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Old 11-29-2008, 05:20 PM   #15
Rivet Master
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I'm sorry though, most all electronic battery testors I've seen are akin to snake oil products.
We must be talking about two different things, I think. I do not know what battery diagnostic devices you are familiar with but the good conductance devices I am thinking about are in wide commercial use and run around $1k or more. They essentially 'ping' the battery with a variety of frequencies and look at the time domain response to obtain an impedance for each cell in the battery. The analysis and battery modeling they use is fascinating.

A local geothermal power plant that was so impressed with one vendor's test device they got one for their own use. It has saved them quite a bit on battery maintenance and avoiding battery failure. (It also did quite well at a rally diagnosing battery state of health and state of charge to get results that correlated well with age and use patterns of the RV battery banks tested.)

Shorted cells and other such failures are in the low risk but readily apparent area which means you usually don't need fancy tests to figure it out. Most (80% or so) RV batteries fail due to sulfation buildup as an aging thing. The capacity of the battery just decreases over time and how quick that happens depends upon how they are used and abused.

As for "larger battery banks are great for longer running times, but take lots more time to recharge" - this would only be true if your charger was under rated for your battery bank. Most modern converters can provide full charging current for as big a battery bank as you'd find in a typical trailer. The limitation on charge time is usually due to the converters keeping to a safe voltage for the connected appliances - not the size of the battery bank. Many folks don't realize that it takes 8 hours or more to fully charge a typical RV battery properly because of the nature of the beast (it takes time for the chemistry to settle).

The best guide for sizing a battery bank I have seen is to make sure it is big enough you don't take it below about 12.0v measured after it has been quiet for a half hour or so but not so big you don't get at least get it down to 12.4v (after no significant charging or discharging for a half hour or so) as a regular thing.

The idea about an appliance timer is a good one and is essentially what the charge wizard or WFCO converters do automatically. You still need to keep an eye on electrolyte levels every few months to make sure the system you are using isn't drying out the batteries if you can.

re "if you have battery problems, seek out a Battery Specialist in your area" - I agree with this and with the sentiment that they are not so easy to find. I don't agree that you should take some the word of anyone, though, without qualification. There is so much BS, even from specialists who supposedly are giving you the straight scoop that you need to learn enough to see the context. A true 'expert' will help you learn and understand where his "straight scoop" applies and where it comes from (and he'll be open to the idea he doesn't know everything, as well, and be willing to learn).

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Old 11-29-2008, 11:44 PM   #16
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It seems interesting that you find some issue with my each and every point above...I was merely trying to impart some thoughts about how one might care for their on-board RV batteries...some generalized information, without getting too technical, that may assist frscott and others here, with some battery usage and diagnostic suggestions...I have dealt with these issues on a day-to-day basis for over 40 years, and my observations herein are based on my practical emperience...

Ray & Pat; Morada, CA
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Old 11-30-2008, 10:06 AM   #17
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It seems interesting that you find some issue with my each and every point above
Let's try to be factually correct, what say? I agreed with several, expanded on one or two, but took issue with only one that was in error along with the reason why. I think you do not do anyone justice to complain that I "find some issue with each and every" - why address me rather than the ideas I present?

I do not think that the 'appeal to authority' type of argument is a good one, either. Neither is the straw man of 'too technical'. We need to help others (and each other) understand, at least on a conceptual level, what these issues are all about so we can make better decisions. It is up to all of us with knowledge and experience to educate rather than to inculcate. We should be sharing ideas rather than pronouncing ideologies, IMHO.

I provided examples, rationales, and references to support what I offered. Don't you think it would be better to address those rather than to just dismiss them or complain about the messenger?
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Old 12-02-2008, 09:56 AM   #18
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Blah blah blah... both of you! Your constant bickering is helping no one, but “thank you”, to you both for your input regarding batteries, etc.
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Old 12-04-2008, 08:03 PM   #19
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Ohh boy here we go...

Originally Posted by Newlyweds View Post
Blah blah blah... both of you! Your constant bickering is helping no one, but “thank you”, to you both for your input regarding batteries, etc.

Like he said just get married and get it over with LOL...
1976 Airstream Sovereign International Landyacht (renovating)(found DOM plate said 1976)
1968 Airstream Caravel 17 footer

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Old 12-04-2008, 08:41 PM   #20
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There is a name for this. When you decide that all behavior is equally acceptable, then you will find things perhaps not as you wish they were to be.

When you label things as they are not, you see what is not and that is an attempt to escape from reality. Sometimes useful but not usually productive.
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Old 12-04-2008, 08:45 PM   #21
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Boy, you guys are scaring me with all this technical talk. I just added a second battery (actually replaced the original and added a new second battery). The original was out on the tongue of the trailer, the second is in the storage compartment under the bed. Both are new Lifeline 12 volt batteries. When I bought batteries, I also bought a "Battery Minder" slow charger. I am really confused about how to use the Battery Minder. Do I have to remove the batteries and slowly recharge each of them individually over the winter, or is there a way to charge both of them at the same time and maintain them on the batteryminder. Or???? should I just forget about the Batteryminder and simply plug the shorline in and let the converter charge the batteries all winter long? My AS is a 2005 Safari and the converter is a newer model. jc
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Old 12-04-2008, 10:22 PM   #22
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The BatteryMinder(tm) is a good device for storage maintenance. First make sure your batteries are fully charged by leaving them on a good charger (your converter should do) for a couple of days. Then disconnect them from any load or charger so you can leave them alone with the BatteryMinder. It should be able to handle both batteries connected together as usual, in parallel, for storage.

Do check every month or two to make sure that you have a good battery float voltage (13.2 or so depending upon temperature) and everything looks OK. Read the manuals for both the BatteryMinder and the AGM's to see if they have any concerns or caveats to worry about.
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Old 12-05-2008, 06:59 AM   #23
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no need to be rude or feel personally attacked gentlemen-if Lieppers battery facts dont hold water-post your own--

Liepper-what is the reason that my battery tender wont bring a discharged batt up?

thanx for sticking on point-jim
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Old 12-05-2008, 08:48 AM   #24
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what is the reason that my battery tender wont bring a discharged batt up?
It will, over time, as long as it can provide a charge current greater than the bank's internal self discharge rate. Multiple batteries in the bank extend the time as can battery age and condition. It is generally better to not have batteries sit around without a full charge so a charge that will take days or weeks (or more) is not as good as one that will take less time.

Battery charging and battery maintenance, while related, are two different tasks requiring two different approaches.

When the batteries are charged and the task is maintaining the charge for storage, the challenge changes. There you want to keep sulfation from forming. This means keeping the electrolyte mixed and the battery fully charged. Those tasks don't take a lot of current capability but can involve a rather tricky balance as 'fully charged' depends upon temperature and other things. Don't do enough and the battery grows sulfate crystals. Do too much and you boil off the electrolyte and wear the plates.

facts dont hold water-post your own
We should all be sharing the same facts. Explaining how we interpret them and the rationale we use to draw conclusions based on them can help others understand how things fit together, what is perceived as important and what isn't, and consider what might be missing.

This process is especially valuable on some of the more technical issues. It also seems rather rare so working towards an intellectually honest discussion remains a distant goal, it seems. A first step is probably to get everyone on board that it is a desirable goal worth working towards.

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