Costo Interstate Battery best price/performance of any Flooded Lead Acid Battery?

[Willy T]

It also illustrates that if one sizes the bank so that 50% DOD meets load capacity, that initially the battery will need to be discharged to 80% until the plates are broken in?

That is true, but it's not a GC-2 battery, It's more for a Industrial type or Traction battery ( 80% dod ). When you put a Rolls battery into service the SG level and capacity is all over the place as you cycle, the plates form at maybe 50 cycles or so, then you finally begin to get some consistency. A GC-2 takes maybe 20-30 cycles ( 50% dod ) and they smooth out and become predictable.

[lkruper]

A little hard to analyze since it is not clear what DOD is used for the test nor what exactly % of rated cycle life refers to. There is some indication that they are using 50% of original capacity as the EOL point.

It is also interesting to note the increase is capacity at the beginning as the battery plates form through the initial charge/discharge cycles.

It also illustrates that if one sizes the bank so that 50% DOD meets load capacity, that initially the battery will need to be discharged to 80% until the plates are broken in?

[Willy T]

A little hard to analyze since it is not clear what DOD is used for the test nor what exactly % of rated cycle life refers to. There is some indication that they are using 50% of original capacity as the EOL point.

It is also interesting to note the increase is capacity at the beginning as the battery plates form through the initial charge/discharge cycles.

Agreed, it's pretty generic, but it does give a visual of cycle life. I guess they collect the data from their members, but there is a large disparity in everything about the way batteries are used, charged and serviced that effect cycle life I don't know how anyone can make comparisons.

[inetdog]

Here is a graph from The Battery Council International for Traction / Deep Cycle Batteries that supposedly shows cycle life at a couple different charge returns.

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A little hard to analyze since it is not clear what DOD is used for the test nor what exactly % of rated cycle life refers to. There is some indication that they are using 50% of original capacity as the EOL point.

It is also interesting to note the increase is capacity at the beginning as the battery plates form through the initial charge/discharge cycles.

[Willy T]

Here is a graph from The Battery Council International for Traction / Deep Cycle Batteries that supposedly shows cycle life at a couple different charge returns. While it doesn't show much, it does show the drop off and the capacity as the plates are forming when the battery is new.

ScreenHunter_862.jpg

[inetdog]

Standard warranties and performance graphs for FLA batteries use 80% capacity as the End Of Life cutoff.
That is still pretty good for most solar RE installations, but I have heard that the decline is much more steep from there.
Among other things the C/10 charging rate has become C/8 and the 20% DOD has become 25% DOD, accelerating the decay.

[lkruper]

That is what I was driving at when I asked did you do it based on Calendar Life because I believe you intending to use batteries as a small backup. If that is what in fact you are doing, cycle life is meaningless. I don't have to do it on paper or calculator to determine which battery is the smarter money. A Trojan will most likely last twice as long as the Interstate. That means you have to buy 2 sets of Interstate for each set of Trojans. You do not have to do much math as the Trojans would have to cost more than twice as much as the Interstate.

Don't let me talk you into Trojans. All I am pointing out is your assumptions are all wrong leading you to a false conclusion. Garbage In > Garbage Out. This is your first set, and Intersate is good learner battery. No real difference starting with an Interstate to learn from because you will destroy the battery in a year or two. No reason spend the bucks until you get some experience. Another good Starter better than Interstate is US Battery. Same price point as Interstate, just a better product IMO. At the end of the day makes me no difference what battery you use. but do not make a buy decision on incorrect information.

I am evolving and have killed at least three sets of "virtual" batteries My primary focus has been on a small backup for quiet time in the event we are without power at night and I don't want to listen to the generator.

However, the thought of letting SCE pay for my batteries with CA TOU intrigues me, and that can only be done by time-shifting the 10 hours of nighttime power available at 1 cent / kWh to charge my batteries for use during the day.

Unfortunately, when I use Trojan T-105 (at $125 each with 1200 cycles) to power my loads my cost is 17.33 cents / kWh and if I use Costco Interstate (at $83.99 each with 1220 cycles) it is 13.05 cents / kWh which is below my baseline cost by 1.5 cents / kWh.

If the Costco Interstate batteries cannot provide 1220 cycles at 1 cycle per day (3.34 years) it won't work anyway. But you said Costco batteries were 2-3 year batteries.

The other factor is what happens to the Costco batteries at 2-3 years? Are you predicting a catastrophic failure or a gradual loss of capacity to the point of 80% or less? If the bank started out over capacity a bit, that might work as well.

BTW, my break even with the Costco batteries at a savings of 1.5 cents /kWh is almost exactly 3 years.

That being said, I don't want to be a slave to my batteries and likely won't attempt this.

[Sunking]

That makes sense. I did not think of that.

That is what I was driving at when I asked did you do it based on Calendar Life because I believe you intending to use batteries as a small backup. If that is what in fact you are doing, cycle life is meaningless. I don't have to do it on paper or calculator to determine which battery is the smarter money. A Trojan will most likely last twice as long as the Interstate. That means you have to buy 2 sets of Interstate for each set of Trojans. You do not have to do much math as the Trojans would have to cost more than twice as much as the Interstate.

