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Author Topic: Batteries  (Read 14285 times)

bsberry99

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Batteries
« on: July 27, 2007, 07:38:41 PM »
Okay,  I've been reading on here for awhile about batteries.  Can anyone tell me if I got this correct on batteries. I currently have  2 12 volt marine batteries, (I have Interstate HD 24p rated at Hours @ Ampere Load: 11.6@5; 3.2@15; 1.7@25) .  If I go to 2 6 volt lead batteries (about $65 at Sam's Club) and they are rated at 220ah each.  Does this mean my batteries under equal loads will last about 50 times longer. ( averaged 2.2 ah for the 20 hour for comparison only). Current batteries 2.2 ah at 20 hours X2 vs. 2 6 volt at 220 ah.  I have a TC and am planning a big trip out west.  I just had a 130kw solar installed but want to make sure my batteries last.  My biggest problem is I have the Tundra refrigerator (an upgrade, but not sure if worth it, it runs on DC or AC only.) It runs at 4.6 amps so I need a good DC power bank.  Any help, thoughts would be appreciated.
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Ned

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Re: Batteries
« Reply #1 on: July 27, 2007, 08:18:08 PM »
Marine batteries are not good deep cycle batteries.  They are a compromise between starting and deep cycle and don't do either very well.  The 2 golf cart (6V) batteries will be much, much better for your application.

130kw is a lot of solar :)  I suspect you meant 130W, which is about 10A in full on sunlight.  Under realistic conditions, about 6-8A.  If you can run the refrigerator on propane, it won't drain the batteries.  It will run a long time on even a small propane tank.
-- Ned -- Fulltimer 1997-2013
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Carl L

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Re: Batteries
« Reply #2 on: July 27, 2007, 08:21:09 PM »
However, if that Tundra is a AC/DC only unit, with no propane option, then you have a problem.   What is its amperage draw on DC ?
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bsberry99

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Re: Batteries
« Reply #3 on: July 27, 2007, 08:52:57 PM »
I just checked the fridge and it is rated at 12v 4.56 amps.  It does not run on propane.  The dealer sold me on it since it does not have to be level and it has no outside venting.  The fridge works great aside from the power requirements.  The panel is 130w, and I have the two marine deep cycles which came with the camper.  I want to go with the 6 volt but I am not sure if they are worth it.  Two lifeline 6 volt are almost $500 while two 6 volts from Sam's club is $120.  I have tried to do some research on several forums but can't get a straight answer.  Any help would be greatly appreciated.  We are leaving in 2 1/2 weeks for a 17 day trip out west.  I do not want to have to worry about my power.
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Ron

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Re: Batteries
« Reply #4 on: July 27, 2007, 10:05:59 PM »
I think the Sam's club batteries are made by Exide and if this is still the case IMHO they aren't worth the time to carry them to the checkout.   Trojans or Interstate Deep Cycle batteries are a good choice.
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Tom

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Re: Batteries
« Reply #5 on: July 27, 2007, 10:48:05 PM »
Call your local golf course(s) and ask who supplies their golf cart (6 volt) batteries, then buy your batteries from them.

Just remember that you need to connect two 6 volt batteries in series to give you 12 volts. A pair of golf cart batteries will give you roughly 220 amp hours at 12 volts.
« Last Edit: July 27, 2007, 10:53:43 PM by Tom »
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Gary RV_Wizard

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Re: Batteries
« Reply #6 on: July 28, 2007, 12:16:53 AM »
Quote
I have Interstate HD 24p rated at Hours @ Ampere Load: 11.6@5; 3.2@15; 1.7@25

Multiply the above hours x amperes to get the amp-hours available at each amp rate. They amp hours will not be equal because batteries deliver a different total power output at each discharge (amp) rate.

