About lithium ion battery last SIC-PAC Document

These Rotax branded batteries in the service instruction contain an internal BMS (Battery Management System) that allows a ‘drop in’ replacement of an existing lead acid chemistry battery and charger and interface it with the Lithium Ion cells. Hence the fault monitoring circuit to show an issue identified by the BMS.

Note section 3.2.7 indicates they are compatible with “most” lead acid chargers, i suspect the Ducati regulator/rectifier in the 912 is compatible, however be nice to 100% confirm this.

Drop in replacement Lithium Ion cell compatible with all the existing electrical system has a lot of appeal, especially the weight and cranking capacity improvements.

Alejandro, there is no concern with the Silent Hektik regulator.  Quoting from the product page that you linked:

"The Silent Hektik smart IUU battery charging management for LiFePo4 batteries The F4126 charge controller can be used for both previous lead batteries and especially for modern LiFePo4 batteries thanks to the smart IUU characteristic."

These new Rotax batteries are very obviously re-labeled EarthX ETX-680s and ETX-900s.  They use LiFePO4 (Lithium Iron Phosphate) cells, not Lithium-ion.  According to the Silent Hektik text above, their regulator is programmed to accommodate LiFePO4-based batteries.

Further quoting from the Silent Hektik page:

"The LiFePo4 batteries have the advantage of delivering a very high starting current despite their small dimensions and low weight.  However, this low battery impedance has a major disadvantage when charging. After starting, the battery is empty and over 20A of current can flow. The LiFePo4 battery becomes very hot due to the excessive current, has difficulty dissipating heat and damage can occur."

It's completely absurd to say that "after starting the battery is empty."  A typical engine start uses a tiny fraction of the energy contained in a properly maintained battery, and replacing the starting energy takes just a few minutes.  The charging current limits on the Rotax/EarthX batteries are 60A for the -680 and 80A for the -900.  The output current limit for the Silent Hektik regulator is 30A, so it cannot damage either battery.

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All of that said, my first reaction after reading this SI PAC is that it must be an IQ test for operators of Rotax 9-series engines.  Why would anyone pay Rotax pricing for a re-labeled EarthX battery?  Just buy it from EarthX.  You'll get a fresher battery that hasn't been shipped twice across the globe and you'll have access to OEM warranty support.

Hi Eric

Consider this.  Not everyone lives in the USA and has easy access to EarthX.  Rotax took on the project to find a good supplier and offer them via the network to reduce the many issues they saw with the introduction of the injected engines.  At that time may builders and OEM were starting to use the new battery technologies and with mixed results.  I personally saw some Tecnam aircraft fail early version Lithium systems when they released them on the Tecnam 912iS installations.  This was what precipitated the call out for cell balancing and the search for  good unit they could provide as a branded alternative for users.  

just my opinion.

Cheers

Fair point, RW, but I strongly suspect that ordering from the EarthX website and paying international shipping and customs duties will still be cheaper than a Rotax-branded battery from a Rotax authorized parts supplier.  For the sake of non-U.S. and non-European operators I hope that I'm wrong, but given Rotax's pricing on other re-branded items (e.g. the infamous $70 USB-to-serial adapter that Rotax turns into a $2,300 B.U.D.S. dongle), I'll be very surprised if I am.

For European operators, EarthX batteries are available from Aircraft Spruce's Eschbach, Germany warehouse, so for the vast majority of Rotax's worldwide market, an OEM EarthX battery is readily available.

Sorry, I'm not trying to start an argument and I don't want to sound like I'm unloading on you personally -- truly, I'm not! -- but the way Rotax prices some of their items is really egregious.  It's especially galling when, like in the case of the stator-to-regulator connector debacle, the factory used a completely inappropriate Deutsch connector, then profited handsomely from their own error by selling an over-specified replacement connector at a 5x mark-up (which, incidentally, required uncommon and expensive tooling to install).

I wonder if Rotax has any idea of the level of discontent over these issues among operators of their engines?  Do they care?  I haven't even flown my engine yet and I already regret spending >$28,000 for it.  It would have been nice to know up front that (a) I would have to spend nearly $400 (plus tooling) to fix a serious factory wiring error --- which in any other industry would be a warranty repair -- and, (b) that I would have to spend almost 10% of the cost of the engine for an adapter cable just to properly conduct condition inspections.

And no, I'm not interested in taking the airplane to a certified Rotax mechanic for B.U.D.S. downloads.  One of my primary motivations for building an Experimental aircraft was to avoid high maintenance costs by doing the majority of the maintenance and inspection work myself.  So yeah, I'll eventually grit my teeth and buy a B.U.D.S. dongle (if I can find a distributor who actually has one in stock), but I won't be happy about it.

Rant over.  I sincerely hope that I haven't offended, and my apologies to Alejandro for hijacking the thread.

Well, at least I now know that the EarthX EXT900 that I have been running in my 912is aircraft for the last six years is now Rotax approved! I believe they made a good choice here and I hope they offer them to their customers at a similar price to the EarthX battery. If their motivation is to offer a degree of standardization around a LiFe battery that Rotax will stand behind, then it’s a good thing. If the motivation is other than that, this will become obvious also.  

Now to continue the hijacking…

I do agree with Eric that it’s hard to understand some of the decisions Rotax makes, and unfortunately this forces you to question the company’s culture.  As Eric points out, the original “regulator B” connector for the iS engine was obviously not up to the task, and probably should have been a mandatory upgrade and fully compensated.  And then to charge that much for the upgraded connector just added insult to injury, and moreover it suggests that they were ambivalent to this engineering failure. And of course, this is not the only example. I believe Rotax makes a great product overall, but a good company can only be a great company if it stands behind its failures.