Author Topic: Best value in batteries - Cadillac or Chevy?  (Read 7306 times)

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madlabs

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Best value in batteries - Cadillac or Chevy?
« on: June 17, 2014, 11:19:56 AM »
Hi All,

As we all know, batteries are the bane of off-grid systems. I'm trying to figure out what the best deal for batteries is, measured by cost per year.

It seems like folks with money buy batteries like Surettes and the rest of us use all sorts of things, with golf cart batteries being very common. I myself have used golf cart batteries for the last six years. Either this year or next I'm going to have to replace them so I thought I'd start a debate here.

Here is my very limited experience. I got my batteries a little over six years ago at a cost of about US$1000. This works out to $166.66 a year, or $13.88 a month. Now, I realize that there are other costs like fuel for the genny that I didn't keep track of.

I think a key factor is how you use the batteries. I made sure I had a bank large enough to really meet my needs ( 10 batteries). I made sure I had a reasonably efficient charging system that had enough power for a reasonable recharge time (160 amps from an alternator). On a cloudy day, I run the genny for a short time in the morning, until the voltage gets up around 14V. Then in the afternoon, after I've gotten whatever I might from solar and used most of my electricity for the day, I run it again to 14 or so V. So I never go days without a charge. Further, the solar and charger I had in the beginning were inadequate, so the batteries weren't all that well treated for a couple of years, especially in terms of absorption charge. I really wish I had kept records of fuel consumed. With the next bank I'm going to. I am adding even more PV panels, so the next set will be treated much better. I expect to get a couple more years out of them next time.

I have two friends with expensive high quality batteries. One got 10 years out of his last set of Surettes,  but his cost/year is much, much higher than mine. He goes several days without charging and runs his genny less than me for sure. The other it is hard to say, he didn't treat his batteries well, leaving them flat for long periods etc. His cost/year is way higher, but I don't think his experience is relevant.

So here is my hypotheses: Golf cart batteries, properly sized and charged, can provide a better value in terms of cost/year. Thoughts?

Jonathan

DamonHD

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #1 on: June 17, 2014, 12:11:39 PM »
To me an important factor is the zero maintenance and zero acid spills of my big (20 days' capacity) set of gel batteries.

I don't want to spend the time topping up batteries, nor keeping my kids away from nasty reagents.

Difficult to cost those, but worth a fair amount to me.

Sorry to mess up your point, if I am!

Rgds

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« Last Edit: June 17, 2014, 04:02:38 PM by DamonHD »
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Frank S

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #2 on: June 17, 2014, 03:24:02 PM »
I like my Golf cart batteries for 2 reasons
  #1 they were cheap enough that should 1 or 2 go bad they can be replaced without a big outlay of cash.
 #2  they are  small enough and light enough to handle when it comes time to service them (Being that they are in my RV
 I would like to have a bank of Trogan  L16s  for 3 reasons
 # 1 less finicky about charging.
 # 2 much larger usable amp HR cap.
 #3  nearly double  the number of charge cycles over the golf cart batts.
  The down side for me at least would be they simply will not fit in the RV without extensive remodeling.
 After we move to West Texas and build our house we plan on a Special room lare enough for a very large bank Then we will most likely  go with extreme cycle Industrial batteries.
 Dollar cost averaging doesn't always enter into play for the final decision .
  Available storage, the amount of High amp draw energy available on tap. the ability to recover from several poor charging cycles.
  Or being discharged below the normal threshold and left there for an extended period of time before returned to full charge  without damage.
  But these are only  things I think about 
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kitestrings

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #3 on: June 17, 2014, 09:20:24 PM »
It's good you started a year or so in advance (hopefully), because you're sure to get a wide variety of responses ;)

I think Frank raises some good points.  In short that there are more factors to weigh (I'll come back to that one) - and, I'll add at least one more - the guy we bought our last bank from (L16's) insured they were sequential production serial numbers, something I wouldn't have considered.  He delivered the new ones, paid a salvage fee for the to-be-recycled ones, and took them when he left.