The golf cart batteries are rated at 220 Amp-hours, which is measured using a standard test, which is defined  as follows:

[Per the Optima battery site:]

 The Amp Hour rating tells you how much amperage is available when discharged evenly over a 20 hour period. The amp hour rating is cumulative, so in order to know how many constant amps the battery will output for 20 hours, you have to divide the amp hour rating by 20. Example: If a battery has an amp hour rating of 75, dividing by 20 = 3.75. Such a battery can carry a 3.75 amp load for 20 hours before dropping to 10.5 volts. (10.5 volts is the fully discharged level, at which point the battery needs to be recharged.) A battery with an amp hour rating of 55 will carry a 2.75 amp load for 20 hours before dropping to 10.5 volts.

As you can see, the pair of golf carts will deliver much, much more power than your mediocre 12v dual purpose batteries. Dual purpose batteries aren't very good deep cycles, in general.

Here is more info on battery ratings.
« Last Edit: July 28, 2007, 12:19:04 AM by RV Roamer »
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John From Detroit

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Re: Batteries
« Reply #7 on: July 28, 2007, 09:35:36 AM »
When you want to start an engine, espically on a cold winter in the north morning, then COLD CRANKING AMPS are good, you need lots of them 

Thus starting batteries are long on cranking (peak) amps, even when cold, but short on Amp Hours

When you want to listen to the radio, watch TV, read a book or just pump heat or water, AMP HOURS are good, you want lots of them,  Thus Deep Cycle batteries are long on AMP HOURS, but short on cranking amps.

MARINE batteries are half breeds.  They are long on nothing and short on everythign (Medium actually on everything)

Example. One popular size 12 volt battery is 68 AH starting,  83 Marine and 100 DEEP CYCLE

Marine are often called "Marine/Deep Cycle" but any battery that ilsts "CRANKING AMPS (CCA or MCA) on it's lable is not a True Deep Cycle

Six Volt V/S 12 volt:

Many folks say six volt is better,   NOT TRUE, first there are no six volt batteries in RV's,  Just 12 volt batteries that come in two pieces  (Think of each pair of six volt batteries as one 12 volt and many questions self answer, Example "Do they both have to be the same?"  A: Would you buy a 12 volt battery that was half interstate and half excide?)

There are a lot of golf carts out there, and thus a lot of companies make six volt golf cart batteries (Cause that is what Golf Carts use) and thus due to both the size of the production runs and the number of competitors prices for Golf Cart batteries are low in compairson to other types of Deep Cycle batteries.  At one time in fact about the only reasonable size TRUE DEEP CYCLE battery you could get was a golf cart battery (Other Deep Cycles were made for things like Fork Lifts and such and.. Well, you need a fork lift to lift a fork lift battery,  Trust me on that, I've use one)

So RV makers used golf cart batteries

Today due in no small part to the size of the RV industry, more and more we are finding 12 volt DEEP CYCLE batteries in sizes you can pick up and carry (24,27,31,and the like) up to about 8D. (much bigger and you are gonna get a herina, Been there and done that too)

And the prices are dropping... But I think Golf Cart, at around 50 cents per Amp Hour at Sams or Costco, are still your best bargain,   12 volts are around a buck an amp hour just now.
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Re: Batteries
« Reply #8 on: July 28, 2007, 02:15:06 PM »
I just checked the fridge and it is rated at 12v 4.56 amps.  It does not run on propane.  The dealer sold me on it since it does not have to be level and it has no outside venting.  The fridge works great aside from the power requirements.  The panel is 130w, and I have the two marine deep cycles which came with the camper.  I want to go with the 6 volt but I am not sure if they are worth it.  Two lifeline 6 volt are almost $500 while two 6 volts from Sam's club is $120.  I have tried to do some research on several forums but can't get a straight answer.  Any help would be greatly appreciated.  We are leaving in 2 1/2 weeks for a 17 day trip out west.  I do not want to have to worry about my power.

