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Old 09-07-2010, 11:24 PM   #1
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1997 21' Excella
Carson City , Nevada
Join Date: Jun 2009
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Battery inquiry

I read some posts about batteries. We are in the market as I see is pretty common here. I have noticed that you should never let the batteries run all the way down. Do you check this from the control panel? Whatever that is called anyway. So when it is at 50% there do a charge? Cause when we are boondocking, the beep beep is usually when we jump to using the generator. It seems that I check the charge at night and as soon as the furnace goes on sometime late in the night it instantly drops to nothing.
So I am favoring the sound of the Lifeline AGM unless there is something newer out that is better? And whatever route we go, we will have to take better care at maintenance.

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Old 09-08-2010, 05:36 AM   #2
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2010 30' Classic
Vintage Kin Owner
South of the river , Minnesota
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There is, in short, no good way to determine battery condition with the stuff on the trailer.

The voltage changes due to charge state are, in the middle range (around 50%), very subtle, and have to be measured with no load after the batteries have been sitting without being charged or discharged for an hour or so. Then the results have to be compensated for battery temperature.

There are shunt products out there that measure amp-hours in and amp-hours out that work very well but they are expensive and most people just use the battery and don't worry about getting the last bit of life out of it.

In general, being in the habit of running the generator for a while every day or every two days works well enough.

I don't think AGMs are worth the extra money but the choice is yours.

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Old 09-08-2010, 06:40 AM   #3
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Woodstock , Georgia
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I used a Yellow Top Optima for years. I disconnected it with a blade switch when it was not needed, and when hooked to shore power if it was already charged fully. It lasted for a long time, never failed. Still going strong
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Old 09-08-2010, 06:49 AM   #4
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1977 27' Overlander
Trotwood , Ohio
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Im having good luck so far with Deep Cycle Marine Batts from AutoZone. I have no idea what yours takes but ours are Group 27's. I pull em and check the water once a month. This is the 3rd season I think SO FAR SO GOOD. OF course I have to consider we dont boon dock. So I dont think mine have ever been cycle down to 50% .
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Old 09-08-2010, 07:30 AM   #5
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We boondock frequently during hunting season in sometimes freezing temps. We just replaced our 4 year old blue top Optima agm batteries after 4 years of service. I think the batteries died because they became undercharged when our converter became disconected. Our observations about battery service is as follows.
1. We use agm's despite the extra cost. I have killed several regular batteries by letting the water run low. I believe agm's last longer but cannot prove it.
2. A solar charger with a good regulator is very useful. It tops up the charge during the day and it has a very good charge charge indicator telling the state of charge. A fully charged battery puts out 12.8 volts. At about 12.2 volts the battery needs recharge. Batteries should never be allowed to go below 12 volts. The charge condition is available at a glance from the solar charger gauge when there is no load on the batteries.
3. On partly cloudy days and below freezing nights, supplemental charging by a generator is necessary. The furnace motor is a power hog. A couple of hours of day of generator is usually all that is necessary to keep the batteries fully charged.
4. The stock Paralax battery charger converter in newer Airstreams is not the best available. It is an all or nothing charger and will eventually kill the batteries by overcharging them if the trailer is left plugged in for long periods. A drop in (engineered for Airstreams) multi stage charger, converter is available at for a little over $200. It senses the charge and drops to a trickle when the batteries are fully charged. If you want to get the longest life possible out of your batteries, it is a worthwhile investment.
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Old 09-08-2010, 09:23 AM   #6
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1975 29' Ambassador
Reno , Nevada
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The control panel can be useful but it does need interpretation. An inexpensive digital voltmeter can also be useful. You don't want your batteries to go below 12.0v as measured at rest. That means no significant charge or discharge for at least a half hour before measurement.

Easiest means, though, is what you have done - notice that you don't get good service.

There are no magic cures when it comes to batteries. Brand, type, or whatever won't solve your problems. Put your money into proper charging and maintenance equipment first and take proper care of your batteries and they should provide good service for 5 years or more.

Yes, there is a lot that can be learned - that is the fun part of an avocation, IMHO - but you really don't need much to have a good time with the RV. What you do need to be careful about is all the stuff you find on these forums that just doesn't apply to solving your problems.

As for AGM style lead acid batteries, evidence indicates perhaps a bit longer life expectancy (re NAWS FAQ) but they really don't offer much for RV use to match their cost premium except, perhaps, some convenience.
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Old 09-08-2010, 10:03 AM   #7
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Oxford, , Mississippi
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The book "Managing 12 Volts" by Harold Barre is well worth the investment. Amazon has it as does Answers all the general and tech questions about managing 12 volt systems in RV's or boats. I found it very informative for both general and technical info.

Bruce & Rachel
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2001 Toyota Tundra
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