My take is get the best, most robust batteries you can afford.  We've been on both sides of this equation, so I understand the appeal of the golf cart batteries, but they don't hold up or perform as well, as long.

Peter Talmage, Talmage Engineering, once told me, if all else was equal get the heaviest battery (dry weight).

~kitestrings

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #4 on: June 17, 2014, 11:11:30 PM »
You could approach the problem with numbers...

Total storage of battery string in Watt-hours (not amp-hours, to make fair comparisons with different voltage systems)
Total cost of the battery set
Battery type and chemistry (sealed/flooded, lead/nicad/iron/lithium/dilitium etc.)
Typical usage (degree of discharge)
Storage conditions (indoor/outdoor)

Collect enough information and maybe you can see some useful comparisons, or trends.  Maybe you'll discover that you get what you pay for, maybe there's a way to show that it doesn't matter...

FYI I have a pair of Trojan's that are 7 years old (my starter-kit), still hold a resting voltage of 6.3 volts each.
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phil b

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #5 on: June 19, 2014, 02:25:54 AM »
I have batteries on both ends of the spectrum.

2 year old golf cart batteries and 3 month old traction batteries.

The 24 cart batteries are very good. They are fairly easy to move and to take care of. They do require more maintenance and seem to get out of balance easier that traction batteries do. I have to inspect the connections for green growths on the terminals occasionally. The 24 new cart batteries were $100 each and are used in several parallel strings.

The traction batteries weigh 1600 lbs each and cost $1900. They don't use any more water than the cart batteries and will allow me to run air conditioning 24/7. They are also pretty much theft proof. The connections are well bonded between the cells so there should not be any green gunk. The lead plates are visibly thicker.

I'd say if I had to choose between the cart and traction batteries, I'd take the traction. I haven't had the traction batteries long enough to say they are cheaper on a yearly basis, but they do require less of my time. They should last at least 10-20 years by what I have seen on this and other RE sites.
Phil

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #6 on: June 19, 2014, 02:20:38 PM »
I have a policy befor I spend a cent on batteries make sure I can charge them and monitor them, so I say invest in as much solar as you can afford, a good energy management system and a good mppt controller befor worrying about batteries, just use them till they are flat dead, but save while doing so.

I am going to stay with the US2200xe batteries as over the last 7 years they have given me flawless service.
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ChrisOlson

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #7 on: June 19, 2014, 09:29:06 PM »
The technology in FLA batteries, and how they work, has not changed in 150 years.  Their primary causes of death are heat, sulfation, and positive grid erosion.  So the same criteria apply now as it did when they were invented:
 
- more electrolyte reserve over the top of the plates means less frequent service intervals
- batteries that are cycled shallow are cycled on the most inefficient part of their charge curve.  Consequently they run hotter than batteries that are properly cycled deeper, and you will get less kWh out of them over their life, but more cycles
- sulfation is a normal part of the chemical process in a FLA battery.  Your battery desulfator is called a "battery charger".  Your battery desulfator calibration device is called a "hydrometer".  Learn how to use the hydrometer and use it to properly set your chargers for the way you cycle your batteries
- any battery that becomes hard sulfated due to either excessive heat or repeated deficit charging can be recovered by charging it at high enough voltage with your battery desulfator.  However, this causes excessive grid erosion
- how thick the plates are determine how much erosion they will handle before there is no active material left
- how deep the sumps are determine how much lead can erode from the grids before they become shorted and the battery is dead

There is only two types currently on the market that are proven 10+ year batteries on off-grid power - traction type and Surrette 5000-series.  Both are VERY heavy because they have grids that are over 1/4" thick and each cell holds 3 gallons of electrolyte.  These heavy duty true deep-cycle batteries will cost you less than 1/2 per kWh that light duty batteries like golf cart batteries will cost you over the long term.  And this is a fact that is not even debatable.  There is a reason applications like forklifts use traction batteries instead of a wad of golf cart batteries stuffed in it.  And there is a reason Surrettes have provided backup and house power for fishing trawlers and offshore yachts from the North Atlantic to the Southwest Caribbean for over 50 years.