That fridge is going to slop up 4.56 amps x 24 hours = 109 amp-hours per day.   Your solar panel will generate something like 10.3 amps x 10 hours of overhead sun x 0.5 efficiency = 50.1 amp-hours per day.   If we were talking about money here, you would go broke pretty quickly.   Remember batteries just store energy they do not generate it.   To run that fridge, you are going to have to inject a generator into your scheme one way or the other -- be it a genset or the alternator on your truck.
Carl L/LA   [Forum Staff]  KI6SEZ

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bsberry99

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Re: Batteries
« Reply #9 on: July 28, 2007, 02:52:47 PM »
I am beginning to see the light.  What is your opinion on the fridge?  Do you think it draws 4.56 24/7 or only a portion of the time?  We usually camp for 3-4 days at a shot before moving on.  I can add another solar panel (I had it prewired so all I have to do is hook it up) but I would prefer to change the batteries.  If I go to a true deep cycle battery, needing an additional 60 amps per day. (Probably less with the current only drawing when needed)  If I get a battery in the 220AH range how will this compute out? (220AH/60AH=3.66, is that 3.66 days to total discharge?)
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Ron

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Re: Batteries
« Reply #10 on: July 28, 2007, 02:58:07 PM »
It is not recommended to draw the batteries down to total discharge as it will shorten the life of the batteries.  Figure around 50% discharge.
Ron & Sam-home is where we park it. Currently located   HERE

King

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Re: Batteries
« Reply #11 on: July 28, 2007, 03:31:45 PM »
Your Interstate batteries, if in good condition, should provide between 60 and 75 Ampere hour capacity each.  That is usually understood to be for a 20 hour basis, and ends with the battery voltage at 10.5 V.  That is 3 Amps or 3.75 Amps.  With the two in parallel, that is 120 AH, or 150 AH.  Clearly, 220 AH is better, but not by a factor of 50.
 Your fridge shouldn't run continuously...  from my experience if you're careful about opening the door, maybe 20 to 30 percent of the time.
 Most 12 v equipment will automatically shut down at 10.5 volts.  All things considered, 2 six volt batteries in series will probably give you a little over twice the time before recharging.

bsberry99

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Re: Batteries
« Reply #12 on: July 28, 2007, 03:43:01 PM »
Thank you,
Now I just have to find some 6 volt batteries. 

On a side note what is the real benefit of AGM vs Gel vs the standard lead plate battery?  Does one charge faster then the other?  Aside from having to add water to the standard is there a real difference if the AH are the same? The prices seem to be very different i.e. Lifelines are about $500 for the pair.  Trojan T105 about $300 and Sam's club Exide $105.
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Ned

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Re: Batteries
« Reply #13 on: July 28, 2007, 03:56:28 PM »
Forget gel batteries.  AGM batteries will take a charge faster than flooded cell batteries, and can be mounted in an unventilated compartment.  The zero maintenance of AGMs is a big plus, in my opinion, and is the primary reason I have them.  If they aren't abused, they should last longer than flooded cell batteries as they can sustain more charge/discharge cycles over their lifetime.
-- Ned -- Fulltimer 1997-2013
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Tom

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Re: Batteries
« Reply #14 on: July 28, 2007, 05:35:56 PM »
Batteries in golf carts at your local golf course are heavily discharged and recharged daily, which is one reason golf cart batteries are designed for repeated heavy discharge and charge.

I've had both AGM and flooded batteries in heavy discharge/charge use for a number of years. The jury is still out on whether one technology is better or lasts longer than the other. The primary advantage I see so far is that I don't need to check & top off fluid in the AGM batteries.

FWIW I also have AGM batteries as starting batteries on my boat; They're 8D size, replacing the original 8D wet cell batteries. The locations made it close to impossible to check and top off water, which was why I went with AGMs in this case.
« Last Edit: July 28, 2007, 06:39:28 PM by Tom »
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bsberry99

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Re: Batteries
« Reply #15 on: July 28, 2007, 08:11:52 PM »
I was just reading a site from Australia.  He was saying that the AGM's charge much faster then the standard battery (http://www.fridge-and-solar.net/agm.htm) I have nothing to go on but it sounds reasonable.

Quote from article taken from link
"because of their very low internal resistance these batteries will fully charge at a lower voltage, and accept a much larger charge current, so when charging from a standard car/truck alternator these batteries will all but fully charge, and fast too, in about 2.5 to 3 hours!"

