Battery Hell ! Could really use some advice ...

[SternWake]

The product linked to is just a solar panel to power the exhaust fan for an absorption(propane) fridge.

I thought you already ruled out solar. Generally you need at least 60 watts in a sunny environment to power a 12vDC compressor fridge in the 2 cubic foot range. More is better.

 

[Clan Graham]

The product linked to is just a solar panel to power the exhaust fan for an absorption(propane) fridge.

I thought you already ruled out solar. Generally you need at least 60 watts in a sunny environment to power a 12vDC compressor fridge in the 2 cubic foot range. More is better.

Uhh .... Nevermind

.

 

[Clan Graham]

As far as ruling out Solar ... That is just for now. I would love to one day rely completely on Solar. But I will first need to get to the Pacific Northwest and see just how good or poorly solar will work on those cloudy days. I will also need some time ( years ) to get enough funds to properly do Solar to power the entire bus with.

 

[user 2252]

Thanks Sternwake for all this information, you seem to be a very knowledgeable guy to this stuff. I plan on something similar, I want to run a refrigerator like this:
http://www.homedepot.com/p/Whynter-...e-Freezer-Gray-FM-62DZ/203569129?N=5yc1vZc3or
plus a laptop and phone charger. I plan on using 2 or 4 6volt AGM batteries and keep them charged with a EU2000 Honda generator and a converter charger. I am still doing research on this arrangement and hope to eventually go solar. Care to give any (repeated) advice? In particular, would you recommend 6 volt batteries? I have a 1988 Chevy G20 with the passenger seat removed. I plan on building a wooden box the will house the batteries below and the charge/converter and battery monitor mounted to the box and the refrigerator mounted on top. What do you think?

 

[SternWake]

Technically, even AGM batteries should be vented, but are obviously a better choice for living compartment duties.

I am not sure you need 4 GC( golf cart 6v) batteries with what you list. It really depends on how long you expect to go between charging.

I recommend using all available charging sources, and the alternator can be very effective bringing batteries upto the 80% level when the batteries themselves start limiting the current they can accept.

The RV converter you get should match the battery manufacturer recommended absorption voltage, or at least come close. unfortunately none of the offerings allow one to set the absorption voltage or duration. The Big 3 rv converters, progressive dynamics, powermax and Iota all use different charge voltages.

If you buy a Powermax converter through best converter, they are having special converters made for them which have an adjustable voltage potentiometer one can dial in, but these require a little more of a hands on appraoch, but if the hands are on, they can more quickly and more fully recharge the batteries.

I've recently gone a little more manual in my AC charging sources, and am using a 500 watt switching power supply that has adjustable voltage from 13.12 to 19.23 volts. It is basically a 40 amp manual charger, and can indeed overcharge the batteries if set to 14.8 volts and left on my battery for over 2.5 hours, but it gives me the control I want.

I find the charge algorithms of automatic converters/chargers to be insulting with their one size fits all mentality. I call them automatic underchargers.

These automatic underchargers, especially when one is using a generator, waste gas when they cut the absorption time off at the knees. When one can hold absorption voltage for longer, about 2 hours, the battery will be in the 95 to 98% charged range.

automatic underchargers will not hold ABSV for very long, or even drop to a lower voltage once the absorption voltage is reached and from that point the battery is charging very slowly, while you listen and smell your generator buzz away while it accomplishes very little.

Most depleted AGM batteries can really take as much amperage as you can feed them, so a high amp charging source that maxes out the generator, and which holds absorption voltage for a while, at least an hour, preferably 2, will get your batteries up near full in as short a time as possible, and the goal for maximum battery longevity and performance during that longevity, is getting them as full as possible as often as possible.

Within reason of course.

Here is a thread on my 40 amp manual charger:
https://vanlivingforum.com/showthread.php?tid=10873

Meanwell makes more powerful power supplies than this, if you go for 2 6v AGM batteries you can certainly go higher than a 500 watt power supply, as with the generator i think minimal run time is more important than babying a battery with a slow charge rate.

That is is you care to adjust and monitor battery charging voltages, otherwise I'd say get a powermax boondocker from Best Converter that has adjustable voltage and is automatic still, just incase you decide to run the genny for 12 hours, or plug into the grid.

