Jeff thank you this has long been my position. The steady state delivery after a dynamo goes down also biases me to SLA... https://youtu.be/FPBaAil4dNg?feature=shared
On Thu, Jun 13, 2024, 4:53 PM Jeff York via KRnet <krnet@list.krnet.org> wrote: > I spent years as an engineer in Industrial Lithium Ion technology. Mostly > BMS like Lithium system charging design and such. I actually even own an EV > and its really cool but its just not prime time and I never see it go > there. > > As loud as I can type it, I would never ever fly using a LIthium Ion > battery as an engine starting battery and I would only fly behind AGM. The > very thing that makes Lithium Ion so called great for propulsion batteries > is the same thing that makes them extremely dangerous. That benefit is low > resistance. Let me explain. > > In an AGM or any wet cell battery, when it goes bad it in 99.9999 % of the > time it creates an open within its cell banks. So, instead of having 12 VDC > you have 10 VDC or 8 VDC or 6 VDC. All fine. > > In a LIthium Ion cell that great low resistance will end up as a dead > short within the cell array. Now typically what will happen first is > probably what you are experiencing. The dead short is causing a logic > voltage ( VCC or TTL) where your logic voltage is typically 5 VDC which is > a portion of the 12 VDC of the battery by way of a voltage regulator > circuit of 12 VDC. Since a Lithium Ion battery has such a low resistance, > the effect will cause the 5 VDC VCC to vary to say 3.5 VDC. This will > cause very strange effects in the logic circuits and you end up with very > strange things happening. > > Now, the worst thing that happens is if you get enough Lithium Ion cells > that go bad and short to ground, you get heat and a fire. This is why > Chevrolet recalled all of its Bolt EV's and why when I was working the > industry I saw so many odd things happen with the logic of a system or so > many fried BMS 's or DC power systems. > > Don't get me started on the myth that there is so much new tech in Lithium > Ion. Bunk...it's the same as it was 40 years ago. The changes are in the > BMS systems. The pipe dream magic LIthium cells are far too expensive to > produce at a cost effective means. > > The battery in my EV had to be replaced at a cost of $ 32,000. Thankfully > it was under warranty. Its not under warranty anymore. Would you like to > buy a very well cared for EV? > > W. Jeff York > > > On Wed, Jun 12, 2024 at 9:13 AM mark jones via KRnet <krnet@list.krnet.org> > wrote: > >> Yesterday I was doing a taxi test and had the following happen more than >> once. This scares me enough that I am now very hesitant to use a Lipo with >> BMS. >> After about five minutes of taxi, my engine shut off as if the ignition >> switch had been shut off. There was absolutely no power at the ignition >> switch. The BMS took over and shut the system down. After about 10 minutes, >> The battery came back to life and she started right up. Only to again shut >> down after a few minutes of running. Why is this happening? Is it due to >> the Dynamo? Why wouldn't my engine keep running just off the Dynamo. Does >> the BMS somehow disable the entire system? I am feeling like Larry Flesner >> said. I think I too will only fly with AGM batteries. Seems this BMS in >> Lipo batteries is a source of failure we do not need. >> >> Mark Jones (N771MJ) >> Oldsmar, FL >> >> flyk...@gmail.com >> www.flykr2s.com >> -- >> KRnet mailing list >> KRnet@list.krnet.org >> https://list.krnet.org/mailman/listinfo/krnet >> > -- > KRnet mailing list > KRnet@list.krnet.org > https://list.krnet.org/mailman/listinfo/krnet >
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