amount. say  30% of that or 88 amp hours

A pair of GC-2 Golf car batteries will 1: COST LESS and two give you at most 230 amp hours (figure 220) but you can safely use half that or 110 amp hours.. give or take, about 25% more usable power.. A very good thign.

Now if the Group 31's are TRUE deep cycle.. not MARINE/deep cycle.. well then they are better.0
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Gary RV_Wizard

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Re: battery advice
« Reply #11 on: August 01, 2017, 09:03:53 AM »
The GC2's will last 7-10 years with a little TLC, but the marine/RV type 12v will be typically last only about 3-4 years no matter how well you treat them.  If you can remember to check the electrolyte level in the cells occasionally and top up as needed with distilled water, the GC2's will deliver a lot more value over their longer lifetime. 

Since the amp-hours are the same, the amount of boondocking you do is of little significance. Either battery type is going to need re-charging at about the same interval. Amps are amps, afterall.

The business about 30% or 50% discharge in some previous posts is highly subjective and only affects battery life expectancy. Deep cycles like the GC2 golf car batteries will withstand deep discharges more often, which is why they typically last several years instead of 3-4.  You can still use 50% or so of the marine type if you need to.
« Last Edit: August 01, 2017, 09:05:29 AM by Gary RV_Wizard »
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Dragginourbedaround

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Re: battery advice
« Reply #12 on: August 01, 2017, 09:19:27 AM »
Thanks for the advice everyone. I have taken pictures and labeled the connections. The hardest part will be lifting the batteries in and out.  :)
Gene

2013 Winnebago Adventurer 37F
2011 Honda Fit

kdbgoat

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I know you believe you understand what you think I said,
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