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I'm asking this question because I felt that an answer would be useful to myself, and anyone else who might design a portable or other battery powered system that is meant to last several decades without requiring a new battery.

What is the longest lasting battery technology. By longest lasting I mean the battery that supplies the required energy for the longest number of years. Answers should either be based on practical experience, manufacturer data sheets, other manufacturer supplied literature including reliability estimates or other white papers or advertising claims.

To keep this from to broad...

  1. The battery must have a capacity of at least 80 watt-hours.
  2. The load will draw 10 W max from the battery.
  3. The battery may take up to 8 hours to charge.
  4. The battery must weigh 10 pounds or less.
  5. The operating temperature range is 5°C to 40°C.
  6. Once per day, the battery will be charged to 100% of its current capacity, and then discharged at up to 10 W for 8 hours.
  7. The battery voltage is not important. Assume we can place a converter at the battery output to make whatever voltage we need, and that the converter efficiency is factored into the 10 W load draw.

The best battery is the one that meets the above operating conditions for the most number of years.

If the battery is lighter or cheaper that's a bonus. Naming a specific battery chemistry is better (rather than just saying Lithium, Alkaline, or Lead Acid, etc).

user4574
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  • Submarine batteries or batteries used in telephone exchanges such as wet nickel cadmium can last decades with proper maintenance. – Solar Mike Sep 12 '20 at 18:20
  • According to NASA, who use them in satellites, where maintenance is somewhat expensive, LiPos last decades if you don't charge to more than 3.92 V, and don't discharge below 30% SOC – Neil_UK Sep 12 '20 at 18:32
  • Lithium Titanate is quoted as 20000+ cycles. –  Sep 12 '20 at 18:32
  • You are really constraining the problem. – cmm Sep 13 '20 at 01:48
  • What does your research show? I'm going with the lemon! – StainlessSteelRat Sep 13 '20 at 02:48
  • This sounds like "homework" or similar. We still help with that but differently. Please advise what this is about or it may get closed rather rapidly. || There are other constraints that you have not listed. eg charge efficiency, DOD, shelf life and ... . || ~~~~ LTO LiFePO4 LiIon NiCd NimH LA ROUGHLY and parameter dependent. – Russell McMahon Sep 13 '20 at 05:21
  • @RussellMcMahon This is certainly not homework. I asked this question because I felt that an answer would be useful to myself, and anyone else who might design a portable or other battery powered system that is meant to last several decades without requiring a new battery. – user4574 Sep 14 '20 at 02:46
  • @RussellMcMahon Depth of discharge was not constrained because the energy requirements were stated (you are not required to supply more than the stated energy). If a battery technology doesn't do well being completely discharged, then you compensate for that by over-sizing the battery. The battery size was loosely constrained by the weight requirement. Charge efficiency was not a requirement, and that's why it wasn't stated. Anything that's not abnormally low like 30% is OK. Shelf life was not a requirement, I am assuming the system starts operation soon after manufacture. – user4574 Sep 14 '20 at 02:48
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    "Once per day, the battery will be charged to 100% ..." This has a rather large influence on some chemistries' cycle life. Is it a hard requirement? – ocrdu Sep 14 '20 at 11:54
  • _"I felt that an answer would be useful to myself"_ - why do you think it would be useful? _"The operating temperature range is 5°C to **60°C**."_ - that is a tough requirement for a battery. What is the application? – Bruce Abbott Sep 15 '20 at 05:31
  • @BruceAbbott I was intimately involved in producing some hundreds of thousands of these (several models). The upper temperature was "hot & variable". The ability to handle 60C "would be nice". http://bit.ly/SL2MINIAFRICA (scroll don't click). || On this model you can see the battery ventilation passages (they go right through the body) https://public.fotki.com/RussellMc/atw/bogo/sl2africa01/?view=roll#20 . || 60C is above reasonably reasonable in most cases - as temperature in the shade is NEVER over 55C, and very seldom over 50C, then various remediation methods usually allow lower ... – Russell McMahon Sep 15 '20 at 05:39
  • ... temperatures. On portable lights with the PV panel hard attached temperature reduction is "challenging". – Russell McMahon Sep 15 '20 at 05:41
  • @ocrdu Not a hard requirement. It doesn't really need to go to 100%, but you need to putt back in 80 watt hours somehow. Also I needed to state the number of charge cycles per day or the question becomes too unconstrained to get a real answer. – user4574 Sep 15 '20 at 05:42
  • @BruceAbbott Well the inside of a lot of electronics gets as hot as 60C (especially if its sealed). I routinely design circuit cards that have to operate with air temperatures in the 90C range inside the box, so I though that 60C was being generous. But I can lower it to 40C if it makes the problem more solvable. – user4574 Sep 15 '20 at 05:52
  • @user4574 I hope to be adding MUCH more to my answer - BUT 40 C is far far far more achievable than 60C. See my links in comment above for some real world products where "it was hard" :-) || Can you tell us what products you have in mind? I'm interested in similar, as noted elsewhere here. – Russell McMahon Sep 15 '20 at 05:58

