Battery technology with the longest float life?

[smily03]

So, I know that there's a lot of discussion about what batteries have the longest cycle life. But, what about the longest float life, for situations that don't have frequent cycling? Would that be a good use case for NiFe, or would LiFePO4 be better? Or something else, like the Trojans with Smart Carbon? Is there a battery technology that could theoretically get 10 or 20 years (or more) if you're just floating them most of the time?

[Mike90250]

Long float life, GEL cells, but they only have a few dozen cycles in them. Not NiFe, too much monthly maintenance, eats up any cost savings. Same with LFP, cost is way high for very little return of power.

[smily03]

Cool, thanks! Is the float life significantly longer for gels than FLA? I'm just curious because (for example) the Trojan 8D-Gel costs ~800, but two T105RE's (same aH comparison) would be ~300. So I could get almost three sets of T105RE's for the cost of one 8D-Gel.

They can't just make one universal long-life inexpensive environmentally-friendly low-maintenace battery, huh? :P

[SunEagle]

Cool, thanks! Is the float life significantly longer for gels than FLA? I'm just curious because (for example) the Trojan 8D-Gel costs ~800, but two T105RE's (same aH comparison) would be ~300. So I could get almost three sets of T105RE's for the cost of one 8D-Gel.

They can't just make one universal long-life inexpensive environmentally-friendly low-maintenace battery, huh? :P

That is a contradiction. Building a long life battery that is inexpensive and eco friendly.

Unfortunately with batteries, if you want the best you pay the price. If you want low cost you get short life.

[smily03]

Totally makes sense I figured that if I was following a pipe dream, I might as well dream big! :P

[Sunking]

Without any doubt is Stationary Flooded Lead Acid Batteries telecom uses. Service life or 30+ years.

The good ole Western Electric KS-2042 now made by GE have service life of 50+ years. But forget about using them for cycle service. They are a Pure Lead plates, and if forced into cycle service you will get 300 cycles or less. Just about all the Telecom Stationary FLA come with 20 year warranties and some with 30 years. There is no better battery for Float Service period. If there was Telecom and Military would use them. They do not, they use Stationary batteries.

[Mike90250]

What is the application you are looking for? Instant UPS backup if the grid glitches ? Run gear for 3 minutes till a generator gets spun up? Money spent on a ginormous battery that never gets used, is wasted/lost. A small battery and a propane genset could be a LOT more affordable.

[smily03]

Cool, thanks guys

No particular application in mind at this point, just being curious and wanting to expand my knowledge a bit Reading all of the speculations and propaganda about the "latest-and-greatest world-changing" new battery technology that seems to come out every few months, and discussions about cycle life, etc. just made me curious about what has the best float life.

[Sunking]

Application and battery type have to be matched. In the narrow world of lead acid batteries, there are at least a dozen applications. A Lead Acid Battery come in many different types for different applications. Example there are SLI (starting lighting & ignition), Traction, Stationary (standby or float service) Deep Cycle, and Hybrid (RV, Marine, Trolling, SLI, Golf Cart, ect...)

For daily cycle, regular cycle, and stationary flooded lead acid are the battery of choice. No others can last as long or have the bang for the buck. For power tools and traction lithium and NiCd are the battery of choice. But you can pretty much ignore all the hype about the latest greatest thing coming down the pike. Example all they hype of a 10 year 3000 cycle lithium battery is on the market. Really? Show us one that has been in service for 10 years with even 1000 cycles and still test 80% capacity. Fact is you cannot do it. There maybe very well be such a battery on the market that can do it, but none that have the documented service. That takes time to prove. Lead Acid batteries have a 200 year track record. Lithium only has 25 years with a poor track record. It is getting better, but still a long way off. Claims is one thing, track record is another.

[inetdog]

...
For daily cycle, regular cycle, and stationary flooded lead acid are the battery of choice. No others can last as long or have the bang for the buck. For power tools and traction lithium and NiCd are the battery of choice.

What do you see as the disadvantages of NiMH?

[Mike90250]

> disadvantages of NiMH

Low cycle life, 200-500 cycles
yard lights last 1-2 years, my old nicad lights still run.

[Sunking]

What do you see as the disadvantages of NiMH?

As you know, every battery has them. I assume you are asking with respect to NiCd? At least that is how I would answer.

• The biggie is obviously toxic. Cadmium is toxic.
• I disagree with Mike on cycle life as NiMh overall does have the advantage when we talk about Storage or Wet NiCd large format cells.
• They have higher Specific Energy aka Energy Density wh/Kg, and higher Energy Density per volume or wh/L. So for a given capacity a NiMh will be smaller size and lighter in weight.
• I would say Memory Effect, but that is not true anymore.

Having said that does not necessarily mean they are better as that depends on the application. While NiMh has better Density, it has poor Specific Power w/Kg and Power Density w/L. If you have an application that demands high Charge and Discharge rates, you would use NiCd. NiMh is used for Fractional Rates, NiCd is good for xC rates greater than 1C charge and discharge rates.

In addition NiMh have significant Peukert Effect where NiCd does not.

Both have one big disadvantage, cell voltage of 1.2 volts and steep charge/discharge curves. To get full operational range on a 12 volt system requires 10 cells that operate from 16 to 8 volts. It also means both with respect to other types have poor Density. Example to equal say a 320 watt hour lithium cell 3.2 volts @ 100 AH requires two cells. The lithium cell would weigh in around 1.5 to 2.5 Kg, and occupy 1 litter of space. A NiMh would weigh in around 10 to 12 Kg, and occupy 4 to 5 liters of space. Thus why Lithium is preferred choice for EV's. FWIW Pb right in the middle of those two extremes.