Anybody boon docking with 12 volt batteries?

[Wetboy5776]

Originally Posted by Shadowcatche

Concord AGM battery, 180W solar panel with Moningstar MPPT controller, conservation all LED lights in our grasshopper design teardrop.

Alright, sure. If you got an 8ft teardrop trailer and a 180 watt panel, you will get by just fine with a small capacity AGM for the weekend!

But for those of us with average and above RV's and extended stays in boondocking areas, you will need a whole lot more capacity than that unless you wanna run your battery dry every night. And that's even if you DO have conservation lighting, and turn everything off when not in use.

At least, you will if you want to enjoy any amenities of modern living like computers, television, cell phones, radio, etc...

[Forest Grump]

Gel batteries: found out something interesting about gel batteries as they age from the tech at the mobility store who was instructing me on how to charge the batteries in below freezing conditions.

It seems with age and with letting the battery run down without recharging as it sits the gel hardens slowly from the bottom up with time. When you do charge only the less viscous top portion now is active and charges. As the cycles continue the conditions grow and worsen. With each recharge the less viscous top tries to mix with the more solid bottom until the battery integrity gives up and the battery swells or worse.

Their solution is to let the batteries run down to about 25% or less and then recharge. He also said to bring them in at night when freezing conditions exist and to charge it inside. Basically not to leave a discharged battery in freezing conditions and not to keep it topped off but to run it down and recycle.

Each chair has two gel cells at 12v each in series for the 24v motor. The bigger the chair the bigger the batterie. And yes these are true deep cycles rated only in Ah.

I don't use mine inside only outside.

What surprised me was how far he wanted me to run it down before recharging and the actual explanation for why the gel cells fail. The chargers supplied with the chairs are state of the art and I got to thinking that they probably had more gel cells in that one location except for the next mobility store and they probably had as much knowledge an experience on the subject as anyone.

[Shadowcatche]

Originally Posted by Wetboy5776

Alright, sure. If you got an 8ft teardrop trailer and a 180 watt panel, you will get by just fine with a small capacity AGM for the weekend!

But for those of us with average and above RV's and extended stays in boondocking areas, you will need a whole lot more capacity than that unless you wanna run your battery dry every night. And that's even if you DO have conservation lighting, and turn everything off when not in use.

At least, you will if you want to enjoy any amenities of modern living like computers, television, cell phones, radio, etc...

Wetboy You are making a number of assumptions, our tear is custom built for boondocking. It is 6X11 all aluminum frame with variable height suspension, sirus and and satellite with a 19"flat screen, three burner cook top, gas electric water heater, shower and portapotty (in a separate tent) Waeco refrigerator which sits in the back of the Subaru when we travel and yes the laptop comes along and the cell phones are plugged in to charge. We will have to run the generator for AC. All tipping the scale at 1350lbs and with the Outback 22MPG.
Teardroppers tend to laugh at the RV'ers who never step out of their rig. If you came to a Tearjerkers (international) gathering you would find folks that are very gregarious who have a lot of fun together and spend very little time inside.

[pkunk1]

I have 2 grp 31 12v Universal AGM's charged with an Iota smart converter/charger and LED lights in every fixture of coach. My biggest consumer of power is the furnace and I can go 2 days in below freezing temps before needing to run the generator. I need to keep the coach at a comfortable temp as we take out parrots with us on every trip.
The one advantage of 12v batteries over pairs of 6's is if one goes bad you're still operational.
The advantages of AGM's over conventional lead acid are much faster recharge times and no loss of water (ie no maintainance)and can be located almost anywhere they will fit. AGM's can tolerate a lower discharge without damage on a regular basis also.

[Forest Grump]

I use 3 12v Trojan batterie, lead acid, 215 Ah each. They last 5 days boon docking running the TV, dish box, microwave, furnace, toaster and lights. Love them!

[BryanL]

re: "The advantages of AGM's" -- a couple of caveats: AGM batteries should still be placed in a proper vented battery box. They, like all other lead acid batteries, will suffer shorter cycle life the deeper they are discharged. They, like all sealed lead acid batteries need a bit more care to keep from overcharging them.

Another caution for the rational reader is to be very careful of the anecdotes provided. The capacity of batteries is something that can be reasonably measured. How long someone can to go before needing a recharge is another matter. Each person's experience is different and the circumstances always change and not everyone has the same lifestyle nor the same ability to discern when it is best to recharge.

This is one reason why warranties for RV batteries are rather poor compared to car starting batteries. How long they last depends to a great deal on how they are used and RV batteries just don't have a typical, narrowly defined use profile that can be used to estimate battery life when your money is behind it.

[Midniteoyl]

Originally Posted by Forest Grump

I use 3 12v Trojan batterie, lead acid, 215 Ah each. They last 5 days boon docking running the TV, dish box, microwave, furnace, toaster and lights. Love them!

They better be good @ $350+

[pkunk1]

Originally Posted by BryanL

re: "The advantages of AGM's" -- a couple of caveats: AGM batteries should still be placed in a proper vented battery box. They, like all other lead acid batteries, will suffer shorter cycle life the deeper they are discharged. They, like all sealed lead acid batteries need a bit more care to keep from overcharging them.
Contrary....AGM's can be discharged more than conventional lead acid and will accept a higher rate of charge.
BryanL has spouted these mis-truths many times before and has been debunked.
I said that I had an Iota Smart converter/charger. It does know what voltage & amperage to give the AGM's .

This is one reason why warranties for RV batteries are rather poor compared to car starting batteries. How long they last depends to a great deal on how they are used and RV batteries just don't have a typical, narrowly defined use profile that can be used to estimate battery life when your money is behind it.

