Friday, December 21, 2018

Why Bespoke Build Portable Power? by Julian oh8stn

Hello Operators
Question keeps coming up, “Why bespoke build portable power when we can buy “off the shelf” saving ourselves the trouble?”.
It’s very good question, with very clear reasons for doing so. The most obvious reason is understanding what’s inside your battery pack or solar generator. I mean literally what’s inside. Unless the battery pack or solar generator has extremely good documentation, all we know is what’s on the labeling on the outside of the enclosure. Every lithium or lithium iron phosphate battery or solar generator is a product of system integration. Individual cells are combined in series and parallel, to build a larger portable power system. Since manufacturers are often more concerned about making you feel their product is special, we are rarely given any clue about the individual components used to make up a pack. That is unless what’s special about the pack, is the cells inside.

Lithium & LiFePO4 packs

One example is the 12v LiFePO4 replacement packs, popular in the ham radio and emergency communications communities. When we look at the outside of those packs we see the specs the company wants us to see about that product. Unfortunately we don’t see any info about the components used to make up those packs. The external enclosure hides:
  • Cells
  • BMS or PCM
  • A low voltage disconnect if it’s not integrated in the BMS or PCM
  • Perhaps fuses or breakers
  • Internal connections
  • …
The manufacturer takes all of these things, puts them inside a box, and prints their logo on it. They label that enclosure with specs about the nominal voltage, watt hours, current draw, over-voltage and low voltage numbers. Again, they may simply omit any information about the cells used. So why is this important? We’ll get to that.
The above image was taken from the buddipole website. I think many operators don’t know that Buddipole also makes up LiFePO4 packs, for portable ham radio operations. This is a logical step in their product line, since their Core Business is portable antennas for amateur radio. As you see in the image, Buddipole clearly tells you what cells were used to make up the packs. A123 is one of the giants in the lithium iron phosphate cell industry. Specifications on all of their cells are well-documented, and include PDF Documentation with every technical specification you could want to have, about their individual cell and cell performance. Unfortunately the cells don’t come in a pretty box with nice labeling, but you can bet your last dollar, you won’t be disappointed with Buddipole battery pack performance.

Battery performance

There’s a couple of different ways to get the capabilities we want, out of a battery pack or solar generator. The two important points are the cells capacity (amp hours), and how fast can that current be discharged (C rating). The resulting capabilities of that pack once integrated, are directly related to those two points.

Bottlenecks

One complaint I often receive on the channel about commercial battery packs is voltage drop when operating QRO. Voltage drop occurs for a few different reasons.
  • The capabilities of the of the battery packs C rating have been exceeded. An example of this is trying to start your car with AA batteries.
  • Inadequate gauge of wires used between the load and the battery. An example of this is trying to push the pressure of a fire hydrant through a garden water hose. You should be really careful with this one. What should be a wire to carry current, now becomes a fuse!
  • Inadequate internal connections between parallel and or series cells making up the pack. These are usually called busbars. Like wire, busbars have a finite amount of current capacity. If too few busbars were used between cell connections, a significant voltage drop at the load will be observed.

Repairing commercial packs

Another problem with some commercial packs is not being able to open them to repair them. Naturally if the pack was built correctly in the first place, using quality components and cells, they’re would rarely if ever be a need to open them up for maintenance, or repair. When we go back to a point made earlier in this article, if some components used to make up your commercial pack were inadequate or substandard to begin with, it’s very likely the pack with its pretty enclosure, won’t last the ~2000 charge cycles, most quality lithium iron phosphate packs achieve. That’s not a problem you say? Just open it up and repair it. Here is the next problem. The manufacturer has designed to the casing, so you will never be able to open it up without damaging it. This is all in an effort to prevent you, from seeing what’s inside.
This is all fine If that pack is within the warranty period. We send the pack back, get a working pack in return, then tell all our friends on Instagram Twitter and Facebook, about the wonderful customer service we received from the company, who built that pack in the first place. What if you were outside the warranty period, using that pack for critical Communications when it fails!?
Whether it’s amateur radio emergency communications or Communications for preparedness, we need to be able to service our portable power solutions. That’s a no-brainer!

Commercial Solar Generators

I don’t want to give the illusion that there’s no benefit to buying an off-the-shelf battery pack or solar generator. there’s some really good products on the market, all designed to meet specific needs for their users. I talked about those solar generators briefly in the introduction video for the solar generator project. Goal Zero makes excellent small solar generators for bloggers and campers. As amateur radio operators, we already know those solar generators are quite RF noisy. We also know those other generators have the limited current capacity on the outputs, so we can’t run our QRO rigs with them. The Bioenno M400 has great storage capacity, and a pretty good price for what you get, but it’s limited to 10 amps on the DC output. The Inergy Kodiak is an exampke of phallus envy, with its 6 AC ports and RV hookup. It’s excessive in everything but practicality.
I can keep on going but it’s not the point to bash the solar generators. Emergency communications and Communications for preparedness requires solar generator which meets or exceeds the current requirements for the HF VHF or UHF radios we are using. Just like we buy power supplies with enough amps to run our radios and or amplifiers, we should also build or buy solar generators which meet or exceed the current requirements of our rigs. Does this make sense?

Manufacturer or systems integrator?

The Chinese are incredibly good at Manufacturing cheap (seemed like a good deal at the time) products, extremely fast. When they have good specifications, requirements and western-style quality control in place, they can even build quality systems, albeit with some delay. They do this all for the most part, cost-effectively. Western companies come in trying to produce a competing product, from those lower spec Chinese products purchased from sites like Alibaba, or eBay. In an effort to compete, Western companies will pretend to be manufacturers, purchasing cheap cells from China, to integrate into battery packs, packs which the customer would assume I’ve been produced in a western country, for example the United States. They usually say assembled in the United States, rather than manufactured in the United States. This is the difference between a manufacturer and a systems integrator. It’s tough to blame them for doing it this way, because they are trying to meet the cost demands, of an amateur radio Community who by its very nature, is extremely cheap. Still, there are those companies who integrate the best components into their products. For the radio operator who values reliability in the field, these are the companies we are looking for, to supply critical portable power.

Portable Power

Portable power is a passion for me. It has been since a fifth grade science fair, where I built a rig to demonstrate DC power. DC power, solar power, portable power, off-grid power this is where my passion is, travelling right alongside off grid or grid down amateur and amateur digital communications. Unfortunately at some point in the amateur radio community, people became cynical in regards to building their own portable power. I’ve heard operator say “I shouldn’t need a University degree to build a battery pack”. My answer to that is “perhaps you’re in the wrong hobby”.
My channel, the blog and everything I do whether you can see it directly or not, leads to a sense of self-reliance in regards to Communications and off-grid Power. I’ve come to recognize many of the Operators watching my channel and reading my blog, will eventually arrive at some level of Independence in regards to off-grid power and amateur communications. This is a magnificent thing!
Anyway, the point here is, not being afraid to build your own Portable Power Solutions. If you don’t want to build them that’s okay, but understand what you’re buying if you’re going to buy it off the shelf. If a company is not willing to properly answer the question in writing, in the published documentation about their product, we shouldn’t be buying their products.
Portable Battery & Solar Power for Off Grid Communications:

It’s not always easy to understand or see the connections between the different content you’re seeing on the channel and blog. If you’re patient enough, over time you’ll begin to see the connecting lines.
If you found this post useful, entertaining, inspiring, or educational, consider dropping a buck in the tip jar, join my Patreon, …
73
Posted by at

No comments:

Post a Comment

Subscribe to: Post Comments (Atom)