Trojan does build their IND-series batteries that are similar to the Surrette 5000's.  But the IND's are relatively new and unproven compared to the workhorses that have been powering heavy duty applications for over 50 years, and where failure is not an option.

Batteries that last cost more money.  But they are repairable and rebuildable with individually replaceable cells or "jars".  In the best of the best, Surrette surpassed the steel-case traction types with the 5000-series using .260" grids instead of .250" and stainless steel bolted interconnects between the jars instead of soldered.  But the Surrettes are more expensive than steel-case traction type.

The downside to these heavy duty batteries is that they do not stand up to shallow cycling.  Their capacity is rated at 80% DoD, at which traction types are designed to run 1500 cycles - the Surrette 5000's 2000 cycles.  If they are shallow cycled they quickly stratify and lose capacity.  Some traction manufacturers like GB Industrial specifically prohibit recharging unless the battery is fully discharged.  Rolls says 50% is OK as long as you discharge to 80% DoD at least once a month.  Since these type of batteries are designed from the ground up to deliver and store most of their amp-hours in the most efficient part of their charge curve, the amount of usable kWh they store over their life is so drastically higher than golf cart types that only last 300 cycles at 80% DoD, that it's not even really comparable.

When setting up an off-grid system you should always buy the cheap golf cart ones first to learn how to destroy batteries before you spend your money on good ones.

Frank S

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #8 on: June 19, 2014, 10:25:12 PM »

The downside to these heavy duty batteries is that they do not stand up to shallow cycling.  Their capacity is rated at 80% DoD, at which traction types are designed to run 1500 cycles - the Surrette 5000's 2000 cycles.  If they are shallow cycled they quickly stratify and lose capacity.  Some traction manufacturers like GB Industrial specifically prohibit recharging unless the battery is fully discharged.  Rolls says 50% is OK as long as you discharge to 80% DoD at least once a month.  Since these type of batteries are designed from the ground up to deliver and store most of their amp-hours in the most efficient part of their charge curve, the amount of usable kWh they store over their life is so drastically higher than golf cart types that only last 300 cycles at 80% DoD, that it's not even really comparable.

When setting up an off-grid system you should always buy the cheap golf cart ones first to learn how to destroy batteries before you spend your money on good ones.

  That last sentence is probably worth a lot more than anyone can imagine, and there is more truth in it than sarcasm.
 One thing Golf cart batteries will teach you is  a MAINTENANCE  routine. either that of you will wonder why they wont last through the night.
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kitestrings

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #9 on: June 19, 2014, 11:00:30 PM »
We've had Trojans (L16's) last for 10-years.  On our second set now.

I went to using a refractometer in place of the hydrometer few years ago.  It's a pricey tool I suppose, but not when you consider the batteries your protecting.  It does take a lot of the inaccuracy out of the readings.  I use one of those plastic pill organizers and an eye-dropper to collect samples.  Then read and record them without fretting the spills, it a more comfortable chair.

I lean toward shallower DOD cycles, with the occasional (monthly, or more) deeper workouts with tasks in the shop and such, but otherwise generally agree with Chris' comments - the heavier/thicker plates in particular.

~ks

ChrisOlson

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #10 on: June 20, 2014, 12:04:03 AM »
Folks who have never had good batteries don't realize the difference.  When we put in our new inverter the dealer told us we're going to need new batteries for it because the ones we had would not power it at full load.  Didn't believe him until we spent $10 Grand on batteries.  Our Surrettes, at 60-70% DoD, can be loaded to 200A to the inverter and still maintain 47-48V nominal at the inverter.  Your cheap batteries go flat as a pancake if you try that and the voltage will "sag" and the inverter shut down at the LBCO.

In the world of cars and performance ever heard the old saying "there ain't no replacement for displacement"?  These batteries are pretty much the same deal.  The Big Block batteries might have the same horsepower rating as the small blocks.  But when it comes to twistin frames and shafts and making rubber smolder the Big Block is gonna kick ass.

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #11 on: June 20, 2014, 12:48:07 AM »
"Lots is good.
More is better.
And too much is just enough."

