861 battery

[Ed in Northern VA]

I'll reveal my ignorance. I'm working with my new-to-me 861. Its been converted to 12v.
What voltage should be showing when I measure my battery across the terminals with a VOM? I just took it off the charger and it showed 10v- not good.
What would be the appropriate replacement battery? ie what CCA rating?
I was considering going to an Optima or similiar battery as the tractor will sit for weeks( maybe months) at time. Any thoughts on the Optima?

 

[old]

A good/new battery should read around 12-13 volts. Less then that its bad. As far as CCA just as big as you can find that will fit in the box. I have used as small as 500CCA up to 800CCA in my 841 over the years. I my self like as big as I can get in the CCA that will fit in to it
Hobby farm

 

[john_Bud]

A new battery will read about 13.2-13.5v with full charge. With the alternator running, it will read 14.2-14.5v.

A reading of 10v shows the battery has 1 dead cell. That's normally a non-recoverable failure.

I like to get the largest battery that will fit. Measure the space and see.

Optima batteries (and the duplicates from Napa) are excellent. A bit more $, but will last longer and don't leak. A double plus in my book!

One thing to check. Do a voltage reading with the engine running about 1200 rpm. You should see 12-13 even with a bad battery. If you don't see that voltage, the voltage regulator or the alternator (or the wiring of it!!!) may be goofy and it is not charging.

Try this too, rev the engine up to 2000 rpms for about 15 seconds and recheck. If it pops up to 12-13 after that, it's probably an alternator that should be wired up with 2 more wires.

Search for the instructions here.

jb