Mostly true.

[BryanL]

I note that, instead of offering the very simple thing I ask for - reliable measure - what happens is the ad hominem attack and more bald assertion.

If you think I "spout mistruths" all I ask is that you provide some reliable citation and reference that is based on objective measure that contradicts what I offer. I think it is a very very bad practice to make accusations that tend towards the person and not the subject at hand.

re: "I said that I had an Iota Smart converter/charger. It does know what voltage & amperage to give the AGM's." -- going off on what I did not say is also a bad thing to do, IMHO. I agree that one of the nice things about AGM batteries is their lower internal resistance which means they can deal with higher currents easier than wet cells, but Puekert's law still applies. It should also be noted that AGM's have been tweaked over the last ten years or so so that they will handle wet cell charging parameters much better than they used to (less risk of damage and less impact on life expectancy). They are lead acid batteries and that chemistry defines much of their behavior.

re: "Mostly true." -- this is another example of poor discussion practice. To quote a large segment that is already on the thread and then toss in an assertion that has no basis provided and does not contribute anything to further the knowledge of those reading the thread wastes via redundancy.

There are two reasons why you want to avoid deep cycling a lead acid battery (and most other battery chemistries as well, see This week in batteries (TWiB)). One is that it increases the risk of reverse charging a weak cell. The other is that the life expectancy of the battery decreases with cycle depth (i.e. damages the battery).

Deep Cycle Battery - Deep Cycle Marine Battery - Deep Cycle Batteries - Powerstridebattery.com says

Wet Golf cart batteries will typically have an average 225 cycles at 80% DoD and 750 cycles at 50% DoD. Always avoid Depth-of-Discharges that are greater than 80%. The "sweet spot" (optimum DoD for the greatest amount of power produced over the service life) is generally somewhere between 20% DoD and 60% DoD average. For the AGM (Ca/Ca) VRLA battery example below the"sweet spot" is approximately 22.5% DoD based on the greatest amount of power produced.

i.e. these guys think you should cycle AGM's only half as far as wet cells. If you find one of the plots of cycle depth vs life, you'll see how their 'sweet spot' is determined. Smartgauge.com also has a good rundown on the 50% DoD target as a cost optimum. (these guys appear to be using power efficiency but the ambiguity only points out the problem in getting reliable objective measure)

That website also repeats the 'deep cycle thick plates myth.' For the typical RV battery, plates run about a tenth of an inch thick plus or minus about half that (re the NAWS FAQ) which busts that one. Also note the cycle life at 'optimum' DoD and compare that to the number of times a battery would be cycled during the typical 5 year life of a battery in RV service.

If you need more support for these "mistruths" you think I am spouting, I'd be willing to help you out. I have been collecting bookmarks for a long long time trying to get the straight scoop on the common myths (as well as on the psychological defense mechanisms I often see used to maintain them).

[Midniteoyl]

That website also repeats the 'deep cycle thick plates myth.' For the typical RV battery, plates run about a tenth of an inch thick plus or minus about half that.....

Ok, I need a clarification of what you think a 'typical RV battery' is? Real question.. trying to follow, not trying to but in.

[BryanL]

re: "'typical RV battery'" -- a lead acid battery commonly available at retail that usually weighs somewhere between 50 and 150 pounds sold for non-commercial application where the use is intermittent and charging usually separated from discharging by a matter of hours or days.

[pkunk1]

A typical RV battery would be either a 6 or a 12v deep cycle battery. Common retail batteries are usually automotive start batteries. If BryanL tries to tell you there is no difference - ignore the advise.

[BryanL]

re: "If BryanL tries to tell you there is no difference - ignore the advise." -- well, here we go again.

What I suggest you do is to try to find some objective measure as my advice is really just what I have seen and measured, not advice.

I do suggest you be very careful of 'advice' that is offered without measure or substance behind it, especially as that seems very common when it comes to batteries. I don't know what it is about being able to measure something reliably that creates such emotional outbursts, but it does seem to show up in these battery discussions quite often.

If you can find a definition for 'deep cycle battery' that is objective and can be seen in battery specifications so as to easily identify one that is a 'deep cycle' and one that is not, please let me know. I have not found one yet.

Note also that what is being attacked here is a clear and objective definition I provided for a battery type. As to advice, I'd suggest being leery about those who object to terms with clear definitions and promulgate those that are ambiguous.

Rather than dismiss what any particular individual says (a form of ad hominem, contrary to the rules of these forums, and not constructive), I suggest you look for measure and clear definition. Look for understandable and reasonable explanations that are in line with what can be observed about why some conclusions or assertions might be reasonable. Look for consistency and for an allowance of the variability that exists in products and measure.

'deep cycle' does have a specific meaning but all lead acid batteries will suffer when cycled that deep. When subject to 'reasonable' cycle depths, even SLI marketed batteries will handle more cycles in the lab than a typical 5 year RV experience is likely to call on them for. You can see this in the NAWS FAQ (one of the few with somewhat objective battery life information) with a bit of extrapolation of their comments on cycle life.

Your choice: objective definitions, specifications, standards, and repeatable measure or ambiguous terms used for marketing eschewing measure and specification.

[pkunk1]

It seems BryanL really wants to be verbose and have it seem to all that he has the most knowledge of any here about batteries. It also seem that there are others here who have practical experience and simply answer questions with a few practical words who have also debunked him. Therefore, I vote to let him have the last word on this thread and if the OP would like more specific info, I invite a PM.