I'm using the Odyssey AGM Extreme Battery PC310 on my 912UL. This is my second one, the first one lasted 16 years and 820 airframe hours. I would definitely recommend the brand.

Mine only has a CCA of 100, so the one that you've suggested should be more than adequate. Just make sure that it fits in your battery box and that you have suitable terminals on your connection cables. Are you aware that is is 4.5kg? Mine is only 2.7kg and that seems quite high.

I know that there are a number of lithium-based batteries now that will be much lighter. I see that one capable of over 300 CCA only weighs about 1.1kg.

https://varleyredtop.com/project/varley-lithium-li-5-12v-5-5ah-battery/

Thank you for the info.  Yes, I am aware of the weight of 4.5kg.  But, the Duracell Deep Cycle that was in the plane when I purchased is 5.89kg. 

I looked at the lithium-based batteries but decided to go with the Odyssey after I looked at several batteries.  The hardware comes with this Odyssey and from what I see on the Odyssey the terminals will work with my connection cables.  It is an inch shorter in length and 

Thanks again! 

The battery debate always grabs my attention:

In Australia;

If you are replacing a battery in a certified/factory built aircraft you are bound by the manufacturers recommendations. Some manufacturers may have several options.

On the other hand, if the aircraft is a homebuilt (scratch/kit/plans or modified factory) it is considered experimental and you may fit whatever battery you deem appropriate.

The experimental designator makes choosing a suitable battery, wide open to whatever the market may offer, including automotive batteries.

My last 912ULS powered aircraft used an "SSB PowerSport" AGM battery, PN VB16L-B, CCA 385, AH 19, Weight 6.5 kg - this is a motorcycle battery, which is a fraction of the cost of an aircraft battery. It performed very well in this application and I only replaced it once in 10 years of use (900 hrs).

My new 912ULS aircraft uses an "EarthX" Model ETX900 - CCA 400, AH 15.6, Weight: 2.2kg. About X5 times the cost of the above battery, plus the cost of special charger. Only done 50 hrs, so can't comment, other than to say it spins the engine very vigorously for a good start.

Here in the UK, the two governing bodies for most 912-powered aircraft have approved the use of a number of lithium batteries. Whilst you can get a cheap motorcycle battery they tend to be heavy and if weight is a concern there are alternatives like the Odyssey AGM and various lithium batteries.

A list of batteries approved by the LAA can be found here.

A list of batteries approved by the BMAA can be found here.

I don't understand why they sell special chargers for lithium batteries when they are effectively charged from the aircraft's constant voltage 'alternator'. All lithium batteries should contain internal protection circuitry to prevent over-charging or over-discharging.

Because my aircraft operates very close to the maximum empty weight limits for its category I am likely to fit a lithium battery next time I need to change it.

Hi Kevin,

"Whilst you can get a cheap motorcycle battery they tend to be heavy"

There is nothing "cheap" about a good motorcycle battery except the price, as compared with so called aviation batteries

As for weight - comparing batteries of the same dimension, the current range of motorcycle batteries are very competitive and often deliver more energy (CCA & Ah) than the equivalent size aviation models.

No lead acid can compare with the weight of lithium types, however if the ultra light lithium does not suit your purpose or purse, the motorcycle battery is ready & waiting in the wings ?(just do your research before diving in, the lowest cost may not be the best bang for the buck).