Why not three batteries

Trailpixie

I fave seen a lot of conversation about adding a second battery. Why doesn't anyone talk about installing three batteries in parallel (or even four smaller 6-V batteries in series and parallel)?

 Much of that expensive solar investment could be avoided with a third $100 battery. 

Trailpixie

One more thing. With four (or even six) 6V batteries, you would have more flexibility as to where you fit the smaller batteries.

Nomad

Where do you propose putting all those batteries?
In my case, another battery would not eliminate my need for solar. At a certain point, the batteries will need charging. I supppose if you're a weejend camper you'll be home in short order to charge the things. If longer, you'd need to hit a campground with hookups.

mash2

I seem to recall that one issue is that the batteries need to generally be matched with regard to capacity (and age).  I think the overall performance is only as good as the weakest link.  However, the good thing about parallel is that a single battery failure won't stop the system from working, only limit the number of amps available.  At least in theory, you could continue to gang up 12v in parallel, including 3 or 4 batteries as needed. 

Sharon_is_SAM

Curious where you would fit 4 or 6 batteries.  The Tabs have limited storage to begin with.  

I suspect there are several reasons that most people prefer only 1 - 2 batteries:  many using full hook ups, simplicity, space, replacement cost (especially after killing your first battery which seems to be a rite of passage here

Rolltide82

On overland vehicles people put lots of batteries in the vehicle....Toolboxes or camper shells....I assume you could run long wires to attach to the camper....

Trailpixie

SAM said:

Curious where you would fit 4 or 6 batteries.  The Tabs have limited storage to begin with.  

...

I think you could mount them in the living space, perhaps under the sink.  Gel-cell batteries are sealed and don't outgas, so they are safe for a living space. 

Sharon_is_SAM

Yes, you can put them under the sink and limit your dishware or put your dishware in your TV.  It may be better to put them closer to the axle, but you will again lose storage space.

Cyclonic

There, theoretically, is no reason not to have more batteries, if you don't mind losing the space they would take up somewhere.

db_cooper

2 6v batteries in the Outback tub requires no modifications, most bang for the buck. And suits my needs.

Verna

By being able to dry camp without the expense of Campground fees, the investment in solar panels and two golf cart batteries will soon pay for themselves. Plus, there's a lot more freedom as to where you can camp. 

Here's a from how I expect my battery and solar panel investment to pay for itself:

I purchased a Zamp 200 watt suitcase because I wanted to spend the money once and not have to upgrade in a few years.  And I purchased two Interstate 6V golf cart batteries, which I wired in series. 

I'm expecting the panels to last 10 years plus, and the batteries to last 5 years plus. The batteries are about $170 each so with an investment of around $340, that makes it $68 per year or less for batteries. Approximately $90 per year for the solar panels for their estimated investment.  So, for $158/year, minus what I save by not having to pay for electric sites 2/3 of the time in Arizona, I think that is a rather good investment.  (I easily save over $158 by not paying for electric sites in the winter.) 

The recommended solar panel size for a T@B is 120 watts with a group 24 battery. You also need to check for PXlated's setup since he fulltimes in his T@B and I "full time" for 3 to 4 months in the winter, plus other camping during other months.  You may need more, depending on what you need to power. 

Your mileage may vary, but this is how I set mine up and how I justify the initial outlay of cost. 

jkjenn

Larger RVs do, sometimes go with larger battery banks but storage is already a premium with the T@b. I chose 2 6v batteries and a modest (200w) solar set-up because I need to be able to work from my T@b, requiring me to be connected to a lot of gadgets, and recharge photo equipment. I also use smaller battery packs, which can also be recharged via a solar panel, car or 120v, to make sure I have plenty of battery to spare.

Once you get into larger battery banks, it really makes sense to install a more advanced power management system that would allow you to charge from more than one source and control the charging with more precision. 

Like Verna, my set-up has more than paid for itself, already. 

rfuss928

I like the idea of a portable battery that rides in the TV for charging and connects to the T@B when needed.  It seems I use the TV every day for something and it would be easy to keep the spare portable charged up.
It would be a third battery with my current set up. 
I'm not sure where I would carry and store it.

Trailpixie

rfuss928 said:

I like the idea of a portable battery that rides in the TV for charging and connects to the T@B when needed.  It seems I use the TV every day for something and it would be easy to keep the spare portable charged up.
It would be a third battery with my current set up. 
I'm not sure where I would carry and store it.

I have a GoalZero Yeti 150 that I used for charging camera batteries on a x-country road trip. It worked very well when I was camping in my rooftop tent.  

I have wondered whether it would fit into a t@b power strategy, and I think it doesn't. It is much smaller with less power than the battery that comes standard with the camper, and it would be difficult to link it into the power system. What I will use it for is to charge camera batteries when I am away from the camper AND have left the car for a hike. 

Around camp the goal goalzero could be used to power electric lanterns and stuff. Could be used to charge USB stuff. 

The yeti 400 might be more useful, but I still think they duplicate the functions of the camper power system so there would be little value in attaching to the RV power. 

As as for something to use for charging in the car: for my x-country road trip I had one of the power ports connected directly to the battery so that it was always powered. Inline with that, I had a battery isolator circuit put in so that when the voltage on the battery went below 11.8V it would shut off.  This gave me another place to charge phones, tablets and etc..

