Hello Operators.
I don’t normally call out other bloggers but today is one of those days. Research is one aspect of my Youtube channel and blog setting it apart from others. It often takes months or sometimes years to collect enough information to substantiate a point or offer a well-tested opinion. I never publish something simply because I have not published in a while. After all, I donẗ make “entertainment”. It is very “hard” work coming up with the ideas, buying and building test equipment then carrying out pragmatic testing. In my opinion, a blogger or YouTuber should clarify their personal opinion from fact. If it is an opinion piece, great, just let us know! We should clarify how we arrived at a certain result, any constraints to our testing, and/or whether or not there was a financial aspect to the conclusion. It would also be nice to know if the content is biased “infotainment” aka clickbait, driving traffic to some sponsor.
Today the blog “Off-Grid Ham” is on my hit list. Over the past year, Off Grid Ham posts have become more subjective. The blog has begun omitting important points to reach an often skewed conclusion. This is a blog that I have followed for quite some time. It is also one which until recently, I respected and often shared regularly. The posts had previously been well-written and objective. Not sure what is happening with the Off Grid Ham blog, but it is anything but fact-based or reliable these days. Sometimes the blog publishes excellent work, other times not so much.
Off Grid Ham posted an article comparing Lead Acid batteries to Lithium. Most of you reading this blog understand we can’t lump all lithium batteries into one basket, since the characteristics are unique for each chemistry. This was the first red flag with the post. You can read his entire post here. ( https://offgridham.com/2022/02/lithium-vs-flooded/ )
Here is a rundown of my feedback about the post.
Comparing Lithium to flooded or AGM
This is a good article when comparing Lithium-ion to Flooded or AGM. Not so good when comparing flooded or AGM to LiFePO4. We mustn’t lump all lithium technologies into one basket, as we wouldn’t lump AGM, Deep cycle or flooded together in a single basket. For lithium-ion, 300-500 cycles are quite normal without any special care given to charging. For LiFePO4 2500-3000 cycles is normal without any special care given to charging. Lumping these two chemistries together creates an erroneous outcome in the numbers. An outcome that favours AGM or Lead Acid batteries. This outcome would be ok if it were true! After all, the accuracy of the results is more important than the outcome!
Cycle life
Next Off Grid Ham incorrectly suggests a very wide average margin for lithium-based cyclic life and is very optimistic for AGM and flooded batteries. The fact is, we will never get a thousand charge cycles out of AGM or flooded technologies, without experiencing diminishing capacity along the way. Diminishing capacity is what happens to flooded, AGM and Deep cycle batteries over their lifespan or damage from deep discharge. It is also one reason AGM and flooded battery manufacturers recommend ˜50% discharge for flooded or AGM or down to ˜30% for deep cycle batteries. This discharge recommendation helps preserve the cyclic life of the battery.
AGM & Flooded Capacity
With these discharge recommendations in mind, it is also important to point out how this affects the stated capacity of an AGM or flooded battery. As an example, if we want 100 amp hours from an AGM or flooded battery, we need two 100 amp hours AGM or flooded batteries in parallel to achieve the 100 amp-hour requirements. This way we can safely discharge the battery down to within the recommendations from the manufacturer. Discharging below this point often directly influences both cycle life and battery capacity. By doubling up on the batteries, the price of AGM or flooded packs exceeds to cost of Lithium-ion or LiFePO4 over the life of the pack. The price at the cash register might be more important at the time of purchase, but we will begin to understand a lead-acid battery is not always the best investment for the long term.
Lithium-Ion LiFePO4 capacity
With lithium-ion or LiFePO4, the capacity listed is a “What you see is what you get” scenario. Where a 100ah AGM or flooded battery only truly nets 50-60% of its stated capacity, lithium-ion or LiFePO4 can discharge down to an honest 90-95% of the stated capacity. This is without long term damage to its cyclic life. It has been just over 2 years since we built the 576 watt-hours LiFePO4 solar generator on the channel. It remains at its original capacity, despite constant usage, charge cycles and its age.
This was such a cost-effective investment (long term) I plan on building a new 1-2 kilowatt-hour solar generator as an upcoming build on the channel, to power my new off-grid ham shack and workshop. When the budget kitty is full, we will pull the trigger on that project.
Peukerts Law
There is another aspect of AGM and flooded not found with lithium-ion of LiFePO4. Peukerts law accounts for the diminishing capacity under various loads. To make up for this effect, we again stack more packs in parallel to minimise the loss of capacity. Contesting or operating FT8 with lead-acid batteries are perfect examples of where lead-acid battery chemistries fail us. They are great for starting vehicles, but not so good for varying inconsistent loads as we find in ham radio. How many times have you heard “then my battery was suddenly dead”?. Peukerts effect is practically nonexistent in lithium-ion or LiFePO4 batteries, so there is no need to double up on parallel sets as with AGM or flooded batteries.
Peukert’s law, presented by the German scientist Wilhelm Peukert in 1897, expresses approximately the change in capacity of rechargeable lead–acid batteries at different rates of discharge. As the rate of discharge increases, the battery’s available capacity decreases, approximately according to Peukert’s law.
Wikipedia: https://en.m.wikipedia.org/wiki/Peukert’s_law
Quality cells
The Off Grid Ham also mentioned validating capacity claims from lithium-based battery suppliers. The cheap battery issue is a real one, but one which is a self-made problem. If we focus on quality cells from manufacturers like Sony, Panasonic, Headway, A123, … we never see the quality and capacity issues mentioned in the OGH article. This is strictly a problem buying repackaged used cells from auction sites where cells have been misrepresented as something they are not. Often used cells are repackaged with badging of other manufacturers. These “too good to be true” cells are a scam! If we are searching fr the best price rather than the best suppliers, we can and do get bit. These days I focus on ebike shops and battery specialists for my packs. Even ham radio shops like GigaParts supply quality lithium-based packs. For this a reputable seller is critical.
Anyway not blasting the article! AGM and flooded do appear cheaper to buy at the cash register but not always the best long term investment.
Bottom line
Use lithium-ion for high current consumption loads where their higher energy density makes for a smaller power supply. Use LiFePO4 as an AGM or flooded replacement with higher cyclic life and lower cost over the life of the pack. Also, remember the 2000+ cycles of a lithium-based battery doesn’t mean end-of-life. It means after 2000+ cycles, we can expect to see slightly lower capacity as cyclic life increases.
Ultimately operators are relying on blogs and YouTube channels to supply good well-researched information. They base many of their purchasing decisions on the videos and posts we publish. People work too hard for their money for us to get it wrong, so let’s ensure the quality and accuracy of what we publish is up to our viewers and readers high standards.
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