LifePo4 Batteries

[Yankee802]

Ok, I don't know if this has been discussed before, so I apologize if it has, but anyway...

I'd like people's opinions on LifePo4 batteries for the coach house batteries instead of the AGM ones. From what I'm reading, it's the way to go. Up front cost being the only real factor, but overall cost is less.

Here, here and here are links to ones from suppliers I'm looking at. The first one is from a supplier I'm planning on getting my solar cells and charger from, so would be nice to get everything from one US supplier.

The first link is to a package that contains the battery in question. The third link is a profile that I know will fit in my battery bay, and I might even be able to double my capacity to 8 batteries, of course I don't know if that is wise.

This is a thread I found where these are discussed (for reference) for use in boats.

So what does the POG collective think?

[Jon Wehrenberg]

The type of batteries used in our coaches is determined by a significant number of factors. Unlike 20 years ago when the choices were a lead acid or a gel cell there are more choices and technologies. What battery is used in my mind is decided based on how the batteries are used, their cost, their weight, their dimensions, their capacity, how they are accessed, their charge cycles, etc.

I think most of us have batteries that have the capacity to enable us to sit unconnected to shore power and with the generator off for at least overnight yet providing enough power for normal loads such as the refrigerator, night lights, TV, etc. Because we all have generators or access to shore power at some point, or we will be running our engines any additional capacity is just a bonus. For those that dry camp a lot the battery capacity becomes a more important consideration than other factors. For those that drive from campground to campground and are rarely without shore power excess battery capacity is both an added maintenance expense and additional weight to drag around.

What seems to be a constant with our batteries, assuming comparable capacities regardless of type, is the batteries still need to be charged and while solar panels along with careful use minimize the amount of charging via the generator, shore power or engine it still has to be done.

You need to determine your priorities. If you are full time and are in a campground anything more than a single lead acid battery may be overkill. If you are dry camping almost all the time even with a roof full of solar panels and a bay full of batteries you may not have enough capacity to live in comfort with air conditioning and all the other loads we have. So in addition to a roof full of panels and a bay full of batteries in order to minimize the need for charging from external sources you may have to treat your coach like a stainless steel and aluminum pup tent and live very basically.

Except for the sophisticated batteries Liberty is now installing for a variety of reasons including the weight savings, most if not all of us have batteries that are a compromise between capacity, weight, cost and physical size. They are not biased towards a specific lifestyle such as always connected to power or always dry camping, but a blend of the needs for all types of use. We select from lead acid, gel or AGM based on cost, where the batteries are installed, and how the converter set up our coaches and we adapt our use of them to match the power they provide.

I think you have selected a battery type that is biased toward a specific style of use and only you are going to be able to decide if you get sufficient benefit for the dollars of cost. I can buy a lot of AGM batteries over a long period of time before I ever spend what those will cost so there has to be a significant benefit to me to justify the batteries you are considering. In my case I get 5 years of life from a set of batteries before they begin to show their age so I would have to 5 times or more life and or capacity to justify the price. Personally I would not spend more than 10% of my coaches value on batteries.

[truk4u]

OK Yank, you've been dragging your feet on these batteries, so let's get er done before another price increase!

[Yankee802]

Truk: I'm getting closer, what do you have (in any) for LifePo4s?

Jon: I understand what you're saying, and thank you for your input. What I'm looking for is the best bang for my buck, ultimately. Even though the up front cost of the LifePos might be greater, I believe the long term cost to be less. Not to mention that if you drain your AGMs below 50%, you shorten your batteries life, while this is not a factor with the LifePos. Even if I'm likely to be on shore power the vast majority of the time, it's not unlikely that I could drain my batteries by that much at some point. I believe I already have (drained them below 50%) while boondocking on our way from Va to FL, because my generator does not automatically turn on.

Regardless of what batteries I get, I plan on augmenting my power with solar. I like having backups and redundancy in my life, and this is no exception, along with my desire to recycle my grey water (looking into reverse osmosis). Besides, when boondocking, the fewer times I have to run the engine or generator, the more $$ I save in diesel. Yeah yeah, you probably think I'm spending a dollar to save a penny, and you're right, except it's a penny a day for the rest of my coach's life. The batteries in question are less than 10% of my coaches value.

From the previously linked thread is this post I find most interesting.

So, it looks like I overstated the volume and weight savings a little bit. Going with (the above mentioned) LiFePO4 batteries, you'll only save between 30-70% space by volume, and shed 45-60% of the weight vs. lead acid. When I run the math, it also turns out that I was being way too kind to the lead acid batteries... the up-front cost of the LiFePO4 batteries in question is only 2x more expensive than for high-end AGMs, and 3x more expensive than golf-cart batteries. (I had said 4-5x.)

Disregarding the weight, space, charging and low-self-discharging advantages of these LiFePO4s... cost-per-cycle wise, they still kick the crap out of lead acid, coming in at anywhere between 3-9 times cheaper over the life of the battery, depending on how little you choose to spend up front. The huge takeaway from this exercise is no matter what kind of battery you buy, the less you spend up front, the more you will spend over time.

So, without further ado... I'll show my homework. For each type/brand of battery, I figured out the volume, weight, and cycle-life (@50% discharge) of a bank of roughly 600Ah@24v. For the bottom line, I divided each value by the total number of Ah@24v in the bank, yielding a value-per-Ah (for those of you with 12v problems, divide by two again.) I then computed the actual cost of each type of battery per 1000 cycles. (Guess which won easily?)


