I am still enthusiastic about the Eremit LiFePO4 batteries. I have a 12V 2 Ah and two with 4 Ah. I also like to use the two larger ones in parallel when I draw larger currents… e.g. for the PA.
I use the smaller one for my small CW TRX (e.g. Mini QCX,…) but it is actually always in my bag to supply the KX2, whose own battery is now 6 years old and not quite as powerful.
Recently I noticed that the buffering of the KX2 battery was not working properly. Somehow there were interruptions.
After some investigations I found that the cause of the problem was the Eremit battery: the cables there have silicone insulation. This is good and brings flexibility. The wire inside is not so flexible, however. And so a cable broke inside the insulation at the edge of the battery, which led to temporary interruptions. The test is quick. You simply twist the cable with your fingertips and see how the insulation twists and then tears.
Unfortunately I didn’t have any more flexible wires at home. So I shortened the old wires.
The battery has 2 blue covers. If you cut open the top one, you can put it back on upside down. To get better access to the soldering points, I cut off the contact tab of the middle battery and soldered it back on later.
I have the same 2Ah battery, since the length of the wires allowed for it I bent them 90 degrees across the side of the battery for stress relief, if they’re going to break they’ll be easier to fix.
The Eremit 4 Ah is a great little battery. It’s noticably lighter than the 4S1P Zippy 4.2 Ah LifePO4 it replaced. When I got it I was a little surprised at the light gauge of wire used on the output compared to the Zippy. Also, the leads appear to be terminated right at the top corner with virtually no shrink wrap to offer strain relief. Perfectly fine if the battery is mounted inside equipment, but not racking up low-cycle fatigue damage on mountain tops.
I’ve taped the leads to the side of the battery, which at least means that any issues will be easy to deal with.
Thank you all for your input, it was really helpful!
As promised, I have contacted Daniel Beck, the owner of Eremit, and sent him a link to this post. He is an open and helpful person who has answered my battery related questions in the past. As you will see, he also likes to improve his products!
Please see the excerpts of his answers which I have translated from German to English using Deepl:
I have read through the discussion and am surprised that the problem seems to be a bit bigger than previously thought.
I myself have one request per about 600 batteries regarding broken cables, so I have not yet recognised the whole thing as a general problem.
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You are right, these are not the fine strand cables we normally use for our projects - but I think there are several problems at play here.
The 12V 2Ah has the output of the connection cables directly behind the soldering points of the BMS. The cables are therefore bent just behind the soldering point, which inevitably leads to breakage after intensive use.
To be honest, I still haven’t found a solution to this problem; a heat shrink tube had the opposite effect when I tried it. And re-routing the cables around one side of the battery would just increase its size. For the next series (December 2024) I will try extremely fine 18AWG cables at the output, but I don’t think this will solve the problem in the long run.
With the 12V 4Ah, we’ll put shrink tubing over the output in the future and use a fine 16AWG here, I think we’ll have the problem under control.
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Pure copper strands are tricky. They are susceptible to oxidation, and the fibres in the silicone cables have a lot of surface area and not much volume, so I’m not sure they won’t oxidise completely after a few years.
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The main problem seems to be the kink point and the number of fibres. I will definitely fit the new 2Ah with better 18AWG with finer fibres, as well as replacing the wire of the 4Ah and covering it with heat shrink tubing. If there are any other ideas, they are welcome.
