4 6v Batteries to 6 6v Batteries?

[Mike8253]

Wow! The power of a single word. So "Damage" maybe wasn't the most appropriate term to use, but it was used in the context of causing harm, or having a detrimental effect on lead acid batteries. I made the statement based on data included in the attached .pdf, with justification provided in the attached video where extensive testing was done on lead acid/AGM/lithium batteries to document positive and negative characteristics of each in terms of performance and longevity. This study included impacts of DOD.

https://www.youtube.com/watch?v=iy3hga_P5YY

(Note: Start this video from the beginning to benefit from the entirety of the study.) Also, there is a Blog regarding this study at https://mortonsonthemove.com/best-rv...-test-results/ that details all the findings of the video.

I subscribe to the doctrine that "There ain't no such thing as a free lunch", and that that things that appear to be free will always have some hidden or implicit cost to someone or something (your LA Batteries) if you consistently use them in a manner that is not optimal. That's all I was referencing to when I stated that 50% number. Charging at that point does not rob you of availability of power (unless you don't have a means to charge your system off grid), it's just the optimal point at which you regenerate your 12v delivery system for delivery of the requisite voltage over the longest possible time.

In any event, I think I've unintentionally hijacked the OP's thread with this side discussion. Wasn't my aim.

[twinboat]

Originally Posted by Mike8253

Wow! The power of a single word. So "Damage" maybe wasn't the most appropriate term to use, but it was used in the context of causing harm, or having a detrimental effect on lead acid batteries. I made the statement based on data included in the attached .pdf, with justification provided in the attached video where extensive testing was done on lead acid/AGM/lithium batteries to document positive and negative characteristics of each in terms of performance and longevity. This study included impacts of DOD.

(Note: Start this video from the beginning to benefit from the entirety of the study.) Also, there is a Blog regarding this study at https://mortonsonthemove.com/best-rv...-test-results/ that details all the findings of the video.

I subscribe to the doctrine that "There ain't no such thing as a free lunch", and that that things that appear to be free will always have some hidden or implicit cost to someone or something (your LA Batteries) if you consistently use them in a manner that is not optimal. That's all I was referencing to when I stated that 50% number. Charging at that point does not rob you of availability of power (unless you don't have a means to charge your system off grid), it's just the optimal point at which you regenerate your 12v delivery system for delivery of the requisite voltage over the longest possible time.

In any event, I think I've unintentionally hijacked the OP's thread with this side discussion. Wasn't my aim.

They reference a flooded 12 volt battery, was that a deep cycle battery ?

Why did the only mention 2 battery manufactures who suggest 50% DOD ? Who were they ?

How about a pair of 6 volt, Deep Cycle, Golf Car batteries ? Any testing on them ?

You don't think that Battleborn is bias ?

[Mike8253]

No, I don't. If there's a straight shooter out there, based on my watching and reading what he's published over time, it's this guy. I refuse to be so jaded to think that everyone is on the take and has some ulterior self-serving motive for publishing data such as this. Believe what you will. I was asked for the rationale for what I submitted above. I've done that and I'm done.

[Winemaker2]

Originally Posted by twinboat

Here is a DOD chart from Lifeline Battery.

It shows 1500 cycles at 25% DOD, 1000 cycles at 50% DOD, and 500 cycles at 80% DOD.

Many will look at that and conclude 25% HAS to be "better"
What they fail to consider is if a user drawing xyz AHrs in a year and gets 1000 cycles from a batty bank by going to 50% DOD. Then another user draws the same xyz AHrs in the same year and only takes the batty bank to 25% DOD they will have to run 2X the # cycles or 2000 and their batty will actually fail before the year is out (only good for 1500 cycles per your chart #s)

A batty is an energy source and will, if treated reasonably well, only deliver a fixed # AH over its life.
1,000 cycles to 50% DOD provides xyz AH
2,000 cycles to 25% DOD provides xyz AH
I'd love to have someone explain why the 2nd case is "better"?
Edit... I just looked back at the graph and in fact the graph shows closer to 2000 cycles at 25% DOD which is almost exactly what the above statement is.

[Mark_K5LXP]

Always missing from the cycle life debate is the calendar. People get all wound around the axle to achieve the maximum number of cycles. But to what practical end?

If one cycles their batteries once a day, every day down to 80% DOD this translates to nominally two years of service and 100% of the delivered Ah the battery is capable of. If the goal is longer calendar life one can reduce to 50% DOD and nominally double that (per the life cycle chart). But the delivered Ah over that service life is no greater, and will result in more frequent genset runs or less time running your stuff (every single day over that entire 4 year timespan). If you're not cycling your batteries once a day, week after week, year after year (which few people -any? actually do) the 50% folly is even more pronounced. You're operating your batteries to achieve the 1000 cycles but end up scrapping the battery before you've used them all up when it ultimately ages out. From a cost efficiency standpoint you're throwing away those unused delivered Ah, making the "twice as much battery/half as much" use model more expensive than an appropriate sized battery that's completely used up.

No question there are operational considerations to limiting DOD such as maintaining a given level of reserve power or to accommodate specific load demands, but battery longevity isn't among them. An appropriately sized battery for the application will reliably deliver power over it's service life irrespective of DOD and in the event you manage to wear it out before it ages out, that's as good as it gets. Pampering a battery merely ensures you won't get your money's worth and you inconvenience yourself by doing it.

Mark B.
Albuquerque, NM

[757driver]

In watching the video and looking through the blog post I have the following observations. In no way am I bashing Battleborn or lithium batteries, I think they are great and worth the upfront cost in the long run and as you can see from my signature I have them.

Is this a paid promotional video for Battleborn, absolutely!

The Battleborn execs state that two major battery manufacturers say that 12.2v represents 50% DOD and then all the comparisons and costs are based off of this. Is this an at rest voltage stated by the battery manufacturers or is it an in use voltage? I suspect (as with most other battery charts and data) it is an at rest voltage. So right there it is no wonder that the video could not get close to 1/2 the rated capacity at 12.2v. Not that this is an accurate judge of a battery’s total capacity.

The video mentions and shows charts for the discharge of the AGM and flooded batteries for 50% and 80% as a 2A draw but the data on the blog shows the tests done at 8A. Which is it?

Why not fully deplete each of the battery makes to the fully discharged voltage and count how many AH you get from each as compared to the stated AH? That would be a better test of what you are getting for your money instead of cutting off the test at an arbitrary 12.2v under load.

I don’t know of too many 12v true deep cycle AGM RV batteries but for this test they found three. Most true deep cycle AGM and flooded RV batteries are 6v GC-2. The only 6v GC-2 batteries in the test were flooded and then only 2 not 4.

They say the batteries were fully charged as per the battery manufacturers specs through Absorb into Float. At what charge rate was this done? How long was the Absorb phase? How long were they left on float? We’re they actually fully charged, who knows?

With regards to the discussion on cold temperature charging of AGM and flooded batteries the video suggests having to change charge parameters back and forth depending on the temperature. Who wants to be bothered with that? It’s called temperature compensated charging and most modern stand alone 3 stage chargers or inverter/chargers have the capacity to do this automatically.

I could go on but I have seen and heard enough to know that while there is some good information in the video there is also plenty of bias and misleading data/tests to sway the viewer towards Battleborn lithium batteries.