1 Answers1

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This answer is to some extent a work in progress. Check back if you care.
As a first step it outlines the requirement and overviews the extreme cycle life capabilities in selected situations.

What is the longest lasting (number of years or cycles) commercially available battery technology?

I asked this question because I felt that an answer would be useful to myself, and anyone else who might design a portable or other battery powered system that is meant to last several decades without requiring a new battery.

Stated specification:

Capacity - at least 80 watt-hours.
Load - 10 W max
May take up to 8 hours to charge.
Weight - 10 pounds or less.
Operating temperature range - 5°C to 60°C.

Once per day, the battery will be charged to 100% of its current capacity, and then discharged at up to 10 W for 8 hours.
The battery voltage is not important. Assume we can place a converter at the battery output to make whatever voltage we need, and that the converter efficiency is factored into the 10 W load draw.

I have long considered a battery with many similarities to this specification.
In my case the application is a street light / refugee camp latrine light / home light for use in developing country role in a more or less "install and forget" mode.

Contenders in roughly descending order of goodness are:

LTO, LiFePO4, LiIon, NiCd, NimH, NiFe, Lead Acid, 'Flow' batteries.

Cycle life:

The "several decades" requirement suggests 365 days x 20 - 30 years = 7300 - 10950
Say 7000 - 10,000 cycles lifetime. That is VERY demanding by any usual standards.
I'll add a 10 year variant of about 4000 cycles.
So 4000 / 7000 / 11000 cycles

LTO (Lithium Titanate) chemistry often claims around 7000 cycles.
This will be examined in more detail below.

LiFePO4 (Lithium Ferro Phosphate) is typically claimed to yield 2000-3000 cycles with substantially larger being possible under very specific conditions.

LiIon / LiPo (Lithium Ion) - under very controlled conditions of limited Vmax & Vmin (resulting in much reduced capacity) cycle lives of about 8000 have been reported. Examples include "Mars planetary Rovers". This is achieved by charging to a maximum of about 3.9V and also limiting lower discharge voltage. This reduces available mAh capacity per cycle to well under 50% but gives much greater whole of life mAh capacity.
This is exceptional performance and well over an order of magnitude better than in typical consumer applications.

NimH (Nickel Metal Hydride) - Low in normal use. 1000+ with care. NimH can achieve 2000+ with well controlled Vmax & Vmin. (2000 cycles with NimH are claimed by the "One laptop per child" organisation - by setting upper and lower voltage limits with some reduction in capacity. Of likely interest is that the open source C code for the charging algorithms is available for inspection. (I've looked at it a few years back).

NiCd (Nickel Cadmium) - now unlikely to be viable due to concerns re Cadmium toxicity. Very long cycle lives if treated well. In use in communications satellites !!!

Lead Acid - Thousands of cycle with extremely limited depth of discharge (maybe 20% - 30% DOD). Resultant reduction of capacity is liable to make total weight unacceptable.

Just maybe:

NiFe (Nickel Iron) A very old technology with low energy density but immensely long lifetimes. Many many decades of operation are not unknown.

'Flow' batteries - Vanadium and other. Active ingredient is a liquid. Potential for very long lifetimes. Not without issues.

WIP ...

Russell McMahon
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  • Thanks for the answer. I believe you also answered another one of my questions like a year ago. I appreciate that you take time to answer the questions that are interesting and hard. – user4574 Sep 15 '20 at 06:07
  • @user4574 I'll try to get back to provide some additional material. There are factors which affect choice. At face value LTO looks rather good. But also liIon run in conservative mode as per eg Mars Rovers looks good. And ... :-) – Russell McMahon Sep 15 '20 at 07:15