 

[user 2252]

OK, I like this idea of manual charge as I am a bit of a "techie" and also enjoy wanting to know how "things" work. (plus, I must admit I am a bit of a "control freak" in my perceived world) so if I went with 2 6v AGM batteries rated at 220 ah, this gives me a total of 440 ah to power "stuff". With this configuration, I theoretically could power my "stuff" till the monitored batteries reach a 50% discharge and then connect to the Honda EU2000 for a couple of hours at a app. 14.5 manually adjusted rate of charge. If I understand the 100% (recharged) battery voltage of the batteries I provide, then I can disconnect the generator and I can start all over again with the process. I know it's not fully technically described, but in your opinion, this is the gist of it?
By the way, I want to stay away from connecting my house batteries to the alternator as I just don't want to add any "unconventional" work to the "designed" function of the starter system. Less is best! Remember also, I will eventually alter the house battery system to solar.

 

[Optimistic Paranoid]

I will note in passing that the world of cruising boats is a LOT more sophisticated than the rv world, and much of their stuff can be adapted to our needs.

Sterling Power, for instance, makes marine battery chargers that allow you to custom program whatever absorbtion and float voltages you desire.

Regards
John

 

[66788]

Even the small diesels used in pick-up trucks need two batteries to provide enough amps to crank them over. A huge diesel like this Cat will almost certainly need two batteries to start it.

I thought the same as you do John, but my Grumman Olson has the Cummins 4BT diesel and the starting battery is a small Honda car size. A single battery that starts the diesel motor without glow plugs. Just insert the key and turn, no waiting necessary. This motor starts faster than any gas vehicle I've owned. Simply amazing.

 

[highdesertranger]

von brown just a heads up but if you wire 2 6v batteries in a series for 12v the amps stay the same as one battery, it doesn't double. highdesertranger

 

[SternWake]

yes, 2 6v batteries in series have 220 AH, not 440. if they were in parallel, then you'd have 440, but only at 6 volts.

I notice a lot of people are afraid of allowing the alternator to charge house batteries.

The alternator can do in an hour of highway driving, what can take a modest solar system all day to accomplish.

There is no major rewiring required. Wiring is added. The starting system is not touched. Stock vehicular wiring need not be touched.

One can do what pleases them of course, but when one lives on battery power, and one decides the biggest recharging source is too scary to employ, then I get a bit frustrated.

Solar is great, don't get me wrong, but it is low and slow. Low and slow on a hungry depleted battery, is like running a hundred yard dash to outrun the Indiana Jones rolling boulder, and trying to breathe through a cocktail straw while wearing flip flops, when there was a choice of running shoes and a bottle of portable oxygen and a beckoning mute playmate at the finish line.

"No thanks, gimme the flip flops and the cocktail straw instead."

ArrrrrrrrrrrrrrrrrrrrrGgggggggggggghhhhhh!!!!!!!!!!!!!!!

 

[user 2252]

Thanks for the heads up highdesertranger, this is my first attempt at "power on the go" so I will keep this in mind when I do start to put this together. Thanks Sternwake, I didn't mean to cause you frustration. I will reconsider this alternator option. I suppose it's my fear of doing anything to compromise my ability to be mobile. I must be able to move at will!.......lol.
OK, I have read many discussions and seen diagrams of manual/auto battery switches, continuous duty solenoid, ect. on this option and can see it working in my head, so, again, I will reconsider this. OK, I have the Honda EU2000 generator in hand in a couple of weeks. I have seen the discussion on adding up my wattage, 50% battery depletion, ect. but with no "hands on" experience, I am considered "wet behind the ears" I will need to keep reading, study, research and ask questions as I go along. My next purchase will be my 2 6 volt batteries because I understand that the "amount" of juice is higher than one 12 volt battery. (please forgive the layman terms....lol) I want to go AGM as they will be inside the vehicle. I hope to purchase these when at the RTR this year. This will take some time. My wholehearted gratitude to you both.

 

[SternWake]

No real frustration.

There are some, who drive regularly, who can use only the alternator as a charging source, and still get a respectable lifespan from the batteries.

I generally recommend using each and every charging source available, when available, so deliberately choosing not to employ what might be the single most effective charger( on a well depleted battery), is not so much frustrating, but perplexing to me.