675Ah@24v built with 12 Trojan TS-105 (3 x 4) -- typical high-end golf-cart batteries.
http://www.trojanbattery.com/pdf/Prt...Guide_0909.pdf
63"x14"x11" -- 9702cu-in (batteries only, no battery boxes which would be required.)
744lbs (12x63lbs)
<300 cycles (@50%)
~$1920 ($160ea) from Trojan Battery T105 (225AH) -- other vendors may vary

bottom line:
per Ah@24v: 14.37cu-in / 1.1lbs / $2.84
per 1000 cycles: $6400


670Ah@24v built with 8 FullRiver DC335-6 AGMs (2 x 4)
specs: http://www.fullriverdcbattery.com/DC335_6.pdf
47"x14"x14" -- 9202cu-in
840lbs (8 x 106lbs)
~800 cycles (@50%) -- estimated
$2985 ($373ea) from Southeast Marine Services :: Absorbed Glass Mat (AGM) Batteries :: Full River Absorbed Glass Mat (AGM) Batteries -- other vendors may vary

bottom line:
per Ah@24v: 13.73cu-in / 1.25lbs / $4.45
per 1000 cycles: $3731


600Ah@24v built with 8 LifeLine GPL-6CT AGMs (2 x 4)
specs: Lifeline Batteries - Marine & RV Deep Cycle Batteries
42"x14"x13" -- 7644cu-in
720lbs (8 x 90)
1100 cycles (@50%)
$2607 ($326ea) from Lifeline GPL-6CT Deep Cycle Marine & RV Battery -- other vendors may vary

bottom line:
per Ah@24v: 12.74cu-in / 1.2lbs / $4.35
per 1000 cycles: $2370


600Ah@24v built with 8 Rolls NS 305 wet-cells (2 x 4) -- these are the most compact, long-lived wet cells I could find:
http://www.rolls-europe.com/PDF/ns305.pdf
49"x15"x14" -- 10290cu-in (batteries only, no battery boxes which would be required.)
872lbs (8x109lbs)
1300 cycles (@50%)
~$2800 ($349ea) from Staab Battery: Rolls Surrette Batteries, Marine Starting and Deep Cycle -- other vendors may vary

bottom line:
per Ah@24v: 17.15 cu-in / 1.45lbs / $4.60
per 1000 cycles: $2154


600Ah@24v built with 16 ThunderSky LiFePO4 (2 x 8):
specs: http://www.thunder-sky.com/pdf/20092131633.pdf
35"x15"x12" -- 6300cu-in (no battery boxes required.)
337lbs (16x21lbs)
>8000 cycles (@50%)
$5808 ($330x16 = $5280, +10%)

bottom line:
per Ah@24v: 10.5cu-in / 0.56lbs / $9.60
per 1000 cycles: $726


Anyone see any problems with my math or methodology? Oh, and please oh please, if you don't see your favorite flavor here, take a minute, do the math and post it.

[Jon Wehrenberg]

Whoever has suggested you are going to get only 300 cycles from an AGM or a lead acid is lying. I'll bet my AGMs as I use them are good for 5000 cycles.

As a full timer, plugged in most of the time if you are serious about the economics get rid of all your batteries and replace them with one lead acid battery. You are plugged in almost all the time. When you are not the alternator(s) are putting out more power than you will consume and as soon as you stop running the engine, plug in or run the generator. Think of the money you save.

My AGMs are typical and I get 5 years out of them and probably more, but at 5 years I get rid of them regardless of condition. I don't feel like chasing battery problems so I toss them before I have to start doing that. I have no idea how many cycles they go through, but I can tell you that with the exception of perhaps 30 or 40 deep discharges (24.5 volts) mine are never discharged lower than 50 % and often never discharged. But there are others on this forum that use their coaches differently and they use autostart for the generator and they still get years of service from a set of AGMs.

If it wasn't for corroded terminals and the need to add water I bet a lot of us would be using lead acid at 1/3 the cost of AGM but we pay the premium for low or no maintenance. Remember the key to battery life is NOT the battery, but how you charge the battery and I suspect a lot of the shortened life spans we see are the result of unnecessarily deep discharges or charging to the wrong protocol for the type battery.

[truk4u]

I think you should go ahead and buy the Binford 3000's, I don't think you'll be happy with Lifeline.

Here's the tech sheet if you want to look at Life Cycles: http://www.lifelinebatteries.com/manual.pdf

[Yankee802]

Ouch, what am I, Tim the Toolman?

[Jon Wehrenberg]

I suspect your coach came originally with lead acid batteries and except for the required cleaning of terminals and adding of water I wonder why you would consider anything else. Since you are connected to shore power almost all the time it is unlikely you will have more than a few deep discharge cycles over the life of the batteries. So it boils down to are you prepared to maintain lead acid, and if not are you willing to pay more for AGM to avoid the hassle of maintenance?

I cannot make the math work out to justify the high tech batteries you think will be better.

[joelselman]

Jon: What type of batteries is Liberty now installing? joel

[LNDYCHT]

Joel,
I believe that Liberty is using Mastervolt batteries in their new coaches.