Hello all,

   It's time for me to choose a battery for my UlPower 260. I am trying to choose between Acid battery or Lithium. What are you guys using for your planes? What brand of battery would you guys recommend. I am also thinking of using 2 batteries for redundancy. What are your thoughts on that?

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We've been using two EarthX 680C batteries for several years with our Viking 130 engine, and they're great.  One easily starts the engine, but have two for redundancy.  They're pricy, but worth it.  While our batteries are not TSO'd, EarthX recently came out with the first ever TSO'd batteries for certified aircraft.   

Satisfied with my dual EarthX batteries/single alternator setup on the UL350iS.  I went dual battery for the increased Amp-Hr capacity in the event of transfomer rectifier issue and less stress on the batteries for cold weather starts.  Mounted on engine side of  firewall and so far, temp strips show that peak heat does not exceed recommended battery temperature operating range. With a ULP engine I would ensure you have a robust electrical system with either dual battery/single alternator or dual alternator/single battery setup.

I concur with Loren and David.  I have two 20C(believe newer designation is 680) EarthX's mounted on the engine firewall side of my Viking 110 powered 750 and have had no issues since 2015.

David - I assume by "temperature strips" you mean the digital read out for the engine temps?  Wonder how that compares to the temps on the firewall in slow flight and while running the engine on the ground.

I've put a deposit on a UL 520T for my 750SD and plan on installing 2 ETX 900 batteries from EarthX on the firewall.  I'm concerned about heat at the firewall however, particularly in that this engine has a turbo. 

Ray at UL Power is designing the cowling as we speak but any comments and suggestions from the group would be appreciated.

Hey Bob, the temperature strips are simple indicators that indicate max heat achieved by changing color (chemical process I assume) through a stepped range of temperatures   They are placed on specific areas of interest and remain in place.  I keep one on the battery box nearest the engine and one on the dual fuel pump assembly.  So far thru 4 summers of flying and floating the temps have been below max recommended operating temp for the EarthX batteries. I would have concerns and would consider all mounting options with the turbo 

I also use the EarthX 680 batteries with my Viking 130 which were mounted firewall forward. After 2 years of use one of the batteries showed a fault and upon inspection the battery case had bulged. EarthX told me that was a sure sign of overheating. I bought new 680's and moved them behind the firewall.

Rather than installing two batteries I went with the next size up EarthX. Installed it on the cabin side of fire wall.

Also, replaced ULP (350i engine) regulator and wiring harness with a more robust version. 


Hi Glenn,

Just curious, were your batteries originally mounted on top of the firewall horizontal stiffener?

Would it be feasible to route a blast tube of cold air from the nose, rather than moving the batteries behind the firewall?

Note: I'm planning to install a Viking in my 601 kit, and was planning to mount the dual batteries firewall forward for easy wiring & access.



Hi Roy,

I agree that the best place for batteries in the 601/650 are FFW. I put my batteries below the stiffener and I think the mistake I made was I installed one battery against the firewall and mounted the other battery next to it horizontally placing it closer to the engine if that explanation makes any sense. I put temp. sensors on the battery during flight testing and the readings were within specs. 

The batteries lasted nearly 200 hrs. and the one that failed was closest to the engine. The other battery installed directly to the firewall is in great shape.  Earthex advised I replace both batteries so I found a non-aviation use for it.

Several people have had good luck installing batteries FFW.


On another note , If you are not installing LiPo batteries be conscious of your W&B if installing anything heavier.

Good luck!


Hi Glenn,

Thank you very much for the explanation and the suggestion! From preliminary W&B calculations (with data from 601's built by others), I may need to compensate for Odyssey battery weight with a couple pounds of ballast at the tail. With any 230 lb engine, the old standard 16 gal header tank would add too much weight on the nose for my liking, so I'm installing just wing tanks (about 22 gal).

Tail ballast is not an ideal solution, but it will compensate for heavy batteries. And those LiPo batteries are so very expensive....



As I indicated earlier, I mounted my EarthX's side by side and below the stiffener R side and they have performed very well since 2015 for my Viking 110 powered 750.

Good luck, Norm

Hi Adam,

Not flying yet, but installed EarthX battery behind passengers seat, photos on my page this site. Look forward to hearing you are in the air.



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