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
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ChrisOlson

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #12 on: June 20, 2014, 12:55:16 AM »
No, most people have too many amp-hours.  If you use golf cart batteries and have say 1,000 amp-hours cycling to 30% DoD on average, you are only using 300ah of capacity.  Switch to good batteries, cut the amp-hour capacity to 700 and cycle them 50% and you still got more capacity than the golf cart batteries will deliver at the same number cycles.

It's all about dollars/kWh, not how much the batteries cost to buy.

ChrisOlson

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #13 on: June 20, 2014, 01:18:30 AM »
Let me put this in a different way, and then you can do your own research on it.  A Surrette 5000 battery will run more cycles at 80% DoD than a GC-2 golf cart battery will run at 50% DoD.  When you factor in CEF (Charge Efficiency Factor), the fact that you do not need as much amp-hour capacity with the Surrettes, and factor in the additional RE capacity you installed to cycle your GC-2's on the most inefficient part of their charge curve - the cost/kWh of the Surrettes will be less than half that of the GC-2's over a 12 year period.

These batteries are considered to be end-of-life when their remaining amp-hour capacity drops to 75% of new.  The GC-2's are 5 year batteries at 50% DoD cycling.  The Surrettes are 10 year batteries at 80% DoD cycling, based on 170 cycles/year before they degrade to 75% of original capacity.  In reality, most golf courses only get 2-3 years from a set of GC-2's in a commercial rental golf cart.  The GC-2's are a pretty fragile and light duty battery in the industrial world.  L-16's are a couple light years ahead of GC-2's for durability and cycle life.

DamonHD

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #14 on: June 20, 2014, 01:28:51 AM »
Stratification under light cycling is presumably not going to apply to gel batteries, though the fact that they are potentially being used in the lowest-roundtrip-efficiency part of their charge curve still will, yes?

Rgds

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Flux

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #15 on: June 20, 2014, 05:55:21 AM »
Correct .Gel and AGM don't stratify, there is no free electrolyte.

They probably fare a little better for efficiency with shallow discharge but the issue still exists.

Flux

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #16 on: June 20, 2014, 09:19:48 AM »
Gel and AGM are different animals.  They are more efficient on charging than flooded because a great majority of the inefficiency in flooded batteries is due to electrolysis and breaking water down into oxygen and free hydrogen.  And I believe they are able to withstand sustained discharge rates at C1.  The downside is that they can be easily destroyed by over-charging and there is no recovery from it once you boil the water out of the electrolyte.  And no way to check specific gravity of your electrolyte to determine if they are being charged properly.  And they are still subject to the same sulfation issues as flooded, with no way to "fix" it by equalizing the cells.

ChrisOlson

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #17 on: June 20, 2014, 09:39:54 AM »
For folks interested in such things, there is an IEEE standard for batteries used in solar applications for PSOC (Partial State of Charge) cycling.  Trojan has certified to it, although Trojan tends to be a bit strong on the marketing propaganda making all sorts of recent press releases on so-called "Smart Carbon" in their batteries.  US Battery says "Smart Carbon" is a bunch of hooey because it is a technology used in VLRA batteries to prevent the effects of sulfation on negative grids.  Flooded batteries sulfate the positive grids as well.  US Battery has certified to it with a new design that uses one extra positive plate to balance sulfation between the positive and negative grids.  Not a single peep from Rolls or the traction battery manufacturers on it because people have been PSOC cycling these batteries for over 50 years and their primary markets are industrial and marine, not RE.

madlabs

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #18 on: June 20, 2014, 11:01:54 AM »
Went away for a few days. Back now and reading all of the information. Thanks to all for taking the time to write!

Ok, ok, Chris, I'll abandon my hypotheses. Thanks for taking the time to write. Now it is a matter of what I can afford. Maybe some L-16's for the next set. Right now I have 10 beat up batteries on the house bank and 6 beat up batteries in the golf cart (I call it my electric ranch utility vehicle :-)). I think I'll buy new batteries for the ERUV and marry the beat batteries into a 2*8 for the 48V inverter and see how long I can smack the crap outta them.