But I understand the confusion. I recall the time when it was confusing to me.

Flooded 6v golf cart batteries are basically the best flooded/wet deep cycle batteries available. So many 12v batteries out there are just dual purpose marine batteries, where as the 6v GC battery was designed only for deep cycling. They've got thick durable plates, and a lot of electrolyte, and space under the plates for plate material to collect before it grows so high it shorts out the cells.

Most every 12v true deep cycle battery, and there are not many actual true 12v deep cycles, are deep cycle internals stuffed into a regular BCI group battery size, so even if the plates are less numerous and thicker, they are not contained within a jar size that was designed for such a task.

Now I am not so sure that a 6v AGM battery has any real cycle life advantage over a 12V AGM battery, as there is no plate shedding that occurs, and no liquid electrolyte, but there are 3 bigger cells in each battery instead of 6 smaller cells.

6v vs 12v battery thread wars can go on forever. I believe with flooded batteries the 6v wins hands down, even over true 12v deep cycle batteries, but with AGM's the difference is less.
Also the flooded 6v batteries are likely the best, most durable bang for the buck.

My large group 31 flooded battery requires very high voltages to recharge fully, and this makes it difficult to pair to a charger.

My AGM battery, my first, I find impressive, so far.

AGMs seem to fall into two categories, those higher $$ ones which say feed them as many amps as you can muster, and those slightly less expensive ones which say no more than such and such amount. The ones which say as much as you can, do not take kindly to low and slow and as such no not make a good solar only battery, unless an alternate high amp charging source is available and employed every so often for long enough, Like a well wired alternator and a 2 hour highway drive, or a 80 amp charger maxing out the generator for 90 minutes.

Lots of charging sources are good enough for the slow 80 to 100% charge area, but when the battery is at 40 or 50%, getting it quickly to 80% or higher is like a slap across the face of a complacent lazy and perhaps punch drunk battery, and if the high amp rate allows the other charging sources to get the battery to a true 100% State of charge, then the battery is basically reset to its maximum available remaining capacity, where as a 95% recharge will only allow the battery back upto the 85% fof maximum available remaining capacity.

The true 100% recharge is the secret to long battery life on a daily cycled battery. True 100% need not be achieved each and every cycle, and might even be abusive if tried, but every 10 to 14 deep cycles, the true 100% should be pursued, and if watched, voltage wise, during the next discharge cycle one will notice the battery is holding higher voltages compared to the previous discharge cycle.

I generally recommend people new to living on 12v batteries, not get expensive batteries, as they usually kill them by overdischarging them and undercharging them. There are a few who are aware of this tendency and are afraid to actually use the batteries, and rarely discharge them below 80%, and live around charging them.

There is a fine line, and one must remember the batteries are rented to work for you, not the other way around.
I need to remind myself of this more often, but i am a battery nerd with too many tools and have been van dwelling for 13 years now.

 

[user 2252]

OK, I am convinced in the use of AGM batteries based on this information:
http://bdchargers.com/batterytypes.php
and this documentation:
http://www.batterystuff.com/kb/articles/battery-articles/battery-basics.html

Now to decide on 6 volt or 12 volt.

Man, you guys are well informed. Thank you. Now on to the next step.

 

[SternWake]

You will find many people who swear the cycle life of flooded batteries is greater than that of AGM. Beware of websites that list info as absolutes, that are selling also something.

What is nice about AGMs is you can rest them on their sides and have access to the terminals.

Plan the size of the enclosure, then find the battery which fits nicely. if you really want a lot of capacity , but can only fit an odd amount of batteries, then go 12v. If you can fit an even number 2 4, or 6 then 6v.

Honestly I'd choose the freshest battery available which can fit the intended space.

With AGMs, the line between 6v and 12v is less drastic than with wet/flooded batteries.

 

[Zil]

I want the flip flops and a straw in a cocktail.
Preferably on New River.

 

[Spaceman Spiff]

Hope I am not muddying the waters too much, but to give a counterpoint to what SternWake is saying.