Don't let me talk you into Trojans. All I am pointing out is your assumptions are all wrong leading you to a false conclusion. Garbage In > Garbage Out. This is your first set, and Intersate is good learner battery. No real difference starting with an Interstate to learn from because you will destroy the battery in a year or two. No reason spend the bucks until you get some experience. Another good Starter better than Interstate is US Battery. Same price point as Interstate, just a better product IMO. At the end of the day makes me no difference what battery you use. but do not make a buy decision on incorrect information.

[inetdog]

That makes sense. I did not think of that.

And if you want to also roll the calendar life into one metric, you would have dollars per kilowatt-hour-year. A truly odd sounding dimensional combination.

[lkruper]

#1 is a metric that you would use for a UPS or a similar situation where you want to get as much energy (not power) as possible at one go but will do that only very infrequently. The cycle life cost is then not particularly meaningful but the energy capacity per dollar and the calendar life are

That makes sense. I did not think of that.

[inetdog]

I did calculate #1 but did not think it was meaningful without cycle information. That cost is embedded in#2. How do you use the latter measure of value?

#1 is a metric that you would use for a UPS or a similar situation where you want to get as much energy (not power) as possible at one go but will do that only very infrequently. The cycle life cost is then not particularly meaningful but the energy capacity per dollar and the calendar life are

[lkruper]

The problem here is if you use these batteries in a solar application, the manufacturer's "life-cycle" data is not very applicable. Last time I talked to the local Interstate Battery distributor, I was told that if their batteries are used in a solar application, it violates the warranty. Its hard to compare different battery brands as the actual battery lifetime can vary widely. Batteries made for a solar application cost more for a reason.

That might be a good follow-up question to the kind man at Interstate who has already answered two of my emails. But let me ask you this. When you say solar application, is that because of the harsher demand of unpredictable weather? My test case is to charge the batteries in 10 hours at night when the CA TOU charges 1 penny for up to the baseline allotment.

This will be the best possible conditions for a battery, to be charged with a smart charger with temperature compensation of at least 10% of the AH rating on a regular basis with no possibility of under-charge or over discharge. In addition, in my basement/quasi root cellar environment it will also probably get better than average calendar lifetime.

[lkruper]

If you compare at Calandar life who wins?

If I remember correctly you get 6/12 on those batteries right? In practice your Costco batteries are 2 to 3 year batteries. Trojans are 4 to 6 years in Float Service. The Trojans would have to cost more than twice as much as Costco. They are not twice as much, and Trojans is even easier to get warranty work. With Costco they have to send your batteries off to be tested. With Trojan take them to any Golf Cart Dealer and they have the load box to test them right on the spot and replace them.

For your first set Costco will work just fine, but don't fool yourself into thinking Costco is a batter value long term. 10 pounds more lead in a Trojan ought to get your attention as that is roughly 16% more lead. Trojan plates are some 300% thicker than your Interstate. When it comes to battery cycle and calendar life, the amount of lead, or lack of lead determines longevity.

If the Costco batteries were as good as Trojan, don't you think golf cart manufactures would jump all over them? Nope they still use Trojan at the factory. Why if there was something out there better and less expensive? Trojan has no influence over Ingersoll Rand, Textron, or Yamaha can use anyone's battery they want. When it comes to Golf Cart batteries there is only 1 real competitor to Trojan called US Battery, they are are distant 2nd, but at the same price point as Costco making it a smarter choice if all you are looking at is initial cost.

Sunking, I will accept your opinion on these batteries based upon your experience and knowledge alone, without any supporting evidence. You have earned that. But I still must ask, what difference does it make if Trojans last 4-6 years in float service when we are comparing Costco batteries being cycled 1220 times? How long do T-105 batteries last if cycled to 50% every day compared to Costco batteries?

That being said, just because I think I have figured a way to save a few dollars (very few!) by time-shifting the CA TOU rates does not mean I am inclined to do that. I do not want to be a slave to my batteries when I have good grid power. It is more likely that my first experiment will be a small battery bank in float service for backup in case the grid fails more than a one day when I am at the cabin.

However, I am also not likely to drive to San Diego to buy T-105-RE's for $125 on sale or purchase 4 T-105s from the company that delivers free locally when at least 4 are bought at one time. So I may end up with Costco batteries for my first set because of convenience. I can just as easily acquire hydrometer skills on these batteries.

My thread here is primarily academic. I am surprised and pleased that it might just be possible to almost break even by time-shifting the CA TOU at 1 cent / kWh.

[solarix]

The problem here is if you use these batteries in a solar application, the manufacturer's "life-cycle" data is not very applicable. Last time I talked to the local Interstate Battery distributor, I was told that if their batteries are used in a solar application, it violates the warranty. Its hard to compare different battery brands as the actual battery lifetime can vary widely. Batteries made for a solar application cost more for a reason.

[Naptown]

Are you taking into account that once a battery reaches 80% of inititial capacity it is considered done per manfscturers specs.
I doubt anyone is replacing them ar that stage unless it was a mission critical application.