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BryanL · 08-12-2011, 04:09 PM

re the Victron Paper: I agree that it is a good resource but I suggest a great deal of caution in taking it too literally. For instance, he asserts that an electron counter is the way to measure state of charge and that is problematic (voltage and specific gravity are the primary measures of SoC)

He also asserts that sulphation can be prevented. It can't and it is the leading cause of battery failure over time. (usual figures run at about 80% of failures)

He also gets in to the plate thickness myth. Battery plates are not built that way.

A key lesson is that any single source is inadequate. Another is that you need to learn how to qualify what is being asserted. See Understanding batteries, start with these links for a rundown on a few of the web available resources about lead acid batteries.

It is the misinformation, misleading information, and so much stuff out there that isn't pertinent or quite accurate that I think it is important to recommend that people looking to evaluate batteries stick to well defined terms and measures that are objective and important.

TechWriter · 08-12-2011, 04:56 PM

Quote:

Originally Posted by BryanL

It is the misinformation, misleading information, and so much stuff out there that isn't pertinent or quite accurate that I think it is important to recommend that people looking to evaluate batteries stick to well defined terms and measures that are objective and important.

For example?

TQ60 · 08-12-2011, 05:31 PM

Each type of battery is designed for a specific use, and given that, they may not be too good for that either.

First and formost, before you select the battery you need to know the requirements and environment.

Someone mentioned you could leave an AGM disconnected for years, that can cause damage and it WILL void the warranty.

All lead acid type batteries will "self-discharge", it is the nature of the beast, higher quality ones maybe at a lesser rate, maybe not, this usually has nothing to do with the quality of the battery when new, rather the condition as is.

If the per cell voltage gets below 1.75 volts per cell, then the battery could be damaged, this is why commercial devices have a low voltage disconnect to protect the battery.

The "FACTS" regarding construction and use are at the manufacturers' web page, a quick email will get things started, and as long as you are clear with your expectations the manufacturer can provide their data as it relates to your question.

You simply cannot state "X is better than Y", you can state something like "for this application X is better than Y because..."

Each type is different, here we go.

VRLA/AGM batteries are designed for a 10 to 20 year installed life...IN FLOAT service, and if the temperature is maintained in the sweet spot of about 72 to 77 degrees, and they are also rated for aproximattely 1000 charge/discharge cycles, so if boondocking and you charge each day with generator, you will have 1000 "camp days" as one limiting factor.

Unless the VRLA/AGM battery is specifically designed for RV use, then you may pay a huge amount of money to have a great battery that performs very well for a few years.

They are also VERY sensitive to rate of charge for recharge and float charge, the float charge should not exceed 1% of the labeled capacity, and the recharge rate should not exceed the manufacturer rating, the "Valve Regulated" part of VRLA means that the chamber of the battery is sealed upto a certian pressure,as anny lead acid battery functions is releases gasses, a VRLA has chambers to contain this gas, if over-charged the gass release will be excessive, building up pressure, then the valve opens to release the gas, then it is GONE.

A flooded battery is more rugged, and if over-charged to where only the water is low, it is easy to restore.

If you have your batteries installed in fron of the MH under the hood, then the temperature of the area could cause rise in battery temperature.

The VRLA will have permenant damage as a loss of capacity after 90 degrees, and for every 10 degrees the loss of capacity is great, each battery is slightly different, their data sheet will indicate the degradation.

So the 150 amp hour battery slowly becomes a 70 amp hour battery, and otherwise tests perfectly good with a volt meter and specific gravity.

There is a new type called "pure lead" that is rated to a higher temperature, and a lot more expensive, but again the design is float service it is difficult to determine how they would perform as primary power in non-float.

In communications environments where the batteries are installed in a box with no source of heat other than the sun and the float charge the life expectancy of the 10 year battery is 2 to 3 years, this is in float service where they may be used one time a year.

High quality flooded batteries can be purchased locally from Walmart for common types or mom and pop stores for odd ones, as long as they are fresh and properly maintined they will provide good service for many years for a fraction of the price of the VRLA.

Maintenance free are simply a flooded battery with a better chamber to keep some of the gas inside, they still can have the covers popped off and watter added, they usually are built to a better quality than the standard type, but this applies to standard automotive units, golf cart and truck batteries are more towards an industrial design where the expectation is for maintenace to be done on a regular basis due to the vehicle being the source of income.

If you have a battery compartment that is at the rear, away from a heat source and the extreems of the environment are such that the high temperatures stay below 95 degrees then you could consider the VRLA/AGM batteries as possible, confirming the rate of charge for recharge and float are next to consider.

Once you have determined your personnal needs and the environment that the batteries are to be installed you then can work with the battery manufacturers directly to determine which battery best suits your needs, and what the general expectations and performance will be.

You also can get a better understanding of the warranty and how it will apply, ask the manufacturer rep give clear language in an email describing how the warranty applies specific to your installation, they may provide it, maybe not, but in the event the battery does not meet the expectations you have some leverage if it is due to defect.

BryanL · 08-12-2011, 05:55 PM

re: "For example?" -- what I suggest you do is to actually read my posts ...

that is now 2 of these 'trolling questions' that could have been easily answered just by reading my posts. It appears that dissonance is not being handled very well.

Quote:

You simply cannot state "X is better than Y", you can state something like "for this application X is better than Y because..."

This is why bringing traction batteries into an RV forum to try to prove a point has problems!

re: "The "FACTS" regarding construction and use are at the manufacturers' web page" you could do this but wikipedia does pretty good on the Faure pasted-plate construction as an overview. The issue here is that the 'deep cycle thick plates' teaching fiction posits solid lead plates and nobody does that anymore (not economical in the use of lead for capacity among other reasons).

I do wonder about the shout out on the word "facts" -- especially since what you get when you contact manufacturers and web sites is usually the marketing department.

As always, use multiple sources and apply a reasonable amount of skepticism to what you hear. Watch out for appeals to authority, straw men, reduce to the absurd, and other logical fallacies. This is good stuff for a course on scientific literacy!

TechWriter · 08-12-2011, 06:16 PM

Quote:

Originally Posted by BryanL

re: "For example?" -- what I suggest you do is to actually read my posts ...

that is now 2 of these 'trolling questions' that could have been easily answered just by reading my posts. It appears that dissonance is not being handled very well.

No, I was actually interested until now.

I don't think you know what you're talking about.

wa8yxm · 08-12-2011, 06:52 PM

I won't bother trying to tell you folks how many hours I've spent researching batteries and the differences between them. My problem with the Victron paper is the lack of comment on the differences between apples and oranges (the fact they did not include the size of the batteries on the charts) not so much plate construction.. I do agree, nobody makes solid plate battery outside a lab for testing.. But that's another matter.

There are many differences between Deep cycle and starting, not just plate thickness but other things as well.

I should point out... I did once (40 years ago) make a battery as a project in Physics class. Not lead acid, but that gives you an idea of how long I've been researching Batteries.

I have no more to say Feel free to disagree, Feel free to spend big bucks on Optima if you like... After all. it is your money. Of all the batteries mentioned in this thread, that is the only one I'd not consider putting in my RV.