"Did you know that if our good quality wet deep cycle batteries have been discharged fairly deeply, it can take 8-12 hours of continuous engine running to achieve just 70-80% charge?"

As long as this is true the AGM's should be very beneficial for a couple of days running that fridge.
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joelmyer

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Re: Batteries
« Reply #16 on: July 28, 2007, 09:28:30 PM »
>>Aside from having to add water to the standard is there a real difference if the AH are the same? The prices seem to be very different i.e. Lifelines are about $500 for the pair.  Trojan T105 about $300 and Sam's club Exide $105.

I did a lot of research before I retired & got my RV.  Bottom line in my memory is AGMs cost twice as much as good wet cells (like the Trojans) and last about twice as long as properly maintained wet cells.  The Sam's club batteries are about half the "good" batteries.  That jibes pretty well with your current $s.

Knowing me, I got the AGMs.  If you're the kind of guy that religiously does periodic maintenance, then the maintenance free aspect might not be important.

Trojans vs Sam's Club?  Trojan performance is known & documented.  Sam's Club is popular but I know of no objective performance documentation.  You pays your money & takes your choice.

Joel
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John From Detroit

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Re: Batteries
« Reply #17 on: July 29, 2007, 09:36:02 AM »
Golf Cart batteries run 220, 230 or 240 AH, the 220 kind can be had for under 70 bucks a pop at Costo or Sams clubs. IN terms of bang for your buck.. That is going to be hard to beat ((Around 130 bucks for 220 AH at 12 volt))

These are flooded wet cells, require ventelation and, from time to time,  checking and perhaps watering

AGM's and Gel can both be mounted with little or no ventelation, upside down, on their side and so on, however AGM charges faster and seems to do a lot better in high capacity conditions.  I Use AGM's on my inverter bank. Very happy.

VRLA Sealed Maintenance free  Other than mounting right side up... See AGM

Slightly different charge settings for all 3 but your charge controller will very likely know how to do that if you tell it what kind of batteries you have... The one bad thing I have to say about Progressive Dynamics Intella-power chargers is.. They don't They are strictly for Flooded wet cells.
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Re: Batteries
« Reply #18 on: July 29, 2007, 09:54:47 AM »
The batteries at Sam's and Costco are made by Exide unless they have changed just recently.  I strongly recommend against any battery made by this company.  Better to spend a few more bucks and get Trojans or Interstate DEEP cycle batteries.
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bsberry99

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Re: Batteries
« Reply #19 on: July 29, 2007, 11:23:10 AM »
I think I will try to find the LifeLine 6 volts.  The quicker charge response should help with my power requirements.
Thanks for all your help.

Bob
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Ron

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Re: Batteries
« Reply #20 on: July 29, 2007, 11:36:49 AM »
I think I will try to find the LifeLine 6 volts.  The quicker charge response should help with my power requirements.
Thanks for all your help.

Bob

Excellent choice Bob.
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Alaskansnowbirds

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Re: Batteries
« Reply #21 on: July 30, 2007, 10:34:25 PM »
I think I will try to find the LifeLine 6 volts.  The quicker charge response should help with my power requirements.
Thanks for all your help.

Bob

Look in the Yellow Pages for a solar store. Most states don't charge sales tax on "alternate energy" products. I bought mine from Northern Arizona Wind & Sun in Flagstaff. Saved 8.5%.
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bsberry99

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Re: Batteries
« Reply #22 on: August 05, 2007, 03:22:20 PM »
I purchased the Lifeline 6 volts on Thursday.  I have been running a test and so far it seems to be working.  Here is the test, tell me what you think.
Every couple of hours I check the Refrigerator temp, outside temp, battery charge, AMPs being generated via the Solar panel and I open the fridge door for 10 seconds.  I am parked in partial shade from 12 -2pm with the rest of the day getting good sun on the panel.  So far I seen to be keeping the battery above 12 volts, which occurs in the am before the panel starts generating.  In the early afternoon I am up to 12.80 volts or there abouts.