Jonathan


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Re: Best value in batteries - Cadillac or Chevy?
« Reply #19 on: June 20, 2014, 12:32:02 PM »
Chris I was wondering are the L16s considered a light traction battery since their intended design was primarily for pallet jacks and limited space walk behind or stand on lift trucks?
 I had a chance to buy 6  brand new Trogens for $600.00+ core charges but didn't because there was just no way to mount them under the RV without cutting out the floor. But we don't plan on living in this thing much longer anyway and the House we will be building of m mobile machine shop I am building will have plenty of room for full sized industrials anyway
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ChrisOlson

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #20 on: June 20, 2014, 01:15:48 PM »
To my way of thinking GC-2's are an excellent choice for smaller systems that see light cycling.  You can't really justify putting in expensive batteries for a part-time off-grid cabin et al.  Age will get the expensive ones before they're worn out in such a case.

L-16's are a medium duty industrial battery, primarily designed for floor maintenance machines and small lift trucks.  They are getting into the tall case category, and once put into service they do not handle setting around not being used very well.  They are also VERY popular with off-grid folks.  But I have seen way too many people wreck L-16's by not working them hard enough and end up with "babied" sulfated batteries that are highly stratified and the bottoms of the grids solid hardened lead sulfate in only 5-6 years.

Industrial tall-case batteries are a "use 'em or lose 'em" type thing.  They age when setting around, just like a person will age sitting in the recliner watching TV all day and not doing anything.  Either way you're gonna die.  You can either die from not exercising enough, or live a long and healthy life and finally die from being worn out.

kitestrings

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #21 on: June 22, 2014, 09:43:35 AM »
Yes, I agree.  When I worked on small off-grid systems we commonly saw two recurring problems: folks not exercising the batteries enough, and folks not charging them enough.  One of the more classic service calls was where folks were sold wind systems on miserably poor sites by over-reaching sales people.  The back up would be a undersized generator and/or charger, and the owners really didn't know what it took to fully charge - especially that last ~20% - let alone equalize a bank.  It's a bit easier nowadays with PV, and the features of most controllers.

My approach has always been to look at how you do all the necessary tasks at a home/site, look at how you can do them most efficiently - this includes looking at fuel choice - and as much as possible reduce the size of the bank that is needed, because let's face it the batteries are damned expensive.  We also look to leverage our energy when it is most available.  For example, many appliances today allow you delay starts, and folks are surprised to learn if they push and hold the start button dish/clothes washing on many models can be delay 1, 2...4 hours.  We're not accustomed to scheduling energy intensive tasks, but there's something to be said for it.

Just to point out bigger isn't always better.  I don't think Chris' message ends there, so don't misinterpret. Regarding kickin' ass and takin' names though, I'd just point out you can kick ass on the race track in one from, at the gas pump in another.

~ks

madlabs

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #22 on: June 22, 2014, 03:09:15 PM »
So, I have been thinking about the discharge and usage profiles that Chris talks about with the different types of batteries. My question is this:

I have quite a bit of solar and when it's sunny, my batteries are full by noon. I'm actually in the process of adding more panels, as my sister and bro inlaw are going to be moving out here. When the new solar is up, I am going to have boatloads of solar.

If I read it right, for L16's I need to discharge them more deeply and so would need in the summer to shut off the solar for a day or so, discharge the batteries and then charge them up. With the golf cart batteries I want to cycle them as shallowly as I can, so always keep them hooked up and charging daily. Is this correct?

Thanks!

Jonathan

ChrisOlson

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Re: Best value in batteries - Cadillac or Chevy?
« Reply #23 on: June 22, 2014, 04:59:17 PM »
With L-16's you wouldn't need quite as much amp-hour capacity in your battery bank so you can cycle them a little deeper.  They're more of a workhorse than the GC-2's.  They require some deeper cycling to keep active plate material exposed to the electrolyte and help prevent stratification of the electrolyte.  The deep cycles cause them to gas longer during absorb, which does a better job of mixing the electrolyte up.