Cub Battery voltage drop

With this setup - O-320 (160hp), Sky Tec 122HT starter, and an under seat powersonic 12180 gel cell what sort of voltage drop would be considered normal with the starter engaged? I have been having intermittent problems with the starter not fully engaging the flywheel. Some other info:
1000 rpm voltage - 13.95 taken at battery
starter engaged voltage at battery - 8.9 volts
Static battery voltage - 12.5 volts
No large (less than .5 volt) drops between battery and starter
My guess is that the battery is dying (5 years old) but thought I would see what others thought.
Thanks
Scott

I had the same set up except I had a standard 35 battery and similar voltages! I tryed everything including hooking the battery straight to the starter to see what happened? The conclusion is that piece of junk Skytec starter (cheap windings and gets to hot next to the exhaust! I dumped it and put a BC unit on it and with the same battery It spins the motor over like twice as fast! Trust me the BC unit is worth the money! Bill is the greatest to work with to and he will ship to you direct and even give an IA a little discount to boot!

Good Luck,

Tim

Voltage drops don't sound that out of whack?

So I replaced the battery and all seems fine now. New battery really does crank things over much faster. I looked through the logs and the old battery was 6-7 years old. Jane at Stoddards seemed suprised I hadn't had problems before now with the Powersonic unit.

Not bad life from a battery in cold weather! Much cheaper than a new starter. (might suggest covering the "hole" in the nosebowl that is only necessary if you have the "long starter".

Tim