Best battery for the Yaesu FT818

Someone asked what the best battery is for the Yaesu ft-818 in the HF pack group. There were lots of good answers, but the question was still kind of missing something from the answer. Here’s my take on it.

There really is no right answer to this question. Also, each and every one of us has a different requirement. So, what we really need to do first, is answer a few questions.

  • What do we plan on doing with the radio?
  • How long will the radio be required to operate on this battery?
  • Do we want to charge the battery while operating, or are we relying solely on the batteries stored capacity?
  • What’s our battery budget $$?
  • Is this a long-term investment or just solving a problem here and now?
  • Are we operating on foot? If so, is other gear also carried?
  • What’s the maximum weight of radio and battery not counting the other gear?

Answering these questions helps us understand what type of battery and additional accessories we might need. For example a portable power supply for an afternoon on a picnic bench is quite different, than what we might take a through hike through the Appalachian Trail.

Yaesu FT-81xND with diy 20ah solar power generator

It’s also important to understand the internal battery pack of the Yaesu Yaesu ft-818 was designed for that picnic bench operator. And operator casually working CW on their lunch break for example. The internal battery is good for about an hour or an hour and a half of operating CW @2.5 watts, but not more. It’s there to get you out of a pickle, like a junkie who needs a quick fix. Unfortunately it’s not really useful for effective communications in the field, because of its very limited battery capacity.

Now for any of you who have watched my YouTube channel, or read this blog, you already know the answer I’m going to give. Lithium Iron Phosphate! Even though you know that’s the answer, you also know that it’s not always the right answer. So let’s go through three different options, and explain the pros and cons of each of them.

Lead Acid or AGM

Lead acid and AGM batteries are generally cheap to buy at the register. In the long-term they’re terribly expensive because you will have purchased and thrown away 4-8x of these batteries, before you even reach the beginning of diminished capacity, for a single lithium iron phosphate battery of similar capacity. Some people will tell you their lead acid batteries lasted eight years. That might be true, but not the entire truth. The only way to effectively measure battery life is using charge cycles. You can expect 500 charge cycles out of your lead acid or AGM battery. A lithium iron phosphate battery of the same capacity may net 2000 to 3000 charge cycles. There’s also the problem of useable capacity. Generally if you use your lead acid or AGM batteries more than 50% of their capacity, you’re damaging the battery! There are lots of opinions on this topic but that is a fact. It’s kind of a deception but not really. It’s more of an omission. We can certainly use lead acid and AGM batteries down below 50%, but that happens at the expense of cycle life. So this 80% usable capacity “myth” for lead acid or AGM batteries is kind of true, but mostly just marketing, since doing so results in diminished cycle life. Then there’s the issue of the weight. Lead acid batteries are not light by any means, so if you’re operating on foot, it’s the absolute worst way to go. Some people will tell you to Simply buy a smaller lead acid battery for example the 7Ah pack. This is ridiculous, if you wouldn’t like to carry around a brick after it’s flat. This is especially true if you’re carrying additional gear other than your radio and Battery. Finally there’s the issue of Peukerts Law.

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.More at Wikipedia

So, if you are able to double up your lead acid battery putting two of them in parallel, in order to accommodate it’s TRUE useable capacity, they are reasonable. If you’re not weight-restricted, lead acid batteries are reasonable. If you’re on an incredibly tight budget, trying to solve a problem right here right now without thinking about the long-term cost, lead-acid batteries are reasonable.

Lithium ion

Without a doubt, Lithium-ion batteries are the most energy-dense batteries of our three choices. They come in the smallest package, and contain the highest density of useable energy. Unfortunately when mishandled, they have a nasty habit of bursting into flames. People try soldering them, harvesting them out of old laptops to build their own packs, and generally do lots of things without understanding how much energy each of these cells actually stores. If you know what you’re doing, if you’re not afraid of blowing yourself up or burning your house down, here’s the first and only lithium-ion pack build we did on the channel.

With the cost of lithium ion cells being so reasonable these days, there’s no point in harvesting lithium ion batteries from old laptops, or buying them used from the variety of sources trying to cheat you. If you’re going to build a pack yourself, it’s relatively simple to do so, using the variety of methods found on my channel. The two most popular no spot welding no soldering methods are the Vruzend 18650 end cap builds, and the sourcing map battery tray method. There’s no welding or soldering, and you can shape the battery in whatever shape you like.


A123 Lithium Iron Phosphate cells

Lithium iron phosphate battery technologies are by far the safest battery technologies, since they don’t explode or burst into flames. They also have a reasonable energy density for their weight. They’re not as energy dense as lithium-ion, but they far exceed the energy density of lead acid batteries. It’s also important to point out neither lithium-ion or lithium iron phosphate suffer the effects of Peukerts Law, to the extreme of lead acid batteries. Lithium iron phosphate batteries are the most forgiving of all of the lithium chemistries. Like lithium ion, they’re more expensive to buy but their cycle life far exceeds any lead acid or AGM technology. People say they’re expensive, but it only hurts once, where you lead acid chemistry will continuously pinch your pocket over the long run. I’ve got a variety of Builds on the Channel with lithium iron phosphate cells. Before I post that video link, I’ll tell you there are companies like Bioenno (Chinese cells) and Dakota Lithium (A123 cells) selling lithium iron phosphate packs. They both sell a variety of packs but they’re always the same shape. A brick! A brick might be nice if it’s under your desk, or in the trunk of your car, but in a backpack, it might be nice to have something flat or a different size or shape. In that case I wouldn’t recommend either of these companies, and would say go ahead and build your own.

Wincamp internal battery

Now if you’d like to avoid all of the trouble of going to the airport with an external battery pack, there is one internal battery pack which functions really well. That’s the Windcamp internal lithium ion battery pack with custom door for the Yaesu Yaesu ft-818. They can’t be charged with the internal battery circuit of the Yaesu ft-818, but they do include an external battery charger. As a Lithium-Ion pack they have more usable capacity than the same physical size of double AA batteries mounted internally. This is by far the closest thing to stock looking for the Yaesu ft-817 and 818. It will also draw the least attention from the Goon squads trying to find reasons for you not to get on an airplane.

That’s it. That’s all I’ve got! I hope this helps.
Julian oh8stn

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