Trailpixie

Verna said:

...
I'm expecting the panels to last 10 years plus, and the batteries to last 5 years plus. The batteries are about $170 each so with an investment of around $340, that makes it $68 per year or less for batteries. Approximately $90 per year for the solar panels for their estimated investment.  So, for $158/year, minus what I save by not having to pay for electric sites 2/3 of the time in Arizona, I think that is a rather good investment.  (I easily save over $158 by not paying for electric sites in the winter.) 
...

That is a really good cost benefit analysis, @Verna . I think the problem I have is that 80% of camping in the eastern US is in the shade. I think I would need a very large array to keep charged from the shade of the trees. 

I am am really attracted to those suitcase setups...if only for the cool self-reliance aspect, but to drop $600 for the bigger suitcase seems to be a bit crazy. Also, with the pace of changes in the battery world, I think we may have some disruptive changes in the camping battery scene, so a large investment may be obsolete soon. Can anyone see fuel cell technology on their RV? Lithium cell array? 

rfuss928

I have some photos of a set-up using a RV battery in a case with a 7 pin socket like most TV.  There was also a special cord for connecting the box to the TV (two 7 pin plugs).  When in camp the T@B's 7 pin cord was plugged into the battery box basically putting it in parallel with the on board battery.  It seems you could make the battery any size you want for Ah capacity and weight.
The photos are .jpe and don't copy or upload?

Nomad

Trailpixie - New battery tech - Lithium etc - right now is way more expensive than a solar array. Can't see the price coming down in the near future can you?

Trailpixie

rfuss928 said:

I have some photos of a set-up using a RV battery in a case with a 7 pin socket like most TV.  There was also a special cord for connecting the box to the TV (two 7 pin plugs).  When in camp the T@B's 7 pin cord was plugged into the battery box basically putting it in parallel with the on board battery.  It seems you could make the battery any size you want for Ah capacity and weight.
The photos are .jpe and don't copy or upload?

I think you are talking about getting a separate battery to plug in after charging in the TV.  You could do that. You would want to be sure the two batteries matched each other in capacity and charge level.  That might be an issue. 

Trailpixie

PXLated said:

Trailpixie - New battery tech - Lithium etc - right now is way more expensive than a solar array. Can't see the price coming down in the near future can you?

Here's one. 
http://www.lithiumion-batteries.com/products/product/12v-100ah-lithium-ion-battery.php

Nomad

Yep, as I mentioned, spendy. Twice as much as my solar setup and still only 100ah.

wizard1880

Just keep in mind that if you buy a lithium battery without a charge controller system, your T@Bs converter will damage it.

If you're only charging by solar and never plugging in at sites, you'll be fine.

Lithium batteries are most definitely the future for RV power systems.  Some high end coach size RVs are coming with built in lithium iron battery systems and come fully prepped.  These RVs are in the several hundred thousand dollar price range already, however.

With what Tesla is doing with batteries and their gigafactory these days, it's within a few years or more before they become defacto, and we can finally lay lead acid technology to rest!

Oh and that's not a typo, they really are lithium IRON phosphate batteries.  Not the same in your phone or a Tesla car.  They're non-flammable, and safer than lead acid batteries even.  Almost all the RV and car, motorcycle etc. replacement batteries of the lithium variety are NOT lithium ion.  Just a little trivia for ya.

Ratkity

Trailpixie said:

I fave seen a lot of conversation about adding a second battery. Why doesn't anyone talk about installing three batteries in parallel (or even four smaller 6-V batteries in series and parallel)?

 Much of that expensive solar investment could be avoided with a third $100 battery. 

One thing that no one has even mentioned is that you can have one battery, but after that, you have to have an even number to get 12V (or 24V in some RVs).  The batteries need to be matched (manufacturer and capacity). There is no configuration I've seen that uses an odd number of batteries other than one.

jkjenn

Ratkity said:

Trailpixie said:

I fave seen a lot of conversation about adding a second battery. Why doesn't anyone talk about installing three batteries in parallel (or even four smaller 6-V batteries in series and parallel)?

 Much of that expensive solar investment could be avoided with a third $100 battery. 

One thing that no one has even mentioned is that you can have one battery, but after that, you have to have an even number to get 12V (or 24V in some RVs).  The batteries need to be matched (manufacturer and capacity). There is no configuration I've seen that uses an odd number of batteries other than one.

Good point. 

Trailpixie

Ratkity said:

One thing that no one has even mentioned is that you can have one battery, but after that, you have to have an even number to get 12V (or 24V in some RVs).  The batteries need to be matched (manufacturer and capacity). There is no configuration I've seen that uses an odd number of batteries other than one.

Why wouldnt three identical 12v batteries in parallel be okay? Wouldn't the amp hours be roughly additive (with some slop for inefficiency). 

mash2

Why not 3....

wizard1880

If you use 6v golf cart batteries, then yes you're limited to an even number of batteries.

But by paralleling 12v's, you can do any combination you want.

wizard1880

mash2 said:

Why not 3....

This works on paper, but if you use it in practice, the battery on the far left will suffer as it won't fully charge.

Simply move the negative connection to electrical devices to the far left battery instead (but leave positive where it is) to solve that problem.

But yes, this is basically how you do it!

mash2

Actually, that is what I did on my two battery setup,   agree that the negative needs to be on left side and + on right side battery.  

Librarydragon

We have Three. The original one plus two others. We did so my husband doesn't have to worry about his CPAP draining the batteries when we are boon docking.