My apologies if seeking battery advice is straying too far from Rotax topics.

My last Rotax powered aircraft was started by a lead acid motorcycle battery - in 10 years I only purchased two batteries, one within weeks of taking ownership and second about 8 years later - so great performance/reliability, at a good price and most importantly, I understood the technology.

I had a discreetly mounted Anderson Plug wired directly to the battery. The wiring was of sufficient capacity that I could, if the battery went flat (never happened), jump start from a charged battery. I could also use this outlet to power a 12V refueling pump, which I used before every flight and occasionally on trips away. It also made the occasional maintenance charging of the battery a very simple task. 

My new Rotax powered aircraft has come with an Earth X ETX 900 battery (& dedicated chargers to suit). Not much smaller than my old lead acid, it weighs, by comparison, almost nothing. I have fitted the battery with a similar Anderson Plug to my old set up, with the intention of using it in the same way.

In my ignorance of the Earth X (lithium) technology I am concerned by two things;

1. Can I jump start the Earth X  from (a) a lead acid battery (b) or must I use something like the Earth X ETX-JMP12/24 jump pack?

2. Can I use the Earth X  to power my refueling pump (at home can use car/motor bike battery) without flattening (below cranking power) the battery? I am unlikely to pump much more than 20L x 2 at a single top up - this is approximately 8-12 minutes run time.

 Note; I have perused the Earth X web site & spoken to the Australian distributer - I find the advise for 1. to be ambiguous & for 2.evasive

  • Re: Earth X

    by » 9 months ago

    Hi Sean, Bert here - I fly a VW powered Fokker DVII and Zenith STOL 750 with rotax engine, BOTH with Earth X for years.  I initially saw your email and honestly thought this is NOT the place to ask these specific Earth X questions, because this is a Rotax site, and you'd be better served at an Earth X site.  Oh, I've also been to two Earth X forums at Sun N Fun and Oshkosh - but that doesn't mean much of course.  

    I thought, why doesn't he just ask the Earth X folks out west, they've always been awesome for me!  Then I saw you were in Australia and that changed me up.  In the Earth X docs, they say do NOT jump start their lithium battery from a car or other lead acid thing - and to use their jump pack.  But at Oshkosh, the rep said the only way he would is if were stuck out in the boonies with no other option, and while not preferable, could start it so he'd get home.

    As to refueling, your battery has so much cranking power and amps I would see no problem with it powering a refueling pump as well.  But who am I to tell you what to do with an Earth X battery - just another pilot.  But if you operated that pump 100 times without recharging or flying the battery, it could lose some power.  I would call the American folks, NOT Australian if you're having that problem.  DOWNLOAD THEIR MANUALS if you haven't because it partially answers that.  The have ALWAYS been helpful and responsive to me, PLUS, they have lots of youtube vids on their site.  I don't know what an Anderson plug is, but I would NOT change any lithium battery connections away from what they come as.


    Thank you said by: Sean Griffin

  • Re: Earth X

    by » 9 months ago

    I have the same Battery ETX 900 and agree with Berts comments

    Refueling no problems it is just a few amps....and I have done that I have a "cigarette" lighter powered pump about 5 amps, often pump 60 l or so and does not seem to discharge the E

    Jump starting will only be occasionally in an emergency so no problems...

    I often fly with a group and one of us carries an automotive Li based jump pack, weighs very little and works well, bought from Repco


    Earth X has an internal BMS so it should not go so flat that jumping is a problem

    So far in 5 years never needed to charge the battery at all

    I also added an Anderson connector for convenience..


    Thank you said by: Sean Griffin

  • Re: Earth X

    by » 9 months ago

    Hi Glen,

    When it comes to Lithium technology I am way behind the eight ball - 

    Ref; Earth X ETX-JMP 12/24 Jump Pack

    From  Earth X's web site ; " This jump pack uses the technology of lithium iron phosphate (LiFePo4) chemistry, not Lithium Cobalt (LiCoO2)!"

    The suggestion seems to be that other technologies (LiCo02) may not compatible with their Earth X batteries.

    There are four Repco/Powerall (currently on special) offerings - which would you suggest?


  • Re: Earth X

    by » 9 months ago

    Hi Sean,

       the chemistry is not "incompatible" a battery being charged just sees Amps and Volts.

    Why people are now "loving" LFP vs Cobalt based chemistries is because...

    Firstly LFP is a "safer" chemistry less likely to fail and if it does only a little smoke no great fire. Having said that a well designed Li-Mn-Co battery is very safe you probably have one in your Pocket (cell phone).

    Secondly some Cobalt is mined in the Congo and can use child labour ! and unsafe practices.

    from an Engineers point of view LFP is naturally a closer voltage match to old Lead acid 12V batteries.

    The Jump pack chemistry I do not know what it is... and really it does not matter it is designed to work with a "nominal 12V battery" and the Earth X is designed as a "nominal 12 V Battery" ...

    When you "jump" a battery to start, most of the power of course goes to the Starter and Engine electronics. The Batteries natural internal resistance, and the batteries BMS if it has one prevents an inrush of current causing problems. Once the engine starts and you disconnect the Jump then the alternator will quickly recharge the battery, again, controlled by the BMS or natural internal resistance.

    Lead acid batteries can take quite a while (20 min) because of surface charging effects. LFP which almost all "12V" replacement batteries are are much quicker.  I have seen after I have been playing around with the electrics on the ground and the Earth X is getting drained, up to 35 Amps charge rate, about the limit of my alternator, but after a few seconds this drops back dramatically and by the time I have finished taxying the battery is fully topped up and getting less that 1 amp.

    With Lead acid as I say can take 20 min, so need to go for a fly....good excuse to aviate...


    Thank you said by: Sean Griffin

  • Re: Earth X

    by » 8 months ago

    Glen -

    Quite a few people have advised doing a maintenance charge between flights. Not sure, but this may be to minimise the load on the charging circuit (you referred to above), on initial engine start.

    Do you agree with this advise?

    Can I use the jump pack to perform any sort of recharge or maintenance charge, in leu of the dedicated mains charger? (my aircraft will be parked well away from a mains supply)

    Could I use the jump pack to power my refuelling pump?

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