Now my next project is installing a charge wizard on my 9145A converter.  Anyone have an opinion on these?  I was reading where the converter can take 70 hours to charge a battery but with the wizard you can reach 90% in 2-3 hours with it taking about 11 hours to reach full charge using the boost mode.  This seems to be a great benefit when using the Honda generator to charge the batteries on a cloudy day.

Thanks fore all your help,
Bob
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Ron

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Re: Batteries
« Reply #23 on: August 05, 2007, 04:08:45 PM »
Make sure your charge wizard or what ever you use to charge the AGM batteries provide the proper charge for AGM batteries.
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Gary RV_Wizard

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Re: Batteries
« Reply #24 on: August 05, 2007, 05:54:48 PM »
Quote
Now my next project is installing a charge wizard on my 9145A converter.  Anyone have an opinion on these?

Excellent choice. Converts an great two stage charger to a great three stage charger.

Quote
I was reading where the converter can take 70 hours to charge a battery but with the wizard you can reach 90% in 2-3 hours with it taking about 11 hours to reach full charge using the boost mode.

The boost mode certainly helps but you get  a high percentage of the charge in the first 2-3 hours either way.

The Lifeline battery is an good choice - they make a superb battery.
Gary
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John From Detroit

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Re: Batteries
« Reply #25 on: August 05, 2007, 07:15:12 PM »
Seconding what RON said.. When I got my motor home I did a lot of research into charger/converters.  And the Progressive Dynamics Intella Power 91xx with charge wizard or 92xx (has the wizard built in) was, at the time, beyond a doubt one of the BEST (if not the best) charger for flooded wet cell batteries ever made.  NOTE: Flooded wet cells.  Not lifeline AGM's.

The thing that makes it so good is very good attention to detail and programming, very good for the batteries charge wize and the auto-equalize feature for preventing sulfication of the plates.  My 9180 w/wizard I need to add water to my Work-a-holics every year or two, it's plugged in about 50 weeks a year.  If you want to know where it is the other two weeks, check the forum home page. it is not in the picture. but it would have been if the photo had been shot a year later :)

HOWEVER:  I could find no evidence of a charge wizard for AGM batteries (slightly different voltage and no auto=equalize mode, manual ok, auto not so good)
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Tom

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Re: Batteries
« Reply #26 on: August 05, 2007, 07:24:53 PM »
.....AGM batteries ....no auto=equalize mode

John, there are conflicting statements/reports on the need to equalize AGMs. Personally, I don't do it on my 8D AGMs. OTOH I also have 10 golf cart flooded wet cell batteries on my boat and 4 on my coach that get equalized periodically.
« Last Edit: August 05, 2007, 07:33:13 PM by Tom »
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John From Detroit

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Re: Batteries
« Reply #27 on: August 06, 2007, 07:01:25 AM »
I agree Tom, there is come discussion on that

From the research I've done it appears that one should equalize AGM's when it appears they need it

Flooded wet cells can take it more often to prevent issues but since an equalization charge is a controlled over charge, I'm a bit leary of over charging my AGM's too often.
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Re: Batteries
« Reply #28 on: August 06, 2007, 02:22:23 PM »
.... one should equalize AGM's when it appears they need it

John, with wet cells I usually know when equalization is needed. i.e. the batteries don't hold their charge as long. For the benefit of folks reading along, I hasten to add that, what this really means is that they have reduced capacity, for reasons explained in this article in our forum library.   *

I haven't experienced this with AGMs and I don't really know if I will, or if there's some other indicator of needing equalization.
« Last Edit: September 18, 2013, 04:13:54 AM by Tom »
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Gary RV_Wizard

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Re: Batteries
« Reply #29 on: August 06, 2007, 03:05:26 PM »
Quote
I could find no evidence of a charge wizard for AGM batteries (slightly different voltage and no auto=equalize mode, manual ok, auto not so good)

Progressive offers two different Smart Charge modules - one for flooded and the other for "gel". I haven't seen any specs that would illustrate what is different.

I don't equalize gels or AGMs and frankly don't worry much about the charge voltage difference either. It's a very minor difference, in my opinion.
Gary
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