Need Help with EarthX battery size

I am running a 0320 with 10:1 pistons. My current battery is an RG 35 ACX Concord. My questions are. what EarthX battery will crank the engine as fast or faster than my current battery, EXT 680, EXT 900 or the EXT 1200.

Also, can anyone share stories about the engine they run and the EarthX battery they are using?

Earthx

I have the ETX900 in my Rv-10. Battery in the back 12’ #2 copper cable, Barrett Io540 with 9:1 pistons. Turns it with no issues...

Any of those will spin your engine faster because they have minimal voltage drop when starting. I have the EXT900 on a high compression 360 with a lightweight prop. It cranks over much better than the PC680 ever did.

ETX680C

I have the ETX680C on a 8.5:1 io-360. Works great. Very small and light. On the firewall using their mounting bracket.

As requested by OP --
Lycoming YIO-360-A1B6, 8.7:1 pistons, Dual LS Plasma III Ignition, Hartzell -7497-2 Prop, and almost very electronic goody that Garmin has

ANY of the ETX series batteries will crank the engine faster because of the difference in resting voltage between chemistries -- the ETX is ~13.2V and the PC680 is ~12.8V.

The ETX900 has more Ah capacity than the ETX680. So, in the case of my electrically dependent RV-7, I decided to upgrade to the ETX900. The thinking is that if (when?) the PP Alternator gives up, the battery will keep the aircraft systems alive for longer.

Cheers...

I had a RV6 with a IO360 and 10-1 pistons. The 680 spun it much faster than the prior battery. Felt like I could taxi with it!
G

Another issue to consider is the capacity of the battery to run your equipment with an alternator failure. You need to compare the true reserve capacity of the different models. Be carefull, as some lithium makers use a misleading AH rating.

Larry

I put an EXT 900 VNT in my RV-8 with high-compression Barrett Performance IO-360 in place of my Concorde behind the back baggage area where the original one had been. Works great. I got the vented version since I installed it aft of the firewall. I put a thread here on VAF with photos of this install about a year ago.

I helped put an EXT 680 on the engine-side of the firewall in a friends' RV-8 with a Superior standard-compression IO-360. Works great.

Both are kept on and advanced Optimate LiFePO4 Lithium battery chargers when parked in their hangars. At the suggestion of EarthX.

In then end I like the idea of the larger capacity EXT 900 when it has longer battery cable runs from the front to the rear of the aircraft. Not sure if extra capacity rating helps with higher-compressions or not but that might be the case. The EXT 680 works great on the firewall where battery cable runs are much shorter. I probably would have initially gone that way for my aft mounted battery location if there was a vented version of the 680.

Thanks for the info.

After reading the posts I think I am going with the 900 series EarthX. That will give me some life with radios and electronic ignition for about 1.2 hours if I lost the alternator. Thanks again guys.

Match the Alternator

Phil,
Hang on a second. For EarthX LiFePO batteries, you must select a battery that matches your alternator output. For example, for a 60 amp alternator, you must use the ETX680. If you have a 70 amp or greater, you move up to the ETX900.

I recommend you call Kathy at EarthX and discuss. She can explain it, and help you possibly avoid a battery mismatch.

Hmm...

I have a 60 amp and a 40 amp alternator with two EarthX ETX900s...

The ETX900 has a MAXIMUM charge rating of 80 AMPS...so a 60 amp alternator will indeed be below the maximum, as will the 40 amp alternator...