One of the authorities that I listen to for RV electrical is MaineSail; he does a lot of testing similar to what SternWake does for the sailing industry. Here is a couple of things he has to say about FLA vs. AGM:

http://www.cruisersforum.com/forums/f14/lead-acids-dying-what-to-replace-with-128445-3.html
(second comment down)

http://forums.sbo.sailboatowners.com/showthread.php?s=2b332041385548b81dce85ad23727c17&t=124973

I went with 6V FLA batteries for a number of reasons:
1 > Cost. AGM's were almost twice the cost of wet cell batteries, I don't have a lot of money to spend and these are my 'learning' batteries.
2 > Checking for 100% charge (I have to learn what that is and how to get it). Hydrometer testing of electrolyte is the best test for full charge, can't do it with AGMs.
3 > Weight. Deka 6V GC2 batteries weigh 60 lbs each. A 12V deep cycle battery of same AH would weigh ~ 120 lb. Rather lift 60 lbs twice.
4 > Equalizing. Can be more aggressive with wet cell batteries and can replace fluid lost to equilization.

Boating industry has been using FLAs for years inside the hull without problems, just have to keep them in their own closed space with outside venting.

-- Spiff

 

[SternWake]

I consider Mainesail to be THE authority with all things DC and Battery related. I don't know if 'counterpoint' is the correct terminology for his posts with regard to mine, I didn't see anything he has written at odds with what I have written, but i have not gone back and perused this whole thread. I've certainly seems some stuff I wrote a year or 2 ago that I no longer agree with or would place some qualifiers next to, if I could go back and edit.

Thanks for those links Spiff. I've been perusing one of those forums for a bit now, and just pretty much scroll past every post until I find one by MaineSail, as he is extremely knowledgeable, very experienced, writes well, admits mistakes he made years previously, and does not buy into manufacturer marketing claims, and will actually test those claims and has the correct tools and knowledge to do so.

I think the most important thing to take away from those 2 posts/threads, is that AGM batteries absolutely need the proper charging profile, and this is basically a minimum 20 amps for a 100 amp hour battery which almost rules them out as a good 'Solar only' recharge battery. Solar to top them off, but when depleted to 50% AGMS require high recharge currents, the more the better, and once 80% is reached then the battery cannot take much anyway, and then solar can do the low and slow topping charge, as a full recharge is absolutely paramount, and perhaps even more important on an AGM compared to a flooded.


The price alone of AGM batteries inspires confidence in the quality of the product by the purchaser, but MaineSail's vast experience in AGMs proves that with few exceptions, better cycle life can be achieved with flooded batteries as long as the user can remember to water them, and treat/prevent any cable corrosion induced by the corrosive gassing, and if the gassing itself is not itself an overwhelming obstacle.

I bought a Northstar AGM last November, and so far, I am impressed, but I only cycle it deeply when I know I will be driving where my alternator can feed it at a high rate, or I have access to grid power where my charging sources can feed it a steady 25 amps+ through the bulk stage, to near the absorption stage.

My experiences with this battery show me that the faster I can recharge it, the higher the amps I can feed it initially when depleted, the happier the AGM is. Right now it is bursting full. It will not accept even 0.01 amps at 13.7 volts, and it will crank my engine so fast it is scary, and I am not going to cycle it unless i know i am able to feed it at least 25 amps until it reaches 14.7v. 35 amps is better, and I've seen my alternator feed this AGM 90 amps and the drive belt started squealing in protest.

Depleted AGMS can be so amp hungry that they can and do regularly overwhelm/overheat alternators, especially those wired to the batteries thickly for minimum voltage drop, as they should be for best recharging performance.

Perhaps this is less of a factor in a moving vehicle than it is in a sailboat's small hot engine compartment, due to airflow, but if an alternator is capable of high output at idle speeds, and the user is idling to recharge, the alternator is more likely to overheat and fail prematurely.

My alternator, while rated for 130 amps, is a joke when hot at idle speeds, and cannot keep up with vehicle demands if the headlamps are on and the blower motor is on high. In such situations, 10 amps are flowing from my batteries to make up for what the alternator cannot produce.

Pre 94 dodge vans have horrible hot Idle speed alternator output. Post 94 are better, but certainly are not much more effective. Most vehicles do poorly recharging at idle speed when hot, and most people believe the opposite, and refuse to believe otherwise even if presented with evidence to the contrary.